Joost L M Van Haren

Interests

Research

- biogeochemistry as related to the cycles of carbon and nitrogen- interaction between plants, microbes, soils and the atmosphere- carbon, nitrogen, and water cycling in tropical ecosystems

Teaching

- Teach students about environmental impacts through activity and field trip based classes- Teach students environmental measurement techniques through hands on, experience based classes in field settings

Courses

Scholarly Contributions

Chapters

• Sengupta, A., Pangle, L., Volkmann, T., Dontsova, K. M., Troch, P. A., Meira, A. A., Neilson, J. W., Hunt, E., Chorover, J. D., Zeng, X., Van Haren, J. L., Barron-Gafford, G. A., Bugaj, A., Abramson, N., Sibayan, M., & Huxman, T. E. (2016). Advancing understanding of hydrological and biogeochemical interactions in evolving landscapes through controlled experimentation and monitoring at the Landscape Evolution Observatory. In Terrestrial Ecosystem Research Infrastructures: Challenges, New developments and Perspectives. CRC Press.
• Sengupta, A., Pangle, L., Volkmann, T., Dontsova, K. M., Troch, P. A., Meira, A. A., Neilson, J. W., Hunt, E., Chorover, J. D., Zeng, X., Van Haren, J. L., Barron-Gafford, G. A., Bugaj, A., Abramson, N., Sibayan, M., & Huxman, T. E. (2017). Advancing understanding of hydrological and biogeochemical interactions in evolving landscapes through controlled experimentation and monitoring at the Landscape Evolution Observatory. In Terrestrial Ecosystem Research Infrastructures: Challenges, New Developments and Perspectives(pp 83-118). CRC Press.
• Van Haren, J. L. (2016). Advancing understanding of hydrological and biogeochemical interactions in evolving landscapes through controlled experimentation and monitoring at the Landscape Evolution Observatory. In Terrestrial Research Ecosystems. Elsevier.
• Volkmann, T. H., Sengupta, A., Pangle, L. A., Dontsova, K. M., Barron-Gafford, G. A., Harman, C. J., Niu, G., Meredith, L., Abramson, N., Alves Meira Neto, A., Wang, Y., Adams, J. R., Breshears, D. D., Bugaj, A., Chorover, J. D., Cueva, A., DeLong, S. B., Durcik, M., Ferre, P. A., , Huxman, T. E., et al. (2017). Controlled Experiments of Hillslope Coevolution at the Biosphere 2 Landscape Evolution Observatory: Toward Prediction of Coupled Hydrological, Biogeochemical, and Ecological Changes. In Hydrology of Artificial and Controlled Experiments. Rijeka, Croatia: IN TECH d.o.o.

Journals/Publications

• Huang, J., Ladd, S. N., Ingrisch, J., Kübert, A., Meredith, L. K., van Haren, J., Bamberger, I., Daber, L. E., Kühnhammer, K., Bailey, K., Hu, J., Fudyma, J., Shi, L., Dippold, M. A., Meeran, K., Miller, L., O'Brien, M. J., Yang, H., Herrera-Ramírez, D., , Hartmann, H., et al. (2024). The mobilization and transport of newly-fixed carbon are driven by plant water-use in an experimental rainforest under drought. Journal of experimental botany.
  More info

  Nonstructural carbohydrates (NSCs) are building blocks for biomass and fuel metabolic processes. However, it remains unclear how tropical forests mobilize, export and transport NSCs to cope with extreme droughts. We combined drought manipulation and ecosystem 13CO2 pulse-labeling in an enclosed rainforest at Biosphere 2, assessed changes in NSCs and traced newly-assimilated carbohydrates in plant species with diverse hydraulic traits and canopy positions. We show that drought caused a depletion of leaf starch reserves and slowed export and transport of newly-assimilated carbohydrates belowground. Drought effects were more pronounced in conservative canopy trees with limited supply of new photosynthates and relatively constant water-status than those with continual photosynthetic supply and deteriorated water-status. We provide experimental evidence that local utilization, export and transport of newly-assimilated carbon are closely coupled with plant water-use in canopy trees. We highlight that these processes are critical for understanding and predicting tree resistance and ecosystem fluxes in tropical forest under drought.
• Kübert, A., Dubbert, M., Bamberger, I., Kühnhammer, K., Beyer, M., van Haren, J., Bailey, K., Hu, J., Meredith, L. K., Nemiah Ladd, S., & Werner, C. (2023). Tracing plant source water dynamics during drought by continuous transpiration measurements: An in-situ stable isotope approach. Plant, cell & environment, 46(1), 133-149.
  More info

  The isotopic composition of xylem water (δ ) is of considerable interest for plant source water studies. In-situ monitored isotopic composition of transpired water (δ ) could provide a nondestructive proxy for δ -values. Using flow-through leaf chambers, we monitored 2-hourly δ -dynamics in two tropical plant species, one canopy-forming tree and one understory herbaceous species. In an enclosed rainforest (Biosphere 2), we observed δ -dynamics in response to an experimental severe drought, followed by a H deep-water pulse applied belowground before starting regular rain. We also sampled branches to obtain δ -values from cryogenic vacuum extraction (CVE). Daily flux-weighted δ O -values were a good proxy for δ O -values under well-watered and drought conditions that matched the rainforest's water source. Transpiration-derived δ O -values were mostly lower than CVE-derived values. Transpiration-derived δ H -values were relatively high compared to source water and consistently higher than CVE-derived values during drought. Tracing the H deep-water pulse in real-time showed distinct water uptake and transport responses: a fast and strong contribution of deep water to canopy tree transpiration contrasting with a slow and limited contribution to understory species transpiration. Thus, the in-situ transpiration method is a promising tool to capture rapid dynamics in plant water uptake and use by both woody and nonwoody species.
• Kühnhammer, K., van Haren, J., Kübert, A., Bailey, K., Dubbert, M., Hu, J., Ladd, S. N., Meredith, L. K., Werner, C., & Beyer, M. (2023). Deep roots mitigate drought impacts on tropical trees despite limited quantitative contribution to transpiration. The Science of the total environment, 893, 164763.
  More info

  Deep rooting is considered a central drought-mitigation trait with vast impact on ecosystem water cycling. Despite its importance, little is known about the overall quantitative water use via deep roots and dynamic shifts of water uptake depths with changing ambient conditions. Knowledge is especially sparse for tropical trees. Therefore, we conducted a drought, deep soil water labeling and re-wetting experiment at Biosphere 2 Tropical Rainforest. We used in situ methods to determine water stable isotope values in soil and tree water in high temporal resolution. Complemented by soil and stem water content and sap flow measurements we determined percentages and quantities of deep-water in total root water uptake dynamics of different tree species. All canopy trees had access to deep-water (max. uptake depth 3.3 m), with contributions to transpiration ranging between 21 % and 90 % during drought, when surface soil water availability was limited. Our results suggest that deep soil is an essential water source for tropical trees that delays potentially detrimental drops in plant water potentials and stem water content when surface soil water is limited and could hence mitigate the impacts of increasing drought occurrence and intensity as a consequence of climate change. Quantitatively, however, the amount of deep-water uptake was low due to the trees' reduction of sap flow during drought. Total water uptake largely followed surface soil water availability and trees switched back their uptake depth dynamically, from deep to shallow soils, following rainfall. Total transpiration fluxes were hence largely driven by precipitation input.
• Ladd, S. N., Daber, L. E., Bamberger, I., Kübert, A., Kreuzwieser, J., Purser, G., Ingrisch, J., Deleeuw, J., van Haren, J., Meredith, L. K., & Werner, C. (2023). Leaf-level metabolic changes in response to drought affect daytime CO2 emission and isoprenoid synthesis pathways. Tree physiology, 43(11), 1917-1932.
  More info

