Ecological Applications[JOURNAL]
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200 papers
Building genomically-informed demographic models to guide management of invasive hybrids.
Cooper RD, Messerman AF, Searcy CA … +3 more , Toffelmier E, Grether GF, Shaffer HB
Ecol Appl · 2025 Oct · PMID 41131726 · Full text
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 salam...
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 ( ) 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.
Acute drought desiccates highly used habitat and drives herbivores into irrigated croplands.
Leclerc M, Ditmer MA, Stoner DC … +4 more , Wang P, Sexton JO, Hersey KR, Carter NH
Ecol Appl · 2025 Oct · PMID 41115775 · Full text
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 irrigat...
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.
Higher spatial than seasonal variation of microbial communities in long-term reclaimed water headwater urban stream.
Yu K, Meng J, Lu D … +6 more , Gan H, Chen H, Lou Y, Gao D, Zhu DZ, Yao Z
Ecol Appl · 2025 Oct · PMID 41115710 · Publisher ↗
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 continuou...
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.
Reducing resilience debt: Mechanical felling and repeated prescribed fires may sustain eastern oak forests.
Taylor MK, Hagan DL, Coates TA … +5 more , DeFeo JA, Callaham MA, Mohr HH, Waldrop TA, Wurzburger N
Ecol Appl · 2025 Oct · PMID 41111267 · Full text
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 easter...
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.
Can fire exclusion zones enhance postfire tree regeneration? A simulation study in subalpine conifer forests.
Keller TT, Abendroth DC, Braziunas KH … +5 more , Dollinger C, Hood PR, Knowlton GJ, Seidl R, Turner MG
Ecol Appl · 2025 Oct · PMID 41099191 · Full text
Climate change and novel fire regimes increasingly challenge stewardship of forests adapted to infrequent, stand-replacing fire. Novel fire regimes may disrupt mechanisms that sustained postfire regeneration historically...
Climate change and novel fire regimes increasingly challenge stewardship of forests adapted to infrequent, stand-replacing fire. Novel fire regimes may disrupt mechanisms that sustained postfire regeneration historically, and whether fire management can promote forest resilience to future fires is uncertain. We used the individual-based forest simulation model iLand to explore how fire exclusion zones that mimic historical burn mosaics may affect postfire tree regeneration in conifer forests of Grand Teton National Park (Wyoming, USA). We asked: (1) How do the amount and configuration of potential fire exclusion zones influence postfire tree regeneration throughout the 21st century under alternative climate scenarios? (2) How do "operational" fire exclusion zones affect postfire tree regeneration within burned patches and across the landscape by the end of the 21st century? We first conducted a factorial simulation experiment with varying amounts (10%, 30%, 50% of the landscape) and configurations (dispersed vs. clumped) of fire exclusion zones. Informed by this experiment and logistical firefighting considerations, we developed an operational scenario in which we designated mature forests surrounded by defensible fuel breaks as fire exclusion zones. Simulations were conducted under four future climate scenarios (warm-wet, hot-wet, warm-dry, hot-dry), and postfire tree regeneration densities with fire exclusion zones were compared to reference scenarios without fire exclusion zones. Regeneration of fire-avoiding conifers (subalpine fir, Abies lasiocarpa and Engelmann spruce, Picea engelmannii) was consistently greater with fire exclusion zones, especially with ≥30% of the landscape in dispersed configuration. Fire exclusion zones had minimal effects on regeneration of fire embracers (lodgepole pine, Pinus contorta var. latifolia) and fire resisters (Douglas-fir, Pseudotsuga menziesii var. glauca). In the operational scenario, postfire regeneration of fire-avoiding species was greater compared to the reference scenario, especially in hot climate scenarios. Although regeneration of fire avoiders declined in operational and reference scenarios throughout the 21st century, regeneration densities were up to 10 times greater in the operational relative to the reference scenario. Our results suggest that mimicking historical burn mosaics by establishing fire exclusion zones could sustain seed sources and afford more time for subalpine conifer forests to adapt to a warmer world with more fire.
Carbon dynamics following variable retention harvesting in boreal mixedwood forests.
