Tropical forests are globally important, but it is not clear whether biodiversity enhances carbon storage and sequestration in them. We tested this relationship focusing on components of functional ...trait biodiversity as predictors. Data are presented for three rain forests in Bolivia, Brazil and Costa Rica. Initial above‐ground biomass and biomass increments of survivors, recruits and survivors + recruits (total) were estimated for trees ≥10 cm d.b.h. in 62 and 21 1.0‐ha plots, respectively. We determined relationships of biomass increments to initial standing biomass (AGBᵢ), biomass‐weighted community mean values (CWM) of eight functional traits and four functional trait variety indices (functional richness, functional evenness, functional diversity and functional dispersion). The forest continuum sampled ranged from ‘slow’ stands dominated by trees with tough tissues and high AGBᵢ, to ‘fast’ stands dominated by trees with soft, nutrient‐rich leaves, lighter woods and lower AGBᵢ. We tested whether AGBᵢand biomass increments were related to the CWM trait values of the dominant species in the system (the biomass ratio hypothesis), to the variety of functional trait values (the niche complementarity hypothesis), or in the case of biomass increments, simply to initial standing biomass (the green soup hypothesis). CWMs were reasonable bivariate predictors of AGBᵢand biomass increments, with CWM specific leaf area SLA, CWM leaf nitrogen content, CWM force to tear the leaf, CWM maximum adult height Hₘₐₓand CWM wood specific gravity the most important. AGBᵢwas also a reasonable predictor of the three measures of biomass increment. In best‐fit multiple regression models, CWMHₘₐₓwas the most important predictor of initial standing biomass AGBᵢ. Only leaf traits were selected in the best models for biomass increment; CWM SLA was the most important predictor, with the expected positive relationship. There were no relationships of functional variety indices to biomass increments, and AGBᵢwas the only predictor for biomass increments from recruits. Synthesis. We found no support for the niche complementarity hypothesis and support for the green soup hypothesis only for biomass increments of recruits. We have strong support for the biomass ratio hypothesis. CWMHₘₐₓis a strong driver of ecosystem biomass and carbon storage and CWM SLA, and other CWM leaf traits are especially important for biomass increments and carbon sequestration.
Summary
Leaf habit has been hypothesized to define a linkage between the slow‐fast plant economic spectrum and the drought resistance‐avoidance trade‐off in tropical forests (‘slow‐safe vs ...fast‐risky’). However, variation in hydraulic traits as a function of leaf habit has rarely been explored for a large number of species.
We sampled leaf and branch functional traits of 97 tropical dry forest tree species from four sites to investigate whether patterns of trait variation varied consistently in relation to leaf habit along the ‘slow‐safe vs fast‐risky’ trade‐off.
Leaf habit explained from 0% to 43.69% of individual trait variation. We found that evergreen and semi‐deciduous species differed in their location along the multivariate trait ordination when compared to deciduous species. While deciduous species showed consistent trait values, evergreen species trait values varied as a function of the site. Last, trait values varied in relation to the proportion of deciduous species in the plant community.
We found that leaf habit describes the strategies that define drought avoidance and plant economics in tropical trees. However, leaf habit alone does not explain patterns of trait variation, which suggests quantifying site‐specific or species‐specific uncertainty in trait variation as the way forward.
At the start of the UN Decade of Ecosystem Restoration (2021–2030), the restoration of degraded ecosystems is more than ever a global priority. Tree planting will make up a large share of the ...ambitious restoration commitments made by countries around the world, but careful planning is needed to select species and seed sources that are suitably adapted to present and future restoration site conditions and that meet the restoration objectives.
Here we present a scalable and freely available online tool, Diversity for Restoration (D4R), to identify suitable tree species and seed sources for climate‐resilient tropical forest landscape restoration.
The D4R tool integrates (a) species habitat suitability maps under current and future climatic conditions; (b) analysis of functional trait data, local ecological knowledge and other species characteristics to score how well species match the restoration site conditions and restoration objectives; (c) optimization of species combinations and abundances considering functional trait diversity or phylogenetic diversity, to foster complementarity between species and to ensure ecosystem multifunctionality and stability; and (d) development of seed zone maps to guide sourcing of planting material adapted to present and predicted future environmental conditions. We outline the various elements behind the tool and discuss how it fits within the broader restoration planning process, including a review of other existing tools.
Synthesis and applications. The Diversity for Restoration tool enables non‐expert users to combine species traits, environmental data and climate change models to select tree species and seed sources that best match restoration site conditions and restoration objectives. Originally developed for the tropical dry forests of Colombia, the tool has now been expanded to the tropical dry forests of northwestern Peru–southern Ecuador and the countries of Burkina Faso and Cameroon, and further expansion is underway. Acknowledging that restoration has a wide range of meanings and goals, our tool is intended to support decision making of anyone interested in tree planting and seed sourcing in tropical forest landscapes, regardless of the purpose or restoration approach.
