Treesearch

Evolutionary theory predicts that the process of range expansion will lead to differences in life-history and dispersal traits between the core and edge of a population. At the edge, selection and genetic drift can have opposing effects on reproductive ability, while spatial sorting by dispersal ability can increase dispersal. However, the context that individuals experience, including population density and mating status, also impacts dispersal behavior. We seek to understand the shifts in traits of populations expanding across natural, heterogenous environments, and the evolutionary and...

Restoration of fire-prone forests can promote resiliency to disturbances, yet such activities may reduce biomass stocks to levels that conflict with climate mitigation goals. Using a set of large-scale historical inventories across the Sierra Nevada/southern Cascade region, we identified underlying climatic and biophysical drivers of historical forest characteristics and projected how restoration of these characteristics manifest under future climate. Historical forest conditions varied with climate and site moisture availability but were generally characterized by low tree density (∼53...

Effective conservation of at-risk species presents a conundrum, often requiring rapid status assessments and timely actions regardless of the adequacy of best available information. Here, we present a case study on Humboldt martens (Martes caurina humboldtensis), a rare and cryptic carnivore listed as threatened in 2020 under the United States Endangered Species Act. Given their rarity, many aspects of Humboldt marten population ecology remain understudied. To help inform marten conservation, we conducted exploratory analyses to estimate population growth by incorporating empirically...

Vocal territory defense can vary within a species due to many factors such as sex and breeding status, influencing territory size and thus population density across a landscape. Therefore, understanding what influences variation in territorial vocalizations can help to illuminate trade-offs between territoriality and other life history demands, which benefits our general understanding of animal ecology as well as helps to inform emerging passive acoustic monitoring approaches. Here, we investigated how sex and breeding status affected territoriality and vocal behavior in the California...

Rapid environmental changes challenge the resilience of wildlands. The western portion of the Lake Tahoe Basin in California is an important ecological and cultural hotspot that is at risk of degradation from current and future environmental pressures. Historical uses, fire suppression, and a changing climate have created forest landscape conditions at risk of drought stress, destructive fire, and loss of habitat diversity. We prospectively modeled forest landscape conditions for a period of 100 years to evaluate the efficacy of 5 unique management scenarios in achieving desired landscape...

Spruce beetle, Dendroctonus rufipennisKirby (Coleoptera: Curculionidae), causes significant mortality of mature spruce, Piceaspp. (Pinales: Pinaceae), in western North America. We evaluated the effectiveness of two formulations of bole injections of emamectin benzoate (TREE-äge® G4 and TREE-äge R10; Arborjet, Inc., Woburn, MA) alone and combined with propiconazole (Propizol®; Arborjet, Inc.) for protecting Engelmann spruce, Picea engelmanniiParry ex Engelm., from mortality attributed to colonization by D. rufipennis. Treatments were injected 16–19 July 2017, and levels of Pi. engelmanniimor...

Invasive predators can have detrimental impacts on native species and biological communities through direct consumptive effects and indirect effects on trophic interactions, yet these relations are often poorly understood through the initial stages of predator expansion. Leveraging early, lethal collection efforts to study invasive barred owls (Strixvaria) at the leading edge of their range expansion in northeastern California, we conducted DNA metabarcoding of intestinal samples to assess the diet of this invasive predator. Through the development of customized primers and this novel...

Unlike streamflow, which can be sampled in aggregate at the catchment outlet, evapotranspiration (ET) is spatially dispersed, challenging large-scale age estimation. Here, we introduce an approach for constraining the age of ET via mass balance and present the minimum flux-weighted age of ET across the continental United States using distributed, publicly available water flux data sets. The lower-bound constraint on ET age can be calculated by assuming that ET is preferentially sourced from the most recent precipitation through a last-in, first-out algorithm. From 2012 to 2017, ET was at...

1. Bats play crucial ecological roles and provide valuable ecosystem services, yet many populations face serious threats from various ecological disturbances. The North American Bat Monitoring Program (NABat) aims to use its technology infrastructure to assess status and trends of bat populations, while developing innovative and community-driven conservation solutions. 2. Here, we present NABat ML, an automated machine-learning algorithm that improves the scalability and scientific transparency of NABat acoustic monitoring. This model combines signal processing techniques and convolutional...

Water budgets are essential for characterizing water supplies from snow-dominated upland catchments where data are sparse, groundwater systems are complex, and measurements are prone to error (ε). One solution is imposing water budget closure (CWB) by ignoring difficult-to-measure variables, including inter-basin groundwater fluxes (G) and ε. However, conventional CWB-based analyses, which derive evapotranspiration (ET) from precipitation (P) and streamflow (Q) (e.g., the Budyko hypothesis), are limited in their ability to take advantage of recent advances in ETproducts, physically-based...