Wu L, Bergeron JAC, Macdonald SE … +4 more , Nock CA, Langor DW, Xing D, Spence JR
Ecol Appl · 2025 Oct · PMID 41099071 · Full text
Retention harvests are promoted as an alternative to clearcuts to enhance ecological values in managed forests. Understanding how retention affects carbon (C) dynamics over time and in various forest types is important f...
Retention harvests are promoted as an alternative to clearcuts to enhance ecological values in managed forests. Understanding how retention affects carbon (C) dynamics over time and in various forest types is important for balancing objectives like timber production and C storage. This is particularly crucial now, as the climate mitigating effects of boreal forests are weakening due to both forest harvests and natural disturbances. Using data from a relatively long-term experiment (pre-harvest to 18-years post-harvest) in previously unharvested boreal mixedwood forest, we compared C pools (mature trees, regenerating trees and shrubs, deadwood, and soil) among harvest levels (clearcuts, 10%, 20%, 50%, 75% retention, and unharvested reference). Soil C appeared to be invariant at the scale of this study, so we focused our analyses on biomass in living and dead vegetation. Total pre-harvest C storage was greater in conifer-dominated and mixed stands than in deciduous (broadleaf)-dominated stands, reflecting mainly greater biomass in live trees but also in downed deadwood. Net loss of C from the forest up to 3-years post-harvest scaled with harvest intensity in all forest types. At 3- and 18-years post-harvest in deciduous and 3-years post-harvest in conifer stands, all retention harvests resulted in larger C stocks than clearcuts; only higher retention levels provided this benefit at 3- and 18-years post-harvest in mixed (75% retention) and at 18 years in conifer stands (50%, 75% retention). In some forest types, the highest retention levels (75% for deciduous and mixed stands, 50% and 75% for conifer stands) maintained total C stocks statistically equivalent to unharvested forest at both 3- and 18-years post-harvest. Deciduous stands became net C sinks by 3-7 years post-harvest, likely due to prolific aspen regeneration and growth. Mixed and conifer stands, however, were nearly C-neutral or were C sources until 12-18 years post-harvest. This reflected persistent effects of pre-harvest forest type, including less aspen regeneration, slower growth of conifer seedlings, and mortality of retained conifers. Our results suggest that strategic retention harvesting could serve as a practical option to couple C storage options to other management considerations.
Investigating the demography and dynamics of a low-density tiger population in Southeast Asia: What limits recovery?
Steinmetz R, Phumanee W, Phoonjampa R … +5 more , Keawsrisod T, Bunchornratana K, Dawrueng T, Bejraburnin T, Bhumpakphan N
Ecol Appl · 2025 Oct · PMID 41097810 · Full text
Prey depletion, direct poaching, and habitat fragmentation are driving global declines of carnivore species, but the specific consequences of these impacts on population demography have not been widely studied, obscuring...
Prey depletion, direct poaching, and habitat fragmentation are driving global declines of carnivore species, but the specific consequences of these impacts on population demography have not been widely studied, obscuring an understanding of why some populations recover while others flounder. This 11-year study sought to uncover what constrains recovery of a low-density tiger population in Thailand, by investigating population dynamics with respect to three key mechanisms potentially affecting vital rates: tiger poaching, prey depletion, and immigration. Our site resembled most Southeast Asian tiger populations in that tiger and prey abundance were both low, but it was unusual in sharing landscape connectivity with the largest tiger population remaining in Southeast Asia. We identified tigers with camera traps and applied a Pradel robust design model to estimate survival, recruitment, immigration, and population growth rate. We obtained information on cub production through observations of dependent young with their mother. The small population (7-11 adults) was stable over time but did not increase ( = 1.006). This inertia corresponded with the status of key prey species, which occurred at low density and had flat population trends. Female survival rate was high (0.823), but reproduction rate (0.514) and cub survival (0.313) were 2-3 times lower than other tiger populations in Asia where prey availability is higher. This pattern of flat population trend, high adult survival, and low reproduction is indicative of the effects of prey scarcity, rather than direct poaching, as the essential constraint on recovery. Most recruitment of new tigers came from immigration, with 67% of the resident females being born outside, rather than locally. High female survival plus immigration were critical to sustaining this population, and represent an essential foundation for future recovery, but this potential is impeded by prey scarcity which suppresses reproductive success. Managers can unblock the path to recovery by increasing abundance and distribution of preferred prey. This would allow resident females to reproduce more consistently and boost survival rates of their cubs, while creating new high-quality habitats for additional females to settle in, whether they are locally born or arrive through immigration.
