Ecological Applications最新文献

Coastal subarctic systems are inhabited by bivalve and gastropods, which due to their lifecycle and longevity are reliable indicators of ecological alterations in the environment. Recent laboratory studies have shown that young life stages of invertebrates perceive natural sounds, and their settlement, behavior, and fitness could be altered by anthropogenic noise. Through a field study conducted on two sites differing by their noise pollution level (pristine [PS] or anthropized [AS]), we tested whether the distances (from 25 to 890 m) of anthropogenic noises might affect the diversity and early recruitment of multiple species in pristine and anthropized sites using artificial collectors moored on transects. Overall, environmental conditions (except sound levels) were homogeneous through the transects. The acoustic scenario differed between the PS (vessel noise, 132–138 dB re 1 μPa² s) and AS (mix of pile driving and vessel noise, >140 dB re 1 μPa² s) sites, with the AS site experiencing a higher level of sound exposure than the PS site. Species richness fluctuated with distance from the noise, but only in the anthropized site. Regarding species diversity and evenness, they varied with distance and month at both sites, displaying a clear negative effect of anthropogenic noises and shifting species composition. Specific early recruitment responses were observed for each species to anthropogenic noise, but with a different pattern for each site due to variations in sound pressure and exposure levels. The findings of our field study document, for the first time, that controlled anthropogenic noise emission leads to ecological shifts in community structure and population metrics of benthopelagic marine invertebrate species. To avoid disruptions in community structure and recruitment, we recommend that a noise threshold level for invertebrates should be below 140 dB re 1 μPa² s.

Global changes in disturbance regimes are reshaping ecosystems, driving shifts in species composition, diversity, and community structure. On islands, these effects are often pronounced due to their unique ecological contexts, including high levels of endemism and vulnerability to invasive species. Using three decades of longitudinal data, we examined vegetation dynamics on Santa Cruz Island, California (SCI), following the removal of feral ungulates, focusing on the interplay of convergence, divergence, and hierarchical complexity in community assembly. Specifically, we asked: (1) To what degree has species composition diverged within communities since ungulate removal? (2) Is there evidence of convergence in species composition among vegetation communities? Our analyses revealed patterns of divergence and convergence influenced by historical grazing intensity and local site variability. Divergence was most pronounced in grassland and fennel-dominated communities, where invasive species continued to dominate or alternate trajectories emerged. Conversely, convergence was observed among woody communities (e.g., coastal scrub, chaparral), characterized by increases in native shrub and tree cover. These shifts demonstrate the role of hierarchical complexity in ecological recovery, with local-scale processes such as competition and priority effects interacting with larger scale drivers like climate variability and disturbance legacies. Novel and hybrid ecosystems emerged in many areas, reflecting the interplay between native and invasive species because of a history of extreme disturbance. These findings demonstrate the challenges of managing ecological recovery in systems influenced by multiple perturbations. As global pressures on ecosystems increase, understanding the hierarchical dynamics of convergence and divergence offers critical insights for setting realistic conservation goals and managing biodiversity in recovering landscapes.

The conservation of native bees and other pollinators is an important consideration for the future of urban sustainability. Parks, urban gardens, cemeteries, and other green spaces can provide habitat space for both native and non-native pollinators in cities. These publicly managed green spaces are not evenly distributed across otherwise inhospitable urban landscapes. Buildings and other human-made structures could act as barriers to the movement of pollinators, especially in highly built-up cities. Little is known about how bees navigate cities, and finding suitable habitat in urban ecosystems may be particularly difficult for native solitary bees, which have small foraging ranges. In this study, we utilized open GIS data as well as open-source software (Quantum GIS and Python) to model the shortest flight paths between parks and other public green spaces in New York City, New York, USA. We also used open light detection and ranging (LiDAR) data to assess plausible pollinator habitat in New York City parks. We found that the majority of straight-line (Euclidean) paths between parks intersected at least one building and that shortest paths around buildings were generally 20% longer than their Euclidean equivalent. We found that most managed properties alone, or within connected clusters, did not have sufficient plausible pollinator habitat to support pollinators with medium foraging distances, which include most solitary native bees. Our findings suggest limited connectivity and potential barriers between managed properties in New York City. Increasing pollinator habitat within smaller managed properties and building green roofs on shorter buildings and establishing stepping stone habitats like tree pits and vacant lots could increase overall green space connectivity. This technique for assessing connectivity between green spaces utilizes open data and tools that can be used by conservationists, planners, and policymakers to explore questions related to supporting pollinators or other species of interest in urban landscapes.

