Introduction The health of grassland ecosystems is of great significance for regional ecological security. The alpine grassland is fragile and sensitive to climate change and human activities, but studies on the assessment and mechanism of the grassland ecosystem health are scarce. Methods Based on the Pressure-State-Response (PSR) model, together with the entropy method, obstruction degree model and optimal parameter-based geographical detector, we constructed a health assessment system for the grassland ecosystem in Eastern Kunlun Mountains (EKM) and systematically assessed the spatio-temporal dynamics changes of the ecosystem health in EKM from 1990 to 2020. Moreover, we dynamically identified the obstacle factor and driving factor of the grassland ecosystem health in EKM. Results The results show that: (1) Over the past 30 years (1990-2020), the health index (HI) of the grassland ecosystem in EKM exhibited a fluctuating upward trend with average value of 0.2231. The grassland presented a healthier pattern in the southeast than in the northwest of EKM, generally at a medium-to-low health level (nearly 70%). (2) The health grades of the grassland ecosystem in EKM underwent significant changes. The percentage of the low health area dropped to 34.42%, and the combined percentage of the health and high health area fluctuated upward to 23.50%. The net improvement rate of the whole EKM region was +7.35%, but there was a slight degradation in the internal part of the grassland with a net improvement rate of -1.84%. (3) During 1990-2000, the structural pressure caused primarily by grassland area reduction and water resource constraints was the major obstacle, then in 2005-2015, it shifted to functional and climate stress featured with vegetation degradation (NDVI decline), and climatic drought. In 2020, a compound pressure pattern was formed with the simultaneous appearance of high obstruction degrees of multiple factors, including NDVI, standardized precipitation evapotranspiration index (SPEI) and precipitation. (4) The factor detection results show that the land use area ratio (Q = 0.247), grassland area ratio (Q = 0.238), sediment flux (Q = 0.181) and grazing intensity (Q = 0.123) are the key factors dominating the spatial differentiation of grassland health. All the factor pairs exhibit either bivariate enhancement or nonlinear enhancement. Discussion Overall, this study has integrated the obstacle diagnosis model with the geographical detector and revealed the dynamic evolution and spatial differentiation mechanisms of alpine grassland ecosystem health from the dual perspectives of constraint and driving. This is a valuable basis for protecting grassland ecological system in alpine regions and performing corresponding management.

Introduction Non-timber forest products such as bush mango ( Irvingia gabonensis ) are critical to rural economies in West Africa, yet their harvesting remains poorly understood in terms of economic returns and sustainability. Methods This study assessed the harvesting and economic potential of I. gabonensis in Edo State, Nigeria, using a purposive survey of 79 harvesters. Data were analysed through descriptive statistics, correlation, and regression, complemented with thematic analysis of qualitative responses. Results The results showed that harvesting is predominantly male-driven (68%), with a mean respondent age of 41 years, an average household size of 6, and a mean harvesting experience of 11 years. The activity was seasonal, occurring mainly from June to September, with an average weekly harvest volume of 124 kg per household. Regression analysis indicated that household size (β = 0.28, p < 0.05), years of experience (β = 0.32, p < 0.01), and access to productive trees (β = 0.41, p < 0.01) were significant predictors of profitability (R² = 0.47). Profitability analysis indicated that on average, each household earned a gross margin of 1 ₦103,800 (USD 71.5) per season, corresponding to a rate of return on investment of 91%. Constraints included limited access to trees (63%), declining yields (56%), and overdependence on wild stocks (72%). Discussion These findings highlight that sustainable harvesting and domestication of I. gabonensis can serve as Nature-Based Solutions (NbS), enhancing ecosystem services and promoting climate-resilient livelihoods in forest-dependent communities. The study concludes that I. gabonensis harvesting is economically viable but ecologically vulnerable, and that it requires domestication, sustainable practices, and improved access rights to secure its future contribution to rural incomes.

Under global climate change and intensified human activities, habitats in northwestern China’s Altay region—comprising forests, grasslands, deserts, and alpine areas—are increasingly fragmented. This study assessed the suitable habitat distribution and fragmentation characteristics of three ungulate species: red deer, goitered gazelle, and Siberian ibex. An ensemble species distribution model based on BIOMOD2 was used, and fragmentation metrics were calculated with the landscapemetrics R package. Red deer had the largest suitable area (20,688.54 km²), followed by goitered gazelle (16,342.25 km²) and Siberian ibex (11,477.62 km²). Fragmentation analysis revealed that red deer habitat patches in forest areas had the highest patch density (PD = 0.042); grasslands showed the largest dominant patches (LPI = 63.31) and highest aggregation (AI = 74.45). Gazelle habitats in deserts were the least fragmented (PD = 0.017, AI = 92.06), while ibex habitats in grasslands had higher fragmentation (PD = 0.046) but moderate aggregation (AI = 75.31). The results reveal clear interspecific differences in habitat suitability and landscape patterns, highlighting species-specific responses to environmental gradients. This study provides a scientific basis for habitat management, conservation planning, and connectivity enhancement for large herbivores in cold-arid ecotones.