A model for regional-scale oak savanna management: The roles of fire, canopy, and soils for understory plant diversity.
Bassett TJ, Behrens E, Grundel R … +3 more , Nifosi J, Pavlovic NB, Brudvig LA
Ecol Appl · 2025 Oct · PMID 41091097 · Full text
Predicting the outcomes of land management on biodiversity is difficult without a mechanistic understanding of how management approaches, ecosystem structure, environmental conditions, and biodiversity interact. Manageme...
Predicting the outcomes of land management on biodiversity is difficult without a mechanistic understanding of how management approaches, ecosystem structure, environmental conditions, and biodiversity interact. Management effects may be direct or indirect, context- or scale-dependent, or obscured by local environmental conditions. Resolving these relationships at the regional scale may be difficult, given heterogeneity in local environmental conditions, yet understanding broad-scale patterns can elucidate context dependencies and improve restoration outcomes. We confronted these challenges within globally rare oak savannas in the midwestern United States, which have been altered by fire exclusion and resulting woody encroachment. By modeling direct and indirect pathways by which management influences diversity, we test a general framework for savanna restoration. Across 100 oak savannas spanning five US states, management by prescribed fire and mechanical thinning of woody vegetation affected groundlayer plant species richness through changes to ecosystem structure (canopy openness and litter depth), and these effects were both context- and scale-dependent. Frequent prescribed fires and canopy thinning promoted greater canopy openness, which in turn increased richness at small (1 m), but not larger (1000 m) scales. Frequent fire additionally increased richness at small and larger scales through effects independent of ecosystem structure. While management effects were large relative to the influence of local edaphic conditions, soil productivity had two largely offsetting effects on small-scale richness, increasing richness directly but decreasing richness indirectly by promoting closed canopy structure. These results suggest using a combination of fire and canopy thinning to reverse the effects of decades of fire exclusion. However, management effects were also context-dependent, emphasizing that management outcomes vary regionally. Here, 1-m plant species richness increased with both fire frequency and canopy thinning under low, but not high, productivity soil conditions. By demonstrating how specific management practices influence savanna structure and biodiversity by manipulating ecological processes across broad geographic and edaphic gradients, our findings provide a framework for understanding management outcomes at short and medium intervals (e.g., within and between decades, respectively), in the form of a model that can be refined by testing additional hypotheses to better predict savanna restoration outcomes.
The recruitment niche of mountain birch (Betula pubescens ssp. tortuosa) and implications for woodland restoration.
Óskarsdóttir G, Svavarsdóttir K, Speed JDM … +1 more , Thórhallsdóttir TE
Ecol Appl · 2025 Oct · PMID 41085326 · Publisher ↗
The extensive restoration of fragmented woodlands calls for practices appropriate to large-scale efforts. These simultaneously require an understanding of ecosystem-level processes and the plant-scale environment. The re...
The extensive restoration of fragmented woodlands calls for practices appropriate to large-scale efforts. These simultaneously require an understanding of ecosystem-level processes and the plant-scale environment. The recruitment niche of the target species is crucial, that is conditions required for seed germination to seedling establishment. Our study contributes to underpinning the science behind successfully promoting the utilization of natural regeneration in woodland restoration in a subarctic environment. We identified the recruitment niche of the only native forest-forming species in Iceland. From 2018 to 2020, we quantified mountain birch seed accumulation, germination, and early seedling survival in relation to substrate types within 500-m-long transects at two study sites on Skeiðarársandur outwash plain, southeast Iceland. At the time of the study, the founding population in this early successional environment had recently reached reproductive maturity. Mountain birch seeds were most likely to accumulate on vegetated surfaces and to germinate in low-growing vegetation, with unimpeded sunlight. Survival was not significantly influenced by substrate types, but was surprisingly high (generally >50%) for the first 1-2 years, although most seedlings were still very small. Overall, recruitment was consistently greater than expected in thin moss (~1 cm), which may be considered a key substrate type for mountain birch recruitment success. Due to high cover of suitable substrate types in the study area, the spatial pattern of the first locally recruited generation of mountain birch was determined at the earliest life history stage, by dispersal limitation. Our study highlights the importance of the recruitment niche for successful restoration and of securing seed input when dispersal may be limited. This allows for scaling up the restoration of severely fragmented woodlands, for which the pending restoration of Icelandic woodlands serves as a case study. The rapid mountain birch establishment on Skeiðarársandur shows that woodland restoration may not need major interventions; however, they must be based on profound knowledge of colonizing processes. Thus, restoration with minimal human assistance can be a practical, low-cost option.
