Tropical Forest Landscape Research Articles

Reducing intensification by shifting cultivation through sustainable climate-smart practices in tropical forests: A review in the context of UN Decade on Ecosystem Restoration

The tropical forests provide important ecosystem services at local and global scales (i.e. climate regulation, carbon cycling, and food resources). Shifting cultivation (SC) is the most common traditional farm system in tropical forest landscapes, which along with hunting and gathering from forests, have been the main food sources and livelihoods. This traditional SC was probably sustainable for nomadic indigenous populations for centuries. However, the non-traditional shifting cultivation is a consequence of cultural changes of indigenous communities influenced by western culture that induce land-use changes using new technologies, promoting the high local-scale expansion and intensification, and overhunting. The intensification occurs due to the short-term farm system, low crop diversity or monocultures, and larger slash and burn forest patches inducing agricultural expansion due to higher commercial crop demand. This expansion and intensification determine the loss of biodiversity and ecosystem services, forest degradation and fragmentation, higher greenhouse gas emissions, defaunation and local extinction. Thus, degraded forest rehabilitation with different sustainable food systems (i.e. Agroforestry) can reduce the expansion and intensification of SC. Restored forest, agroforestry, and second-growth forests can be restored as reservoirs for valuable biodiversity and a host of different ecosystem services. Tropical forests are central to climate change mitigation efforts and should prioritize the UN Decade on Ecosystem Restoration. In this context, we provide a review on the effects of shifting cultivation intensification on tropical forest landscapes as a base to apply sustainable climate-smart practices in the context of UN Decade on Ecosystem Restoration.

Forest cover and heterogeneous pastures shape the diversity of predatory rove beetles in tropical riparian habitats

In tropical landscapes, forest remnants have been reduced to narrow strips of vegetation along rivers and streams surrounded by agricultural land that affects biodiversity, depending on the habitat and landscape characteristics. To assess the effect of riparian forest loss on the diversity of Staphylininae predatory rove beetles, we considered two habitat conditions (river sites with riparian vegetation and sites with heterogeneous pastures) within two micro-basin types (with >70% and <40% forest cover) in a tropical montane cloud forest landscape, Mexico. Beetles were collected using baited pitfall traps during the rainy season of 2014. No differences were found between micro-basin types and, although species richness (0D) was similar between habitat conditions, when the diversity of common (1D) and dominant (2D) species was considered, sites with heterogeneous pastures were almost twice as diverse as those with riparian vegetation. All diversity measurements were greater in sites with heterogeneous pastures of either micro-basin type. Air temperature and canopy cover were the environmental variables that best explained the variation in beetle species composition. The greatest environmental differences related to species composition were detected between habitat conditions and were more evident in sites with heterogeneous pastures and low forest cover in the surroundings. The results suggest that replacing riparian vegetation with heterogeneous pastures, within micro-basins that lost between 30% and 60% of their forest cover, does not significantly reduce the diversity of predatory rove beetle but rather modifies the beetle composition. Effective formulation of management strategies to mitigate the impact of land use modification therefore requires an understanding of the interaction between vegetation remnants and landscape characteristics.

Effects of thinning on the demography and functional community structure of a secondary tropical lowland rain forest

Tropical secondary forests play a prominent role in conserving biodiversity and providing ecosystem services, but their recovery can be slow and their succession trajectory is distinct from old-growth forests. Thinning is an essential silvicultural approach to enhance the recovery rate and timber production of forests. However, the selection of trees to thin has been mainly based on size class rather than on species identity. There is little empirical or experimental evidence of species-focused thinning with the goal of altering species composition. We examined the effects of thinning on community structure, demographic rates, species richness and functional diversity of woody plants in a detailed investigation of 60-year-old secondary tropical lowland rain forest on Hainan Island, South China. The density and basal area of trees ≥5 cm DBH (diameter at breast height) increased significantly after five years' recovery with no significant change for saplings (DBH < 5 cm). Species composition after thinning changed significantly and mid-to late-successional species of both saplings and trees were more abundant after five years’ recovery. The relative growth rates (RGR) and recruitment rates were significantly higher in thinning plots for both saplings and trees, and RGRs increased by 127% and 48%, respectively. The mortality rate decreased by 13% for trees and increased by 47% for saplings in thinning plots compared to the control. The community weighted mean (CWM) of the specific leaf area (SLA) of saplings showed a significantly decreasing trend while CWMs of wood density (WD) and mean maximum height (Hmax) of saplings increased after thinning. By contrast, CWMs of SLA and Hmax of trees were significantly higher, but WD was significantly lower- in thinning plots than the control. RGR and recruitment rate of saplings and trees increased significantly as thinning intensity increased. However, the thinning intensity had a weak or nil effect on the mortality rate. Our results support the selective removal and girdling of pioneer and mid-successional species in a way that could accelerate recovery and improve the growth and recruitment of late-successional species in tropical secondary forests. Thinning at a relatively low intensity can maintain species diversity and alter species functional composition. This outcome shows promise for improved future management of tropical forests in human-modified tropical forest landscapes.

