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Martha Wohlfeil Zillig

Abstract (from Remote Sensing in Ecology and Conservation): The use of unmanned aerial vehicles (UAVs) to map and monitor the environment has increased sharply in the last few years. Many individuals and organizations have purchased consumer‐grade UAVs, and commonly acquire aerial photographs to map land cover. The resulting ultra‐high‐resolution (sub‐decimeter‐resolution) imagery has high information content, but automating the extraction of this information to create accurate, wall‐to‐wall land‐cover maps is quite difficult. We introduce image‐processing workflows that are based on open‐source software and can be used to create land‐cover maps from ultra‐high‐resolution aerial imagery. We compared four machine‐learning...
Cheatgrass (Bromus tectorum) has increased the extent and frequency of fire and negatively affected native plant and animal species across the Intermountain West (USA). However, the strengths of association between cheatgrass occurrence or abundance and fire, livestock grazing, and precipitation are not well understood. We used 14 years of data from 417 sites across 10,000 km(2) in the central Great Basin to assess the effects of the foregoing predictors on cheatgrass occurrence and prevalence (i.e., given occurrence, the proportion of measurements in which the species was detected). We implemented hierarchical Bayesian models and considered covariates for which > 0.90 or < 0.10 of the posterior predictive mass...
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