Maximizing the potential benefits of beaver restoration for fire resilience and water storage.
Moravek JA, Brashares J, Girotto M … +8 more , Spivak R, Kerr A, Molod A, Feirer S, Johnson R, Getirana A, Fairfax E, Ruhí A
Ecol Appl · 2025 Oct · PMID 41084124 · Full text
Restoring populations of native keystone species can increase landscape resilience to global change when those species create or modify ecosystems. The North American beaver (Castor canadensis) is an ecosystem engineer t...
Restoring populations of native keystone species can increase landscape resilience to global change when those species create or modify ecosystems. The North American beaver (Castor canadensis) is an ecosystem engineer that increases river water storage and residence time, increasing fire resilience at the landscape level. Beaver populations in North America are significantly lower than they were historically, but over the last decade, beavers have been increasingly recognized for their ecosystem services, and reintroduction efforts throughout their historic range have become more prevalent. Here, we modeled potential beaver dam-building capacity, associated surface water storage, and fire resilience in California's Sierra Nevada, a region at high risk of drought and wildfire. We estimate that 51% of beaver dam-building capacity remains in this region compared to historical levels, and considerable dam capacity remains in all watersheds. Our conservative estimates suggest that beaver dams have the potential to store a total of 120 million m of surface water and create 2200 km of fire resilience in high fire risk areas. Additionally, streams where beavers have the potential to create the greatest water and fire benefits due to physical landscape and habitat characteristics are frequently found within watersheds that are at high risk for both drought and fire. Specifically, we identified five priority watersheds that have both high risk for drought and fire impacts, and have high potential to benefit from beaver conservation and restoration. Even in areas where fire and drought are less probable, the reestablishment of beavers will likely provide similar benefits. This unique approach to quantifying potential beaver benefits illustrates that wildlife can increase resilience to global change stressors and suggests that biodiversity and nature-based climate solutions are intertwined.
Dendrochronology reveals the response of a riparian forest to water management in an arid river basin.
Patterson NK, Dong X, Lane BA … +3 more , Csank A, Rood SB, Sandoval-Solis S
Ecol Appl · 2025 Oct · PMID 41074917 · Full text
Riparian corridors in arid climates sustain life in otherwise inhospitable environments, creating zones of ecological and cultural importance. However, rivers in arid climates are often managed to provide water for human...
Riparian corridors in arid climates sustain life in otherwise inhospitable environments, creating zones of ecological and cultural importance. However, rivers in arid climates are often managed to provide water for human populations at the expense of a river's freshwater biodiversity. In this study, ecosystem response to river flow management is assessed using mature cottonwood tree-ring growth and carbon isotope composition as bio-indicator proxies for river ecosystem health. We examine the ecological impacts of flow management on the Lower Truckee River in Nevada, USA, which runs through an arid-climate basin that has been subject to decades of heavy flow diversion and management. Particular attention is given to the effects of major lawsuits in 1973 and 1982 that restored spring and summer flows to the river following progressive dewatering since 1905. Most mature trees (>30 years old) downstream of diversions responded strongly to restored flows, with average annual tree-ring growth increases of 160%. Among tested streamflow metrics, average annual flow had the strongest positive influence on cottonwood growth, and aspects of the spring snowmelt recession were also influential. Precipitation was also linked with cottonwood growth, primarily during the period of management before 1973 when dry season flows were severely limited. Not all floodplain trees responded similarly to changes in flow metrics, suggesting that individual tree attributes and heterogeneity in floodplain soils are highly important to tree growth. Results offer promising evidence that flow restoration can lead to measurable improvement in riparian forest productivity, although site-specific considerations including channel form and location on the floodplain are important in determining response to changes in flow patterns.
Water availability boosts multidimensional plant diversity in a temperate grassland despite anthropogenic disturbances.
