Abstract High‐elevation Andean peatlands hold particularly deep, dense carbon deposits even among peatlands and are a major regional carbon stock. These peatlands are often used for open‐range cattle grazing, which has the potential to destabilize peat carbon stocks, releasing greenhouse gases (GHG) in the form of CO 2 and CH 4 . There is currently very little information on the impacts of grazing on undrained or partially drained peatlands. We tested the hypotheses that (1) grazing increases GHG emissions (CO 2 and CH 4 ) from Andean peatlands in general when measured across a wide range of different vegetation types and water table depths and (2) the magnitude of impact of grazing on CO 2 and CH 4 emissions varies by dominant vegetation type. We conducted a survey of CH 4 and CO 2 fluxes at 31 high‐elevation peatlands across Ecuador. We then quantified the influence of environmental parameters (water table depth, vegetation type, and grazing pressure) on GHG emissions. We found that heavier grazing intensities were associated with increased CH 4 emissions and that the effect of grazing on CH 4 emission was largest in areas with high water tables and sedge‐dominated vegetation. Grazing in cushion plant‐dominated peatlands also increased both gross primary productivity and ecosystem respiration, with the net effect of increasing CO 2 release and an overall increase in global warming potential. Overall, our results support the hypothesis that grazing leads to increased GHG emissions from tropical Andean peatlands, with the effect size dependent on vegetation type, degree of drainage, and the intensity of grazing.
Abstract Expanding human activities increasingly influence animal movement. Yet, conservation interventions often overlook intraspecific variation in how movement is structured across populations inhabiting distinct ecosystems. For wide‐ranging generalists such as African savanna elephants ( Loxodonta africana ), understanding how responses to resource availability and anthropogenic pressure vary across populations is critical for effective conservation planning. Here, we analyze long‐term GPS tracking data from 175 African elephants to contrast how movement is structured across mesic (Mara–Serengeti) and xeric (Samburu–Laikipia) savannas in East Africa. We delineate the landscape of elephant movement (a “movescape”), using a network‐based approach that integrates movement path, use intensity, and connectivity metrics to describe how animals use discrete locations for different functions. We focused on identifying highly used areas and movement corridors, then used mixed‐effects spatial regressions to evaluate how environmental context influenced the occurrence of these areas within and across ecosystems. All analyses in Mara–Serengeti represent a new application of this framework and are compared with previously published results from Samburu–Laikipia. Elephant movement structure differed between ecosystems. In the Mara–Serengeti, movement networks were dense and clustered, with more locations used repeatedly and connected by redundant pathways. Movement in Samburu–Laikipia was more spatially dispersed. Most locations were used by elephants with low intensity, and connectivity was concentrated in fewer corridors. Across both ecosystems, core‐use areas comprised a small proportion of the landscape, highlighting locations where conservation efforts could be targeted in unprotected areas. In the Mara–Serengeti, elephants concentrated use in areas with low boma density and away from villages. In Samburu–Laikipia, core areas and corridors were strongly associated with permanent water and consistent vegetation productivity, likely reflecting more ecological constraints on movement. Conservation planning in the Mara–Serengeti could prioritize riparian woodlands and bush thickets on hillsides to protect connectivity between core elephant areas. In Samburu–Laikipia, protecting existing limited corridors that provide access to seasonally productive forage and access to permanent natural water sources could be effective. Our combined delineation of core‐use areas and the corridors that link them provides a framework for prioritizing both core habitat patches and the movement pathways that sustain landscape‐scale connectivity.
Abstract There is increasing evidence that the traits of organisms can differ in urban environments, but defining what makes an environment “urban” is difficult. There are many variables associated with increasing human impacts that might be associated with urbanization, and this makes it challenging to identify both how traits vary across diverse urbanized landscapes and the variables that might drive that variation. To better define the mosaic of urban environmental heterogeneity and identify similar environments that are comparable across its complexity, we developed a multivariate landscape classification framework and applied it to classification of land area in the state of California, USA. We then asked if these multivariate Environmental Zones were better able to explain trait variation than univariate urban versus nonurban dichotomies or gradients, using a case study of the invasive, annual plant Maltese starthistle ( Centaurea melitensis ), commonly found throughout much of California. We used a hierarchical cluster analysis to group 7829 government census tracts into Environmental Zones based on a set of 19 independent environmental characteristics, including climate, land cover, pollution, and socioeconomic variables. This analysis identified nine major Environmental Zones, which were differentiated based upon complex combinations of variables that did not align with urban versus natural dichotomies or gradients. Environmental Zones also occurred as mosaics of many zones within cities and differed in their relative abundance between cities, reflecting complex urban landscapes unique to each area. Seeds from 17 populations of Maltese starthistle were collected from six of the Environmental Zones, including two more heavily urbanized zones, and four more natural/agricultural. Seeds were grown in greenhouse conditions, and eight vegetative traits were measured. No trait differed significantly between qualitatively urban versus nonurban sites, or across a quantitative gradient of impervious surface area, but four traits differed according to Environmental Zones (length of longest leaf, specific leaf area [SLA], root diameter, and the number of flowerheads). Traits differed between the more urbanized zones, as well as among the more natural zones. Our results reveal that more complex multivariate classifications of the urban mosaic can identify similar, comparable environments across complex landscapes and better explain trait variation in organisms navigating urbanized environments.