The Diversity for Restoration tool enables non‐expert users to combine species traits, environmental data and climate change models to select tree species and seed sources that best match restoration site conditions and restoration objectives. Originally developed for the tropical dry forests of Colombia, the tool has now been expanded to the tropical dry forests of northwestern Peru–southern Ecuador and the countries of Burkina Faso and Cameroon, and further expansion is underway. Acknowledging that restoration has a wide range of meanings and goals, our tool is intended to support decision making of anyone interested in tree planting and seed sourcing in tropical forest landscapes, regardless of the purpose or restoration approach.
Pervasive human impact in heavily transformed landscapes may lead disturbance‐adapted species to thrive, resulting in floristic homogenization across forest stands. However, environmental ...heterogeneity and dispersal limitation may be antagonistic forces to homogenization, maintaining inherent floristic differentiation across sites.
We evaluated the extent to which peri‐urban Andean forests are undergoing floristic homogenization in both late‐ and early‐successional stands. We considered seedling assemblages as well, as they provide key insights into forests’ future. We then quantified the relative importance of dispersal limitation and environmental filtering in determining the observed patterns of floristic similarity across the landscape.
We used tree, seedling, soil and climatic data from six sites located in the high plain where Bogotá lies (Colombia). Within each site, we established six 20 × 20 m plots, three in early‐successional stands and three in late‐successional stands, for a total of 36 plots.
To evaluate the extent of floristic homogenization, we defined tree floristic similarity among late‐successional stands as a baseline, reflecting our best‐guess of the original species composition that would have once occurred previous to intense anthropogenic intervention. Tree floristic turnover across the landscape was alike in late‐ and in early‐secondary stands, a finding that does not support the homogenization scenario. Seedling species composition, in contrast, was more homogeneous among early‐ than among late‐secondary stands, an outcome suggestive of homogenization.
The relative importance of spatial and environmental drivers shifted between life stages. Distance between plots was the best predictor of tree species dissimilarity (29% of variance explained), whereas seedling compositional variation was more sensitive to changes in environmental conditions (41% of the variance explained). Relative humidity and several variables related to soil fertility showed a significant effect on floristic dissimilarity across the landscape, although significant factors were often different between life stages.
Synthesis. Despite high anthropogenic transformation, we found little trace of floristic homogenization in these peri‐urban landscapes. Inherent floristic differentiation, promoted both by dispersal limitation and environmental heterogeneity, suggests that all patches are important to the conservation in these Andean forests, critical centres of endemism.
Despite high anthropogenic transformation, we found little trace of floristic homogenization in the peri‐urban landscapes surrounding Bogotá city (Colombia). Both distance among sites and environmental heterogeneity contribute to the maintenance of inherent floristic differentiation across the landscape. Under such a scenario, all patches are important to the conservation in these Andean forests, critical centres of endemism. The photo was taken by Juan Camilo Muñoz.
Ectomycorrhizal (ECM) symbioses support forest functioning globally, yet both the structure and function of ECM fungal communities in seasonally dry neotropical forests (SDTFs), known for extreme ...heterogeneity in vegetation and edaphic properties, remain under characterized.
Here, we evaluated the relative influences of seasonal versus spatial variation in ECM fungal community structure in soils from four environmentally divergent SDTFs. We also assessed the importance of biotic and abiotic drivers of SDTF ECM fungal community structure at regional scales, as well as ECM impacts on soil carbon (C) and nitrogen (N) cycling.
ECM fungal frequency, relative abundance and richness all increased in the wet season, but spatial rather than seasonal effects explained more variation in community composition. Across the four SDTFs investigated, differences in tree communities drove ECM fungal community turnover more than geographic distances, site abiotic conditions or soil chemistry. Although soil moisture and ECM tree basal area were stronger predictors of soil biogeochemistry, incorporating ECM fungal community composition and relative abundance added explanatory power to models of soil C and N cycling in the wet season.
Synthesis: Our results highlight the importance of seasonality and plant community composition in shaping different aspects of SDTF ECM fungal community structure and diversity as well as the potential for both the plant and fungal components of ECM symbioses to impact soil functioning across heterogenous SDTFs. Furthermore, our findings suggest that alterations in SDTF plant community composition due to climate or land‐use change will have important consequences for ECM fungal diversity and associated effects on soil biogeochemical cycling.
RESUMEN
Las ectomicorrizas mantienen el funcionamiento de los bosques a nivel global, sin embargo, pocos estudios han caracterizado la estructura y función de las comunidades de hongos ectomicorrícicos (ECM) en los Bosques Secos Neotropicales (BST), los cuales poseen una alta heterogeneidad en su composición florística y propiedades edáficas.