Hu B, Ilghar W, Zhai H … +4 more , Mo L, Wang C, Xu W, Sun W
Ecol Appl · 2025 Oct · PMID 41074905 · Publisher ↗
Global changes present significant challenges to biodiversity. However, how plant communities respond to climate change under various anthropogenic disturbances, and how different species groups contribute to these respo...
Global changes present significant challenges to biodiversity. However, how plant communities respond to climate change under various anthropogenic disturbances, and how different species groups contribute to these responses, remains poorly understood. Using an 8-year dataset from a temperate grassland and a multidimensional diversity framework (taxonomic, functional, and phylogenetic), we explored the interactive effects of climate change and anthropogenic disturbances (grazing, fertilization, and their combination). We found that (1) increasing water availability consistently boosted multidimensional plant diversity over time across all treatments. (2) However, disturbances, particularly their combination, weakened this positive climatic effect. (3) Differentiating the contributions of rare, common, and dominant species revealed contrasting responses to climate drivers, highlighting the importance of a multidimensional assessment. Grazing also heightened the community's sensitivity to climate change. Our study reveals that anthropogenic disturbances fundamentally modify plant community responses to climate change, providing critical insights for biodiversity conservation and sustainable grassland management under future climate scenarios.
Does tidal marsh restoration lead to the recovery of trophic pathways that support estuarine fishes?
Pagliaro MD, De La Cruz SEW, Woo I … +5 more , Sousa J, Rich N, Grimaldo L, Colombano D, Ruhí A
Ecol Appl · 2025 Oct · PMID 41074701 · Full text
Evaluation of tidal marsh restoration success is typically based on the recovery of habitat size and target species. However, food-web structure may provide valuable insight into ecosystem functioning trajectories. Here,...
Evaluation of tidal marsh restoration success is typically based on the recovery of habitat size and target species. However, food-web structure may provide valuable insight into ecosystem functioning trajectories. Here, we studied restored tidal marshes of different ages (new, young, old; spanning 1-150 years) in comparison with nearby reference sites along the San Francisco Estuary. We asked: (1) How does restoration help recover energy pathways that support fishes? (2) Do fishes rely more on algal versus detrital pathways in restored sites?; and (3) How does food-web structure vary as a function of species origin and life history? To answer these questions, we sampled fish (n = 806) and basal resources (emergent vegetation and phytoplankton; n = 109) seasonally over two hydrologically contrasting years. Using stable isotopes (δC, δN, and δS), we calculated fish isotopic niche volumes, food chain lengths, and the relative importance of algal versus detrital energy pathways. We found that food chains in restored sites were 8% shorter than in their paired reference sites. Additionally, the young and old restored sites had 37% smaller niche volumes than their references, but the opposite was true for the new restored site (11% larger), illustrating the characteristic trophic surge of early succession. Fishes found in restored sites relied significantly less on detrital energy (7% less) than fishes found in reference sites, and resident fishes showed 12% higher reliance on the detrital pathway than transient species. Finally, most of the native niche volume overlapped with that of introduced fish, which was in turn 38% larger, and a similar pattern was observed when comparing resident to transient fish. Our findings demonstrate that food-web structure does not immediately recover with tidal marsh restoration, even if fish assemblages are species-rich; and show that transient trophic surges may complicate restoration success assessments of newly restored marshes. We contend that incorporating recovery of energy pathways as an indicator of performance may help strengthen monitoring and design of wetland ecosystem restoration projects.
Non-native prey availability and over-compensatory density dependence drive population dynamics of a native fish predator.
Cochrane MM, Cline TJ, Schmidt TS … +3 more , Dunnigan JL, Warnock WG, Muhlfeld CC
Ecol Appl · 2025 Oct · PMID 41070939 · Full text
Understanding the factors that regulate population dynamics is crucial for conserving imperiled species. Bull trout (Salvelinus confluentus), a piscivorous salmonid and one of North America's most threatened cold-water s...
