Journals
2025 EN
Russell Ann E. · Hall Steven J. · Bedoya Ricardo
+2 more
Abstract Wet tropical forests play an important role in the global carbon (C) cycle, but given current rates of land‐use change, nitrogen (N) and phosphorus (P) limitation could reduce productivity in regenerating forests in this biome. Whereas the strong controls of climate and parent material over forest recovery are well known, the influence of vegetation can be difficult to determine. We addressed species‐specific differences in plant traits and their relationships to ecosystem properties and processes, relevant to N and P supply to regenerating vegetation in experimental plantations in a single site in lowland wet forest in Costa Rica. Single‐tree species were planted in a randomized block design, such that climate, soil (an Oxisol), and land‐use history were similar for all species. In years 15–25 of the experiment, we measured traits regarding N and P acquisition and use in four native, broad‐leaved, evergreen tree species, including differential effects on soil pH, in conjunction with biomass and soil stocks and fluxes of N and P. Carbon biomass stocks increased significantly with increasing soil pH ( p = 0.0184, previously reported) as did biomass P stocks ( p = 0.0011). Despite large soil N pools, biomass P stocks were weakly dependent on traits associated with N acquisition and use (N 2 fixation and leaf C:N, p < 0.09). Mass‐balance budgets indicated that soil organic matter (SOM) could supply the N and P accumulated in biomass via the process of SOM mineralization. Secondary soil P pools were weakly correlated with biomass C and P stocks ( R = 0.47, p = 0.08) and were large enough to have supplied sufficient P in these rapidly growing plantations, suggesting that alteration of soil pH provided a mechanism for liberation of soil P occluded in organo‐mineral soil complexes and thus supply P for plant uptake. These results highlight the importance of considering species' effect on soil pH for restoration projects in highly weathered soils. This study demonstrates mechanisms by which individual species can alter P availability, and thus productivity and C cycling in regenerating humid tropical forests, and the importance of including traits into global models of element cycling.
Journals
2025 EN
Scheiner Samuel M. · Kosman Evsey · Presley Steven J.
+1 more
Abstract Biodiversity is a central concept in ecology and biology. Its underpinnings are multifaceted and complex and involve multiple spatiotemporal scales, and many ways of measuring relevant characteristics. Its comprehensive understanding requires a framework on which to organize concepts and associated metrics. The analysis of biodiversity is based on combinations of two types of units: study units (i.e., the inferential domain in time and space that characterizes sampling) and measurement units (i.e., metrics). We provide an integrated framework for the units of study derived from three aspects of organisms: their spatiotemporal relationships (geography), their evolutionary relationships (phylogeny), and their ecological relationships based on their requirements and effects (niche). We systematize the units of measurement based on four types of data (identity, abundance, phylogeny, traits), two properties of those data (magnitude and variability), and three approaches for their measurement (total, pairwise, nearest neighbor). Together, they define 14 basic elements that can be combined in many ways and be subject to various mathematical operations. The result is 130 different metrics, including those in the literature and those developed herein. We propose standardized symbols for these metrics and provide formulas using standard notations for their parameters. Importantly, we show how our framework can be used to align study units and measurement units with questions concerning the causes and consequences of biodiversity. We provide case studies on bats in Peru and trees in the eastern United States to ecological gradient theory, niche theory, and theory about relationships between biodiversity and productivity, and we discuss which metrics might be most appropriate in tests of island biogeography theory and the dilution effect of pathogen transmission. Our key recommendations are that researchers should: (1) harmonize study unit properties with explicitly defined questions, (2) couple metric properties with underlying processes, and (3) compare metrics with similar properties. By providing an overarching framework that clearly delineates units of study and units of measurement, we hope to ensure that appropriate data are applied to particular scientific questions, especially those of a comparative nature, thereby leading to robust conclusions of theoretical import or practical use in management or conservation.
Journals
2025 EN
Railsback Steven F. · Bair John H.
