The Importance of Biotic Interactions Under Global Change in the Alpine

The response of organisms to a rapidly changing environment depends not only on the abiotic conditions they experience, but also their biotic interactions. Here I examine the role of biotic interactions in shaping species responses to global change in an alpine ecosystem. First, I use a long-term experiment to address whether plant communities mediate soil microbial response to simulated nitrogen deposition where I find a decoupling of the plant and microbial communities such that the soil microbial community shifts under nitrogen independently of directional shifts in the plant community. Then I characterize how plant-microbial interactions shape the composition of microbes that live in the roots of alpine plants migrating uphill into previously unvegetated areas by examining the effects of alpine plant migrant density and resultant changes in soil properties. I find that bacterial and fungal root endophytes were only weakly shaped by environmental variables shifting with climate change and that the overall explained variation in community composition was low. Next, I present work from a plant community survey to demonstrate that morphology of a habitat-forming species drives differences in beta diversity but not richness. I then use a manipulative experiment to assess how a habitat-forming species informs the uphill movement of a subalpine plant where I find that the habitat-former increased survival. Finally, I assess the implications of habitat-forming species for associated taxa under climate change in a conceptual paper that focuses on the roles of facilitation, connectivity, and heterogeneity.</p

SoDaH: the SOils DAta Harmonization database, an open-source synthesis of soil data from research networks, version 1.0

Data collected from research networks present opportunities to test theories and develop models about factors responsible for the long-term persistence and vulnerability of soil organic matter (SOM). Synthesizing datasets collected by different research networks presents opportunities to expand the ecological gradients and scientific breadth of information available for inquiry. Synthesizing these data is challenging, especially considering the legacy of soil data that have already been collected and an expansion of new network science initiatives. To facilitate this effort, here we present the SOils DAta Harmonization database (SoDaH; https://lter.github.io/som-website, last access: 22&nbsp;December&nbsp;2020), a flexible database designed to harmonize diverse SOM datasets from multiple research networks. SoDaH is built on several network science efforts in the United States, but the tools built for SoDaH aim to provide an open-access resource to facilitate synthesis of soil carbon data. Moreover, SoDaH allows for individual locations to contribute results from experimental manipulations, repeated measurements from long-term studies, and local- to regional-scale gradients across ecosystems or landscapes. Finally, we also provide data visualization and analysis tools that can be used to query and analyze the aggregated database. The SoDaH v1.0 dataset is archived and available at https://doi.org/10.6073/pasta/9733f6b6d2ffd12bf126dc36a763e0b4 (Wieder et al., 2020). Full List of Authors William R. Wieder1,28, Derek Pierson2,29, Stevan Earl3, Kate Lajtha2, Sara G. Baer4,5, Ford Ballantyne6, Asmeret Asefaw Berhe7, Sharon A. Billings8,5, Laurel M. Brigham1,9, Stephany S. Chacon2,10, Jennifer Fraterrigo11, Serita D. Frey12, Katerina Georgiou13,30, Marie-Anne de Graaff14, A. Stuart Grandy12, Melannie D. Hartman15,31, Sarah E. Hobbie16, Chris Johnson17, Jason Kaye18, Emily Kyker-Snowman12, Marcy E. Litvak19, Michelle C. Mack20, Avni Malhotra21, Jessica A. M. Moore22, Knute Nadelhoffer23, Craig Rasmussen24, Whendee L. Silver25, Benjamin N. Sulman26, Xanthe Walker20, and Samantha Weintraub27 1Institute of Arctic and Alpine Research, University of Colorado Boulder, CO, USA 2Department of Crop and Soil Sciences, Oregon State University, Corvallis, OR, USA 3Global Institute of Sustainability, Arizona State University, Tempe, AZ, USA 4Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, USA 5Kansas Biological Survey, University of Kansas, Lawrence, KS, USA 6Odum School of Ecology, University of Georgia, Athens, GA, USA 7Department of Life and Environmental Sciences, University of California, Merced, CA, USA 8Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, USA 9Department of Ecology and Evolutionary Biology and Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, USA 10Climate and Ecosystem Sciences, Lawrence Berkeley National Laboratory, Berkeley, CA, USA 11Department of Natural Resources and Environmental Sciences, University of Illinois, Urbana, IL, USA 12Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH, USA 13Department of Earth System Science, Stanford University, Stanford, CA, USA 14Department of Biological Sciences, Boise State University, Boise, ID, USA 15Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder CO, USA 16Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN, USA 17Department of Civil and Environmental Engineering, Syracuse University, Syracuse, NY, USA 18Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, PA, USA 19Department of Biology, University of New Mexico, Albuquerque, NM, USA 20Center for Ecosystem Science and Society and Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA 21Department of Earth System Science, Stanford University, Stanford, CA, USA 22Bioscience Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA 23Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA 24Department of Environmental Science, The University of Arizona, Tucson, AZ, USA 25Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA, USA 26Climate Change Science Institute and Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA 27National Ecological Observatory Network, Battelle, Boulder, CO, USA 28Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, CO, USA 29Department of Biological Sciences, Idaho State University, Pocatello, ID, USA 30Lawrence Livermore National Laboratory, Livermore, CA, USA 31Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, USA </ul