Understanding the factors that regulate population dynamics is crucial for conserving imperiled species. Bull trout (Salvelinus confluentus), a piscivorous salmonid and one of North America's most threatened cold-water species, has declined significantly due to habitat loss, overfishing, invasive species, and climate change. While recovery efforts have primarily targeted these threats, the role of prey availability in influencing bull trout population dynamics under multiple stressors remains poorly understood. Using a stage-based integrated population model, we quantified the effects of non-native prey availability (kokanee; Oncorhynchus nerka), angling pressure, climatic variation, and density-dependent processes on bull trout population dynamics in Lake Koocanusa, a transboundary reservoir and river system (United States and Canada), over a 40-year period (1980-2023). Our results show that bull trout populations are regulated by density-dependent processes, including over-compensation in sub-adult recruitment and reduced adult survival at high densities. Increased kokanee biomass and restricted harvest significantly enhanced bull trout survival and abundance, whereas reduced water availability had a limited negative effect on sub-adult production. Model simulations indicate that as kokanee biomass availability increases, the number of bull trout that can be sustainably harvested also increases. In fact, a modest annual fishery (300 individuals) can be sustained, especially under moderate to high kokanee biomass conditions. These results underscore the importance of prey availability, including non-native species, in supporting bull trout populations. Effective management of threatened apex fish predators like bull trout requires addressing the complex interplay between environmental threats, prey dynamics, and density-dependent mechanisms across all life stages.
Plant community composition and dominant species drive stability in aboveground production of biofuel agroecosystems.
Stahlheber KA, Gross KL
Ecol Appl · 2025 Oct · PMID 41065326 · Full text
The relationship between diversity and stability remains a key question in ecology and has important consequences for understanding the sustainability (and profitability) of bioenergy cropping systems; yet to date, littl...
The relationship between diversity and stability remains a key question in ecology and has important consequences for understanding the sustainability (and profitability) of bioenergy cropping systems; yet to date, little work has been done to examine these relationships in agricultural systems directly. In this study, we evaluated the relationship between biodiversity (in number of planted species) and the stability of biomass production in four experimental bioenergy cropping systems established in Wisconsin and Michigan. Species composition and aboveground production were monitored at all sites for 8-10 years (2010-2019) allowing us to evaluate the temporal stability of biomass yield (defined as the temporal mean divided by the temporal SD) in these cropping systems. A major regional drought in 2012 also allowed us to evaluate resistance and resilience. Although three of the cropping systems were established with the same seed mixtures and were managed in the same way, species composition differed markedly between sites. This limited our ability to attribute differences within cropping systems across sites to the abundance of specific species. Overall, there was no clear relationship between planted species richness and yield stability in biomass production at these sites. At both sites, the lowest diversity system (switchgrass monoculture) had the highest interannual stability in production and was equivalent to that of the highest diversity treatment (prairie). Resilience to the drought was high in all treatments and did not differ among the four cropping systems; however, resistance to drought differed among systems and was highest in the switchgrass monocultures at both sites. The abundance of perennial C grasses increased over time in all cropping systems, except for the successional plots. The persistence of annual species in the successional treatments at both sites likely contributed to low stability and high interannual turnover in this system. We found no evidence that increasing the diversity of planted species in bioenergy cropping systems enhances stability in aboveground biomass production; nor was there any difference in resistance or resilience to drought. The higher costs of establishing more diverse bioenergy cropping systems may be warranted if other ecosystem services, such as supporting diverse pollinator and predator insect species at the landscape scale, are desired from bioenergy crops in addition to biomass production.
Native megafauna (Bison bison) act as a surprising inhibitor of cedar tree expansion in a Great Plains grassland.
Noble S, Ratajczak Z, Noble B
Ecol Appl · 2025 Oct · PMID 41052790 · Publisher ↗
In the Central Great Plains of North America, fire suppression is causing transitions from grasslands to shrublands and woodlands. This woody encroachment alters plant community composition, decreases grassland biodivers...