Abstract The dominant conceptual model for how river flow affects when and where riparian hardwood trees establish (the “recruitment box model”) considers streamflow recession and a survivable rate of stage decline to predict survival of seedling desiccation. However, to become established, plants must also survive the pre‐seedling life stages and avoid inundation and scour mortality in high flows. We examine the relative importance of these flow‐dependent mechanisms by representing them in a two‐dimensional simulation model. Analysis of the model as applied to a low‐gradient reach of a large mountain river indicates that the soil characteristic determining moisture elevation (the “capillary fringe” height) is the most important process driving establishment rates; also important are the dates of seed deposition, inundation mortality, and the time needed for sprouted seeds to develop roots. Root growth rate had only moderate effect on seedling survival. These results indicate that the conventional conceptual model of establishment is incomplete. At our site, natural rates of decline in soil moisture elevation exceeded root growth rates, so widespread establishment required periods of near‐steady flows. Further, under both reservoir‐controlled and unimpaired flow regimes, establishment was strongly determined by post‐deposition flow increases : seeds deposited at elevations low enough to support rooting were often killed via inundation or scour in flow fluctuations that occurred under both reservoir‐regulated and unregulated flow scenarios. When soil moisture dynamics are represented even simply, the survivable rate of stage decline is not constant but depends on capillary fringe height, seed elevation, and the duration of stage decline. A more complete conceptual model of hardwood establishment considers that seeds need to be deposited where soil is moist long enough to develop roots but far enough from the water's edge to avoid mortality in flow fluctuations; for soil moisture to remain within reach of roots, which could require unusually steady flows, a high capillary fringe, or favorable groundwater gradients; and to avoid mortality due to scour or inundation in winter high flows. Model sensitivity and lack of literature suggest the time and moisture requirements for seeds to develop roots and inundation mortality of seedlings as research priorities.
Journals
2025 EN
Kenyon Tania M. · Mumby Peter J. · Webb Gregory E.
+3 more
Abstract Natural ecosystems are routinely impacted by acute disturbances that generate space for early colonizers. Following disturbances, the interaction strengths of top‐down and bottom‐up factors across environmental gradients influence community succession. On coral reefs, rubble beds commonly form following major disturbances and can persist for decades. Yet, there is little understanding of the successional pathways that lead to rubble binding—where rubble is bound and consolidated to form stable substrate suitable for coral recruitment—and subsequent coral recovery. This study used observational and experimental methods to determine: (1) binding likelihood in unstabilized in situ rubble beds 2.5 years following a coral bleaching event in 2016 in the Maldives, and how it varied according to rubble characteristics across environmental gradients; and (2) how the number of binds and binder community composition on experimentally stabilized rubble varied temporally over 1.5 years across environmental gradients. Surveys of rubble beds found that binding was lowest on the reef flat (8% of rubble was bound) and highest at exposed deeper sites (38%), where flow appears low enough to maintain rubble stability but high enough to support binder growth. When experimentally stabilized, ~100% of rubble was bound by at least one bind within 6 months. Yet, while the number of binds per rubble piece in experimental units continued to increase over time on the reef slope, it remained low on the reef flat, and binder community composition was distinct between reef flat and slope—likely due to higher sediment transport on the reef flat. Community composition also was distinct between exposed and cryptic rubble microhabitats. On reefs where rubble is mobilized more frequently than every 6 months, rubble beds will likely have low binding potential and delayed coral recruitment. Where sediment flux and deposition is high, recovery is unlikely even if rubble is actively stabilized. In contrast, infrequently mobilized areas with lower sediment flux are more likely to facilitate natural binding and coral recovery, and thus may not require intervention. Our findings can help to effectively guide managers toward the best strategies that facilitate the recovery of rubble‐dominated coral reefs, while optimizing limited intervention resources through careful prioritization.
Journals
2025 EN
Hahn Aleah · Tullos Desiree D. · Railsback Steven F.
Abstract Low‐tech river habitat restoration techniques, including Stage 0 treatments, are increasingly applied but often lack robust evaluation of their effects and benefits. In 2018, 1 km of the South Fork McKenzie (SFMK) River, Oregon was modified to Stage 0 conditions for the benefit of ESA‐listed Chinook salmon by raising the incised channel to the geomorphic grade line, reconnecting relic side channels, increasing floodplain connectivity, and distributing large wood throughout the reach. Field observations indicated depths and velocities were lower at the treated site than at the untreated site. To understand how these changes in physical habitat may translate into changes in juvenile Chinook length, abundance, and emigration timing, this study combined field observations with the individual‐based model inSALMO. Model results indicated that the new habitat conditions can produce longer outmigrants, a result of rearing longer in the treated reach than in the untreated reach. The treated reach also produced more outmigrants at the end of the season in dry and wet water years, a result of more higher quality juvenile habitat conditions (i.e., lower velocities and depths, more cover) that favored fish remaining in the reach. No evidence of the treatment on spawning or incubation success was found. Numerical experimentation indicated that, under both treated and untreated conditions, outmigrant abundance was more sensitive to changes in temperature than to food resources due to the particularly low water temperatures released from an upstream dam impacting hatching success within this site. Mean outmigrant length was more sensitive to changes in food availability than to temperature. Collectively, the model results demonstrated that the Stage 0 activities at SFMK may increase juvenile length and number of reared individuals, though results should be evaluated across the diverse styles of Stage 0 projects. Further, the methods reflect the utility of moving beyond species‐habitat indices as a tool in evaluating restoration practices.
