Global expansion of marine protected areas and the redistribution of fishing effort.

The expansion of marine protected areas (MPAs) is a core focus of global conservation efforts, with the "30x30" initiative to protect 30% of the ocean by 2030 serving as a prominent example of this trend. We consider a series of proposed MPA network expansions of various sizes, and we forecast the impact this increase in protection would have on global patterns of fishing effort. We do so by building a predictive machine learning model trained on a global dataset of satellite-based fishing vessel monitoring data, current MPA locations, and spatiotemporal environmental, geographic, political, and economic features. We then use this model to predict future fishing effort under various MPA expansion scenarios compared to a business-as-usual counterfactual scenario that includes no new MPAs. The difference between these scenarios represents the predicted change in fishing effort associated with MPA expansion. We find that regardless of the MPA network objectives or size, fishing effort would decrease inside the MPAs, though by much less than 100%. Moreover, we find that the reduction in fishing effort inside MPAs does not simply redistribute outside-rather, fishing effort outside MPAs would also decline. The overall magnitude of the predicted decrease in global fishing effort principally depends on where networks are placed in relation to existing fishing effort. MPA expansion will lead to a global redistribution of fishing effort that should be accounted for in network design, implementation, and impact evaluation.

Underlying and proximate drivers of biodiversity changes in Mesoamerican biosphere reserves.

Protected areas are of paramount relevance to conserving wildlife and ecosystem contributions to people. Yet, their conservation success is increasingly threatened by human activities including habitat loss, climate change, pollution, and species overexploitation. Thus, understanding the underlying and proximate drivers of anthropogenic threats is urgently needed to improve protected areas' effectiveness, especially in the biodiversity-rich tropics. We addressed this issue by analyzing expert-provided data on long-term biodiversity change (last three decades) over 14 biosphere reserves from the Mesoamerican Biodiversity Hotspot. Using multivariate analyses and structural equation modeling, we tested the influence of major socioeconomic drivers (demographic, economic, and political factors), spatial indicators of human activities (agriculture expansion and road extension), and forest landscape modifications (forest loss and isolation) as drivers of biodiversity change. We uncovered a significant proliferation of disturbance-tolerant guilds and the loss or decline of disturbance-sensitive guilds within reserves causing a "winner and loser" species replacement over time. Guild change was directly related to forest spatial changes promoted by the expansion of agriculture and roads within reserves. High human population density and low nonfarming occupation were identified as the main underlying drivers of biodiversity change. Our findings suggest that to mitigate anthropogenic threats to biodiversity within biosphere reserves, fostering human population well-being via sustainable, nonfarming livelihood opportunities around reserves is imperative.

The role of funding in the performance of Latin America's protected areas.

Conservationists have long argued that inadequate funding for managing protected areas (PAs) jeopardizes their ability to achieve conservation goals. However, this claim has rarely been substantiated by quantitative evaluations. To address this, we examined the impact of funding on PA effectiveness both at the scale of 17 national PA systems across Latin America and within a PA system (Ecuador), for which we had precise historical financial data. Most PAs reduced deforestation between 2000 and 2010, demonstrating their crucial role in forest conservation. However, large deficits in funding considerably reduced the effectiveness of PAs in Ecuador (on average, a unit decrease in deficit leads to a 3.07% increase in effectiveness in avoiding deforestation). While differences in effectiveness between individual PAs in Ecuador were associated with funding deficits, national-level socioeconomic metrics (e.g., the Human Development Index) were the major factor when comparing PA system-level effectiveness among countries. This result suggests that while funding plays a major role in the performance of individual PAs, the quality of the socioeconomic context at the country level is critical for the overall performance of the PA systems. We, therefore, emphasize that maximizing the effectiveness of PAs requires a multilevel approach that includes better and more strategic resource allocation for individual PAs, combined with actions for strengthening the governance and institutions that regulate PA systems.

Private management of African protected areas improves wildlife and tourism outcomes but with security concerns in conflict regions.

