Demographic composition, not demographic diversity, predicts biomass and turnover across temperate and tropical forests.

The growth and survival of individual trees determine the physical structure of a forest with important consequences for forest function. However, given the diversity of tree species and forest biomes, quantifying the multitude of demographic strategies within and across forests and the way that they translate into forest structure and function remains a significant challenge. Here, we quantify the demographic rates of 1961 tree species from temperate and tropical forests and evaluate how demographic diversity (DD) and demographic composition (DC) differ across forests, and how these differences in demography relate to species richness, aboveground biomass (AGB), and carbon residence time. We find wide variation in DD and DC across forest plots, patterns that are not explained by species richness or climate variables alone. There is no evidence that DD has an effect on either AGB or carbon residence time. Rather, the DC of forests, specifically the relative abundance of large statured species, predicted both biomass and carbon residence time. Our results demonstrate the distinct DCs of globally distributed forests, reflecting biogeography, recent history, and current plot conditions. Linking the DC of forests to resilience or vulnerability to climate change, will improve the precision and accuracy of predictions of future forest composition, structure, and function.

Interactions between all pairs of neighboring trees in 16 forests worldwide reveal details of unique ecological processes in each forest, and provide windows into their evolutionary histories.

When Darwin visited the Galapagos archipelago, he observed that, in spite of the islands' physical similarity, members of species that had dispersed to them recently were beginning to diverge from each other. He postulated that these divergences must have resulted primarily from interactions with sets of other species that had also diverged across these otherwise similar islands. By extrapolation, if Darwin is correct, such complex interactions must be driving species divergences across all ecosystems. However, many current general ecological theories that predict observed distributions of species in ecosystems do not take the details of between-species interactions into account. Here we quantify, in sixteen forest diversity plots (FDPs) worldwide, highly significant negative density-dependent (NDD) components of both conspecific and heterospecific between-tree interactions that affect the trees' distributions, growth, recruitment, and mortality. These interactions decline smoothly in significance with increasing physical distance between trees. They also tend to decline in significance with increasing phylogenetic distance between the trees, but each FDP exhibits its own unique pattern of exceptions to this overall decline. Unique patterns of between-species interactions in ecosystems, of the general type that Darwin postulated, are likely to have contributed to the exceptions. We test the power of our null-model method by using a deliberately modified data set, and show that the method easily identifies the modifications. We examine how some of the exceptions, at the Wind River (USA) FDP, reveal new details of a known allelopathic effect of one of the Wind River gymnosperm species. Finally, we explore how similar analyses can be used to investigate details of many types of interactions in these complex ecosystems, and can provide clues to the evolution of these interactions.

Importance of species translocations under rapid climate change.

Species that cannot adapt or keep pace with a changing climate are likely to need human intervention to shift to more suitable climates. While hundreds of articles mention using translocation as a climate-change adaptation tool, in practice, assisted migration as a conservation action remains rare, especially for animals. This is likely due to concern over introducing species to places where they may become invasive. However, there are other barriers to consider, such as time-frame mismatch, sociopolitical, knowledge and uncertainty barriers to conservationists adopting assisted migration as a go-to strategy. We recommend the following to advance assisted migration as a conservation tool: attempt assisted migrations at small scales, translocate species with little invasion risk, adopt robust monitoring protocols that trigger an active response, and promote political and public support.

Importancia de las Reubicaciones de Especies bajo el Cambio Climático Acelerado Resumen Las especies que no pueden adaptarse o mantener el ritmo del cambio climático probablemente requieran de la intervención humana para mudarse a climas más adecuados. Mientras que cientos de artículos mencionan el uso de las reubicaciones como una herramienta de adaptación al cambio climático, en la práctica, la migración asistida todavía es rara como una acción de conservación, especialmente para animales. Lo anterior probablemente se debe a la preocupación que existe por la introducción de especies a sitios en los que podrían volverse invasoras. Sin embargo, existen otras barreras que deberían considerarse, como aquellas ocasionadas por el desfase en el marco temporal, cuestiones sociopolíticas, de conocimiento o de incertidumbre para los conservacionistas que adoptan a la migración asistida como la estrategia de cajón. Recomendamos lo siguiente para que la migración asistida avance como herramienta de conservación: intentar realizar migraciones asistidas a pequeñas escalas, reubicar especies con poco riesgo de invasión, adoptar protocolos de monitoreo robustos que generen una respuesta activa y promover el apoyo público y político.

