A framework to assess biogeochemical response to ecosystem disturbance using nutrient partitioning ratios

Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Ecosystems 19 (2016): 387-395, doi:10.1007/s10021-015-9934-1.Disturbances affect almost all terrestrial ecosystems, but it has been difficult to identify general principles regarding these influences. To improve our understanding of the long-term consequences of disturbance on terrestrial ecosystems, we present a conceptual framework that analyzes disturbances by their biogeochemical impacts. We posit that the ratio of soil and plant nutrient stocks in mature ecosystems represents a characteristic site property. Focusing on nitrogen (N), we hypothesize that this partitioning ratio (soil N: plant N) will undergo a predictable trajectory after disturbance. We investigate the nature of this partitioning ratio with three approaches: (1) nutrient stock data from forested ecosystems in North America, (2) a process-based ecosystem model, and (3) conceptual shifts in site nutrient availability with altered disturbance frequency. Partitioning ratios could be applied to a variety of ecosystems and successional states, allowing for improved temporal scaling of disturbance events. The generally short-term empirical evidence for recovery trajectories of nutrient stocks and partitioning ratios suggests two areas for future research. First, we need to recognize and quantify how disturbance effects can be accreting or depleting, depending on whether their net effect is to increase or decrease ecosystem nutrient stocks. Second, we need to test how altered disturbance frequencies from the present state may be constructive or destructive in their effects on biogeochemical cycling and nutrient availability. Long-term studies, with repeated sampling of soils and vegetation, will be essential in further developing this framework of biogeochemical response to disturbance.This material is based upon work supported by the National Science Foundation under Grant No. DEB-1145815 and 0949420.2016-11-1

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)

Refsland and Fraterrigo Drought-fire effects on microclimate, nitrogen and juvenile Quercus alba

This database includes raw data on the forest microclimate, soil nitrogen availability and juvenile white oak (Quercus alba) physiological and growth responses to drought and fire treatments

Local-scale biotic interactions embedded in macroscale climate drivers suggest Eltonian noise hypothesis distribution patterns for an invasive grass

Abstract A hierarchical view of niche relations reconciles the scale-dependent effects of abiotic and biotic processes on species distribution patterns and underlies most current approaches to distribution modeling. A key prediction of this framework is that the effects of biotic interactions will be averaged out at macroscales -an idea termed the Eltonian noise hypothesis (ENH). We test this prediction by quantifying regional variation in local abiotic and biotic niche relations and assess the role of macroclimate in structuring biotic interactions, using a non-native invasive grass, Microstegium vimineum, in its introduced range. Consistent with hierarchical niche relations and the ENH, macroclimate structures local biotic interactions, while local abiotic relations are regionally conserved. Biotic interactions suppress M. vimineum in drier climates but have little effect in wetter climates. A similar approach could be used to identify the macroclimatic conditions under which biotic interactions affect the accuracy of local predictions of species distributions

Species traits as generalized predictors of forest community response to human disturbance

During the past decade, substantial effort has been aimed at identifying a group of easily measured, widely applicable plant traits that could serve as a metric to predict temporal change in plant communities. Traits that transcend regional differences in species composition and ecological conditions through their consistent response to disturbance would give managers a simple tool for tracking ongoing and future forest change in response to human disturbance. Although a wide range of plant traits has been associated with human disturbance, consistent traits have not emerged in the literature. However, this may due to differences in methodology among studies. Previously collected data from two eastern deciduous forest floras of North America (Iowa and Massachusetts) allowed us to evaluate whether such traits emerged, while controlling for methodological differences. We created a plot × traits matrix for each site and ordinated them used using principal components analysis (PCA) to identify disturbance gradients. We then assessed how well the traits most strongly associated with the disturbance gradients corresponded. The data sets shared only 4 of the 12 traits associated with disturbance and 6 of 12 traits associated with undisturbed sites. We did not find a consistent association between dispersal limitation and undisturbed sites or high dispersal capacity associated with disturbed sites. However, in both data sets degree of habitat specialization was an important variable on both ends of the disturbance gradient. Habitat generalists were associated with disturbance and habitat specialists were associated with more pristine sites in both data sets. These results agree with the findings of a wide range of site-specific studies, and we therefore propose that this variable is a promising candidate trait to provide a signal of forest community response to human disturbance. Our results are should be particularly encouraging for managers because in many regions morphological trait data are not readily available, and compiling such data is a very time-intensive task and unlikely to be feasible for most managers to undertake. With a list of species and a published flora, upwards of several hundred species can quickly be coded for degree of habitat specialization and used to track the impact of current disturbance, to predict future impacts, and to target specific species for reintroduction or restoration.This is a manuscript of an article published as Mabry, Catherine M., and Jennifer M. Fraterrigo. "Species traits as generalized predictors of forest community response to human disturbance." Forest Ecology and Management 257, no. 2 (2009): 723-730. doi:10.1016/j.foreco.2008.10.002. Posted with permission. This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License

Stochastic disturbance regimes alter patterns of ecosystem variability and recovery.

Altered ecosystem variability is an important ecological response to disturbance yet understanding of how various attributes of disturbance regimes affect ecosystem variability is limited. To improve the framework for understanding the disturbance regime attributes that affect ecosystem variability, we examine how the introduction of stochasticity to disturbance parameters (frequency, severity and extent) alters simulated recovery when compared to deterministic outcomes from a spatially explicit simulation model. We also examine the agreement between results from empirical studies and deterministic and stochastic configurations of the model. We find that stochasticity in disturbance frequency and spatial extent leads to the greatest increase in the variance of simulated dynamics, although stochastic severity also contributes to departures from the deterministic case. The incorporation of stochasticity in disturbance attributes improves agreement between empirical and simulated responses, with 71% of empirical responses correctly classified by stochastic configurations of the model as compared to 47% using the purely deterministic model. By comparison, only 2% of empirical responses were correctly classified by the deterministic model and misclassified by stochastic configurations of the model. These results indicate that stochasticity in the attributes of a disturbance regime alters the patterns and classification of ecosystem variability, suggesting altered recovery dynamics. Incorporating stochastic disturbance processes into models may thus be critical for anticipating the ecological resilience of ecosystems