Protected areas can conserve wildlife and benefit people when managed effectively. African governments increasingly delegate the management of protected areas to private, nongovernmental organizations, hoping that private organizations' significant resources and technical capacities actualize protected areas' potential. Does private sector management improve outcomes compared to a counterfactual of government management? We leverage the transfer of management authority from governments to African Parks (AP)-the largest private manager of protected areas in Africa-to show that private management significantly improves wildlife outcomes via reduced elephant poaching and increased bird abundances. Our results also suggest that AP's management augments tourism, while the effect on rural wealth is inconclusive. However, AP's management increases the risk of armed groups targeting civilians, which could be an unintended outcome of AP's improved monitoring and enforcement systems. These findings reveal an intricate interplay between conservation, economic development, and security under privately managed protected areas in Africa.

Predicting undetected native vascular plant diversity at a global scale.

Vascular plants are diverse and a major component of terrestrial ecosystems, yet their geographic distributions remain incomplete. Here, I present a global database of vascular plant distributions by integrating species distribution models calibrated to species' dispersal ability and natural habitats to predict native range maps for 201,681 vascular plant species into unsurveyed areas. Using these maps, I uncover unique patterns of native vascular plant diversity, endemism, and phylogenetic diversity revealing hotspots in underdocumented biodiversity-rich regions. These hotspots, based on detailed species-level maps, show a pronounced latitudinal gradient, strongly supporting the theory of increasing diversity toward the equator. I trained random forest models to extrapolate diversity patterns under unbiased global sampling and identify overlaps with modeled estimations but unveiled cryptic hotspots that were not captured by modeled estimations. Only 29% to 36% of extrapolated plant hotspots are inside protected areas, leaving more than 60% outside and vulnerable. However, the unprotected hotspots harbor species with unique attributes that make them good candidates for conservation prioritization.

A diverse portfolio of marine protected areas can better advance global conservation and equity.

Marine protected areas (MPAs) are widely used for ocean conservation, yet the relative impacts of various types of MPAs are poorly understood. We estimated impacts on fish biomass from no-take and multiple-use (fished) MPAs, employing a rigorous matched counterfactual design with a global dataset of >14,000 surveys in and around 216 MPAs. Both no-take and multiple-use MPAs generated positive conservation outcomes relative to no protection (58.2% and 12.6% fish biomass increases, respectively), with smaller estimated differences between the two MPA types when controlling for additional confounding factors (8.3% increase). Relative performance depended on context and management: no-take MPAs performed better in areas of high human pressure but similar to multiple-use in remote locations. Multiple-use MPA performance was low in high-pressure areas but improved significantly with better management, producing similar outcomes to no-take MPAs when adequately staffed and appropriate use regulations were applied. For priority conservation areas where no-take restrictions are not possible or ethical, our findings show that a portfolio of well-designed and well-managed multiple-use MPAs represents a viable and potentially equitable pathway to advance local and global conservation.

High exposure of global tree diversity to human pressure.

Safeguarding Earth's tree diversity is a conservation priority due to the importance of trees for biodiversity and ecosystem functions and services such as carbon sequestration. Here, we improve the foundation for effective conservation of global tree diversity by analyzing a recently developed database of tree species covering 46,752 species. We quantify range protection and anthropogenic pressures for each species and develop conservation priorities across taxonomic, phylogenetic, and functional diversity dimensions. We also assess the effectiveness of several influential proposed conservation prioritization frameworks to protect the top 17% and top 50% of tree priority areas. We find that an average of 50.2% of a tree species' range occurs in 110-km grid cells without any protected areas (PAs), with 6,377 small-range tree species fully unprotected, and that 83% of tree species experience nonnegligible human pressure across their range on average. Protecting high-priority areas for the top 17% and 50% priority thresholds would increase the average protected proportion of each tree species' range to 65.5% and 82.6%, respectively, leaving many fewer species (2,151 and 2,010) completely unprotected. The priority areas identified for trees match well to the Global 200 Ecoregions framework, revealing that priority areas for trees would in large part also optimize protection for terrestrial biodiversity overall. Based on range estimates for >46,000 tree species, our findings show that a large proportion of tree species receive limited protection by current PAs and are under substantial human pressure. Improved protection of biodiversity overall would also strongly benefit global tree diversity.

Trade-offs between bycatch and target catches in static versus dynamic fishery closures.