Relative costs of conserving threatened species across taxonomic groups.

Bias toward legally protecting and prioritizing charismatic taxonomic groups, such as mammals and birds, and against others, such as insects and plants, is well documented. However, the relative costs of conserving various taxonomic groups and the potential of these costs to interact with existing biases have been much less explored. We analyzed conservation programs across more than 2,000 species in 3 countries to investigate the costs of conserving species within taxonomic groups and how these costs might affect conservation planning. For each data set, we tested for differences in mean annual cost among taxonomic groups. For the data set from the United States, recovery plans differed in duration, so we also tested for differences in total costs among taxonomic groups. Although the costs for individual species varied widely, there were strong international consistencies. For example, mammals cost 8-26 times more on average to conserve than plants and 13-19 times more to conserve than aquatic invertebrates. On average, bird species cost 5-30 times more to conserve than plants and 6-14 times more to conserve than aquatic invertebrates. These cost differences could exacerbate unequal resource allocation among taxonomic groups such that more charismatic groups both receive more attention and require more resources, leading to neglect of other taxonomic groups.

Costos Relativos de la Conservación de Especies Amenazadas entre Grupos Taxonómicos Resumen El sesgo hacia la protección legal y la priorización de grupos taxonómicos carismáticos, como los mamíferos y las aves, y el sesgo que no favorece a otros grupos, como los insectos y las plantas, está bien documentado. A pesar de esto, los costos relativos de la conservación de varios grupos taxonómicos y el potencial que tienen estos costos para interactuar con los sesgos existentes no han sido explorados a profundidad. Analizamos los programas de conservación para más de 2,000 especies en tres países y así investigar los costos de la conservación de especies limitada a los grupos taxonómicos y cómo estos costos podrían afectar a la planeación de la conservación. Buscamos diferencias en el costo medio anual entre los grupos taxonómicos en cada conjunto de datos. Para el conjunto de datos de los Estados Unidos, los planes de recuperación difirieron en su duración, por lo que también buscamos diferencias en los costos totales entre los grupos taxonómicos. Aunque los costos para cada especie individual variaron ampliamente, hubo consistencias internacionales sólidas. Por ejemplo, la conservación de los mamíferos cuesta en promedio de 8-26 veces más que la de las plantas y de 13-19 veces más que la de los invertebrados acuáticos. En promedio, cuesta de 5-30 veces más la conservación de especies de aves que la de las plantas y de 6-14 veces más que la de los invertebrados acuáticos. Estas diferencias en los costos podrían agravar la asignación desigual de recursos entre los grupos taxonómicos de tal manera que los grupos taxonómicos más carismáticos reciben más atención y requieren de más recursos, resultando en el descuido de otros grupos taxonómicos.

Climatic-Induced Shifts in the Distribution of Teak (Tectona grandis) in Tropical Asia: Implications for Forest Management and Planning.

Modelling the future suitable climate space for tree species has become a widely used tool for forest management planning under global climate change. Teak (Tectona grandis) is one of the most valuable tropical hardwood species in the international timber market, and natural teak forests are distributed from India through Myanmar, Laos and Thailand. The extents of teak forests are shrinking due to deforestation and the local impacts of global climate change. However, the direct impacts of climate changes on the continental-scale distributions of native and non-native teak have not been examined. In this study, we developed a species distribution model for teak across its entire native distribution in tropical Asia, and its non-native distribution in Bangladesh. We used presence-only records of trees and twelve environmental variables that were most representative for current teak distributions in South and Southeast Asia. MaxEnt (maximum entropy) models were used to model the distributions of teak under current and future climate scenarios. We found that land use/land cover change and elevation were the two most important variables explaining the current and future distributions of native and non-native teak in tropical Asia. Changes in annual precipitation, precipitation seasonality and annual mean actual evapotranspiration may result in shifts in the distributions of teak across tropical Asia. We discuss the implications for the conservation of critical teak habitats, forest management planning, and risks of biological invasion that may occur due to its cultivation in non-native ranges.

Cascading effects of climate extremes on vertebrate fauna through changes to low-latitude tree flowering and fruiting phenology.

