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  1. Windecker, Saras (Ed.)
    1. The ecological and environmental science communities have embraced machine learning (ML) for empirical modelling and prediction. However, going beyond prediction to draw insights into underlying functional relationships between response variables and environmental ‘drivers’ is less straightforward. Deriving ecological insights from fitted ML models requires techniques to extract the ‘learning’ hidden in the ML models. 2. We revisit the theoretical background and effectiveness of four approaches for deriving insights from ML: ranking independent variable importance (Gini importance, GI; permutation importance, PI; split importance, SI; and conditional permutation importance, CPI), and two approaches for inference of bivariate functional relationships (partial dependence plots, PDP; and accumulated local effect plots, ALE). We also explore the use of a surrogate model for visualization and interpretation of complex multi-variate relationships between response variables and environmental drivers. We examine the challenges and opportunities for extracting ecological insights with these interpretation approaches. Specifically, we aim to improve interpretation of ML models by investigating how effectiveness relates to (a) interpretation algorithm, (b) sample size and (c) the presence of spurious explanatory variables. 3. We base the analysis on simulations with known underlying functional relationships between response and predictor variables, with added white noise and the presence of correlated but non-influential variables. The results indicate that deriving ecological insight is strongly affected by interpretation algorithm and spurious variables, and moderately impacted by sample size. Removing spurious variables improves interpretation of ML models. Meanwhile, increasing sample size has limited value in the presence of spurious variables, but increasing sample size does improves performance once spurious variables are omitted. Among the four ranking methods, SI is slightly more effective than the other methods in the presence of spurious variables, while GI and SI yield higher accuracy when spurious variables are removed. PDP is more effective in retrieving underlying functional relationships than ALE, but its reliability declines sharply in the presence of spurious variables. Visualization and interpretation of the interactive effects of predictors and the response variable can be enhanced using surrogate models, including three-dimensional visualizations and use of loess planes to represent independent variable effects and interactions. 4. Machine learning analysts should be aware that including correlated independent variables in ML models with no clear causal relationship to response variables can interfere with ecological inference. When ecological inference is important, ML models should be constructed with independent variables that have clear causal effects on response variables. While interpreting ML models for ecological inference remains challenging, we show that careful choice of interpretation methods, exclusion of spurious variables and adequate sample size can provide more and better opportunities to ‘learn from machine learning’. 
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  2. Elmer Ottis Wooton (1865–1945) was one of the most important early botanists to work in the Southwestern United States, contributing a great deal of natural history knowledge and botanical research on the flora of New Mexico that shaped many naturalists and scientists for generations. The extensive Wooton legacy includes herbarium collections that he and his famous student Paul Carpenter Standley (1884–1963), prolific botanist and explorer, used for the first Flora of New Mexi co by Wooten and Standley 1915 , along with resources covering botany and range management strategies for the northern Chihuahuan Desert, and an extensive, yet to be digitized, historical archive of correspondence, field notes, vegetation sketches, photographs, and lantern slides, all from his travels and field work in the region. Starting in 1890, the most complete set of Wooton’s herbarium collections were deposited in the NMC herbarium at New Mexico State University (NMSU), and his archives, now stored in a Campus library, have together been underutilized, offline resources. The goals of this ongoing project are to secure, preserve, and promote Wooton’s important historical resources, by fleshing out the botanical history of the region, raising appreciation of herbarium collections within the community, and emphasizing their unique role in facilitating contemporary research aimed at addressing pressing scientific questions such as vegetation responses to global climate change. Students and the general public involved in this project are engaged through hands-on activities including cataloging, databasing and digitization of nearly 10,000 herbarium specimens and Wooton’s archives. These outputs, combined with contemporary data collection and computational biology techniques from an ecological perspective, are being used to document vegetation changes in iconic, climate-sensitive, high-elevation mountainous ecosystems present in southwestern New Mexico. In a later phase of the project, a variety of public audiences will participate through interactive online story maps and citizen science programs such as iNaturalist , Notes from Nature , and BioBlitz . Images of herbarium specimens will be shared via an online database and other relevant biodiversity portals ( Symbiota , iDigBio , JStor ) Community members reached through this project will be better-informed citizens, who may go on to become new stewards of natural history collections, with the potential to influence policies safeguarding the future of our planet’s biodiversity. More locally, the project will support the management of Organ Mountains Desert Peaks National Monument, which was established in 2014 to protect the area's human and environmental resources, and for which knowledge and data are currently limited. 
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  3. Abstract

    The cover of woody perennial plants (trees and shrubs) in arid ecosystems is at least partially constrained by water availability. However, the extent to which maximum canopy cover is limited by rainfall and the degree to which soil water holding capacity and topography impacts maximum shrub cover are not well understood. Similar to other deserts in the U.S. southwest, plant communities at the Jornada Basin Long‐Term Ecological Research site in the northern Chihuahuan Desert have experienced a long‐term state change from perennial grassland to shrubland dominated by woody plants. To better understand this transformation, and the environmental controls and constraints on shrub cover, we created a shrub cover map using high spatial resolution images and explored how maximum shrub cover varies with landform, water availability, and soil characteristics. Our results indicate that when clay content is below ~18%, the upper limit of shrub cover is positively correlated with plant available water as mediated by surface soil clay influence on water retention. At surface soil clay contents >18%, maximum shrub cover decreases, presumably because the amount of water percolating to depths preferentially used by deep‐rooted shrubs is diminished. In addition, the relationship between shrub cover and density suggests that self‐thinning occurs in denser stands in most landforms of the Jornada Basin, indicating that shrub–shrub competition interacts with soil properties to constrain maximum shrub cover in the northern Chihuahuan Desert.

     
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