  In the near future, climate change will cause enhanced frequency and/or severity of droughts in terrestrial ecosystems, including tropical forests. Drought responses by tropical trees may affect their carbon use, including production of volatile organic compounds (VOCs), with implications for carbon cycling and atmospheric chemistry that are challenging to predict. It remains unclear how metabolic adjustments by mature tropical trees in response to drought will affect their carbon fluxes associated with daytime CO2 production and VOC emission. To address this gap, we used position-specific 13C-pyruvate labeling to investigate leaf CO2 and VOC fluxes from four tropical species before and during a controlled drought in the enclosed rainforest of Biosphere 2 (B2). Overall, plants that were more drought-sensitive had greater reductions in daytime CO2 production. Although daytime CO2 production was always dominated by non-mitochondrial processes, the relative contribution of CO2 from the tricarboxylic acid cycle tended to increase under drought. A notable exception was the legume tree Clitoria fairchildiana R.A. Howard, which had less anabolic CO2 production than the other species even under pre-drought conditions, perhaps due to more efficient refixation of CO2 and anaplerotic use for amino acid synthesis. The C. fairchildiana was also the only species to allocate detectable amounts of 13C label to VOCs and was a major source of VOCs in B2. In C. fairchildiana leaves, our data indicate that intermediates from the mevalonic acid (MVA) pathway are used to produce the volatile monoterpene trans-β-ocimene, but not isoprene. This apparent crosstalk between the MVA and methylerythritol phosphate pathways for monoterpene synthesis declined with drought. Finally, although trans-β-ocimene emissions increased under drought, it was increasingly sourced from stored intermediates and not de novo synthesis. Unique metabolic responses of legumes may play a disproportionate role in the overall changes in daytime CO2 and VOC fluxes in tropical forests experiencing drought.
• Pugliese, G., Ingrisch, J., Meredith, L. K., Pfannerstill, E. Y., Klüpfel, T., Meeran, K., Byron, J., Purser, G., Gil-Loaiza, J., van Haren, J., Dontsova, K., Kreuzwieser, J., Ladd, S. N., Werner, C., & Williams, J. (2023). Effects of drought and recovery on soil volatile organic compound fluxes in an experimental rainforest. Nature communications, 14(1), 5064.
  More info

  Drought can affect the capacity of soils to emit and consume biogenic volatile organic compounds (VOCs). Here we show the impact of prolonged drought followed by rewetting and recovery on soil VOC fluxes in an experimental rainforest. Under wet conditions the rainforest soil acts as a net VOC sink, in particular for isoprenoids, carbonyls and alcohols. The sink capacity progressively decreases during drought, and at soil moistures below ~19%, the soil becomes a source of several VOCs. Position specific C-pyruvate labeling experiments reveal that soil microbes are responsible for the emissions and that the VOC production is higher during drought. Soil rewetting induces a rapid and short abiotic emission peak of carbonyl compounds, and a slow and long biotic emission peak of sulfur-containing compounds. Results show that, the extended drought periods predicted for tropical rainforest regions will strongly affect soil VOC fluxes thereby impacting atmospheric chemistry and climate.
• Smith, M., Stark, S., Taylor, T., Schietti, J., Almeida, D., Torralvo, K., Lima, A., de Oliveira, G., de Assis, R., Leitold, V., Pontes-Lopes, A., Scoles, R., de Sousa Vieira, L., Resende, A., Coppola, A., de Athaydes Silva Junior, J., Lobato, L., Freitas, W., Souza, M., , Minor, D., et al. (2023). Diverse anthropogenic disturbances shift Amazon forests along a structural spectrum. Frontiers in Ecology and the Environment, 21(1). doi:10.1002/fee.2590
  More info

  Amazon forests are being degraded by myriad anthropogenic disturbances, altering ecosystem and climate function. We analyzed the effects of a range of land-use and climate-change disturbances on fine-scale canopy structure using a large database of profiling canopy lidar collected from disturbed and mature Amazon forest plots. At most of the disturbed sites, surveys were conducted 10–30 years after disturbance, with many exhibiting signs of recovery. Structural impacts differed in magnitude more than in character among disturbance types, producing a gradient of impacts. Structural changes were highly coordinated in a manner consistent across disturbance types, indicating commonalities in regeneration pathways. At the most severely affected site – burned igapó (seasonally flooded forest) – no signs of canopy regeneration were observed, indicating a sustained alteration of microclimates and consequently greater vulnerability to transitioning to a more open-canopy, savanna-like state. Notably, disturbances rarely shifted forests beyond the natural background of structural variation within mature plots, highlighting the similarities between anthropogenic and natural disturbance regimes, and indicating a degree of resilience among Amazon forests. Studying diverse disturbance types within an integrated analytical framework builds capacity to predict the risk of degradation-driven forest transitions.
• Byron, J., Kreuzwieser, J., Purser, G., van Haren, J., Ladd, S. N., Meredith, L. K., Werner, C., & Williams, J. (2022). Chiral monoterpenes reveal forest emission mechanisms and drought responses. Nature, 609(7926), 307-312.
  More info

  Monoterpenes (CH) are emitted in large quantities by vegetation to the atmosphere (>100 TgC year), where they readily react with hydroxyl radicals and ozone to form new particles and, hence, clouds, affecting the Earth's radiative budget and, thereby, climate change. Although most monoterpenes exist in two chiral mirror-image forms termed enantiomers, these (+) and (-) forms are rarely distinguished in measurement or modelling studies. Therefore, the individual formation pathways of monoterpene enantiomers in plants and their ecological functions are poorly understood. Here we present enantiomerically separated atmospheric monoterpene and isoprene data from an enclosed tropical rainforest ecosystem in the absence of ultraviolet light and atmospheric oxidation chemistry, during a four-month controlled drought and rewetting experiment. Surprisingly, the emitted enantiomers showed distinct diel emission peaks, which responded differently to progressive drying. Isotopic labelling established that vegetation emitted mainly de novo-synthesized (-)-α-pinene, whereas (+)-α-pinene was emitted from storage pools. As drought progressed, the source of (-)-α-pinene emissions shifted to storage pools, favouring cloud formation. Pre-drought mixing ratios of both α-pinene enantiomers correlated better with other monoterpenes than with each other, indicating different enzymatic controls. These results show that enantiomeric distribution is key to understanding the underlying processes driving monoterpene emissions from forest ecosystems and predicting atmospheric feedbacks in response to climate change.
• Buessecker, S., Zamora, Z., Sarno, A. F., Finn, D. R., Hoyt, A. M., Van Haren, J. L., Urquiza-Munoz, J. D., & Cadillo-Quiroz, H. (2021). Microbial communities and the putative interactions of methanogens with nitrogen oxides in diverse peatlands of the Amazon basin. Environmental Microbiology.
• Durrer, A., Margenot, A. J., Silva, L. C., Bohannan, B. J., Nusslein, K., Van Haren, J. L., Andreote, F. D., Parikh, S. J., & Rodrigues, J. L. (2021). Beyond total carbon: conversion of amazon forest to pasture alters indicators of soil C cycling. Biogeochemistry, 152, 179-194. doi:10.1007/s10533-020-00743-x
• Kroeger, M. E., Meredith, L. K., Meyer, K. M., Webster, K., de Camargo, P. B., de Souza, L. F., Tsai, S. M., Van Haren, J. L., Saleska, S. R., Bohannan, B. J., Rodrigues, J. L., Berenguer, E., Barlow, J., & Nusslein, K. (2021). Rainforest-to-pasture conversion stimulates soil methanogenesis across the Brazillian Amazon. ISMJ.
• Van Haren, J. L., Brewer, P. E., Kurtzberg, L., Wehr, R. N., Springer, V. L., Tello Espinoza, R., Solignac Ruiz, J., & Cadillo-Quiroz, H. (2021). A versatile gas flux chamber reveals high tree stem CH4 emissions in Amazonian peatland. Agricultural and Forest Meteorology, 307, 108504. doi:10.1016/j.agrformet.2021.108504
• Werner, C., Meredith, L. K., Ladd, S. N., Ingrisch, J., Kübert, A., van Haren, J., Bahn, M., Bailey, K., Bamberger, I., Beyer, M., Blomdahl, D., Byron, J., Daber, E., Deleeuw, J., Dippold, M. A., Fudyma, J., Gil-Loaiza, J., Honeker, L. K., Hu, J., , Huang, J., et al. (2021). Ecosystem fluxes during drought and recovery in an experimental forest. Science (New York, N.Y.), 374(6574), 1514-1518.
  More info