En este trabajo se evaluó la influencia relativa de la variación estacional vs. espacial sobre la estructura de la comunidad de hongos ECM en suelos de cuatro BST que divergen en sus características ambientales. También se estimó la importancia de los factores bióticos y abióticos sobre la estructura de las comunidades de hongos ECM de estos bosques a escalas regionales, y su impacto en el ciclo del carbono (C) y nitrógeno (N) en los suelos.
La frecuencia, abundancia relativa, y riqueza de los hongos ECM incrementó durante la estación lluviosa. No obstante, la variación en la composición comunitaria de hongos EM fue mayormente explicada por factores espaciales. En comparación con las distancias geográficas, las condiciones abióticas y la química de los suelos, las diferencias en la composición de especies de árboles tuvieron un rol más determinante en el recambio comunitario de los hongos ECM entre los cuatro BST estudiados. Aunque la humedad del suelo y el área basal de los árboles con ECM fueron los predictores más fuertes de la biogeoquímica de los suelos, la incorporación de la composición de las comunidades de hongos ECM y su abundancia relativa, mejoró el poder explicativo de los modelos de ciclado de C y N en los suelos durante la época de lluvias.
Síntesis: Los resultados de este estudio resaltan la importancia de la estacionalidad de las lluvias y la composición de las comunidades vegetales como determinantes de diferentes aspectos de la estructura y diversidad de las comunidades de hongos ECM en los BST, además del potencial que tanto las plantas, como el componente simbiótico de las ectomicorrizas tienen para impactar el funcionamiento de los suelos en los BST heterogéneos. Mas aún, los resultados sugieren que las alteraciones en la composición de las comunidades de plantas en los BST generados por cambios climáticos o en el uso del suelo, tendrán importantes consecuencias sobre la diversidad de hongos ECM y efectos asociados en el ciclado biogeoquímico en los suelos.
These results highlight the importance of seasonality and plant community composition in shaping different aspects of SDTF ECM fungal community structure and diversity as well as the potential for both the plant and fungal components of ECM symbioses to impact soil functioning across heterogenous SDTFs. Furthermore, these findings suggest that alterations in SDTF plant community composition due to climate or land‐use change will have important consequences for ECM fungal diversity and associated effects on soil biogeochemical cycling.Editor's Choice
The availability of nitrogen (N) and phosphorus (P) controls the flow of carbon (C) among plants, soils, and the atmosphere, thereby shaping terrestrial ecosystem responses to global change. Soil C, ...N, and P cycles are linked by drivers operating at multiple spatial and temporal scales: landscape-level variation in macroclimate and soil geochemistry, stand-scale heterogeneity in forest composition, and microbial community dynamics at the soil pore scale. Yet in many biomes, we do not know at which scales most of the biogeochemical variation emerges, nor which processes drive cross-scale feedbacks. Here, we examined the drivers and spatial/temporal scales of variation in soil biogeochemistry across four tropical dry forests spanning steep environmental gradients. To do so, we quantified soil C, N, and P pools, extracellular enzyme activities, and microbial community structure across wet and dry seasons in 16 plots located in Colombia, Costa Rica, Mexico, and Puerto Rico. Soil biogeochemistry exhibited marked heterogeneity across the 16 plots, with total organic C, N, and P pools varying fourfold, and inorganic nutrient pools by an order of magnitude. Most soil characteristics changed more across space (i.e., among sites and plots) than over time (between dry and wet season samplings). We observed stoichiometric decoupling among C, N, and P cycles, which may reflect their divergent biogeochemical drivers. Organic C and N pool sizes were positively correlated with the relative abundance of ectomycorrhizal trees and legumes. By contrast, the distribution of soil P pools was driven by soil geochemistry, with larger inorganic P pools in soils with P-rich parent material. Most earth system models assume that soils within a texture class operate similarly, and ignore subgrid cell variation in soil properties. Here we reveal that soil nutrient pools and fluxes exhibit as much variation among four Neotropical dry forests as is observed across terrestrial ecosystems at the global scale. Soil biogeochemical patterns are driven not only by regional differences in soil parent material and climate, but also by local-scale variation in plant and microbial communities. Thus, the biogeochemical patterns we observed across the Neotropical dry forest biome challenge representation of soil processes in ecosystem models.
