Ecosphere最新文献

Human activities in the marine environment are expanding rapidly, with much of the growth in the Northeast Atlantic driven by offshore wind development. While offshore wind is critical for achieving net zero carbon targets, planning decisions must also address the twin challenge of conserving and restoring biodiversity. We combined open-access data from hundreds of grab and core surveys with random forest modeling to provide new insights into patterns of benthic biodiversity across the Northeast Atlantic continental shelf. Multiple dimensions of biodiversity were mapped using Hill numbers (q = 0, 1, 2) and raw abundance, assessed within the Whittaker framework (alpha-, beta-, and gamma-diversity) to reveal patterns at different spatial scales. These metrics were synthesized into a single biodiversity map using clustering, delineating areas of seabed with shared biodiversity characteristics. This analysis offers an evidence-based framework for safeguarding benthic biodiversity and informing management decisions in an era of rapidly expanding offshore development. Our results also highlight key environmental drivers, with higher biodiversity consistently associated with greater gravel coverage and moderate to high current speeds.

A shifting climate poses threats to alpine-adapted species including mountain goats. We used long-term (12 years) citizen science monitoring data and Bayesian N-mixture modeling to estimate population trends and drivers of population metrics among mountain goats in Glacier National Park (GNP). Median goats per site (n = 37 sites) declined by 45% (95% credible interval [CRI] = 32%, 57%) from 77.8 (95% CRI = 64.4, 95.1) in 2008 to 42.3 (95% CRI = 34.3, 52.2) in 2019, with consistent declines from 2008 until 2015, when the number of estimated goats stabilized. The decline exceeds IUCN criteria for classifying a population as vulnerable, >30% declines over only two generations. Across years, relatively few goats occupied northwestern GNP. Goat numbers declined the most at northeastern sites, trended toward decline in most southern sites, and increased at only two west-central sites. The proportion of permanent snow and glaciers, the presence of natural mineral licks, and habituation strongly increased the initial abundance of goats in the area. Weather variables had the greatest influence on population growth rates, particularly precipitation between May 15 and June 15 of the previous summer, the neonatal period. Lower growth occurred with less snow water equivalent and lower mean winter temperature, early summer temperature, and early summer precipitation. Projected reductions of permanent snow, increasing spring and summer temperatures, and insufficient and variable spring precipitation raise concerns for the future of native goats in this region. Our analyses reveal ways to improve detection rates of goats during surveys, which is important for optimizing the precision of estimates and the power to detect future trends. Detection increased with goat habituation, retention of observers with experience, use of binoculars, and conducting surveys at lower temperatures and earlier dates. Improving detection will be particularly important given the lower number of goats currently observed in the park. Research to estimate park-wide population size, evaluate genetic structure and diversity, assess changing habitat, human recreation levels and forage, and forward-project climate effects on persistence will be crucial to understanding the context of these results and conserving this iconic, metapopulation at the southern edge of the distribution of native mountain goats.

Land managers use hazard (susceptibility) and risk rating systems to guide the application of forest management treatments that aim to reduce future damages to forests. Rating systems are typically designed for individual damage agents, but tree mortality often results from multiple agents without a clear proximate cause. In interior Douglas-fir (DF, Pseudotsuga menziesii var. glauca) forests in the Northern Rocky Mountains, USA, multiple damage agents are commonly associated with DF tree mortality, such as insects, disease, weather, and fire. We investigated how recent DF tree mortality from insects and diseases (excluding fire and harvest) shifted stand structure and composition in DF forests and was influenced by susceptibility (e.g., stand structure and composition, topography, and spatial variability in climate) and risk (biotic agent pressure). Our multi-scale analysis used 884 plots remeasured after 10 years from the USDA Forest Inventory and Analysis program with support from spatial datasets. Across a large, forested landscape, 60% of the plots had no new DF mortality, and most plots (80%) experienced mortality <10% of DF basal area. However, severe tree mortality, defined as >25% loss of DF basal area, occurred in 6% of plots. Most of the dead DF trees (68%) were smaller diameter (12.7–29 cm at breast height) and mortality rates of smaller trees were significantly greater than those of larger diameter trees (>29 cm), a finding consistent with natural stand development processes. During the remeasurement period, average DF tree size increased in most plots (80%) and <4% of DF-dominated plots with severe mortality shifted in dominance from DF to another tree species. Greater DF mortality (percentage of initial DF basal area) was associated with lower tree growth rates, larger average tree sizes, greater availability of DF tree hosts for biotic agents, cooler and wetter topo-climatic locations, and higher Douglas-fir beetle population pressure. The relative importance of each variable differed west and east of the Continental Divide. By identifying thresholds in susceptibility and risk variables associated with higher DF tree mortality, our results support adaptive forest management for multiple damage agents, when the goal is to reduce tree mortality of a widespread and abundant conifer.