  Severe droughts endanger ecosystem functioning worldwide. We investigated how drought affects carbon and water fluxes as well as soil-plant-atmosphere interactions by tracing CO and deep water HO label pulses and volatile organic compounds (VOCs) in an enclosed experimental rainforest. Ecosystem dynamics were driven by different plant functional group responses to drought. Drought-sensitive canopy trees dominated total fluxes but also exhibited the strongest response to topsoil drying. Although all canopy-forming trees had access to deep water, these reserves were spared until late in the drought. Belowground carbon transport was slowed, yet allocation of fresh carbon to VOCs remained high. Atmospheric VOC composition reflected increasing stress responses and dynamic soil-plant-atmosphere interactions, potentially affecting atmospheric chemistry and climate feedbacks. These interactions and distinct functional group strategies thus modulate drought impacts and ecosystem susceptibility to climate change.
• Arevalo, J., Zeng, X., Durick, M., Sibayan, M., Pangle, L., Abramson, N., Bugaj, A., Ng, W., Barron-Gafford, G. A., Van Haren, J. L., Niu, G., Adams, J., Ruiz, J., & Troch, P. A. (2020). Highly Sampled Measurements in a Controlled Atmosphere at the Biosphere 2 Landscape Evolution Observatory. Scientific Data, 7, 306. doi:10.1038/s41597-020-00645-5
• Finn, D. R., Ziv-El, M., Van Haren, J. L., Park, J., del Aguila-Pasquel, J., Urquiza-Munoz, D., & Cadillo-Quiroz, H. (2020). Methanogen and methanotroph communities show nutrient-dependent patterns across tropical peatlands of the Pastaza-Marañón Basin, Peruvian Amazonia. Frontiers in Microbiology, 11, 746. doi:10.3389/fmicb.2020.00746
• Meyer, K. M., Morris, A. H., Webster, K., Klein, A. M., Kroeger, M. E., Meredith, L. K., Braendholt, A., Nakamura, F., Venturini, A., de Souza, L. F., Shek, K. L., Danielson, R., Van Haren, J. L., de Camargo, P. B., Tsai, S. M., Andreote, F. D., de Souza, J. M., Nusslein, K., Saleska, S., , Rodrigues, J. L., et al. (2020). Belowground changes to community structure alter methane-cycling dynamics in Amazonia. Environment international.
• Smith, M. N., Taylor, T. C., Van Haren, J. L., Rosolem, R., Restrepo-Coupe, N., Adams, J., Berry, J. A., Wu, J., de Oliveira, R. C., da Silva, R., de Araujo, A., Huxman, T., & Saleska, S. R. (2020). Evidence that tropical forest photosynthesis is not directly limited by high temperature. Nature Plants.
• Barba, J., Bradford, M. A., Brewer, P. E., Bruhn, D., Covey, K., van, H. J., Megonigal, J. P., Mikkelsen, T. N., Pangala, S. R., Pihlatie, M., Poulter, B., Rivas-Ubach, A., Schadt, C. W., Terazawa, K., Warner, D. L., Zhang, Z., & Vargas, R. (2019). Methane emissions from tree stems: a new frontier in the global carbon cycle. NEW PHYTOLOGIST, 222(1), 18-28.
• Cueva, A., Volkmann, T. H., Van Haren, J. L., Troch, P. A., & Meredith, L. (2019). Reconciling negative soil CO2 fluxes: insights from a large-scale experimental hillslope.. Soil Systems. doi:10.3390/soilsystems3010010
• Dusza, Y., Sanchez-Canete, E. P., Le Galliard, J., Ferriere, R. H., Chollet, S., Massol, F., Hansart, A., Juarez, S., Dontsova, K. M., Van Haren, J. L., Troch, P. A., Pavao-Zuckerman, M. A., Hamerlynck, E., & Barron-Gafford, G. A. (2019). Biotic soil-plant interaction processes explain most of hysteric soil CO2 efflux response to temperature in cross-factorial mesocosm experiment.. Scientific Reports.
• Evaristo, J., Kim, M., van, H. J., Pangle, L. A., Harman, C. J., Troch, P. A., & McDonnell, J. J. (2019). Characterizing the Fluxes and Age Distribution of Soil Water, Plant Water and Deep Percolation in a Model Tropical Ecosystem. WATER RESOURCES RESEARCH, 55(4), 3307-3327.
• Taylor, T. C., McMahon, S. M., Smith, M. N., Boyle, B., Violle, C., van, H. J., Simova, I., Meir, P., Ferreira, L. V., de, C., da, C., Enquist, B. J., & Saleska, S. R. (2018). Isoprene emission structures tropical tree biogeography and community assembly responses to climate. NEW PHYTOLOGIST, 220(2), 435-446.
• Sanchez-Canete, E. P., Scott, R. L., van, H. J., & Barron-Gafford, G. A. (2017). Improving the accuracy of the gradient method for determining soil carbon dioxide efflux. JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES, 122(1), 50-64.
• van Haren, J., Dontsova, K., Barron-Gafford, G. A., Troch, P. A., Chorover, J., Delong, S. B., Breshears, D. D., Huxman, T. E., Pelletier, J. D., Saleska, S. R., Zeng, X., & Ruiz, J. (2017). CO2 diffusion into pore spaces limits weathering rate of an experimental basalt landscape. GEOLOGY, 45(3), 203-206.
• Sagarin, R. D., Adams, J., Blanchette, C. A., Brusca, R. C., Chorover, J., Cole, J. E., Micheli, F., Munguia-Vega, A., Rochman, C. M., Bonine, K., van, H. J., & Troch, P. A. (2016). Between control and complexity: opportunities and challenges for marine mesocosms. FRONTIERS IN ECOLOGY AND THE ENVIRONMENT, 14(7), 389-396.
• Sagarin, R., Troch, P. A., Adams, J., Brusca, R., Blanchette, C., Chorover, J. D., Cole, J. E., Micheli, F., Munguia-Vega, A., Rochman, C., & Van Haren, J. L. (2016). Between Control and Complexity: Opportunities and Challenges for Marine Mesocosms. Frontiers in Ecology and the Environment, 14, 389-396.
• Troch, P. A., Maier, R. M., Chorover, J. D., Neilson, J. W., Root, R., Dontsova, K. M., Matos, K., Meira, A. A., Wang, Y., & Sengupta, A. (2016). Soil Lysimeter Excavation for Coupled Hydrological, Geochemical, and Microbiological Investigations. JoVE, e54536. doi:10.3791/54536
• Pangle, L. A., DeLong, S. B., Abramson, N., Adams, J., Barron-Gafford, G. A., Breshears, D. D., Brooks, P. D., Chorover, J., Dietrich, W. E., Dontsova, K., Durcik, M., Espeleta, J., Ferre, T., Ferriere, R., Henderson, W., Hunt, E. A., Huxman, T. E., Millar, D., Murphy, B., , Niu, G., et al. (2015). The Landscape Evolution Observatory: A large-scale controllable infrastructure to study coupled Earth-surface processes. GEOMORPHOLOGY, 244, 190-203.
• Van Haren, J. L. (2015). Chemical analysis of rainfall and throughfall in the Tapajos National Forest, Belterra, Para, Brazil. Ambiente & Água - An Interdisciplinary Journal of Applied Science.
• Jardine, K., Wegener, F., Abrell, L., Haren, J. V., & Werner, C. (2014). Phytogenic biosynthesis and emission of methyl acetate. Plant, Cell and Environment, 37(2), 414-424.
  More info

  Abstract: Acetylation of plant metabolites fundamentally changes their volatility, solubility and activity as semiochemicals. Here we present a new technique termed dynamic 13C-pulse chasing to track the fate of C1-3 carbon atoms of pyruvate into the biosynthesis and emission of methyl acetate (MA) and CO2. 13C-labelling of MA and CO2 branch emissions respond within minutes to changes in 13C-positionally labelled pyruvate solutions fed through the transpiration stream. Strong 13C-labelling of MA emissions occurred only under pyruvate-2-13C and pyruvate-2,3-13C feeding, but not pyruvate-1-13C feeding. In contrast, strong 13CO2 emissions were only observed under pyruvate-1-13C feeding. These results demonstrate that MA (and other volatile and non-volatile metabolites) derive from the C2,3 atoms of pyruvate while the C1 atom undergoes decarboxylation. The latter is a non-mitochondrial source of CO2 in the light generally not considered in studies of CO2 sources and sinks. Within a tropical rainforest mesocosm, we also observed atmospheric concentrations of MA up to 0.6 ppbv that tracked light and temperature conditions. Moreover, signals partially attributed to MA were observed in ambient air within and above a tropical rainforest in the Amazon. Our study highlights the potential importance of acetyl coenzyme A (CoA) biosynthesis as a source of acetate esters and CO2 to the atmosphere. In this study, we present a new technique termed dynamic 13C-pulse chasing to track the fate of C1-3 carbon atoms of pyruvate into the biosynthesis and emission of methyl acetate (MA) and CO2. Our results demonstrate that MA (and other volatile and non-volatile metabolites) derive from the C2,3 atoms of pyruvate while the C1 atom undergoes decarboxylation. The results highlight the potential importance of acetyl CoA biosynthesis as a source of acetate esters and CO2 to the atmosphere. © 2013 John Wiley & Sons Ltd.
• Jardine, K., Wegener, F., Abrell, L., van, H. J., & Werner, C. (2014). Phytogenic biosynthesis and emission of methyl acetate. PLANT CELL AND ENVIRONMENT, 37(2), 414-424.
• Haren, J. V., Cosme, R., Beldini, P. T., Barbosa, P., Keller, M., & Saleska, S. (2013). Tree species effects on soil properties and greenhouse gas fluxes in east-central amazonia: Comparison between monoculture and diverse forest. Biotropica, 45(6), 709-718.
  More info