Abstract
We tested the idea that functional trade‐offs that underlie species tolerance to drought drive shifts in community composition via their effects on demographic processes and subsequently on ...shifts in species' abundance. Using data from 298 tree species from tropical dry forests during the extreme ENSO‐2015, we scaled‐up the effects of trait trade‐offs from individuals to communities. Conservative wood and leaf traits favoured slow tree growth, increased tree survival and positively impacted species abundance and dominance at the community‐level. Safe hydraulic traits, on the other hand, were related to demography but did not affect species abundance and communities. The persistent effects of the conservative–acquisitive trade‐off across organizational levels is promising for generalization and predictability of tree communities. However, the safety–efficient trade‐off showed more intricate effects on performance. Our results demonstrated the complex pathways in which traits scale up to communities, highlighting the importance of considering a wide range of traits and performance processes.
Extreme drought events have negative effects on forest diversity and functioning. At the species level, however, these effects are still unclear, as species vary in their response to drought through ...specific functional trait combinations. We used long‐term demographic records of 21,821 trees and extensive databases of traits to understand the responses of 338 tropical dry forests tree species to ENSO2015, the driest event in decades in Northern South America. Functional differences between species were related to the hydraulic safety‐efficiency trade‐off, but unexpectedly, dominant species were characterised by high investment in leaf and wood tissues regardless of their leaf phenological habit. Despite broad functional trait combinations, tree mortality was more widespread in the functional space than tree growth, where less adapted species showed more negative net biomass balances. Our results suggest that if dry conditions increase in this ecosystem, ecological functionality and biomass gain would be reduced.
Extreme drought events have negative effects on forest diversity and functioning. We used long‐term demographic records of 21,821 trees and extensive databases of traits to understand the responses of 338 tropical dry forests tree species to an extreme. Our results indicate that irrespective of the drought adaptations, most trees will be negatively affected under drier scenarios predicted for tropical dry forests.
Tropical dry forests (TDF) are known to be resource‐limited due to a marked seasonality in precipitation. However, TDF are also shaped by factors such as solar radiation, wind speed, soil fertility, ...and land‐cover transformation. Together, these factors may determine different gradients of environmental harshness that are likely to drive changes in plant community attributes. Here, we evaluated the effects of environmental harshness on plant community diversity and structure of Colombian TDF, based on floristic and environmental data from 15 1‐ha permanent plots. We also analyzed these effects on legumes species only (including both deciduous and non‐deciduous species), deciduous species only (including both legumes and non‐legumes species), and on the whole community excluding either legumes or deciduous separately. Drier conditions and higher land‐cover transformation had the strongest negative effects on species diversity, basal area (BA), and canopy height. Soil fertility, on the contrary, did not have a significant effect on any of the evaluated response variables. Interestingly, legumes maintained their diversity and BA along the climatic gradient, while deciduous species were negatively affected by drier conditions and by an increase in secondary vegetation at the landscape level. Our results suggest that although TDF are limited by water availability, land‐cover transformation strongly increases environmental harshness. Yet, both legumes and deciduous species were differentially impacted by climatic and land transformation variables. Thus, to better understand TDF plant community attributes, it is necessary to consider these gradients and to disentangle their effects on different plant functional groups.
in Spanish is available with online material.
Resumen
Es ampliamente conocido que los bosques secos tropicales (BST) tienen fuertes limitaciones de recursos derivadas de estacionalidad de la precipitación. Sin embargo, otros factores como la radiación solar, la velocidad del viento, la fertilidad de los suelos y la transformación de las coberturas también dan forma a las condiciones ambientales restrictivas de este ecosistema. En conjunto, estos factores determinan la dureza ambiental que rige el BST y probablemente explican los cambios en los atributos comunitarios de las plantas a lo largo de gradientes. Evaluamos los efectos de la dureza ambiental sobre la diversidad de plantas y atributos estructurales del BST con base en datos florísticos y ambientales para 15 parcelas permanentes de 1 ha, para toda la comunidad de plantas, y subgrupos de plantas que incluyeron solo especies de leguminas y solo caducifolias por separado. Las condiciones secas y coberturas altamente transformadas tuvieron los efectos negativos sobre la diversidad de especies, el área basal y la altura del dosel a nivel comunitario, mientras que la fertilidad del suelo no afectó a ninguno de los atributos evaluados. Interesantemente, el grupo de especies leguminosas mantuvieron su diversidad y área basal a lo largo del gradiente de severidad climática, mientras que el grupo de especies de hoja caduca se vio negativamente afectado por las condiciones más secas y el aumento en el área de coberturas secundarias. Nuestros resultados sugieren que, aunque el BST esta claramente limitado por la disponibilidad del agua, la transformación de las coberturas naturales impulsa el aumento de la dureza ambiental en este ecosistema. Donde, las especies de leguminosas y caducifolias se ven afectadas de manera diferente a toda la comunidad de plantas. De tal forma, para un mejor entendimiento de como cambian los atributos comunitarios de las plantas en los BST es necesario tener en cuenta todas las fuentes de variación ambiental, así como, desagregar los efectos particulares para determinados grupos funcionales de plantas.
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