Habitat loss and fragmentation can have a substantial impact on biodiversity loss. Modeling studies showing these effects generally work under the implicit assumption that all species in the community have equal dispersal capacities. Here, we consider the more realistic assumption that species are not ecological equivalents with respect to dispersal capacity. Using an individual-based model, we investigate how such variation in dispersal capacity between species impacts the effects of habitat loss and fragmentation on biodiversity loss at two spatial and two temporal scales. Our results show that the effects of habitat loss and fragmentation on the loss of species richness are amplified when considering variation in species' dispersal capacities. Furthermore, the effects of the spatial configuration of habitat loss depend on when and at what scale we measure biodiversity loss. Our results indicate that species' dispersal capacities as well as the spatial configuration of habitat loss need to be considered when evaluating the risks of habitat loss.

Flower plantings in agricultural landscapes can contribute to sustainable crop production by enhancing pollination and biological control services. However, selecting plant species that promote multiple ecosystem services is challenging, since plants that favor pollinators may not equally foster natural enemies, and potential trade-offs, such as inadvertently promoting crop pests, must be considered. This complexity increases when accounting for belowground effects. We evaluated 27 candidate plant species for their ability to host functionally important above- and belowground organisms—pollinators, natural enemies, herbivores, and decomposers—and assessed how plant characteristics such as floral area, timing of peak bloom, life cycle, and plant cover affect these organism groups. We found that certain plant species have the potential to support several groups of beneficial organisms, suggesting they can enhance multiple ecosystem services. Annual plants had higher abundances of both above- and belowground beneficial organisms compared to perennials. Greater plant cover was positively associated with hoverfly abundance. Several functionally important organism groups were positively correlated across plant species, but these positive correlations were not explained by shared responses to plant characteristics. Our findings underscore the significance of plant species identity and characteristics in designing flower plantings for enhancing biodiversity and ecosystem services and highlight the importance of including belowground organisms like nematodes in future studies. Our results for specific plant species and plant characteristics can be used to design flower mixtures supporting several ecosystem service providers while considering potential trade-offs, thereby increasing the efficiency of flower plantings.

Environmental and human factors shape the distribution and habitat of Mediterranean woody plants, influencing their population structure and conservation. The Iberian wild pear (Pyrus bourgaeana), a keystone fleshy-fruited species supporting wildlife during resource-scarce periods, is one such example. However, its habitat association and spatial patterns in Mediterranean managed woodland areas remain poorly understood. This study investigates its associations with microtopography and habitat heterogeneity in two key managed areas—dehesa (DEH) and abandoned olive grove (AOG)—within its core range in southern Spain. All trees ≥5 cm in diameter were mapped in a 223.3-ha plot, classified by size and age, and analyzed using spatial analysis, generalized linear models, and the torus translation test. Results showed stronger tree clustering in the AOG, with overall aggregation at small to intermediate scales (10–30 m), especially in older and larger trees. Positive associations were found between tree age, size, and microtopographic features. This light-demanding species preferred higher elevations and sunnier slopes. Human activities have significantly altered the species' structure: forest conversion to olive groves eliminated the Iberian wild pears, but abandonment allowed some regeneration via animal-dispersed seeds. However, increased ungulate density from hunting and cattle grazing, particularly in DEH, now severely limits regeneration, causing local declines. These findings highlight how historical land use and current grazing pressures affect the species viability and underscore the importance of targeted conservation strategies to preserve its role in Mediterranean ecosystems.

Microorganisms have implications for plant health and agricultural production, yet we are just beginning to understand the complexity of plant–microbe interactions in multispecies environments. Studies conducted to date have shown that plants are able to control the makeup of their microbial communities, yet their ability to control these communities is limited when grown near other plant species. Increased knowledge about these observations and their role in intercropping success is needed to allow us to utilize plant–microbe interactions to improve agricultural sustainability. Therefore, the goal of our study was to elucidate how the bacterial community may be contributing to the high yields observed in the pea–canola intercropping system (peaola). We aimed to determine if intercropping (1) alters bacterial abundance in bulk and rhizosphere soils; (2) affects plant recruitment of rhizosphere bacteria from bulk soil; (3) changes the predicted functions of bacterial communities related to nitrogen cycling; and (4) increases nitrogen availability in bulk soil and leaf tissue of peaola. In the bulk soil bacterial community, genera were not found to be differentially abundant despite previous findings that shifts were observed in the structure of the core microbiome. In the rhizosphere, we found that the composition of the bacterial community of pea and canola remained distinct when intercropped. Functional predictions suggested the enrichment of genes involved in nitrogen cycling processes, yet no significant differences were observed in nitrogen availability and plant tissue content.