A serious emerging threat to southern California riparian ecosystems is the invasive shot hole borer ( Euwallacea spp.; SHB), a non-native beetle that cultivates a pathogenic fungus that kills trees of 66 reproductive host species. We examined the response of the bird community at the Tijuana River, California, to a massive SHB infestation in 2015 using data from a Monitoring Avian Productivity and Survivorship (MAPS) station operated during 7 pre-infestation (2009-15) and 7 post-infestation (2017-23) years. Species richness did not change between pre- and immediate (2017-18) post-SHB periods, but average annual adult captures declined by 27%. Among the species making up ≥ 5% of the total individuals caught in any one year (n=15), abundance declined by up to 76% in 10 species, including those most abundant at the station (Bushtit ( Psaltriparus minimus ), Song Sparrow ( Melospiza melodia ), Common Yellowthroat ( Geothlypis trichas ), Orange-crowned Warbler ( Leiothlypis celata ), and Wilson’s Warbler ( Cardellina pusilla )). Mean annual abundance increased slightly for the endangered Least Bell’s Vireo ( Vireo bellii pusillus ) and Northern Yellow Warbler ( Setophaga aestiva ) and doubled for House Finch ( Haemorhous mexicanus ) and Western Warbling-Vireo ( V. swainsoni ). We compared species trends at the Tijuana River to those at a nearby uninfested MAPS station on the Santa Margarita River to isolate the effect of SHB from other factors influencing annual abundance. The contribution of SHB to changes in abundance post-SHB was high (63-80%) for 7 declining species, moderate (22-45%) for 4 species, and weakly to moderately positive (18-40%) for 3 species. By 2019, the SHB infestation at the Tijuana River had abated and canopy cover was recovering through resprouting of mature willows ( Salix spp.) and seedling establishment. Bird abundance tracked this regrowth, with all of the species strongly affected by SHB increasing between 2019-23. The rapid recovery of the Tijuana River habitat and the associated response by the bird community are encouraging signs that the threat of the invasive shot hole borer to regional biodiversity may not be as great as originally anticipated.

We investigated the diet of the invasive black rat ( Rattus rattus ) and its overlap with co-occurring small native mammals in protected areas of the temperate forests of southern Chile. Our study was conducted during three consecutive winters between 2022 and 2025. We collected 165 fecal samples that were pooled together by location into 26 pools to describe the diet breadth of the black rat. For metabarcoding analysis, we analyzed pooled extracts aggregated by locality × sampling period (up to six 6 pellets per pool; 21 black rat pools, four small native-mammal pools and one for the only marsupial species present in the study area, Dromiciops gliroides ), using a multi-marker strategy (trnL, COI, 16S). Results are interpreted as pool-level trophic overlap and potential interference rather than direct evidence of individual-level competition. Dietary overlap was quantified using Pianka’s index and Jaccard similarity. Rattus rattus exhibited a broad omnivorous diet spanning 37 plant families, 9 arthropod orders, and eight vertebrate families, including native rodents and D. gliroides . Small native mammals displayed narrower niches, with dietary overlap being high for arthropods (Pianka = 0.835), moderate for plants at higher taxonomic level (family level) (Pianka = 0.40), and low for plant species (Jaccard = 0.11). Substantial inter-individual variation indicated that some black rats relied heavily on anthropogenic subsidies (processed foods, exotic plants, human DNA), whereas other individual black rats overlapped directly with native taxa. Black rats demonstrated the ability to exploit both native and anthropogenic resources, resulting in trophic interference with native small mammals. This overlap increases the risk of competitive pressure and predation of small native mammals in globally significant southern temperate rainforests.

Niche theory is a cornerstone of ecology for understanding species coexistence. However, its application to guide conservation remains challenging. This study focuses on Rosa anemoniflora , a threatened plant endemic to China, and adopts a novel perspective by shifting from traditional interspecific niche comparisons to the analysis of intraspecific variation in niche breadth. We quantified niche breadth across different habitats using a newly developed circular sliding window technique, and then applied correlation, regression, and structural equation modeling to identify key soil factors associated with greater expression of intraspecific niche breadth. Our results indicate that high niche overlap in the herb layer may constrain population regeneration. Notably, soil total potassium (TK) and available potassium (AK) showed contrasting associations with niche breadth: TK was positively correlated, while AK was negatively correlated. This pattern suggests that variation in soil potassium status is closely associated with differences in the realized niche breadth of R. anemoniflora . Our sliding window–based analytical approach provides a methodological pathway for applying niche theory to precision conservation by linking fine-scale environmental variation to intraspecific niche expression. The approach offers a potentially transferable strategy and practical guidance for conserving other threatened species.