Journals
2025 EN
Gurney Steven M. · Christensen Sonja A. · Nichols Melissa J.
+5 more
Abstract Evaluating changes in population abundance is essential to assess the efficacy of conservation actions. Antler point restrictions are a high‐profile regulatory action aimed to advance male age structure in cervid populations, but there is a limited understanding of how restrictions affect population size and structure. Our study evaluated population‐level effects of an antler point restriction on white‐tailed deer ( Odocoileus virginianus ) abundance and sex and age composition using a before–after control–impact design. Antler point restrictions are intended to increase the abundance of legal‐antlered deer, but the impact on the abundance of antlerless deer is less known. By limiting the harvest of yearling males, antler point restrictions may lead hunters to shift harvest toward antlerless deer, potentially increasing female mortality and reducing population fecundity. We conducted camera‐trap surveys of deer in zones with and without antler point restrictions before and 3 years after the implementation of restrictions and used N‐mixture models to estimate annual abundance by sex and age class. The restriction prohibited the harvest of antlered deer with fewer than four points on a single antler beam (i.e., on one side). Our results suggest that the restrictions did not influence population abundance of deer. The abundance of legal‐antlered deer increased in both the restriction zone and the non‐restriction zone (opposing predictions), as did the abundance of females, sublegal‐antlered deer, and fawns (opposing predictions). Partial controllability, or a failure of the regulation to influence realized harvest, likely explains these results, since antlerless deer harvest did not change throughout the duration of our study while slight but insignificant changes in antlered harvest were observed in the restriction zone. Our results highlight potential limitations of antler point restrictions achieving desired effects for population reduction goals and the importance of independently evaluating conservation and management actions.
Journals
2025 EN
Eash Lisa · Russell Kathleen · Berrada Abdel F.
+6 more
Abstract Replacing bare fallow periods with cover crops in dryland agroecosystems can help reverse soil degradation and control erosion but may also result in cash crop yield penalties due to water limitations. Two field trials were conducted on the Colorado Plateau to quantify the impact of cover cropping on crop production, multiple ecosystem services, and economic trade‐offs in this semiarid region. No‐till and different cover crop planting windows (fall and spring) were explored as strategies to optimize ecosystem service provision and productivity trade‐offs. After three full cover crop cycles (6 years), fall‐planted cover crops improved soil structure and erosion control, offering critical soil health benefits for dryland producers. However, these benefits were associated with a decrease in available soil moisture at planting, causing lower and more variable wheat yields (average 48% yield penalty) and a US$176 ha −1 cycle −1 average decrease in net returns. Including the hypothetical sale of forage (based on 50% cover crop biomass removal) more than offset these costs in fall‐planted treatments; with both forage and wheat revenue, cover cropping increased net returns as compared to the fallow control by US$92 ha −1 cycle −1 . Spring‐planted cover crops presented a lower productivity trade‐off (24% average wheat yield penalty) but did not provide clear ecosystem service benefits and did not produce enough biomass to offset costs of cover cropping. Our findings indicate that fall‐planted cover crops have the potential to reverse soil degradation and control erosion in dryland systems globally, but productivity trade‐offs and decreased economic returns must be compensated for by alternative revenue sources, conservation payments, or other incentives to ensure their feasibility.
Journals
2025 EN
Stralberg Diana · Sólymos Péter · Docherty Teegan D. S.