Forest vertebrate fauna provide critical services, such as pollination and seed dispersal, which underpin functional and resilient ecosystems. In turn, many of these fauna are dependent on the flowering phenology of the plant species of such ecosystems. The impact of changes in climate, including climate extremes, on the interaction between these fauna and flora has not been identified or elucidated, yet influences on flowering phenology are already evident. These changes are well documented in the mid to high latitudes. However, there is emerging evidence that the flowering phenology, nectar/pollen production, and fruit production of long-lived trees in tropical and subtropical forests are also being impacted by changes in the frequency and severity of climate extremes. Here, we examine the implications of these changes for vertebrate fauna dependent on these resources. We review the literature to establish evidence for links between climate extremes and flowering phenology, elucidating the nature of relationships between different vertebrate taxa and flowering regimes. We combine this information with climate change projections to postulate about the likely impacts on nectar, pollen and fruit resource availability and the consequences for dependent vertebrate fauna. The most recent climate projections show that the frequency and intensity of climate extremes will increase during the 21st century. These changes are likely to significantly alter mass flowering and fruiting events in the tropics and subtropics, which are frequently cued by climate extremes, such as intensive rainfall events or rapid temperature shifts. We find that in these systems the abundance and duration of resource availability for vertebrate fauna is likely to fluctuate, and the time intervals between episodes of high resource availability to increase. The combined impact of these changes has the potential to result in cascading effects on ecosystems through changes in pollinator and seed dispersal ecology, and demands a focused research effort.

CTFS-ForestGEO: a worldwide network monitoring forests in an era of global change.

Global change is impacting forests worldwide, threatening biodiversity and ecosystem services including climate regulation. Understanding how forests respond is critical to forest conservation and climate protection. This review describes an international network of 59 long-term forest dynamics research sites (CTFS-ForestGEO) useful for characterizing forest responses to global change. Within very large plots (median size 25 ha), all stems ≥ 1 cm diameter are identified to species, mapped, and regularly recensused according to standardized protocols. CTFS-ForestGEO spans 25 °S-61 °N latitude, is generally representative of the range of bioclimatic, edaphic, and topographic conditions experienced by forests worldwide, and is the only forest monitoring network that applies a standardized protocol to each of the world's major forest biomes. Supplementary standardized measurements at subsets of the sites provide additional information on plants, animals, and ecosystem and environmental variables. CTFS-ForestGEO sites are experiencing multifaceted anthropogenic global change pressures including warming (average 0.61 °C), changes in precipitation (up to ± 30% change), atmospheric deposition of nitrogen and sulfur compounds (up to 3.8 g N m(-2) yr(-1) and 3.1 g S m(-2) yr(-1)), and forest fragmentation in the surrounding landscape (up to 88% reduced tree cover within 5 km). The broad suite of measurements made at CTFS-ForestGEO sites makes it possible to investigate the complex ways in which global change is impacting forest dynamics. Ongoing research across the CTFS-ForestGEO network is yielding insights into how and why the forests are changing, and continued monitoring will provide vital contributions to understanding worldwide forest diversity and dynamics in an era of global change.

Spatial and life history variation in a trait-based species vulnerability and impact model.

Anthropogenic pressures threaten biodiversity, necessitating conservation actions founded on robust ecological models. However, prevailing models inadequately capture the spatiotemporal variation in environmental pressures faced by species with high mobility or complex life histories, as data are often aggregated across species' life histories or spatial distributions. We highlight the limitations of static models for dynamic species and incorporate life history variation and spatial distributions for species and stressors into a trait-based vulnerability and impact model. We use green sea turtles in the Greater Caribbean Region to demonstrate how vulnerability and anthropogenic impact for a dynamic species change across four life stages. By incorporating life stages into a trait-based vulnerability model, we observed life stage-specific vulnerabilities that were otherwise unnoticed when using an aggregated trait value set. Early life stages were more vulnerable to some stressors, such as inorganic pollution or marine heat waves, and less vulnerable to others, such as bycatch. Incorporating spatial distributions of stressors and life stages revealed impacts differ for each life stage across spatial areas, emphasizing the importance of stage-specific conservation measures. Our approach showcases the importance of incorporating dynamic processes into ecological models and will enable better and more targeted conservation actions for species with complex life histories and high mobility.

Quantifying the sampling error in tree census measurements by volunteers and its effect on carbon stock estimates.