Restoring a low-intensity, frequent-fire regime in fire-prone forests offers a promising natural climate solution. Management interventions that include prescribed fire and/or mechanical treatments have effectively reduced fire hazards in the Western United States, yet concerns remain regarding their impact on forest carbon storage. This study used results from a long-term, replicated field experiment to assess the impacts of a restored disturbance regime on carbon dynamics in a Sierra Nevada, mixed conifer forest. The carbon consequences of the treatments were compared to a dynamic baseline of untreated controls (Control). After 19 years of wildfire mitigation, all treated stands stored less carbon than Control, but a larger proportion was sequestered in wildfire-resistant pools (i.e., large trees or fire-resistant species). Notably, only the most intensive treatment regime—thinning, mastication, and prescribed fire (Mech+Fire)—became a net carbon source by Year 20 (−60 MgC/ha). Annual average net ecosystem productivity (NEP) in Control and prescribed fire-only (Fire, 5.6–5.8 MgC/ha/year) more than doubled that of the mechanical treatments (2.0–2.1 MgC/ha/year). Moreover, temporal trends diverged. By the 3rd post-fire interval, the live vegetation carbon accumulation stalled in Control (0.9 ± 1.0 MgC/ha/year, mean ± SE) and accelerated in Fire (6.6 ± 1.2 MgC/ha/year). In contrast, surface fuel recovery was initially faster in Fire but slowed significantly by the 3rd interval, suggesting that the increased productivity under a frequent-fire regime does not necessarily lead to rapid surface fuel buildup once the regime is established. A simulated wildfire in Year 20 killed 6×–16× more live tree carbon in Control (46% mortality). Still, Control maintained the highest post-fire carbon storage. Despite the inherent carbon costs of wildfire mitigation, our 20-year study highlights management pathways that minimize the trade-off between wildfire hazard and carbon storage in Sierra Nevada mixed conifer forests.

Recreation (i.e., hiking and biking) and hunting can occur simultaneously in time and space, and both sources of disturbance affect wildlife behavior, leading to reactions resembling anti-predator behavior. However, the additive effects of lethal and non-lethal human disturbances on wildlife are only beginning to be understood, and research on the impact of hunting on non-target species is limited. Recreation and hunting commonly co-occur in areas where wildlife is present, and understanding their combined effects on wildlife behavior is crucial for protected area management. Using records from 122 camera traps placed along trails and in surrounding forests, we assessed the effect of varying intensities of hunting and recreation over space and time on the temporal activity of red deer (Cervus elaphus), roe deer (Capreolus capreolus), wild boar (Sus scrofa), red fox (Vulpes vulpes), and Eurasian lynx (Lynx lynx) in the Bavarian Forest National Park, Germany. We documented the relative abundance of these species on trails versus in forests and applied Bayesian models to assess how hunting and recreation influenced wildlife nocturnality. Our results suggest that hunting is a strong driver behind wildlife temporal behavior. Hunting amplified avoidance of non-lethal recreation and potentially impacts species interactions. Red deer exhibited the most pronounced temporal avoidance of both hunting and recreational activity, increasing nocturnality and trail avoidance as these disturbances increased. Red deer were more diurnal in the non-hunting zone and decreased nocturnal activity with increasing distance from the hunting zone. Wild boar and non-hunted species exhibited moderate or negligible responses. However, high hunting effort led to species not targeted by hunting (roe deer and red fox) increasing their temporal avoidance of recreational activities, with wild boar and roe deer avoiding trails more strongly. In the context of protected area management, our results suggest that strictly reducing hunting in space and time while concentrating recreation in certain areas to create disturbance-free habitat year-round has great potential to reduce the temporal avoidance of humans by wildlife, thereby fostering nature conservation goals by protecting natural processes.