In the Central Great Plains of North America, fire suppression is causing transitions from grasslands to shrublands and woodlands. This woody encroachment alters plant community composition, decreases grassland biodiversity, undermines key ecosystem services, and is difficult to reverse. How native grazers affect woody encroachment is largely unknown, especially compared to domesticated grazers. Bison were once the most widespread megafauna in North America and are typically categorized as grazers, with negative effects on grasses that indirectly benefit woody plants. However, bison can negatively impact woody plants through occasional browsing and mechanical disturbance. This study reports on a 30-year experiment at Konza Prairie Biological Station, a mesic grassland in the Central Great Plains of North America, under fire suppression and experimental presence/absence of bison. Based on remote sensing, deciduous tree canopy cover was lower with bison (6% grazed vs. 16% ungrazed). Shrub land cover showed no difference (42% grazed vs. 41% ungrazed), while herbaceous land cover was higher with bison (51% grazed vs. 40% ungrazed). Evergreen tree canopy cover (Juniperus virginiana L.), which decreases biodiversity and increases wildfire risk, was approximately 0% with bison compared to 4% without bison. In the survival trial of J. virginiana seedlings, we found a 40% overwinter mortality with bison, compared to 5% mortality without bison. Compared to ungrazed areas, native plant species richness was 97% and 38% higher in bison-grazed uplands and lowlands, respectively. Species evenness and Shannon's index were higher in the bison treatment in uplands, but not in lowlands. Bison affected community composition, resulting in higher cover of short grass species and lower tree cover. While grazers are generally assumed to favor woody plants, we found that bison had the opposite effect at low fire frequencies. We argue that the large size of bison and their behaviors account for this pattern, including trampling, horning, and occasional browsing. From a conservation perspective, bison might hamper tree expansion and increase plant diversity in tallgrass prairies and similar grasslands.
The impact of urbanization on genetic connectivity of 10 mammal species in New Jersey.
Chmura HE, Fowles G, Pilgrim KL … +4 more , Strand JM, Theobald DM, Zeller KA, Schwartz MK
Ecol Appl · 2025 Oct · PMID 41047850 · Publisher ↗
Rapid human modification of landscapes around the world has made understanding how humans affect the genetic connectivity of wildlife populations urgent. The consistency of anthropogenic impact on genetic connectivity ac...
Rapid human modification of landscapes around the world has made understanding how humans affect the genetic connectivity of wildlife populations urgent. The consistency of anthropogenic impact on genetic connectivity across taxa is unclear, in part because it is rare to have data representing functional connectivity for multiple taxa on the same landscape. We use microsatellite data for 10 mammalian species in New Jersey, USA, to assess cross-taxonomic patterns in the impact of urbanization on genetic connectivity. In doing so, we also evaluate the efficacy of species-specific and species-agnostic approaches for representing landscape resistance in landscape genetics analyses. We found relative consistency in the relationship between genetic connectivity and a resistance surface built using a species-agnostic index of human modification. High levels of human modification impeded genetic connectivity in 7/10 species. However, despite this relative consistency, for 7/10 species the highest performing resistance surfaces reflected a suite of variables individually tailored to each species' ecology, rather than species-agnostic representations of human infrastructure. Other land cover covariates, like forest, shrub, and herbaceous cover, consistently facilitated genetic connectivity. These results show that while human modification of the environment is important in explaining patterns of genetic connectivity across taxa, there is enough variation in how species respond to the suite of factors that define a landscape that functional connectivity is not always well represented by human modification alone.
Effects of forest disturbances and an introduced ungulate on carbon storage in boreal forests.
Moran R, Leroux SJ, Wiersma YF … +1 more , Whitaker DM
Ecol Appl · 2025 Sep · PMID 40985727 · Publisher ↗
Selective browsing by ungulates alters forest structure and composition, with research suggesting that these effects may be amplified in recently disturbed forests and in novel environments (i.e., introduced ungulates)....
Selective browsing by ungulates alters forest structure and composition, with research suggesting that these effects may be amplified in recently disturbed forests and in novel environments (i.e., introduced ungulates). Though the net effects of herbivory following disturbances on carbon storage in boreal forests are not well understood, they are likely important to inform climate-smart ecosystem management. We conducted observational and experimental (i.e., 24- to 27-year-old paired exclosure-control plots) field studies to determine the effects of non-native moose and common boreal forest disturbances (i.e., fires and insect outbreaks) on total, aboveground, and belowground carbon storage in Newfoundland, Canada. We measured carbon stocks at 46 plots in the field and used published allometric equations to estimate the carbon stored in trees, deadwood, woody shrubs, saplings, herbaceous plants, ground vegetation, and roots. We also collected samples of forest litter and organic soil layers for analysis of carbon content. We then fit a suite of generalized linear models to assess the effects of disturbances and moose herbivory on carbon storage. Using our observational data, we found that total carbon stored was highest in mature forests (198.18 ± 136.77 kg C/9 m; mean ± SD), compared to insect-disturbed (57.47 ± 30.72 kg C/9 m) and previously burned (42.57 ± 34.28 kg C/9 m) areas. We found further evidence of this using our experimental data, as aboveground carbon storage was reduced in disturbed forests. Although, on average, exclosures stored more carbon (133.54 ± 134.69 kg C/9 m; mean ± SD) than their paired controls (95.23 ± 66.94 kg C/9 m), we did not detect a statistically significant effect of moose presence on carbon storage after 24-27 years of exclusion. We also did not find a relationship between moose density and carbon storage in our observational data. Overall, we demonstrated that forest disturbances are a key driver of carbon storage and that moose effects on carbon storage are highly variable across the landscape. We recommend that future research be done in areas having consistent ungulate management and long-term population data and that detailed plant community data be collected to better understand the roles of ungulate density and plant palatability on carbon storage.