  Abstract: Tropical plantations are considered a viable option to sequester carbon on abandoned agricultural lands, but implications of tree species selection for overall greenhouse gas budgets on plantations have been little studied. During three wet seasons, we investigated the influence of nine tree species on soil pH, temperature (ST), bulk density (BD), moisture content water filled pore space (WFPS), and greenhouse gas fluxes in diverse forest sites and monoculture plantation plots. All sites were on clay-rich soils of the Barreiras formation, in east-central Amazônia, Brazil. We found that ST and BD were 0.6°C and 0.2 g/cm3 higher in the plantation relative to the forest, and soil CH4, CO,2 and N2O fluxes were, respectively, 38, 12, 62, percent lower in the plantation. Tree growth rates were highly variable on the plantation, with the mean comparable to the forest sites. Tree species identity mattered (P < 0.01) for all soil properties and gas fluxes on the plantation, but only for pH, BD, WFPS, and N2O fluxes in the forest. The species rank order of pH and N2O fluxes in the forest, however, were unlike the plantation. Tree growth rates were a strong predictor for soil WFPS, and together with location, they also explained 75 percent of the mean N2O flux variation. Our study indicates that: (1) tree species influence soil processes; and (2) high tree growth and low soil gas emissions imply a reduced climate forcing effect from plantations, especially when planted with fast-growing legume species on abandoned farmland. © 2013 The Association for Tropical Biology and Conservation.
• Jardine, K., Serrano, A. Y., Arneth, A., Abrell, L., Jardine, A., van, H. J., Artaxo, P., Rizzo, L. V., Ishida, F. Y., Karl, T., Kesselmeier, J., Saleska, S., & Huxman, T. (2011). Within-canopy sesquiterpene ozonolysis in Amazonia. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 116.
• van, H., Cosme Jr., d., Restrepo-Coupe, N., Hutyra, L., de, C., Keller, M., & Saleska, S. R. (2010). Do plant species influence soil CO2 and N2O fluxes in a diverse tropical forest?. JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES, 115.
• Pyle, E. H., Santoni, G. W., E., H., Hutyra, L. R., Vieira, S., Curran, D. J., Haren, J. V., Saleska, S. R., Chow, V. Y., Carmago, P. B., Laurance, W. F., & Wofsy, S. C. (2009). Dynamics of carbon, biomass, and structure in two Amazonian forests. Journal of Geophysical Research G: Biogeosciences, 114(1).
  More info

  Abstract: Amazon forests are potentially globally significant sources or sinks for atmospheric carbon dioxide. In this study, we characterize the spatial trends in carbon storage and fluxes in both live and dead biomass (necromass) in two Amazonian forests, the Biological Dynamic of Forest Fragments Project (BDFFP), near Manaus, Amazonas, and the Tapajós National Forest (TNF) near Santarém, Pará. We assessed coarse woody debris (CWD) stocks, tree growth, mortality, and recruitment in ground-based plots distributed across the terra firme forest at both sites. Carbon dynamics were similar within each site, but differed significantly between the sites. The BDFFP and the TNF held comparable live biomass (167 ± 7.6 MgC.ha-1 versus 149 ± 6.0 MgC.ha-1, respectively), but stocks of CWD were 2.5 times larger at TNF (16.2 ± 1.5 MgC.ha-1 at BDFFP, versus 40.1 ± 3.9 MgC.ha-1 at TNF). A model of current forest dynamics suggests that the BDFFP was close to carbon balance, and its size class structure approximated a steady state. The TNF, by contrast, showed rapid carbon accrual to live biomass (3.24 ± 0.22 MgC.ha-1.a-1 in TNF, 2.59 ± 0.16 MgC.ha-1.a-1 in BDFFP), which was more than offset by losses from large stocks of CWD, as well as ongoing shifts of biomass among size classes. This pattern in the TNF suggests recovery from a significant disturbance. The net loss of carbon from the TNF will likely last 10-15 years after the initial disturbance (controlled by the rate of decay of coarse woody debris), followed by uptake of carbon as the forest size class structure and composition continue to shift. The frequency and longevity of forests showing such disequilibruim dynamics within the larger matrix of the Amazon remains an essential question to understanding Amazonian carbon balance. Copyright 2008 by the American Geophysical Union.
• McClaran, M. P., Moore-Kucera, J., Martens, D. A., Haren, J. v., & Marsh, S. E. (2008). Soil carbon and nitrogen in relation to shrub size and death in a semi-arid grassland. Geoderma, 145(1-2), 60-68.
  More info

  Abstract: Nutrient accumulation as fertile islands beneath invasive trees and shrubs in grasslands may provide opportunities for carbon sequestration. In a southwestern USA grassland, our objectives were to describe 1) the accumulation beneath Prosopis velutina (velvet mesquite) and isolated grass plants, and 2) the loss of accumulated nutrients 40 y after P. velutina death. We compared organic carbon (OC), total nitrogen (TN) and δ13C in soil organic matter among large living, large dead, and small living P. velutina and open grassland, and between grass plants and bare ground. Soil samples were collected at 0-5, 5-10, 16.8-23.2, and 36.8-43.2 cm depths, and separated into five size/density fractions: particulate organic matter (Macro- and Micro-POM), mineral associated organic matter (Micro-MAOM), Silt, and Clay. We expected that differences in OC, TN, and δ13C among soil fractions would suggest mechanisms and rates of accumulation with P. velutina persistence and loss following P. velutina death. Soil OC and TN accumulation was ~ 80-750% greater for large P. velutina than open grassland for whole soil and 4 of 5 fractions at 0-5 cm depth, but only 50-250% greater at 5-10 cm depth for whole soil and 3 of 5 fractions. Total OC and TN accumulation at 0-10 cm depth was 6.12 kg C m- 2 and 0.55 kg N m- 2, respectively. Accumulation did not occur in whole soil or any fraction at 16.8-23.2 cm and 36.8-43.2 cm depths, or in the Micro-MAOM fraction at any depth. Accumulation under small P. velutina was less than large plants, and not significantly different from open grassland. Beneath isolated grass plants, accumulation of TN occurred at 0-5 cm depth, and OC accumulation at 0-5 and 5-10 cm depths in whole soils only, but change in δ13C did not accompany accumulations. Forty years after death of large P. velutina, 67-106% of accumulated OC and TN were lost from whole soil and soil fractions at 0-5 cm depth. At 5-10 cm depth, loss (78-93%) was only detected in whole soils. Greater accumulation of OC and TN in the POM than the Silt and Clay fractions is consistent with the large physical size of recent organic matter inputs from P. velutina, but no differences in loss rates among fractions following P. velutina death suggests density dependent rates of organic matter consumption. Declines in δ13C accompanied OC accumulation and increases occurred during loss. A 20-30 y mean residence time (MRT) for whole soil and the Clay fraction over those 40 y is suggested by changes in OC and δ13C, but MRT based on changes in OC and δ13C differ for Macro-POM (1-3 y versus 20-25 y, respectively) and Silt (> 50 y versus 20-30 y, respectively). Activities that remove P. velutina should focus on small plants and protect large plants thereby maintaining their carbon sequestration potential. © 2008 Elsevier B.V. All rights reserved.
• McClaran, M. P., Moore-Kucera, J., Martens, D. A., van, H. J., & Marsh, S. E. (2008). Soil carbon and nitrogen in relation to shrub size and death in a semi-arid grassland. GEODERMA, 145(1-2), 60-68.
• Pyle, E. H., Santoni, G. W., Nascimento, H., Hutyra, L. R., Vieira, S., Curran, D. J., van, H. J., Saleska, S. R., Chow, V. Y., Carmago, P. B., Laurance, W. F., & Wofsy, S. C. (2008). Dynamics of carbon, biomass, and structure in two Amazonian forests. JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES, 113.
• Pegoraro, E., Rey, A., Abrell, L., Haren, J. V., & Lin, G. (2006). Drought effect on isoprene production and consumption in Biosphere 2 tropical rainforest. Global Change Biology, 12(3), 456-469.
  More info