Supratidal forests are defined by their position relative to the tidal frame where inundation and salinity patterns are potentially influenced by both tidal and nontidal regimes. Despite their recent inclusion in national blue carbon initiatives, knowledge of the processes that influence their carbon storage in supratidal forests remains limited. In this study, we report on new datasets of vegetation structure, carbon cycling parameters, inundation, and salinity patterns across 18 sites spanning more than 4000 km of Australia's temperate coastlines. We report site-specific ecosystem carbon stocks ranging from 169 to 635 Mg C_org ha⁻¹, with mean aboveground biomass (134 ± 63 Mg DM ha⁻¹) and belowground carbon stocks to 1 m soil depth (193 ± 98 Mg C_org ha⁻¹), which are within the range of national estimates for mangrove and saltmarsh ecosystems. While there are variations in vegetation structure between sites dominated by the genera Melaleuca and Casuarina, this does not lead to discernible differences in above- or belowground carbon stocks. Organic matter decomposition trends within supratidal forest substrates were similar to those of adjacent mangrove and saltmarsh, though there were differences among study sites and between labile and recalcitrant tea litters. Soil–atmospheric flux measurements conducted at one site were also within the range of adjacent blue carbon ecosystems. We hypothesize that the high degree of preservation of belowground carbon and low soil–atmosphere flux of greenhouse gases is driven by a combination of infrequent surface inundation, high water tables, and typically saline groundwater in supratidal forests, as measured across multiple settings. Supratidal forests are carbon-rich ecosystems influenced by coastal processes associated with tidal inundation. While further research is required to understand the full distribution, carbon cycling, and abiotic drivers of supratidal forests, our findings strongly support their inclusion in blue carbon and other management initiatives that support the response and recovery of these endangered ecological communities in a time of change.

Invasive species present one of the most challenging threats to native biodiversity, particularly when they hybridize with imperiled native taxa. In California, hybridization between the endangered California tiger salamander (“CTS,” Ambystoma californiense) and the invasive barred tiger salamander (“BTS,” Ambystoma mavortium) is one of the best understood examples of this management challenge. Reclusive life history and cryptic hybridization, often on private land, render eradication programs difficult or impossible. This study evaluates hydroperiod management as a tool to conserve and maintain native CTS populations threatened by hybridization. We adapt a recent, empirically informed Bayesian integral projection model (IPM) for CTS to incorporate new results that link genotype and ecology to fitness, and use this individual-based model to evaluate alternative management scenarios. We found overwhelming support for the importance of hydrology in both native and hybrid populations, where a 10-day increase in hydroperiod can increase population growth rate ($��\lambda �$) 17% and triple the carrying-capacity (K). We assess hydroperiod management as a strategy to control and contain hybrid introgression, and suggest a three-pronged strategy. First, for native populations not at risk of hybridization, hydroperiod should be increased to >120 days to support robust populations. Second, within the geographic hybrid zone, hydroperiod should be reduced to limit hybrid populations, maintain vernal pool function, and improve the efficiency of adult hybrid removal. Finally, our models indicate that managers should combine hydroperiod management with rapid field-based genotyping and hybrid removal, focusing on ponds where hybrids are rare, typically at the leading edge of the hybrid swarm. Efforts should also prioritize high-intensity surveys and early removal as opposed to long-duration (10+ years), lower effort surveys. This study demonstrates the value of integrating demographic, genetic, and ecological information to evaluate strategies for endangered species management, and may serve as modeling framework for a wide variety of imperiled species.