Introduction River herring (alewife, Alosa pseudoharengus , and blueback herring, Alosa aestivalis ) are native along the East Coast of North America. These fish are culturally important and provide critical ecosystem linkages between marine and freshwater habitats. Due to overfishing, and habitat loss (through degradation and damming), river herring populations are at historical lows across their native range. In the last 200 years, dams and other impoundments have reduced access to spawning habitat for these and other anadromous fish. Methods To assess the theoretical coast-wide spawning potential for river herring, we quantified historically accessible spawning habitat (pre-dam) in coastal freshwater rivers using physical river characteristics (width and gradient). To assess the impact of dams on spawning habitat, we used a dams database to segment river reaches. This allowed us to characterize spawning habitat upstream and downstream of dams. River-specific population models were then used to estimate the number of potential spawners for each species, based on habitat estimates and life history parameters. We investigated three scenarios: no dams, favorable dam passage, and no dam passage. We use these simulations to compare the theoretical spawning potential for river herring prior to and after dam construction coastwide. Results We estimated that 52% of alewife and 51% of blueback herring habitat is located upstream of dams throughout the East Coast of North America. This results in a theoretical loss of ~880 million alewife and ~100 million blueback herring potential spawners due to dams, reducing both the ecological connection and fishery potential of these species. Discussion Even with the best-case “current” scenario for fish passage, we observed marginal increases in spawner abundance. These results highlight the relatively small theoretical influence current passage structures may have on restoring river herring to their historical abundances compared to dam removal. Our sensitivity analyses demonstrate that upstream passage to access additional habitat is only advantageous when effective juvenile and adult downstream passage are in place.

Introduction Habitat degradation, changes to hydrology, over-harvest, and hatchery practices have contributed to the decline of salmon populations in California over the past two centuries. The accumulation of these stressors led to such low salmon population numbers in California’s Central Valley that Sacramento River winter-run Chinook salmon (SRWRC; Oncorhynchus tshawytscha ) were federally listed as endangered in 1994. Since then, significant effort and resources have gone towards supporting the recovery of these populations, including habitat restoration, hydrology modifications, harvest restrictions, and revisions to hatchery management practices. Despite these efforts, the SRWRC population remains at risk. There is an urgent need to explore what combination of management actions are needed to substantially improve their status. Methods In this study, we use a long-term population dynamics model, specifically an updated version of the Winter-run Chinook salmon life cycle model (WRLCM), to evaluate a large suite of potential recovery scenarios that include both singular actions and multiple actions to identify which scenarios best support population recovery of endangered SRWRC. The WRLCM couples water-planning models, hydrodynamic models, habitat capacity models, and life stage-specific survival models within an encompassing stage-structured salmon life cycle model, to predict how SRWRC will respond to changes in suites of management actions. We evaluated scenarios that included increased quantity and quality of rearing, outmigration, and spawning habitat, modified reservoir operations to increase egg survival, reduced incidental harvest in ocean fisheries, and modified hatchery practices. Results Our results demonstrate that no singular recovery action was sufficient to achieve recovery objectives over a 26-year simulation period (1995–2020), but scenarios that included multiple actions could increase total population size by over 7 times the historical population size, without the need for hatchery supplementation. These results illustrate the synergistic effects that habitat, flow and other actions can have when taken in concert. Discussion Our results indicate that a holistic, multi-faceted set of recovery actions will likely be required to recover endangered winter-run Chinook salmon in the Sacramento River.

Intensively monitored watersheds provide long-term data sets for evaluating land management activities and can also identify causal mechanisms for population-level changes in aquatic species including life history diversity in salmonids. The influence of dam removal (ecosystem restoration), conservation hatchery practices, and an in-river fishing moratorium (i.e., management actions) on life history diversity in salmonids has not been fully evaluated. We used scale and genetic samples collected during intensive monitoring following these management actions in the Elwha River to determine their influence on the expression of life history traits in Oncorhynchus mykiss. We evaluated adult migratory patterns, age at migration, and degree of repeat spawning to determine if they changed through time, in both hatchery- and natural-origin individuals. We also assessed if genetic diversity shifted through time, reflecting demographic changes after these management actions. Using age data from scales, together with run timing data, we identified 39 different O. mykiss life history (hatchery- and natural-origin) strategies in the Elwha River from 2013 to 2024 based on age at migratory events. The number of life history strategies identified increased from 18 strategies during dam removal impacts to 38 strategies after dam removal impacts; however, this difference was largely due to differences in temporal and spatial sampling effort through time. Life history diversity and the increase from during- to post-dam removal impacts were much greater for natural-origin than for hatchery-origin O. mykiss . Although life history diversity appeared to increase over time, overall genetic structure decreased, and diversity was largely unchanged. Resident and anadromous individuals were observed, with anadromous individuals displaying winter and summer migration timing. Winter steelhead smolt age, time spent at sea, total age, and repeat spawning life histories varied by period and origin. Intensive monitoring allowed us to document the combined positive influence of large-scale dam removal, conservation hatchery supplementation, and a fishing moratorium on life history diversification in O. mykiss in the Elwha River.