  Abstract: Isoprene is the most abundant of the hydrocarbon compounds emitted from vegetation and plays a major role in tropospheric chemistry. Models predict that future climate change scenarios may lead to an increase in global isoprene emissions as a consequence of higher temperatures and extended drought periods. Tropical rainforests are responsible for more than 80% of global isoprene emissions, so it is important to obtain experimental data on isoprene production and consumption in these ecosystems under control of environmental variables. We explored isoprene emission and consumption in the tropical rainforest model ecosystem of Biosphere 2 laboratory during a mild water stress, and the relationship with light and temperature. Gross isoprene production (GIP) was not significantly affected by mild water stress in this experiment because the isoprene emitters were mainly distributed among the large, canopy layer trees with deep roots in the lower soil profile where water content decreased much less than the top 30 cm. However, as found in previous leaf level and whole canopy studies, the ecosystem gross primary production was reduced by (32%) during drought, and as a consequence the percentage of fixed C lost as isoprene tended to increase during drought, from ca. 1% in wet conditions to ca. 2% when soil water content reached its minimum. GIP correlated very well with both light and temperature. Notably, soil isoprene uptake decreased dramatically during the drought, leading to a large increase in daytime net isoprene fluxes. © 2006 Blackwell Publishing Ltd.
• L.M., J., Handley, L. L., Biel, K. Y., Kudeyarov, V. N., McLain, J. E., Martens, D. A., & Colodner, D. C. (2005). Drought-induced nitrous oxide flux dynamics in an enclosed tropical forest. Global Change Biology, 11(8), 1247-1257.
  More info

  Abstract: El Niño-La Niña cycles strongly influence dry and wet seasons in the tropics and consequently nitrous oxide (N2O) emissions from tropical rainforest soils. We monitored whole-system and soil chamber N2O fluxes during 5-month-long droughts in the Biosphere 2 tropical forest to determine how rainfall changes N2O production. A consistent pattern of N2O flux changes during drought and subsequent wetting emerged from our experiments. Soil surface drying during the first days of drought, presumably increased gas transport out of the soil, which increased N2O fluxes. Subsequent drying caused an exponential decrease in whole-system (4.0±0.1% day-1) and soil chamber N2O flux (8.9±0.8% day-1; south chamber; and 13.7±1.1% day-1; north chamber), which was highly correlated with soil moisture content. Soil air N2O concentration ([N2O]) and flux measurements revealed that surface N2O production persisted during drought. The first rainfall after drought triggered a N2O pulse, which amounted to 25% of drought-associated reduction in N2O flux and 1.3±0.4% of annual N2O emissions. Physical displacement of soil air by water and soil chemistry changes during drought could not account for the observed N2O pulse. We contend that osmotic stress on the microbial biomass must have supplied the N source for pulse N2O, which was produced at the litter-soil interface. After the pulse, N2O fluxes were consistently 90% of predrought values. Nitrate change rate, nutrient, [N2O], and flux analyses suggested that nitrifiers dominated N2O production during the pulse and denitrifiers during wet conditions. N2O flux measurements in Biosphere 2, especially during the N2O pulse, demonstrate that large-scale integration methods, such as flux towers, are essential for improving ecosystem N2O flux estimates. © 2005 Blackwell Publishing Ltd.
• Pegoraro, E., Abrell, L., Van, H. J., Barron-Gafford, G., Grieve, K. A., Malhi, Y., Murthy, R., & Lin, G. H. (2005). The effect of elevated atmospheric CO2 and drought on sources and sinks of isoprene in a temperate and tropical rainforest mesocosm. GLOBAL CHANGE BIOLOGY, 11(8), 1234-1246.
• van, H. J., Handley, L. L., Biel, K. Y., Kudeyarov, V. N., McLain, J., Martens, D. A., & Colodner, D. C. (2005). Drought-induced nitrous oxide flux dynamics in an enclosed tropical forest. GLOBAL CHANGE BIOLOGY, 11(8), 1247-1257.
• Guerenstein, P. G., Yepez, E. A., van, H. J., Williams, D. G., & Hildebrand, J. G. (2004). Floral CO2 emission may indicate food abundance to nectar-feeding moths. NATURWISSENSCHAFTEN, 91(7), 329-333.
• Murthy, R., Griffin, K. L., Zarnoch, S. J., Dougherty, P. M., Watson, B., Van, H. J., Patterson, R. L., & Mahato, T. (2003). Carbon dioxide efflux from a 550 m(3) soil across a range of soil temperatures. FOREST ECOLOGY AND MANAGEMENT, 178(3), 311-327.
• van, H. J., & Woensdregt, C. F. (2001). Melt growth of spessartine (Mn3Al2Si3O12). JOURNAL OF CRYSTAL GROWTH, 226(1), 107-110.
• Ague, J. J., & L., J. (1996). Assessing metasomatic mass and volume changes using the bootstrap, with application to deep crustal hydrothermal alteration of marble. Economic Geology, 91(7), 1169-1182.
  More info

  Abstract: A statistically rigorous approach for determining likely errors on estimates of mass and volume change in metasomatic systems is presented and then used to assess mass transfer resulting from hydrothermal alteration of marble during regional metamorphism. Analysis of metasomatic effects using standard statistical methods designed for unconstrained, univariant data often fails to provide useful results for several important reasons: 1. The concentration of any constituent in a composition is constrained to be between 0 and 100 wt percent. 2. The sum of the concentrations of all constituents must be 100 wt percent (the closure constraint). Compositions are multivariate and provide information only about the relative proportions of constituents. 3. The maximum possible mass or volume loss is -100 percent (-100% corresponds to complete mass or volume loss). 4. Rock bulk density must be greater than 0 g cm -3. 5. The underlying probability distributions for mass and volume changes are commonly non-normal. To address these issues, we use statistical procedures recently developed to treat the special properties of compositional data, including closure, and the bootstrap method to compute accurate confidence intervals for assessing how far in error best estimates of mass and volume change are likely to be. The bootstrap deals effectively with non-normality and constraints (1), (3), and (4). We apply our approach to gain a better understanding of synmetamorphic (Acadian orogeny) hydrothermal alteration of upper greenschist facies and amphibolite facies marble beds of the Wepawaug Schist, Connecticut. The marbles lost significant amounts of volatiles (dominantly CO 2 and H 2O), Si, Ti, K, Rb, Sr, and Ba. Best estimates of total mass and volume change are -27 and -32 percent, respectively. The bulk of the lost mass was volatiles (∼140 g kg -1), SiO 2 (∼60 g kg -1), and K 2O (∼15 g kg -1) (numbers are g lost per kg of parent rock). Volatile loss was probably regional in scope. Loss of Si, Ti, K, Rb, Sr, and Ba occurred over minimum length scales on the order of typical hand sample dimensions; maximum length scales remain to be determined. The FORTRAN 77 computer code that performs the calculations described herein is available from the senior author.
• L., J., Ague, J. J., & Rye, D. M. (1996). Oxygen isotope record of fluid infiltration and mass transfer during regional metamorphism of pelitic schist, Connecticut, USA. Geochimica et Cosmochimica Acta, 60(18), 3487-3504.
  More info