While there have been recent improvements in reducing bycatch in many fisheries, bycatch remains a threat for numerous species around the globe. Static spatial and temporal closures are used in many places as a tool to reduce bycatch. However, their effectiveness in achieving this goal is uncertain, particularly for highly mobile species. We evaluated evidence for the effects of temporal, static, and dynamic area closures on the bycatch and target catch of 15 fisheries around the world. Assuming perfect knowledge of where the catch and bycatch occurs and a closure of 30% of the fishing area, we found that dynamic area closures could reduce bycatch by an average of 57% without sacrificing catch of target species, compared to 16% reductions in bycatch achievable by static closures. The degree of bycatch reduction achievable for a certain quantity of target catch was related to the correlation in space and time between target and bycatch species. If the correlation was high, it was harder to find an area to reduce bycatch without sacrificing catch of target species. If the goal of spatial closures is to reduce bycatch, our results suggest that dynamic management provides substantially better outcomes than classic static marine area closures. The use of dynamic ocean management might be difficult to implement and enforce in many regions. Nevertheless, dynamic approaches will be increasingly valuable as climate change drives species and fisheries into new habitats or extended ranges, altering species-fishery interactions and underscoring the need for more responsive and flexible regulatory mechanisms.

Climate benefits from establishing marine protected areas targeted at blue carbon solutions.

Marine protected areas (MPAs) are recognized as highly effective tools for marine conservation. They may also play an important role in mitigating climate change. A variety of climate change solutions are rooted in the ocean, centered primarily around "blue carbon" and the capacity of marine life to sequester carbon dioxide (CO2) with some potential to reduce emissions. However, the global potential of these solutions remains misunderstood and untapped. Here, we analyze the potential impact on carbon removal and emissions reduction of adopting six ocean-based solutions in MPAs: coastal wetlands protection, coastal wetlands restoration, macroalgae protection, macroalgae restoration, seafloor protection, and seaweed farming. The carbon removal and avoided emissions achieved by implementing these solutions globally through 2060 were estimated using meta-analysis of existing studies. Applying all six ocean solutions under global implementation scenarios yields total emissions reduction by 2060 of 16.2 ± 1.82 gigatonnes of carbon dioxide equivalent (GtCO2-eq) for the plausible scenario and 24.8 ± 2.46 GtCO2-eq for the ambitious scenario. That equates to around 2% of the total carbon mitigation needed to meet the Paris Agreement goals of limiting global warming to 2 °C by 2050. Around 70% of this reduction is attributable to carbon removal and 30% to avoided emissions. Enhancing MPAs' blue carbon potential could be a key contributor to drawing down carbon and could provide many additional benefits to the marine environment and human society, such as rebuilding biodiversity and sustaining food production. However, more regional-scale studies are needed to inform the best strategies for preserving and enhancing carbon removal in ocean sinks.

Global protected areas seem insufficient to safeguard half of the world's mammals from human-induced extinction.

Protected areas (PAs) are a cornerstone of global conservation and central to international plans to minimize global extinctions. During the coming century, global ecosystem destruction and fragmentation associated with increased human population and economic activity could make the long-term survival of most terrestrial vertebrates even more dependent on PAs. However, the capacity of the current global PA network to sustain species for the long term is unknown. Here, we explore this question for all nonvolant terrestrial mammals for which we found sufficient data, ∼4,000 species. We first estimate the potential population size of each such mammal species in each PA and then use three different criteria to estimate if solely the current global network of PAs might be sufficient for their long-term survival. Our analyses suggest that current PAs may fail to provide robust protection for about half the species analyzed, including most species currently listed as threatened with extinction and a third of species not currently listed as threatened. Hundreds of mammal species appear to have no viable protected populations. Underprotected species were found across all body sizes, taxonomic groups, and geographic regions. Large-bodied mammals, endemic species, and those in high-biodiversity tropical regions were particularly poorly protected by existing PAs. As new international biodiversity targets are formulated, our results suggest that the global network of PAs must be greatly expanded and most importantly that PAs must be located in diverse regions that encompass species not currently protected and must be large enough to ensure that protected species can persist for the long term.

Rarity mediates species-specific responses of tropical reef fishes to protection.