A typical way to quantify aboveground carbon in forests is to measure tree diameters and use species-specific allometric equations to estimate biomass and carbon stocks. Using "citizen scientists" to collect data that are usually time-consuming and labor-intensive can play a valuable role in ecological research. However, data validation, such as establishing the sampling error in volunteer measurements, is a crucial, but little studied, part of utilizing citizen science data. The aims of this study were to (1) evaluate the quality of tree diameter and height measurements carried out by volunteers compared to expert scientists and (2) estimate how sensitive carbon stock estimates are to these measurement sampling errors. Using all diameter data measured with a diameter tape, the volunteer mean sampling error (difference between repeated measurements of the same stem) was 9.9 mm, and the expert sampling error was 1.8 mm. Excluding those sampling errors > 1 cm, the mean sampling errors were 2.3 mm (volunteers) and 1.4 mm (experts) (this excluded 14% [volunteer] and 3% [expert] of the data). The sampling error in diameter measurements had a small effect on the biomass estimates of the plots: a volunteer (expert) diameter sampling error of 2.3 mm (1.4 mm) translated into 1.7% (0.9%) change in the biomass estimates calculated from species-specific allometric equations based upon diameter. Height sampling error had a dependent relationship with tree height. Including height measurements in biomass calculations compounded the sampling error markedly; the impact of volunteer sampling error on biomass estimates was +/- 15%, and the expert range was +/- 9%. Using dendrometer bands, used to measure growth rates, we calculated that the volunteer (vs. expert) sampling error was 0.6 mm (vs. 0.3 mm), which is equivalent to a difference in carbon storage of +/- 0.011 kg C/yr (vs. +/- 0.002 kg C/yr) per stem. Using a citizen science model for monitoring carbon stocks not only has benefits in educating and engaging the public in science, but as demonstrated here, can also provide accurate estimates of biomass or forest carbon stocks.

Arbuscular mycorrhizal trees influence the latitudinal beta-diversity gradient of tree communities in forests worldwide.

Arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) associations are critical for host-tree performance. However, how mycorrhizal associations correlate with the latitudinal tree beta-diversity remains untested. Using a global dataset of 45 forest plots representing 2,804,270 trees across 3840 species, we test how AM and EcM trees contribute to total beta-diversity and its components (turnover and nestedness) of all trees. We find AM rather than EcM trees predominantly contribute to decreasing total beta-diversity and turnover and increasing nestedness with increasing latitude, probably because wide distributions of EcM trees do not generate strong compositional differences among localities. Environmental variables, especially temperature and precipitation, are strongly correlated with beta-diversity patterns for both AM trees and all trees rather than EcM trees. Results support our hypotheses that latitudinal beta-diversity patterns and environmental effects on these patterns are highly dependent on mycorrhizal types. Our findings highlight the importance of AM-dominated forests for conserving global forest biodiversity.

Author Correction: Tropical protected areas reduced deforestation carbon emissions by one third from 2000-2012.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

A decision tree for assessing the risks and benefits of publishing biodiversity data.

Inadequate information on the geographical distribution of biodiversity hampers decision-making for conservation. Major efforts are underway to fill knowledge gaps, but there are increasing concerns that publishing the locations of species is dangerous, particularly for species at risk of exploitation. While we recognize that well-informed control of location data for highly sensitive taxa is necessary to avoid risks, such as poaching or habitat disturbance by recreational visitors, we argue that ignoring the benefits of sharing biodiversity data could unnecessarily obstruct conservation efforts for species and locations with low risks of exploitation. We provide a decision tree protocol for scientists that systematically considers both the risks of exploitation and potential benefits of increased conservation activities. Our protocol helps scientists assess the impacts of publishing biodiversity data and aims to enhance conservation opportunities, promote community engagement and reduce duplication of survey efforts.

Tropical protected areas reduced deforestation carbon emissions by one third from 2000-2012.

Tropical deforestation is responsible for around one tenth of total anthropogenic carbon emissions, and tropical protected areas (PAs) that reduce deforestation can therefore play an important role in mitigating climate change and protecting biodiversity and ecosystem services. While the effectiveness of PAs in reducing deforestation has been estimated, the impact on global carbon emissions remains unquantified. Here we show that tropical PAs overall reduced deforestation carbon emissions by 4.88 Pg, or around 29%, between 2000 and 2012, when compared to expected rates of deforestation controlling for spatial variation in deforestation pressure. The largest contribution was from the tropical Americas (368.8 GgC y-1), followed by Asia (25.0 GgC y-1) and Africa (12.7 GgC y-1). Variation in PA effectiveness is largely driven by local factors affecting individual PAs, rather than designations assigned by governments.