  Abstract: We present petrologic and oxygen isotopic evidence for the interaction of deep crustal fluids with kyanite zone pelitic schist during amphibolite facies metamorphism of the Wepawaug Schist, south-central Connecticut. We focus on a sample of schist (sample MBW-1) cut by a 2-6 cm wide quartz vein. The vein is surrounded by zones of wallrock alteration (selvages) that are rich in micas relative to quartz and feldspar, have low Si/Al and Na/Al, contain staurolite and kyanite, and vary in thickness from about 1-5 cm. Staurolite and kyanite are rare or absent beyond the selvage margins. We have measured the δ18O of quartz, plagioclase, muscovite, garnet, kyanite, staurolite, garnet, and biotite along several mm-scale resolution traverses across the quartz vein and the adjacent schist. Garnets in the selvages record core-to-rim increases in δ18O of nearly 2‰. Modeling of prograde reaction histories indicates that this zonation requires the infiltration of external fluids. Beyond the selvage margins, isotopic zonation in garnet is about 0.8‰ from core-to-rim and is consistent with prograde reaction with little or no infiltration. We suggest, therefore, that the selvages were zones of significant fluid infiltration and that the region now occupied by the quartz vein was the major fluid conduit. Earlier petrologic studies (Ague, 1994b) indicated that quartz veins and adjacent selvages were conduits for major down-temperature flow of H2O-rich fluids with time-integrated fluid fluxes of ∼3 × 105 m3 m-2. Isotopic modeling of advective flow suggests that down-temperature fluxes of this magnitude would have increased bulk δ18O by ∼1‰, consistent with the isotopic record preserved by zoned selvage garnets. Quartz in veins surrounded by selvages from five other localities throughout the amphibolite facies have δ518O that is statistically indistinguishable from that of the bulk of the quartz in MBW-1. Thus, we conclude that the amphibolite facies portion of the Wepawaug Schist was a zone of major, channelized outflow of metamorphic fluids down the regional temperature gradient. During the latter stages of amphibolite facies metamorphism subsequent to the bulk of vein and selvage formation, MBW-1 was infiltrated by isotopically light fluids that were probably derived from synmetamorphic igneous intrusions. This infiltration modified the isotopic composition of plagioclase throughout the rock and, therefore, we suggest that the infiltration was pervasive. Muscovite retains its pre-infiltration isotopic composition, however, which suggests short timescales of fluid-rock interaction on the order of 103-104 years. The total duration of flow may have been longer than this because our calculations do not take episodic flow into account. Modeling of possible isotopic shifts resulting from diffusion of oxygen isotopes between matrix phases during slow cooling indicates that MBW-1 must have been dry for most of its retrograde cooling history.

Presentations

• Dontsova, K. M., Chorover, J. D., Van Haren, J. L., Juarez, S., & Pohlmann, M. (2021, November). Inorganic Carbon Accumulation in Soils during Early Development of Landscapes. Soil Science Society of America Annual Meeting. Salt Lake City, UT: Soil Science Society of America.
• Chavarria, H. I., Lopez, J. M., Hunt, E., Meredith, L., Van Haren, J. L., & Dontsova, K. M. (2019, December 2019). EP53F-2209: Biosphere 2: The Changes of Soil Composition and Properties in Time in the Rainforest Biome.. American Geophysical Union Fall Meeting. San Francisco, CA: American Geophysical Union.
• Michaletz, S., Duran, S., Leavitt, S. W., McDowell, N., Saleska, S. R., van Haren, J. L., Troch, P. A., & Enquist, B. J. (2019, Aug.). Re-evaluating a stable isotope (δ18O) approach for estimating the temperature of photosynthesis. Ecological Society of America Annual Meeting. Louisville, Kentucky: Ecological Society of America.
• Dontsova, K. M., Juarez, S., Villasenor, E., Le Galliard, J., Chollet, S., Llavata, M., Massol, F., Hunt, E., Barre, P., Daval, D., Gelabert, A., Barron-Gafford, G. A., Van Haren, J. L., Troch, P. A., & Ferriere, R. H. (2019, January). Influence of Climate on Plant-Rock Interactions during Early Soil Development.. Science Society of America (SSSA) International Soils Meeting “Soils Across Latitudes”. San Diego, CA: Science Society of America.
• Van Haren, J. L. (2018, January). Gas exchange lessons learned from enclosing tropical forest trees in a giant glass house.. 27th Western Photosynthesis Conference. Biosphere 2.
• Dontsova, K. M., Volk, M., Webb, C., Hunt, E., Tfaily, M. M., Van Haren, J. L., Sengupta, A., Chorover, J. D., Troch, P. A., & Ruiz, J. (2017, December 2017). Carbon and nitrogen accumulation and fluxes on Landscape Evolution Observatory (LEO) slopes. American Geophysical Union Fall Meeting. San Francisco, CA: American Geophysical Union.
• Juarez, S., Dontsova, K. M., Le Galliard, J., Chollet, S., Cros, A., Llavata, M., Barre, P., Massol, F., Gelabert, A., Daval, D., Troch, P. A., Barron-Gafford, G. A., Van Haren, J. L., & Ferriere, R. H. (2016, April 2016). Effect of elevated CO2 and temperature on abiotic and biologically-driven basalt weathering and C sequestration. 2016 EGU General Assembly. Vienna, Austria: European Geosciences Union.
• Troch, P. A., Meredith, L., Pangle, L., Harman, C. J., Kim, M., Van Haren, J. L., & Volkmann, T. H. (2017, Dec). Real-time isotope monitoring network at the Biosphere 2 Landscape Evolution Observatory resolves meter-to-catchment scale flow dynamics. AGU International Annual Meeting. New Orleans, LA.
  More info

  Stable isotope analysis is a powerful tool for tracking flow pathways, residence times, and the partitioning of water resources through catchments. However, the capacity of stable isotopes to characterize catchment hydrological dynamics has not been fully exploited as commonly used methodologies constrain the frequency and extent at which isotopic data is available across hydrologically-relevant compartments (e.g. soil, plants, atmosphere, streams). Here, building upon significant recent developments in laser spectroscopy and sampling techniques, we present a fully automated monitoring network for tracing water isotopes through the three model catchments of the Landscape Evolution Observatory (LEO) at the Biosphere 2, University of Arizona. The network implements state-of-the-art techniques for monitoring in great spatiotemporal detail the stable isotope composition of water in the subsurface soil, the discharge outflow, and the atmosphere above the bare soil surface of each of the 330-m2 catchments. The extensive valving and probing systems facilitate repeated isotope measurements from a total of more than five-hundred locations across the LEO domain, complementing an already dense array of hydrometric and other sensors installed on, within, and above each catchment. The isotope monitoring network is operational and was leveraged during several months of experimentation with deuterium-labelled rain pulse applications. Data obtained during the experiments demonstrate the capacity of the monitoring network to resolve sub-meter to whole-catchment scale flow and transport dynamics in continuous time. Over the years to come, the isotope monitoring network is expected to serve as an essential tool for collaborative interdisciplinary Earth science at LEO, allowing us to disentangle changes in hydrological behavior as the model catchments evolve in time through weathering and colonization by plant communities.
• Villasenor, E., Ferriere, R. H., Van Haren, J. L., Dontsova, K. M., Juarez, S., Barron-Gafford, G. A., Le Galliard, J., Troch, P. A., Daval, D., Chollet, S., Gelabert, A., Llavata, M., Barré, P., Massol, F., Massol, F., Barré, P., Llavata, M., Gelabert, A., Chollet, S., , Daval, D., et al. (2017, December 2017). The effect of elevated CO2 and temperature on nutrient uptake by plants grown in basaltic soil. American Geophysical Union Fall Meeting. San Francisco, CA: American Geophysical Union.
• Volkmann, T. H., Sengupta, A., Pangle, L. A., Abramson, N., Barron-Gafford, G. A., Breshears, D. D., Bugaj, A., Chorover, J. D., Dontsova, K. M., Durcik, M., Ferre, P. A., Harman, C. J., Hunt, E. A., Kim, M., Maier, R. M., Matos, K. A., Alves Meira Neto, A., Meredith, L., Monson, R. K., , Niu, G., et al. (2017, December). Controlled Experiments of Hillslope Co-evolution at the Biosphere 2 Landscape Evolution Observatory: Toward Prediction of Coupled Hydrological, Biogeochemical, and Ecological change. AGU International Annual Meeting. New Orleans, LA: American Geophysical Union (AGU).
• Juarez, S., Dontsova, K. M., Le Galliard, J., Chollet, S., Cros, A., Llavata, M., Barre, P., Massol, F., Gelabert, A., Daval, D., Troch, P. A., Barron-Gafford, G. A., Van Haren, J. L., & Ferriere, R. H. (2016, October 2016). Effect of CO2 and temperature on basalt weathering and microbial activity.. International Conference on Ecological Sciences sfecologie2016. Marseille, France.
• McDonnell, J., Kim, M., Pangle, L. A., Van Haren, J. L., Harman, C. J., & Troch, P. A. (2016, 12). Soil, Water, Plants and Preferred Flow in All Directions: A Biosphere-2 Experiment (Invited). AGU Fall Meeting 2016. San Francisco: AGU.
• Smith, M., Taylor, T., Van Haren, J. L., Rosolem, R., Restrepo-Coupe, N., Wu, J., de Oliveira, R. C., da Silva, R., de Araujo, A., de Camargo, P., Huxman, T. E., & Saleska, S. R. (2016, 12). Evidence that Tropical Forest Photosynthesis is Not Directly Limited by High Temperatures. AGU Fall Meeting 2016. San Francisco: AGU.
• Van Haren, J. L. (2016, February). What if tropical forests are more resilient to climate change?. Biosphere 2 public What if series. Biosphere 2: Biosphere 2/College of Science.
• Van Haren, J. L. (2015, December). METHANE FLUX OF AMAZONIAN PEATLAND ECOSYSTEMS: LARGE ECOSYSTEM FLUXES WITH SUBSTANTIAL CONTRIBUTION FROM PALM (MARITIA FLEXUOSA) STEM EMISSIONS. AGU Fall Meeting 2015. San Francisco: American geophysical Union.
• Van Haren, J. L. (2015, October). What if drought hits tropical forests?. Biosphere 2. Biosphere 2: Biosphere 2/College of Science.
• Chorover, J. D., Huxman, T. E., Maier, R. M., Burghelea, C., Dontsova, K. M., & Zaharescu, D. (2014, December). Cracking the Code of Soil Genesis. The Early Role of Rare Earth Elements. American Geophysical Union (AGU) Fall Meeting. San Francisco, CA.
• Ruiz, J., Barron-Gafford, G. A., Van Haren, J. L., Dontsova, K. M., Troch, P. A., & Chorover, J. D. (2014, December). Rapid CO2 consumption during incipient weathering of a granular basaltic hillslope in the Landscape Evolution Observatory, Biosphere 2.. American Geophysical Union’s Annual Fall Meeting.
• Troch, P. A., Barron-Gafford, G. A., Dontsova, K. M., Fang, Y., Niu, Y., Pangle, L. A., Tuller, M., & Van Haren, J. L. (2014, December). Monitoring and Modeling Water, Energy and Carbon Fluxes at the Hillslope Scale in the Landscape Evolution Observatory.. AGU International Annual Meeting. San Francisco, CA: American Geophysical Union.

