MSB-FRA: The influence of biological diversity on land-atmosphere exchange in forests: confronting theory with data

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Biological diversity is important to human well-being and to the maintenance of a healthy environment. Without an array of species inhabiting a range of environments, the cycles of water, nutrients and biomass on which life depends would be severely compromised. Despite this, understanding exactly how diversity influences specific environmental processes is challenging. Although there are theories describing the influence of plant species diversity on environmental processes, they?ve primarily been tested in grasslands and other systems dominated by small plants, where diversity can be manipulated through planting and weeding. Forests present a challenge because the size and lifespans of trees make it difficult to conduct manipulative diversity experiments and because natural diversity gradients also vary in climate, making results difficult to interpret. Overcoming this hurdle is critical given the importance of forests to many environmental processes and the degree to which forest diversity is declining. This award will examine whether theories of biological diversity and environmental processes that have been largely tested in small-statured ecosystems also apply to macro-scale processes over North American forests. By integrating data on carbon, water, and energy exchanges between forests and the atmosphere, remote sensing of forest diversity, and field measurements, will enable the development of forest diversity for the US and the relationship to land-atmosphere exchange of carbon and water. It will quantify the important role of forests in the Earth system and the degree to which forest diversity is declining. The award will involve undergraduate and graduate students in all phases of the project, and through additional activities that bring new methods of remote sensing to private citizens, teachers and students at multiple levels. This will be accomplished through workshops and through development of focused activities that can be adopted by teachers and used in the classroom. The undergraduates working on the project will participate in the University of New Hampshire?s Undergraduate Research Conference (URC), one of the largest undergraduate research events in the country. Understanding how diversity influences specific ecosystem and earth system functions within individual biomes is extremely difficult and is considered one of the grand challenges in ecology. Meeting this challenge is important given the number of species worldwide that have already gone extinct or have been threatened by habitat loss, pests and pathogens, harvesting, competition from non-native species, pollution, and climate change. This award will examine the effects of tree diversity in forests across the U.S. on the uptake of CO2, the transfer of water from soils to the atmosphere, and on the stability of these processes in response to climate variability. The award will test the following specific hypotheses:(A) Biological diversity in North American forests has a positive effect on primary production and a negative effect on evapotranspiration, leading to increased water use efficiency. (B) Forests with high levels of diversity are less susceptible to extreme events and exhibit less temporal variability in carbon and water fluxes in response to climate fluctuations than low-diversity forests. These hypotheses will be addressed by bringing together several unique sources of data that have not previously been used to address this question. First, the research sites to be used are equipped with instrumented towers that make detailed measurements of CO2 and water vapor above the forest canopy, as well as a range of climate and ecological variables. Second, advanced remote sensing instruments will be used to measure tree canopy diversity in ways that field surveys alone cannot. These data will come from unmanned aerial systems as well as instruments that are part of the National Ecological Observatory. Through the unique nature of these data sets and advanced methods of data analysis, results will be used to quantify the specific signature of diversity on important processes at a broad geographic scale.