In arid and semiarid regions, extreme, extended droughts are becoming more frequent due to climate change. Drought is driving wildlife to seek out food or water resources where they are not as limited, such as in irrigated croplands. We collected GPS locations from 41 mule deer, a generalist herbivore reliant on primary productivity, within three study areas in Utah, USA, during a summer without drought conditions and a summer with extreme drought. This natural experiment provided an opportunity to assess how mule deer shifted their habitat selection, specifically whether drought increased mule deer's use of anthropogenic resources. We integrated remotely sensed estimates from ECOSTRESS, an instrument mounted on the International Space Station that measures evapotranspiration, to characterize a shift in resource use. Mule deer resource use was strongly influenced by the amount of evapotranspiration. In the drought year, shrub habitats lost succulence and mule deer avoided them (57.0% shrub habitat use in baseline vs. 44.6% during drought) and sought out agricultural croplands (increase from 6.2% to 11.8% from baseline to drought). Critically, this behavioral switch from shrub to crop was mediated by the rate of evapotranspiration and we identify the shift when evapotranspiration was >1.03 mm/day. We estimated that the proportion of shrub habitat in the study area with evapotranspiration >1.03 mm/day dropped from 68.8% to 27.2% between the baseline and the acute drought year. Evapotranspiration measured by ECOSTRESS provides complementary information to normalized difference vegetation index (NDVI), a commonly used metric of vegetative greenness, and offers a mechanistic understanding of ungulate resource use that increases the performance of habitat selection models for herbivores. As the impacts of climate change become more acute, wildlife will be drawn from natural areas to locations with anthropogenic resources, elevating the risk of human–wildlife conflict and mortality. Our study points to the need for the use of new data streams, like data derived from ECOSTRESS, into adaptive wildlife management and climate change adaptation planning to minimize human–wildlife risk and damages to humans.

Revealing the ecological impact of reclaimed water (RW) replenishment on bacterioplankton communities is crucial to promote RW utilization, yet less attention has been paid to the RW headwater urban stream with continuous RW recharge. Here, we collected water samples from Lujia stream to investigate the bacterioplankton community diversity, network, and assembly in spatiotemporal variation. Based on statistical analyses, bacterioplankton diversity in the midstream section was the lowest, especially in the dry season. Furthermore, spatial heterogeneity was more significant than seasonal heterogeneity for both biotic and abiotic factors. Dissolved oxygen and nitrite were the environmental driving factors of the bacterioplankton community in the wet and dry seasons, respectively. Intriguingly, a series of indicator bacteria related to nutrient nitrogen cycling were identified in the midstream section. Meanwhile, co-occurrence network analysis showed that the midstream section had the strongest competitive antagonism. Furthermore, the results of community assembly also showed that the midstream section harbored the highest proportions of stochastic processes, which were obviously different from the two other sections. Consequently, the midstream section was presumed to be a community coalescence area. Overall, our findings not only filled gaps in understanding the characteristics of bacterioplankton communities in long-term RW headwater urban streams but also highlighted the importance of the midstream section as a key objective of river restoration and management.

The misalignment of species adaptations with current environmental conditions can cause ecosystems to lose resilience, accumulate resilience debt, and transition to another state. Such a state change is evident in eastern North American broadleaf forests where dominant tree species are shifting from oaks (Quercus spp.) to mesophytic species such as maples (Acer spp.). The replacement of oaks is widespread and threatens the ecosystem services these forests provide, generating interest in using forest management to halt or reverse this change. The national Fire and Fire Surrogate (FFS) study was a large-scale study of forest management practices, and the Green River FFS site in western North Carolina (initiated in 2001) offers the opportunity to understand how management actions affect oak forest resilience. The Green River FFS site implemented three experimental treatments replicated across three spatial blocks: mechanical felling of saplings and ericaceous shrubs (Mech), prescribed fire (Fire), and a combination (Mech + Fire), which were compared to untreated controls (Control). Here, we used this long-running experiment to evaluate oak forest resilience by examining changes in overstory basal area and forest composition among overstory trees, saplings, and seedlings. We found that basal area increased in the Control and Mech treatments, was unchanged in the Fire treatment, and decreased in the Mech + Fire treatment as a result of mortality. Oak sapling abundances increased with reduced basal area, a pattern not found with the major mesophytic representative, maples. This suggests that oaks are well positioned to recruit to the overstory where basal area has decreased due to overstory mortality, and at the Green River FFS site, this was best achieved in the Mech + Fire treatment. Creating conditions where oak saplings have an advantage over maples requires the mortality of some overstory trees, including desirable oaks. Taken together, our findings suggest that the misalignment of oak traits and current environmental conditions has led to resilience debt, which may be reduced when management actions mimic a severe disturbance that results in the opening of the canopy. Thus, management actions that combine mechanical felling and repeated prescribed fires may promote sustained oak dominance in the future.