Poster Presentations

• McNerney, K., Saleska, S. R., Ng, W., Van Haren, J. L., Leford, S., Nabours, R., Hardy, J., Peterson, M., Burks, J., Pytosh, A., Durcik, M., Dontsova, K. M., & Bugaj, A. (2023, December). EP53D-1761: Effects of Sunlight, Temperature and Moisture on Small CO2 Fluctuations of Bare Soil, Soil with Moss and Soil with a Biocrust on a Landscape Evolutionary Observatory.. 2023 American Geophysical Union Fall Meeting. San Francisco, CA.
• Reynoso, A., Peterson, M., Dontsova, K. M., Fehmi, J. S., Van Haren, J. L., & Rasmussen, C. (2023, October). Exploring the potential for enhanced weathering for carbon sequestration in Arizona agricultural systems.. Soil Science Society of America (SSSA) International Annual Meeting. St. Louis, MO.
• Van Haren, J. L., Van Haren, J. L., Kuhnhammer, K., Kuhnhammer, K., Kuebert, A., Kuebert, A., Beyer, M., Beyer, M., Tuller, M., Tuller, M., Babaeian, E., Babaeian, E., Hu, J., Hu, J., Dubbert, M., Dubbert, M., Meredith, L., Meredith, L., Werner, C., & Werner, C. (2020, May). Water Cycling (Pools and Movement) Through an Enclosed Tropical Forest in Response to Drought. EGU General Assembly. Virtual: European Geosciences Union.
• Van Haren, J. L., Kuehnhammer, K., Kübert, A., Dubbert, M., Tuller, M., Babaeian, E., Beyer, M., Meredith, L., & Werner, C. (2019, December). Water cycling (pools and movement) through an enclosed tropical forest in response to drought. AGU Fall Meeting. San Francisco, CA: American Geophysical Union (AGU).
• Dontsova, K. M., Juarez, S., Le Galliard, J., Chollet, S., Cros, A., Llavata, M., Barre, P., Massol, F., Gelabert, A., Daval, D., Troch, P. A., Barron-Gafford, G. A., Van Haren, J. L., & Ferriere, R. H. (2016, June 2016). Basalt Weathering under Controlled Conditions as Influenced by Biota, Temperature, and CO2. The 26th Goldschmidt Conference. Yokohama, Japan: The European Association for Geochemistry and Geochemical Society.
• Howard, E., Van Haren, J. L., & Dontsova, K. M. (2017, December). Carbon uptake in granular basalt is mitigated by added organic carbon. American Geophysical Union fall meeting. New Orleans, LA: American Geophysical Union.
• Meraz, J. C., Meredith, L., Van Haren, J. L., & Volkmann, T. H. (2017, Dec). Measuring volatile organic compounds and stable isotopes emitted from trees and soils of the Biosphere 2 Rainforest. AGU International Annual Meeting. New Orleans, LA.
  More info

  Rainforest trees and soils play an important role in volatile organic compound (VOC) emissions. It is known that many rainforest tree species emit these organic compounds, such as terpenes, which can have an impact on the atmosphere and can be indicative of their metabolic functions. Some VOCs also absorb infrared radiation at wavelengths at which water isotopes are measured with laser spectrometers. Normal concentrations are not high enough for ambient sampling, but increased concentrations resulting from soil and plant samples extracted using equilibrium methods affect observed isotope ratios. There is thus a need to characterize volatile emissions from soil and plant samples, and to develop better methods to account for VOC interference during water isotope measurements. In this study, we collected soil and leaf samples from plants of the Biosphere 2 Rainforest Biome, a mesocosm system created to stimulate natural tropical rainforest habitats . Volatile concentrations were measured using a Gasmet DX4015 FTIR analyzer and a custom sampling system with sulfur hexafluoride (SF6) used as a tracer gas to test for leakage, and a commercial laser spectrometer was used for isotopic analysis. We determined that the different types of tree species emit different kinds of VOCs, such as isoprenes, alcohols, and aldehydes, that will potentially have to be accounted for. This study will help build the understanding of which organic compounds are emitted and develop new methods to test for water isotopes and gas fluxes in clear and precise measures. Such measures can help characterize the functioning of environmental systems such as the Biosphere 2 Rainforest Biome.
• Saleska, S. R., Siu Mui, T., Barbosa de Camargo, P., Van Haren, J. L., Nüsslein, K., Pedrinho, A., Piccini, W., Meredith, L., & Webster, K. (2017, Dec). Recovery of Methane Consumption by Secondary Forests in the Amazon River Basin. AGU International Annual Meeting. New Orleans, LA.
  More info

  Methane (CH4) is a major greenhouse gas in Earth’s atmosphere and its atmospheric global mole fraction has roughly doubled since the start of the industrial revolution. The tropics are thought to be a major CH4 emitter, with the Amazon River Basin estimated to contribute 7 % of the annual flux to the atmosphere. The Amazon has experienced extensive land use change during the past 30 years, but we lack an understanding of the qualitative and quantitative effects of land use change on CH4 flux from the Amazon and the associated reasons. To illuminate the factors controlling CH4 flux across land use gradients in the Amazon we measured the CH4 fluxes and will measure the associated stable isotopic composition from pastures, primary forests, and secondary forests, at Ariquemes (Western Amazon, more deforested), and Santarem (Eastern Amazon, less deforested), Brazil. The sites near Santarem were sampled in June of 2016 and the sites near Ariquemes were sampled in March and April of 2017, both at the end of the wet season. Little difference was observed between land use types in Santarem with each land use type slightly consuming atmospheric CH4. However, pasture fluxes at Ariquemes were higher (+520 μg-C m-2 hr-1) than in primary (0 μg-C m-2 hr-1) and secondary forests (-20 μg-C m-2 hr-1; p = 6*10-4). CH4 flux from individual Santarem sites was not correlated with environmental variables. CH4 flux from Airquemes was correlated with several parameters across all samples including soil temperature (p = 7*10-4), and soil humidity (p = 0.02). Despite the fact that pastures experienced higher soil temperatures than forest soils this appears to be a low predictor of CH4 flux from these environments as it was seen at both Santarem and Ariquemes. The analysis of the stable isotopic composition of CH4 from these chambers will aid in understanding the competing processes of microbial CH4 consumption and production in these soils and why pastures may become CH4 sources and secondary forests are able to regain the function as a CH4 sink in some instances. Support: NSF, FAPESP-Biota, CNPq, CAPES.
• Troch, P. A., Zeng, X., Wang, Y., Van Haren, J. L., Tuller, M., Sibayan, M., Schaap, M. G., Saleska, S. R., Ruiz, J., Rasmussen, C., Pelletier, J. D., Niu, G., Monson, R. K., Meredith, L., Alves Meira Neto, A., Matos, K. A., Maier, R. M., Kim, M., Hunt, E. A., , Harman, C. J., et al. (2017, December). Controlled Experiments of Hillslope Co-evolution at the Biosphere 2 Landscape Evolution Observatory: Toward Prediction of Coupled Hydrological, Biogeochemical, and Ecological change. 2017 AGU Fall Meeting, Abstract B43A-2105. New Orleans, LA: American Geophysical Union (AGU).
  More info