All plant organs have the potential to harbor microbial communities and each organ may form unique niches for specialized microbial communities. There have been very few detailed investigations of microbiomes within a single plant organ along different developmental stages. Here, we investigated the bacterial and fungal communities associated with the endosphere and rhizoplane of primary aerial roots, mature aerial roots, and subterranean parts of mature aerial roots of Cissus verticillata. Our results showed that the proportions of dominant bacterial and fungal genera varied across the three aerial root types both for the endosphere and for the rhizoplane. For the endosphere bacteria, the highest diversity indices were observed in subterranean aerial roots, while mature aerial roots had a higher rhizoplane bacteria diversity. For fungal diversity indices, mature aerial roots had the highest richness for both endosphere and rhizoplane fungi. The study also found that the microbial assemblage composition of each aerial root type was distinctly unique. Generally, our network analysis revealed that fungi had higher network property values compared to bacteria. Additionally, the rhizoplane had higher network property values than the endosphere, particularly within the fungal community. Furthermore, bacterial functions were similar across the three aerial root types, which suggests the stability of bacterial functions. By contrast, considerable shifts in the relative abundance of fungal functional groups across aerial root development were observed. Additionally, fungi and bacteria show differential responses to three aerial root types. This study provides a new perspective for understanding the characteristics of plant aerial root microbial communities along developmental stages.

Restoration treatments have been implemented in many of the dry conifer forests of the western United States. By decreasing forest density and increasing forest heterogeneity, these treatments are generally effective at meeting their primary objective of reducing the risk of uncharacteristically severe wildfire. Treatments also commonly achieve a secondary objective of increasing overall native understory plant species richness and cover. However, it is less certain how treatments affect the recruitment, loss, and growth of individual understory plant species and, in turn, shape the composition of the understory plant community. We investigated these finer effects of forest restoration treatments on understory communities in the Colorado Front Range by collecting data pre-treatment and 1–2 years and 4–6 years post-treatment at 155 plots in treated and untreated areas. Treatments were implemented mechanically by cutting trees with heavy equipment or chainsaw; cut material was either removed, piled, piled and burned, scattered, or masticated. Species turnover analysis indicated that at 4–6 years post-treatment, losses of pre-treatment native species, as well as losses in the cover of pre-treatment native species, were attributable to background turnover rather than to treatment. Species turnover analysis also showed that the post-treatment recruitment of native species was greater in treated than untreated plots and that native species persisting from pre- to post-treatment contributed the most to the increased cover found in treated plots. Multivariate analysis demonstrated subtle but statistically significant differences in species composition in treated versus untreated plots after treatment. Indicator species analysis clarified which species contributed to post-treatment turnover and composition differences. No strong native or non-native indicator species were found for untreated plots at any sampling period, or for treated plots pre-treatment. However, at 4–6 years post-treatment, eight native species and two non-native species were strongly indicative of treated plots, most of which were open forest species. Based on these results, and our previous results that identified positive treatment effects on overall native cover and species richness, we conclude that mechanical forest restoration treatments benefited native understory plant communities in the Colorado Front Range both at broad and fine levels.

We created the first annually resolved records of historical fire occurrence coupled with precise estimates of tree establishment for the northern half of the west slope of the Oregon Cascades, a region that is home to some of the most productive forests on earth. Our reconstructions at 36 randomly located sites document exceptional diversity in historical fire disturbance and successional dynamics. Most stands where we collected data appear to have initiated following stand-replacing fire between 200 and 750 years ago, although many sites exhibited evidence of moderate-severity fire that created multi-aged stands. More than two-thirds of sites experienced multiple non-stand-replacing fires following stand initiation. A spatial generalized linear mixed model demonstrated that historical fire occurrence was negatively associated with average snow disappearance day and time since last fire and positively associated with drought. Significant variability in the number of fires, length of fire return intervals, and sample depth across sites made calculation of informative mean fire return intervals (MFRIs) difficult. Site-level annual probability of fire from our mixed model ranged from 0.039 to 0.003, equivalent to MFRIs of 26–389 years. We used fire and tree establishment records to infer the general location of several large historical fire events that likely burned as much or more area as the >50,000 ha fires that burned across our study region in 2020. We also identified periods of extensive burning and subsequent tree establishment that occurred across seven centuries within six large river drainages that made up our study region. Although tree establishment occurred for up to a century following stand-replacing fire at some sites, we show that these apparent long periods of establishment were relatively short pulses of regeneration separated by reburns. This study demonstrates that many highly productive Douglas-fir-dominated stands in western Oregon are significantly departed from historical fire disturbance regimes. Management that emphasizes rapid re-establishment of closed canopy forest conditions following fire and development of old-growth forest conditions in the absence of fire may fail to provide for the unique and highly valued ecosystem services associated with these forests.