Besides aridity, plant communities are a non-negligible factor in determining soil bacterial and fungal diversity.
Su N, Zhang Q, Rineau F … +3 more , Gong X, Ding Y, Soudzilovskaia NA
Ecol Appl · 2025 Sep · PMID 40985568 · Publisher ↗
The impact of aridity on above- and belowground biodiversity can be profound. However, it remains unclear how drought stress influences belowground biodiversity through the complex interplay of soil quality, plant commun...
The impact of aridity on above- and belowground biodiversity can be profound. However, it remains unclear how drought stress influences belowground biodiversity through the complex interplay of soil quality, plant communities, and the direct effects of soil moisture deficit. In this study, we randomly selected 80 sampling plots along a 1000-km natural aridity gradient from east to west of the Inner Mongolia grasslands to identify the factors that influence soil bacterial and fungal diversity in arid and semiarid regions. Our results revealed that both soil bacterial and fungal diversity decreased with increasing aridity. Structural equation models demonstrated that aridity indirectly affected regional-scale soil bacterial and fungal diversity by regulating plant diversity and biomass. Plant biomass and community composition elicited a much stronger impact on soil fungal diversity than on soil bacterial diversity. A detailed analysis revealed that soil fungal and bacterial diversity were significantly correlated with specific plant taxa biomass. However, plant traits did not explain the positive or negative correlations between soil bacterial and fungal diversity and plant species dynamics. Instead, our data suggest that plant biomass is the primary driver controlling soil microbial (mainly fungal) diversity. Our study shows that aridity reduces soil bacterial and fungal diversity on a regional scale and indicates that aridity indirectly influences soil community composition through plant communities. Our findings indicate that plant community dynamics should be considered in assessing soil bacterial and fungal diversity on a regional scale.
Scale-dependent controls on forest gaps shaped by large trees and topographic heterogeneity.
Chen J, Jucker T, Wang X … +14 more , Fischer FJ, Zhang B, Zhang Z, Hu J, Yang Q, Wang X, Liu Y, Zhang M, Lian J, Ye W, Li B, Chu C, Liang X, Zhang J
Ecol Appl · 2025 Sep · PMID 40983464 · Publisher ↗
The size, number, and distribution of forest canopy gaps vary significantly across spatial scales, yet their relationships with underlying drivers, such as large trees, topography, and soil properties, remain insufficien...
The size, number, and distribution of forest canopy gaps vary significantly across spatial scales, yet their relationships with underlying drivers, such as large trees, topography, and soil properties, remain insufficiently comprehended. We utilized an unmanned aerial vehicle to measure forest gap patterns (size, number, and aggregation) at seven spatial scales (20-400 m) in four subtropical forests and quantified the effect of large trees, topography, and soil in shaping gap patterns using ground inventory data. Gap size and aggregation showed significant variation across scales. Large trees and topographic complexity were major factors of gap patterns, with their effects depending on scale. Large trees in two forests had a significantly negative effect on gap size and density at the 20-m scale, but this effect was weaker and positive at the 100-m scale. Topography had the strongest effect on gap aggregation at a small scale (20 m) and on gap size and density at a larger scale (100 m). These results underscore the importance of spatial scale in understanding forest dynamics and highlight how community-level factors shape canopy structure. Identifying scale-dependent drivers of gap patterns can inform gap-based restoration and conservation strategies. Forest managers can reduce gap clustering by protecting large trees, especially in wind-prone areas, helping to maintain canopy structure, promote species diversity, and enhance ecosystem resilience.
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