+13 more
Abstract Spatially explicit estimates of species abundance and distribution are increasingly needed to support conservation planning and management across multiple spatial scales. We present a generalized modeling framework that bridges the gap between local studies and regional to national planning by compiling and harmonizing diverse datasets to predict avian abundance at fine resolution and broad extent. We applied detectability offsets to integrate point‐count data from over 250,000 locations across subarctic Canada. Data were subsampled by two time periods and 16 geographic regions, and we used boosted regression trees to model the density of 143 boreal landbird species as a function of climate, vegetation composition (local [250 m] and landscape [~1.5 km]), land cover, and topography. Bootstrapped regional predictions were combined to generate density maps, region‐ and habitat‐specific estimates, and Canada‐wide population totals. We estimated ~3.56 billion breeding males (7.13 billion individuals), with most occurring in boreal and hemi‐boreal regions. Forest generalists accounted for nearly half the total (1.57 billion males), followed by boreal specialists (1.05 billion), habitat generalists (350 million), and species associated with eastern forests (274 million), grasslands (124 million), western forests (74.7 million), wetlands (63.5 million), and Arctic tundra (17.7 million). Introduced species totaled 48.9 million breeding males. Across species, landscape‐level vegetation composition explained most variation in abundance, indicating that climate effects are primarily indirect, operating through vegetation. Landscape‐scale variables were critical to capturing this variation. Model classification accuracy was highest for forest‐ and grassland‐associated species (lowest for mountain and urban species), and for the families Regulidae and Phasianidae (lowest for Bombycillidae and Paridae). This work provides a standardized, updatable, and reproducible workflow for generating spatially explicit bird abundance estimates. These products can be revised as new data become available and used to support ongoing conservation and land‐use decisions.
Journals
2025 EN
Davenport Rebecca N. · Barton Christopher · Cox John
+5 more
Abstract Surface coal mining and subsequent reclamation efforts in the Appalachian Mountains, USA, transform the ecological characteristics of natural landscapes. The Forestry Reclamation Approach (FRA) is a mine reclamation method that emphasizes best management practices in forestry. FRA practices have demonstrated success in establishing native forests and accelerating natural succession on coal mines; however, no studies have empirically examined the effects of the FRA on bird communities. Our study aimed to assess the avian community composition within young forests reclaimed using the FRA after one decade of forest growth. Whereas traditional reclamation practices often support grassland avian guilds, we expected that the FRA would provide habitat for shrubland and young forest avian guilds. Moreover, we sought to determine whether FRA forests would contain known avian indicator species of the native forest land cover. In June 2022, we conducted point count surveys in high‐elevation, red spruce‐northern hardwood (RS‐NH) forests in the Appalachian Mountains of eastern West Virginia, USA. Using Bayesian multispecies occupancy models, we assessed avian guild occupancy and species richness within two FRA forest age classes (2–5 years and 8–11 years). We also examined avian community composition within two older RS‐NH reference age classes to predict the future avian composition within FRA forests if reclamation succeeds. We found that the FRA breeding bird community included all of the avian indicator species expected to inhabit a young RS‐NH forest. These results suggest that after approximately one decade, legacy mines reclaimed using the FRA are progressing toward a native RS‐NH forest that supports associated forest bird communities.
Journals
2025 EN
Winter Steven N. · Sargeant Glen A. · Wild Margaret A.
+4 more
Abstract Environments can shape the occurrence and extent of disease outbreaks in wildlife. We studied the effects of environmental features on the occurrence of treponeme‐associated hoof disease (TAHD), an emerging infectious disease of free‐ranging elk ( Cervus canadensis ), in southwestern Washington, USA. During the 2016–2022 harvest seasons, successful elk hunters returned mandatory harvest reports and noted the presence or absence of hoof abnormalities indicative of TAHD. We used generalized linear models and an information‐theoretic approach to model selection to relate (1) the spatial distribution of hoof abnormalities to features of landscapes (land cover, topography, and soil characteristics) and (2) the temporal distribution of hoof abnormalities to precipitation during the year preceding the harvest season. The probability of hoof disease increased with soil clay content and proportion of agricultural land (88% of model weight). We found no conclusive evidence for an effect of precipitation on the occurrence of TAHD, but this could relate to relatively high annual precipitation (>140 cm) in the study area. Nevertheless, disease cases may have been negatively associated with precipitation during February–June (55% of model weight). Soils and land management practices may increase the risk of hoof disease by promoting the survival of pathogens that cause TAHD, the susceptibility of elk to infection, or the intensity of pathogen transmission among elk when congregated. Focusing on areas where the risk of disease is greatest may facilitate the detection of TAHD during surveillance. Likewise, removing infected elk and dispersing uninfected elk from areas with the greatest risk of disease may enhance the effectiveness of efforts to reduce transmission. Basing this work on the knowledge that disease risk is modified by factors of hosts, pathogens, and environments, this study serves as an application of the epidemiological triad framework to better understand the ecology and epidemiology of an emerging infectious disease in wildlife.