Giant reed (Arundo donax) has invaded biologically diverse riparian ecosystems in warm and arid regions globally, yet its impacts on wildlife are still poorly understood. Resolving the multi-taxa, scale-explicit impacts of giant reed in the broader context of the riparian vegetation mosaics that support wildlife can help target ecological restoration efforts. We quantified effects of giant reed and other dominant riparian vegetation on bird and butterfly habitat occupancies at two spatial scales along the Rio Grande in west Texas, USA. Birds and butterflies are diverse in riparian systems and can be efficiently surveyed, making them useful indicator taxa. We surveyed 167 sites three times per year in 2016 and 2017, and used occupancy models to relate occupancy to cover proportions of dominant vegetation types derived from high-resolution aerial imagery at two scales (100 m and 500 m radii) to assess local vs. broader floodplain-scale effects. Five of 16 bird species (31
Soil microbial communities regulate key ecosystem functions, from nutrient cycling to organic matter decomposition. Yet, we lack a basic understanding of how microbial predators, such as collembola, influence these functions via microbial mediation. This study aims to investigate how collembola (Folsomia candida) influence soil microbial communities and associated ecosystem functions in a grassland context. We conducted a microcosm experiment simulating grassland vegetation, including high and low microbial diversity with and without the collembola F. candida. We measured microbial community composition, enzyme activities, nutrient cycling, and plant biomass to evaluate collembola effects on soil function. Collembola influenced microbial community composition, likely through feeding preferences, which in turn affected nutrient cycling and function. Soil microbial diversity promoted nutrient cycling, and F. candida inoculation supported even stronger positive effects on nutrient cycling and plant biomass. The effects of collembola on soil function were indirectly driven via changes in microbial taxa, leading to greater N-acetylglucosaminidase activity and nutrient cycling potential. Our results demonstrate that springtail-mediated top-down effects can significantly alter carbon and nitrogen cycling by regulating microbial community composition in controlled microcosms. These findings highlight the necessity of incorporating trophic interactions and their underlying mechanisms into ecological models to improve predictions of belowground processes, while caution is required when extrapolating these insights to more complex natural ecosystems.
During periods of heightened wildland fire activity in the United States, multiagency coordinating groups must prioritize among multiple on-going fires to allocate scarce suppression resources. While many studies have explored factors that influence wildfire suppression expenditures and personnel allocation, understanding the specific factors that affect daily wildfire prioritization has remained unexplored. In this study, we first examine wildfire reporting and ranking processes across different regions of the United States to provide insight into criteria used for fire ranking. We then focus on examining the 12 criteria used for ranking fires daily by California's multiagency coordination group. We developed a computer program to replicate the California prioritization process and found that fire rankings generated by this program align well with the historical rankings, indicating close adherence of California's fire managers to their ranking rules. A correlation analysis revealed weak correlations among the 12 criteria, suggesting that no criterion should serve as a proxy for another during fire priority evaluations. We further applied a Random Forest machine learning model, which identified threats and damage to structures, fire size, and evacuations as the most impactful criteria in determining fire priority. Our findings can benefit wildfire decision makers by providing clear insights into the existing wildfire priority assessment process, so that adjustments to the process can be made for better management outcomes. Policymakers can also leverage these insights to develop evidence-based fire management policies, regulations, and practices that promote more efficient responses to fire risks while fostering greater public trust in fire management efforts.
Over the last half-century, land use changes, including deforestation, urban sprawl, and open-pit surface mining, have accelerated across the Susurluk Basin in northwestern T & uuml;rkiye. This study analysed how land use changes, damming and mining activities affected basin hydrology using empirical and analytical methods and the process-based Water Supply Stress Index Model (WaSSI). The monthly WaSSI water balance model was validated using streamflow data from gaging stations between 1980 and 2005. Two of the eight subbasins exhibited streamflow reductions of about 32%-42%, with mean annual discharge decreasing between 1980-1989 and 1990-2005, primarily due to land use change rather than climate variability. The runoff coefficient (Runoff/Precipitation) dropped from 22% during 1980-1989 to 12% during 1990-2005 in one rural subbasin containing several surface-mine ponds. Overall, empirical and process-based modelling indicated that land use dynamics, rather than climate, were responsible for the hydrological change. The monthly WaSSI showed satisfactory performance in subbasins with low human impacts (NSE > 0.50) but considerably lower performance (NSE < 0.20) in highly human-modified areas. This integrated study concludes that land use activities, especially pond creation for pit mining, were the dominant drivers of hydrological changes in the study area.
Enemy release may promote plant invasions and trigger rapid evolution in traits related to growth and defence in non-native populations. However, to what extent plants escape enemies, such as root-associated pathogens, is little known as comparisons between native and non-native ranges remain scarce. Also, whether plant-pathogen interactions vary between native and non-native populations under common garden conditions, and if such differences coincide with plant performance, is poorly understood. We identified putative fungal pathogens (hereafter pathogens) in roots and rhizosphere soil of the invader Conyza canadensis. We sampled 17 populations in the native range and 17 in the non-native range spanning wide and comparable environmental gradients across both ranges. We also sampled soil from adjacent plant communities where C. canadensis was absent. Potential evolutionary shifts in how C. canadensis shapes pathogen communities were assessed by growing native and non-native populations in native soil in the glasshouse (round 1). We then grew seedlings from the same populations in their conditioned soil from round 1 and compared growth to plants grown in sterile soil (round 2). Pathogen communities were dominated by generalist taxa and differed between ranges for both C. canadensis and adjacent communities. However, pathogen richness associated with C. canadensis was greater in the non-native range and proportionally more pathogens occurred in the rhizosphere than in roots relative to C. canadensis in the native range. The ratio of pathogen abundance in rhizosphere versus roots correlated positively with C. canadensis shoot biomass in the non-native, but not native, range. In the glasshouse, non-native C. canadensis promoted more and different pathogens in the rhizosphere than native C. canadensis in round 1, yet was less suppressed by soil biota in round 2. Synthesis. Differences in pathogen communities across ranges may have caused evolutionary changes in plant-pathogen associations in C. canadensis. Populations from the non-native range accumulated pathogens in their rhizosphere while appearing better defended, which coincided with greater performance in both the field and glasshouse relative to native populations. Our findings are relevant to shifting defences, fungal multifunctionality, and the overlooked role of generalist pathogen accumulation in exotic plant invasions.