Marine protected areas (MPAs) are the most widely applied tool for marine biodiversity conservation, yet many gaps remain in our understanding of their species-specific effects, partly because the socio-environmental context and spatial autocorrelation may blur and bias perceived conservation outcomes. Based on a large data set of nearly 3000 marine fish surveys spanning all tropical regions of the world, we build spatially explicit models for 658 fish species to estimate species-specific responses to protection while controlling for the environmental, habitat and socio-economic contexts experienced across their geographic ranges. We show that the species responses are highly variable, with ~40% of fishes not benefitting from protection. When investigating how traits influence species' responses, we find that rare top-predators and small herbivores benefit the most from MPAs while mid-trophic level species benefit to a lesser extent, and rare large herbivores experience adverse effects, indicating potential trophic cascades.

A grazer's niche edge is associated with increasing diet diversity and poor population performance.

The core-periphery hypothesis predicts niche cores should be associated with greater survivorship, reproductive output and population performance rates than marginal habitats at niche edges. However, there is very little empirical evidence of whether niche centrality influences population trends in animals. Using the Cape mountain zebra (Equus zebra zebra) as a model system, we evaluated whether niche centrality is associated with population trends, resource availability and diet across a core-periphery gradient. Population growth rates and density progressively declined towards niche peripheries. Niche peripheries were resource-poor and Cape mountain zebra consumed more phylogenetically diverse diets dominated by non-grass families. In core habitats they consumed grass-rich diets and female reproductive success was higher. This combination of spatial niche modelling and functional ecology provides a novel evaluation of how bottom-up resource limitation can shape species distributions, population resilience and range change and can guide conservation management.

Principles for area-based biodiversity conservation.

Recent international agreements have strengthened and expanded commitments to protect and restore native habitats for biodiversity protection ("area-based biodiversity conservation"). Nevertheless, biodiversity conservation is hindered because how such commitments should be implemented has been strongly debated, which can lead to suboptimal habitat protection decisions. We argue that, despite the debates, there are three essential principles for area-based biodiversity conservation. These principles are related to habitat geographic coverage, amount, and connectivity. They emerge from evidence that, while large areas of nature are important and must be protected, conservation or restoration of multiple small habitat patches is also critical for global conservation, particularly in regions with high land use. We contend that the many area-based conservation initiatives expected in the coming decades should follow the principles we identify, regardless of ongoing debates. Considering the importance of biodiversity for maintenance of ecosystem services, we suggest that this would bring widespread societal benefits.

Integration of genomic and ecological methods inform management of an undescribed, yet highly exploited, sardine species.

Assessing genetic diversity within species is key for conservation strategies in the context of human-induced biotic changes. This is important in marine systems, where many species remain undescribed while being overfished, and conflicts between resource-users and conservation agencies are common. Combining niche modelling with population genomics can contribute to resolving those conflicts by identifying management units and understanding how past climatic cycles resulted in current patterns of genetic diversity. We addressed these issues on an undescribed but already overexploited species of sardine of the genus Harengula. We find that the species distribution is determined by salinity and depth, with a continuous distribution along the Brazilian mainland and two disconnected oceanic archipelagos. Genomic data indicate that such biogeographic barriers are associated with two divergent intraspecific lineages. Changes in habitat availability during the last glacial cycle led to different demographic histories among stocks. One coastal population experienced a 3.6-fold expansion, whereas an island-associated population contracted 3-fold, relative to the size of the ancestral population. Our results indicate that the island population should be managed separately from the coastal population, and that a Marine Protected Area covering part of the island population distribution can support the viability of this lineage.

Body mass mediates spatio-temporal responses of mammals to human frequentation across Italian protected areas.

Protected area (PA) networks are a pivotal tool to fight biodiversity loss, yet they often need to balance the mission of nature conservation with the socio-economic need of giving opportunity for outdoor recreation. Recreation in natural areas is important for human health in an urbanized society, but can prompt behavioural modifications in wild animals. Rarely, however, have these responses being studied across multiple PAs and using standardized methods. We deployed a systematic camera trapping protocol at over 200 sites to sample medium and large mammals in four PAs within the European Natura 2000 network to assess their spatio-temporal responses to human frequentation, proximity to towns, amount of open habitat and topographical variables. By applying multi-species and single-species models for the number of diurnal, crepuscular and nocturnal detections and a multi-species model for nocturnality index, we estimated both species-specific- and meta-community-level effects, finding that increased nocturnality appeared the main strategy that the mammal meta-community used to cope with human disturbance. However, responses in the diurnal, crepuscular and nocturnal site use were mediated by species' body mass, with larger species exhibiting avoidance of humans and smaller species more opportunistic behaviours. Our results show the effectiveness of standardized sampling and provide insights for planning the expansion of PA networks as foreseen by the Kunming-Montreal biodiversity agreement.