Biodiversity in changing environments: An external‐driver internal‐topology framework to guide intervention

Accompanying the climate crisis is the more enigmatic biodiversity crisis. Rapid reorganization of biodiversity due to global environmental change has defied prediction and tested the basic tenets of conservation and restoration. Conceptual and practical innovation is needed to support decision making in the face of these unprecedented shifts. Critical questions include: How can we generalize biodiversity change at the community level? When are systems able to reorganize and maintain integrity, and when does abiotic change result in collapse or restructuring? How does this understanding provide a template to guide when and how to intervene in conservation and restoration? To this end, we frame changes in community organization as the modulation of external abiotic drivers on the internal topology of species interactions, using plant-plant interactions in terrestrial communities as a starting point. We then explore how this framing can help translate available data on species abundance and trait distributions to corresponding decisions in management. Given the expectation that community response and reorganization are highly complex, the external-driver internal-topology (EDIT) framework offers a way to capture general patterns of biodiversity that can help guide resilience and adaptation in changing environments

SoDaH: the SOils DAta Harmonization database, an open-source synthesis of soil data from research networks, version 1.0

Data collected from research networks present opportunities to test theories and develop models about factors responsible for the long-term persistence and vulnerability of soil organic matter (SOM). Synthesizing datasets collected by different research networks presents opportunities to expand the ecological gradients and scientific breadth of information available for inquiry. Synthesizing these data is challenging, especially considering the legacy of soil data that have already been collected and an expansion of new network science initiatives. To facilitate this effort, here we present the SOils DAta Harmonization database (SoDaH; https://lter.github.io/som-website, last access: 22 December 2020), a flexible database designed to harmonize diverse SOM datasets from multiple research networks. SoDaH is built on several network science efforts in the United States, but the tools built for SoDaH aim to provide an open-access resource to facilitate synthesis of soil carbon data. Moreover, SoDaH allows for individual locations to contribute results from experimental manipulations, repeated measurements from long-term studies, and local- to regional-scale gradients across ecosystems or landscapes. Finally, we also provide data visualization and analysis tools that can be used to query and analyze the aggregated database. The SoDaH v1.0 dataset is archived and available at https://doi.org/10.6073/pasta/9733f6b6d2ffd12bf126dc36a763e0b4 (Wieder et al., 2020)

Warming and shrub encroachment decrease decomposition in arid alpine and subalpine ecosystems

Climate change is shifting species distributions and altering plant community composition worldwide. For instance, with rising temperatures shrubs are encroaching into alpine ecosystems, resulting in important implications for ecosystem functioning. In particular, woody-plant encroachment could slow decomposition in systems traditionally dominated by herbaceous species. To evaluate how litter decomposition responded jointly to warming and shrub presence, we conducted a passive warming chamber experiment in subalpine and alpine plant communities in the White Mountains of California. Passive warming chambers were placed over plots with and without the range-expanding sagebrush Artemisia rothrockii at two elevations. Litter from A. rothrockii and the common perennial herb Trifolium andersonii decomposed for two years under the experimental treatments. Nitrate availability was measured with ion-exchange resins during the same time period. Warming decreased decomposition rates overall, associated with decreased soil moisture, but did not influence soil nitrate availability. Sagebrush presence decreased both decomposition rates and nitrate availability. Hence, future warming in this system will likely reduce decomposition rates, both directly and indirectly, via shrub encroachment. However, impacts on nutrient mineralization are less clear. These findings highlight how shifting species composition, through processes such as range expansions, can influence ecosystem responses to climate change

Drivers of bacterial and fungal root endophyte communities: understanding the relative influence of host plant, environment, and space.

Bacterial and fungal root endophytes can impact the fitness of their host plants, but the relative importance of drivers for root endophyte communities is not well known. Host plant species, the composition and density of the surrounding plants, space, and abiotic drivers could significantly affect bacterial and fungal root endophyte communities. We investigated their influence in endophyte communities of alpine plants across a harsh high mountain landscape using high-throughput sequencing. There was less compositional overlap between fungal than bacterial root endophyte communities, with four 'cosmopolitan' bacterial OTUs found in every root sampled, but no fungal OTUs found across all samples. We found that host plant species, which included nine species from three families, explained the greatest variation in root endophyte composition for both bacterial and fungal communities. We detected similar levels of variation explained by plant neighborhood, space, and abiotic drivers on both communities, but the plant neighborhood explained less variation in fungal endophytes than expected. Overall, these findings suggest a more cosmopolitan distribution of bacterial OTUs compared to fungal OTUs, a structuring role of the plant host species for both communities, and largely similar effects of the plant neighborhood, abiotic drivers, and space on both communities