The impact of climate change on the distribution of two threatened Dipterocarp trees.

Two ecologically and economically important, and threatened Dipterocarp trees Sal (Shorea robusta) and Garjan (Dipterocarpus turbinatus) form mono-specific canopies in dry deciduous, moist deciduous, evergreen, and semievergreen forests across South Asia and continental parts of Southeast Asia. They provide valuable timber and play an important role in the economy of many Asian countries. However, both Dipterocarp trees are threatened by continuing forest clearing, habitat alteration, and global climate change. While climatic regimes in the Asian tropics are changing, research on climate change-driven shifts in the distribution of tropical Asian trees is limited. We applied a bioclimatic modeling approach to these two Dipterocarp trees Sal and Garjan. We used presence-only records for the tree species, five bioclimatic variables, and selected two climatic scenarios (RCP4.5: an optimistic scenario and RCP8.5: a pessimistic scenario) and three global climate models (GCMs) to encompass the full range of variation in the models. We modeled climate space suitability for both species, projected to 2070, using a climate envelope modeling tool "MaxEnt" (the maximum entropy algorithm). Annual precipitation was the key bioclimatic variable in all GCMs for explaining the current and future distributions of Sal and Garjan (Sal: 49.97 ± 1.33; Garjan: 37.63 ± 1.19). Our models predict that suitable climate space for Sal will decline by 24% and 34% (the mean of the three GCMs) by 2070 under RCP4.5 and RCP8.5, respectively. In contrast, the consequences of imminent climate change appear less severe for Garjan, with a decline of 17% and 27% under RCP4.5 and RCP8.5, respectively. The findings of this study can be used to set conservation guidelines for Sal and Garjan by identifying vulnerable habitats in the region. In addition, the natural habitats of Sal and Garjan can be categorized as low to high risk under changing climates where artificial regeneration should be undertaken for forest restoration.

Allometry and growth of eight tree taxa in United Kingdom woodlands.

As part of a project to develop predictive ecosystem models of United Kingdom woodlands we have collated data from two United Kingdom woodlands - Wytham Woods and Alice Holt. Here we present data from 582 individual trees of eight taxa in the form of summary variables relating to the allometric relationships between trunk diameter, height, crown height, crown radius and trunk radial growth rate to the tree's light environment and diameter at breast height. In addition the raw data files containing the variables from which the summary data were obtained. Large sample sizes with longitudinal data spanning 22 years make these datasets useful for future studies concerned with the way trees change in size and shape over their life-span.

Eucalypts face increasing climate stress.

Global climate change is already impacting species and ecosystems across the planet. Trees, although long-lived, are sensitive to changes in climate, including climate extremes. Shifts in tree species' distributions will influence biodiversity and ecosystem function at scales ranging from local to landscape; dry and hot regions will be especially vulnerable. The Australian continent has been especially susceptible to climate change with extreme heat waves, droughts, and flooding in recent years, and this climate trajectory is expected to continue. We sought to understand how climate change may impact Australian ecosystems by modeling distributional changes in eucalypt species, which dominate or codominate most forested ecosystems across Australia. We modeled a representative sample of Eucalyptus and Corymbia species (n = 108, or 14% of all species) using newly available Representative Concentration Pathway (RCP) scenarios developed for the 5th Assessment Report of the IPCC, and bioclimatic and substrate predictor variables. We compared current, 2025, 2055, and 2085 distributions. Overall, Eucalyptus and Corymbia species in the central desert and open woodland regions will be the most affected, losing 20% of their climate space under the mid-range climate scenario and twice that under the extreme scenario. The least affected species, in eastern Australia, are likely to lose 10% of their climate space under the mid-range climate scenario and twice that under the extreme scenario. Range shifts will be lateral as well as polewards, and these east-west transitions will be more significant, reflecting the strong influence of precipitation rather than temperature changes in subtropical and midlatitudes. These net losses, and the direction of shifts and contractions in range, suggest that many species in the eastern and southern seaboards will be pushed toward the continental limit and that large tracts of currently treed landscapes, especially in the continental interior, will change dramatically in terms of species composition and ecosystem structure.