Unveiling the landscape predictors of resilient vegetation in coastal wetlands to inform conservation in the face of climate extremes.

Unveiling spatial variation in vegetation resilience to climate extremes can inform effective conservation planning under climate change. Although many conservation efforts are implemented on landscape scales, they often remain blind to landscape variation in vegetation resilience. We explored the distribution of drought-resilient vegetation (i.e., vegetation that could withstand and quickly recover from drought) and its predictors across a heterogeneous coastal landscape under long-term wetland conversion, through a series of high-resolution satellite image interpretations, spatial analyses, and nonlinear modelling. We found that vegetation varied greatly in drought resilience across the coastal wetland landscape and that drought-resilient vegetation could be predicted with distances to coastline and tidal channel. Specifically, drought-resilient vegetation exhibited a nearly bimodal distribution and had a seaward optimum at ~2 km from coastline (corresponding to an inundation frequency of ~30%), a pattern particularly pronounced in areas further away from tidal channels. Furthermore, we found that areas with drought-resilient vegetation were more likely to be eliminated by wetland conversion. Even in protected areas where wetland conversion was slowed, drought-resilient vegetation was increasingly lost to wetland conversion at its landward optimum in combination with rapid plant invasions at its seaward optimum. Our study highlights that the distribution of drought-resilient vegetation can be predicted using landscape features but without incorporating this predictive understanding, conservation efforts may risk failing in the face of climate extremes.

Interplay of management and environmental drivers shifts size structure of reef fish communities.

Countries are expanding marine protected area (MPA) networks to mitigate fisheries declines and support marine biodiversity. However, MPA impact evaluations typically assess total fish biomass. Here, we examine how fish biomass disaggregated by adult and juvenile life stages responds to environmental drivers, including sea surface temperature (SST) anomalies and human footprint, and multiple management types at 139 reef sites in the Mesoamerican Reef (MAR) region. We found that total fish biomass generally appears stable across the region from 2006 to 2018, with limited rebuilding of fish stocks in MPAs. However, the metric of total fish biomass masked changes in fish community structure, with lower adult than juvenile fish biomass at northern sites, and adult:juvenile ratios closer to 1:1 at southern sites. These shifts were associated with different responses of juvenile and adult fish to environmental drivers and management. Juvenile fish biomass increased at sites with high larval connectivity and coral cover, whereas adult fish biomass decreased at sites with greater human footprint and SST anomalies. Adult fish biomass decreased primarily in Honduran general use zones, which suggests insufficient protection for adult fish in the southern MAR. There was a north-south gradient in management and environmental drivers, with lower coverage of fully protected areas and higher SST anomalies and coastal development in the south that together may undermine the maintenance of adult fish biomass in the southern MAR. Accounting for the interplay between environmental drivers and management in the design of MPAs is critical for increasing fish biomass across life history stages.