  Understanding the process interactions and feedbacks among water, microbes, plants, and porous geological media is crucial for improving predictions of the response of Earth’s critical zone to future climatic conditions. However, the integrated co-evolution of landscapes under change is notoriously difficult to investigate. Laboratory studies are typically limited in spatial and temporal scale, while field studies lack observational density and control. To bridge the gap between controlled lab and uncontrolled field studies, the University of Arizona – Biosphere 2 built a macrocosm experiment of unprecedented scale: the Landscape Evolution Observatory (LEO). LEO consists of three replicated, 330-m2 hillslope landscapes inside a 5000-m2 environmentally controlled facility. The engineered landscapes contain 1-m depth of basaltic tephra ground to homogenous loamy sand that will undergo physical, chemical, and mineralogical changes over many years. Each landscape contains a dense sensor network capable of resolving water, carbon, and energy cycling processes at sub-meter to whole-landscape scale. Embedded sampling devices allow for quantification of biogeochemical processes, and facilitate the use of chemical tracers applied with the artificial rainfall. LEO is now fully operational and intensive forcing experiments have been launched. While operating the massive infrastructure poses significant challenges, LEO has demonstrated the capacity of tracking multi-scale matter and energy fluxes at a level of detail impossible in field experiments. Initial sensor, sampler, and restricted soil coring data are already providing insights into the tight linkages between water flow, weathering, and (micro-) biological community development during incipient landscape evolution. Over the years to come, these interacting processes are anticipated to drive the model systems to increasingly complex states, potentially perturbed by changes in climatic forcing. By intensively monitoring the evolutionary trajectory, integrating data with models, and fostering community-wide collaborations, we envision that emergent landscape structures and functions can be linked and significant progress can be made toward predicting the coupled hydro-biogeochemical and ecological responses to global change.
• Van Haren, J. L., Sanchez-Canete, E., Juarez, S., Howard, E., Dontsova, K. M., Le Galliard, J., Barron-Gafford, G. A., Volkmann, T., & Troch, P. A. (2017, December). Projected effects of vegetation and organic matter on soil carbon dynamics after rainfall in a model basalt landscape. American Geophysical Union fall meeting. New Orleans, LA: American Geophysical Union.
• Volkmann, T. H., Sengupta, A., Pangle, L. A., Abramson, N., Barron-Gafford, G. A., Breshears, D. D., Bugaj, A., Chorover, J. D., Dontsova, K. M., Durcik, M., Ferre, P. A., Harman, C. J., Hunt, E. A., Kim, M., Maier, R. M., Matos, K. A., Alves Meira Neto, A., Meredith, L., Monson, R. K., , Niu, G., et al. (2017, December). Controlled Experiments of Hillslope Co-evolution at the Biosphere 2 Landscape Evolution Observatory: Toward Prediction of Coupled Hydrological, Biogeochemical, and Ecological change. AGU International Annual Meeting. New Orleans, LA: American Geophysical Union (AGU).
• Young, J. C., Young, J. C., Sengupta, A., Sengupta, A., Uren, J. M., Uren, J. M., Van Haren, J. L., Van Haren, J. L., Meredith, L., & Meredith, L. (2017, Dec). Microbial drivers of spatial heterogeneity of nitrous oxide pulse dynamics following drought in an experimental tropical rainforest. AGU International Annual Meeting. New Orleans, LA.
  More info

  Nitrous oxide (N2O) is a long-lived, potent greenhouse gas with increasing atmospheric concentrations. Soil microbes in agricultural and natural ecosystems are the dominant source of N2O, which involves complex interactions between N-cycling microbes, metabolisms, soil properties, and plants. Tropical rainforests are the largest natural source of N2O, however the microbial and environmental drivers are poorly understood as few studies have been performed in these environments. Thus, there is an urgent need for further research to fill in knowledge gaps regarding tropical N-cycling, and the response of soil microbial communities to changes in precipitation patterns, temperature, nitrogen deposition, and land use. To address this data gap, we performed a whole-forest drought in the tropical rainforest biome in Biosphere 2 (B2) and analyzed connections between soil microbes, forest heterogeneity, and N2O emissions. The B2 rainforest is the hottest tropical rainforest on Earth, and is an important model system for studying the response of tropical forests to warming with controlled experimentation. In this study, we measured microbial community abundance and diversity profiles (16S rRNA and ITS2 amplicon sequencing) along with their association with soil properties (e.g. pH, C, N) during the drought and rewetting at five locations (3 depths), including regions that have been previously characterized with high and low N2O drought pulse dynamics (van Haren et al., 2005). In this study, we present the spatial distribution of soil microbial communities within the rainforest at Biosphere 2 and their correlations with edaphic factors. In particular, we focus on microbial, soil, and plant factors that drive high and low N2O pulse zones. As in the past, we found that N2O emissions were highest in response to rewetting in a zone hypothesized to be rich in nutrients from a nearby sugar palm. We will characterize microbial indicator species and nitrogen cycling genes to better resolve N cycling across the forest. Understanding how N2O formation is mediated by soil microbes in response to drought in tropical rainforests is challenging given the great diversity of microbial communities and metabolisms involved, but is critical for understanding the source of global increases in atmospheric N2O.
• Hingley, R., Dontsova, K. M., Juarez, S., Hunt, E., Le Galliard, J., Chollet, S., Cros, A., Llavata, M., Barre, P., Massol, F., Gelabert, A., Daval, D., Troch, P. A., Barron-Gafford, G. A., Van Haren, J. L., & Ferriere, R. H. (2016, December 2016). Effects of Climate Change and Vegetation Type on Carbon and Nitrogen Accumulation during Incipient Soil Formation. American Geophysical Union Fall Meeting. San Francisco, CA: American Geophysical Union.
• Sanchez-Canete, E., Scott, R. L., Van Haren, J. L., & Barron-Gafford, G. A. (2016, 12). The Necessity of Determining the Gas Transfer Coefficient In-situ to Obtain More Accurate Soil Carbon Dioxide Effluxes Through the Gradient Method. AGU Fall Meeting. San Francisco: AGU.
• Van Haren, J. L., & Cadillo-Quiroz, H. (2016, 12). Controls on tree species stem transport and emission of methane from tropical peatlands. AGU Fall Meeting 2016. San Francisco: AGU.
• Juarez, S., Dontsova, K. M., Le Galliard, J., Chollet, S., Cros, A., Llavata, M., Barre, P., Massol, F., Gelabert, A., Daval, D., Troch, P. A., Barron-Gafford, G. A., Van Haren, J. L., & Ferriere, R. H. (2015, 20-24 Sep 2015). Abiotic and biologically-­‐driven basalt weathering and carbon sequestration under changing climate. 5th International Symposium on Soil Organic Matter. Göttingen (DE).
• Van Haren, J. L., Tuller, M., Pangle, L., Niu, Y., Fang, Y., Dontsova, K. M., Barron-Gafford, G. A., & Troch, P. A. (2014, December). Monitoring and Modeling Water, Energy and Carbon Fluxes at the Hillslope Scale in the Landscape Evolution Observatory. American Geophysical Union (AGU) Fall Meeting. San Francisco, CA.

Others

• Van Haren, J. L. (2015, October). A rainforest in the Desert. Arizona Daily Star.