Abstract Documenting distributional shifts in populations is critical for understanding ecosystem function and developing effective conservation strategies, particularly for rare and understudied species. The Critically Endangered eastern population of North Pacific right whale (NPRW) was driven to near extinction by commercial whaling and has not recovered ( N < 35). We analyzed passive acoustic data from seven sites along the eastern Bering Sea shelf (2012–2019) to investigate spatial and environmental associations of NPRW calling patterns on a rapidly warming primary foraging ground. Generalized additive models were used to relate acoustic metrics summarized by ecological year (March–February) to environmental conditions at two scales: (1) cold pool extent (CPE), a shelf‐scale hydrographic feature derived from seasonal sea ice meltwater that structures right whale prey, and (2) site‐specific mean fall bottom temperature (BT), a local thermal expression of cold pool conditions and fall mixing. NPRW phenology, specifically spring arrival and fall departure, was modeled against sea ice retreat and formation dates. NPRW calls occurred at all sites but were most consistently detected within Critical Habitat in the southeastern Bering Sea (SEBS). Calling activity expanded northward during consecutive years of lower CPE (2014–2016), whereas overall few detections occurred during record‐low CPE years (2018 and 2019), suggesting a redistribution associated with environmental conditions. While spatial structure explained much of the observed variation, models incorporating CPE and BT received greater and comparable support, suggesting that NPRW calling patterns are associated with habitat conditions generated by cold pool processes rather than single metrics. The strength of environmental effects implied greater sensitivity of calling intensity to environmental variability than calling occurrence. Significant environmental relationships were restricted to the SEBS, where detections increased with CPE and decreased with warming BTs, consistent with known prey‐temperature associations. These results, combined with no significant trends between whale phenology and sea ice timing, suggest that NPRW calling patterns are associated with trophically mediated effects of sea‐ice‐driven oceanography rather than direct responses to ice timing. More broadly, this study demonstrates how long‐term passive acoustic monitoring can reveal climate‐associated changes in marine predator calling patterns and link detected calling to ecosystem processes operating across spatial scales.
Abstract As resource managers strive to balance marine ecosystem health and services with diverse ocean uses, the spatial and temporal dynamics of species distributions—and their overlap with both static and dynamic human activities—should be carefully considered. Anthropogenic activities and management decisions rarely affect only one species, underscoring the need for spatially and seasonally resolved, multispecies approaches to inform conservation prioritization for effective marine spatial planning. We conducted at‐sea visual surveys for seabirds using strip transect methods during spring, summer, and fall in the Northern California Current over 2 years (2022–2024). Using this dataset, we developed density surface models to describe and predict the seasonal distribution and density of the 22 most abundant seabird species. We then applied spatial clustering to identify seasonal hotspots and coldspots of three distinct metrics: (1) seabird density, (2) species diversity, and (3) relative abundance of conservation‐priority species. To demonstrate management implications associated with using each of these metrics, we evaluated how hotspots and coldspots overlapped with proposed offshore wind energy areas and seasonal commercial fishing activity. Hotspots and coldspots differed both spatially and seasonally, depending on the metric used to construct them. For example, some locations simultaneously supported a density coldspot and a diversity hotspot, and others were a coldspot for conservation‐priority species in spring but a hotspot in summer. Notably, there were no locations where hotspots defined by all three metrics overlapped. Though this study is not an impact assessment, our results have implications for marine spatial planning. In particular, multispecies metrics associated with abundance and diversity may have contrasting implications for spatial management strategies, necessitating careful a priori identification of management objectives. Our study illustrates how hotspots and coldspots can be used to evaluate potential conflicts between marine species and static (offshore wind development areas) and dynamic (seasonal fishing activity) human uses of marine regions. The choice of metrics to define hotspots and coldspots can shape conclusions about conflict or compatibility between species conservation and human use of marine resources.