Los países están ampliando las redes de áreas marinas protegidas (AMP) para mitigar la disminución de las pesquerías y apoyar la biodiversidad marina. Sin embargo, las evaluaciones de impacto de las AMP típicamente estudian la biomasa total de peces. Aquí, examinamos cómo la biomasa de peces desagregada por etapas de vida adultas y juveniles responde a factores ambientales como anomalías de la temperatura superficial del mar (SST) e impacto humano, y múltiples tipos de manejo en 139 sitios de arrecifes en el sistema arrecifal mesoamericano (SAM). Encontramos que la biomasa total de peces en general parece estable en toda la región entre 2006 y 2018, con una recuperación limitada de las poblaciones de peces en las AMP. Sin embargo, la métrica de biomasa total de peces enmascaró los cambios en la estructura de la comunidad de peces, con una biomasa de peces adultos más baja que juveniles en los sitios del norte, y proporciones adulto:juvenil más cercana a 1:1 en los sitios del sur. Estos cambios fueron asociados con diferentes respuestas de peces juveniles y adultos a variables ambientales y de manejo. La biomasa de peces juveniles aumentó en sitios con alta conectividad larvaria y cobertura coralina, mientras que la biomasa de peces adultos disminuyó en sitios con mayor impacto humano y anomalías en la SST. La biomasa de peces adultos disminuyó principalmente en las zonas de uso general (GUZ) hondureñas, lo cual sugiere una protección insuficiente para peces adultos en el sur del SAM. Hubo un gradiente norte­sur en el manejo y los factores ambientales, con menor cobertura de áreas totalmente protegidas y mayores anomalías de SST y desarrollo costero en el sur. En conjunto esto puede degradar el mantenimiento de la biomasa de peces adultos en el sur del SAM. La interacción entre factores ambientales y el manejo en el diseño de las AMP es fundamental para aumentar la biomasa de peces en todas las etapas del ciclo de vida.

Climate-driven shifts in the diversity of plants in the Neotropical seasonally dry forest: Evaluating the effectiveness of protected areas.

Given the current environmental crisis, biodiversity protection is one of the most urgent socio-environmental priorities. However, the effectiveness of protected areas (PAs), the primary strategy for safeguarding ecosystems, is challenged by global climate change (GCC), with evidence showing that species are shifting their distributions into new areas, causing novel species assemblages. Therefore, there is a need to evaluate PAs' present and future effectiveness for biodiversity under the GCC. Here, we analyzed changes in the spatiotemporal patterns of taxonomic and phylogenetic diversity (PD) of plants associated with the Neotropical seasonally dry forest (NSDF) under GCC scenarios. We modeled the climatic niche of over 1000 plant species in five representative families (in terms of abundance, dominance, and endemism) of the NSDF. We predicted their potential distributions in the present and future years (2040, 2060, and 2080) based on an intermediate scenario of shared socio-economic pathways (SSP 3.70), allowing species to disperse to new sites or constrained to the current distribution. Then, we tested if the current PAs network represents the taxonomic and phylogenetic diversities. Our results suggest that GCC could promote novel species assemblages with local responses (communities' modifications) across the biome. In general, models predicted losses in the taxonomic and phylogenetic diversities of all the five plant families analyzed across the distribution of the NSDF. However, in the northern floristic groups (i.e., Antilles and Mesoamerica) of the NSDF, taxonomic and PD will be stable in GCC projections. In contrast, across the NSDF in South America, some cores will lose diversity while others will gain diversity under GCC scenarios. PAs in some NSDF regions appeared insufficient to protect the NSDF diversity. Thus, there is an urgent need to assess how the PA system could be better reconfigured to warrant the protection of the NSDF.

Dada la actual crisis ambiental, la protección de la biodiversidad se presenta como una de las prioridades socio ambientales más urgentes. Sin embargo, la efectividad de las áreas protegidas (AP), la estrategia principal para salvaguardar los ecosistemas, se ve desafiada por el cambio climático global (CCG), con evidencia que muestra que las especies están desplazando sus distribuciones hacia nuevas áreas, provocando conjuntos de especies novedosos. Por lo tanto, es necesario evaluar la efectividad actual y futura de las AP para la biodiversidad bajo el CCG. En este contexto, analizamos cambios en los patrones espacio­temporales de diversidad taxonómica y filogenética de plantas asociadas al bosque estacionalmente seco neotropical (BES) bajo escenarios de CCG. Modelamos el nicho climático de más de 1,000 especies de plantas en cinco familias representativas (en términos de abundancia, dominancia y endemismo) del BES. Pronosticamos sus distribuciones potenciales en los años actuales y futuros (2040, 2060 y 2080) basándonos en un escenario intermedio de trayectorias socioeconómicas compartidas (SSP 3.70), permitiendo que las especies se dispersen a nuevos sitios o estén limitadas a la distribución actual. Luego, evaluamos si la red actual de AP representa las diversidades taxonómicas y filogenéticas. Nuestros resultados sugieren que el CCG podría promover conjuntos de especies novedosos con respuestas locales (modificaciones en las comunidades) en todo el bioma. En general, los modelos pronosticaron pérdidas en las diversidades taxonómicas y filogenéticas de las cinco familias de plantas analizadas en la distribución del BES. Sin embargo, en los grupos florísticos del norte (es decir, Antillas y Mesoamérica) del BSDN, la diversidad taxonómica y filogenética se mantendrá estable en las proyecciones de CCG. En cambio, en toda la región del BES en América del Sur, algunos núcleos perderán diversidad mientras que otros ganarán diversidad bajo escenarios de CCG. Algunas AP en regiones del BES parecen ser insuficientes para proteger la diversidad del bioma. Por lo tanto, es urgente evaluar cómo se podría reconfigurar mejor el sistema de AP para garantizar la protección del BES.

Projected climate and canopy change lead to thermophilization and homogenization of forest floor vegetation in a hotspot of plant species richness.

Mountain forests are plant diversity hotspots, but changing climate and increasing forest disturbances will likely lead to far-reaching plant community change. Projecting future change, however, is challenging for forest understory plants, which respond to forest structure and composition as well as climate. Here, we jointly assessed the effects of both climate and forest change, including wind and bark beetle disturbances, using the process-based simulation model iLand in a protected landscape in the northern Alps (Berchtesgaden National Park, Germany), asking: (1) How do understory plant communities respond to 21st-century change in a topographically complex mountain landscape, representing a hotspot of plant species richness? (2) How important are climatic changes (i.e., direct climate effects) versus forest structure and composition changes (i.e., indirect climate effects and recovery from past land use) in driving understory responses at landscape scales? Stacked individual species distribution models fit with climate, forest, and soil predictors (248 species currently present in the landscape, derived from 150 field plots stratified by elevation and forest development, overall area under the receiving operator characteristic curve = 0.86) were driven with projected climate (RCP4.5 and RCP8.5) and modeled forest variables to predict plant community change. Nearly all species persisted in the landscape in 2050, but on average 8% of the species pool was lost by the end of the century. By 2100, landscape mean species richness and understory cover declined (-13% and -8%, respectively), warm-adapted species increasingly dominated plant communities (i.e., thermophilization, +12%), and plot-level turnover was high (62%). Subalpine forests experienced the greatest richness declines (-16%), most thermophilization (+17%), and highest turnover (67%), resulting in plant community homogenization across elevation zones. Climate rather than forest change was the dominant driver of understory responses. The magnitude of unabated 21st-century change is likely to erode plant diversity in a species richness hotspot, calling for stronger conservation and climate mitigation efforts.

Beyond resilience: Responses to changing climate and disturbance regimes in temperate forest landscapes across the Northern Hemisphere.

Climate change has profound impacts on forest ecosystem dynamics and could lead to the emergence of novel ecosystems via changes in species composition, forest structure, and potentially a complete loss of tree cover. Disturbances fundamentally shape those dynamics: the prevailing disturbance regime of a region determines the inherent variability of a system, and its climate-mediated change could accelerate forest transformation. We used the individual-based forest landscape and disturbance model iLand to investigate the resilience of three protected temperate forest landscapes on three continents-selected to represent a gradient from low to high disturbance activity-to changing climate and disturbance regimes. In scenarios of sustained strong global warming, natural disturbances increased across all landscapes regardless of projected changes in precipitation (up to a sevenfold increase in disturbance rate over the 180-year simulation period). Forests in landscapes with historically high disturbance activity had a higher chance of remaining resilient in the future, retaining their structure and composition within the range of variability inherent to the system. However, the risk of regime shift and forest loss was also highest in these systems, suggesting forests may be vulnerable to abrupt change beyond a threshold of increasing disturbance activity. Resilience generally decreased with increasing severity of climate change. Novelty in tree species composition was more common than novelty in forest structure, especially under dry climate scenarios. Forests close to the upper tree line experienced high novelty in structure across all three study systems. Our results highlight common patterns and processes of forest change, while also underlining the diverse and context-specific responses of temperate forest landscapes to climate change. Understanding past and future disturbance regimes can anticipate the magnitude and direction of forest change. Yet, even across a broad gradient of disturbance activity, we conclude that climate change mitigation is the most effective means of maintaining forest resilience.