The impact of oil palm on rural livelihoods and tropical forest landscapes in Latin America

Abstract Does oil palm boost agricultural growth and reduce rural poverty, or is it a threat to rural livelihoods and tropical forest landscapes? This paper introduces a Special Issue on this question, focusing on Latin America. It reviews available literature and data for countries where oil palm either covers large areas (Brazil, Colombia, Ecuador, Honduras) or has recently expanded (Costa Rica, Guatemala, Mexico, Peru), and presents evidence from nine case studies (including Nicaragua). Combining political economy with a livelihood approach, this article discusses how dissimilar policies supporting oil palm combined with contrasting agrarian change dynamics, market structures, and institutional arrangements driving rural inclusion (and exclusion) in oil palm production have resulted in a variety of expansion trajectories (ranging from smallholder-to plantation-based, plus mixed forms in between) and outcomes across the region. Main findings show that rural livelihoods and landscapes are most threatened where industrial plantations predominate, particularly in weakly governed forest frontiers, while oil palm is beneficial where policies guarantee land access and support smallholders. However, policies that are beneficial to smallholders do not preclude conflicts between oil palm smallholders (often migrant settlers) and forest-dependent (indigenous and Afro-descendant) communities opposing this industry.

Comparing the success of active and passive restoration in a tropical cloud forest landscape: A multi-taxa fauna approach.

Tropical forest restoration initiatives are becoming more frequent worldwide in an effort to mitigate biodiversity loss and ecosystems degradation. However, there is little consensus on whether an active or a passive restoration strategy is more successful for recovering biodiversity because few studies make adequate comparisons. Furthermore, studies on animal responses to restoration are scarce compared to those on plants, and those that assess faunal recovery often focus on a single taxon, limiting the generalization of results. We assessed the success of active (native mixed-species plantations) and passive (natural regeneration) tropical cloud forest restoration strategies based on the responses of three animal taxa: amphibians, ants, and dung beetles. We compared community attributes of these three taxa in a 23-year-old active restoration forest, a 23-year-old passive restoration forest, a cattle pasture, and a mature forest, with emphasis on forest-specialist species. We also evaluated the relationship between faunal recovery and environmental variables. For all taxa, we found that recovery of species richness and composition were similar in active and passive restoration sites. However, recovery of forest specialists was enhanced through active restoration. For both forests under restoration, similarity in species composition of all faunal groups was 60–70% with respect to the reference ecosystem due to a replacement of generalist species by forest-specialist species. The recovery of faunal communities was mainly associated with canopy and leaf litter covers. We recommend implementing active restoration using mixed plantations of native tree species and, whenever possible, selecting sites close to mature forest to accelerate the recovery of tropical cloud forest biodiversity. As active restoration is more expensive than passive restoration, both strategies might be used in a complementary manner at the landscape level to compensate for high implementation costs.

Control over decision-making in eight major oil palm plantation companies in Malaysia

Southeast Asia's mosaics of agricultural and tropical forest landscapes have been significantly shaped by the advance of industrial plantations from colonial times to the present. Controversies over deforestation and oil palm sustainability have emerged in this context. Significant land use changes have been made by industrial plantation companies, which have diversified their activities to sectors ranging from automobiles to banking and telecoms to become corporate giants.&#x0D; The solutions proposed today to curb deforestation for oil palm plantations consist of sectoral market tools such as trade bans, regulations or certification schemes that are supposed to influence the economic decisions of private companies. However, oil palm corporations are so diversified and deeply embedded in national economies that many other factors could influence their corporate decision-making. Studies since Porter and Laporta suggest that the structure of the financial network of company shareholders may have more influence on corporate decisions than the market itself, in other words that the nature of company ownership (government versus private sector) is the essential driver in corporate decision-making.&#x0D; This thesis explores how these structural drivers play out in major oil palm corporations. Using network analysis, we quantified and analysed shareholdings in the main oil palm corporations in Malaysia. We gathered data on 4,331 shareholdings at ten different levels. The study describes the financial topologies and compares them with the nature of company ownership and with measurable decision-making processes, such as structural control and decision loads.&#x0D; We found that decision-making was not influenced by the nature of ownership but was very much influenced by the financial structure of the corporations. We also found that decision loads and structural control seem to predict a structural flexibility which is intrinsic to these corporations.&#x0D; The implications of these findings could help to rethink the political governance of deforestation and open up a new field of research concerned with describing and analysing the deep financial structures that govern the behaviour of corporations. Firstly, understanding the financial forces that shape plantation companies is critical to oil palm and forest sustainability. Secondly, we can now identify and prioritize the most resilient corporations with a view to developing sustainable practices for the long term.

From plots to policy: How to ensure long‐term forest plot data supports environmental management in intact tropical forest landscapes

Societal Impact StatementThe approach that we take to our science is as important as the questions that we address if we would like our research to inform management. Here, we discuss our experience of using networks of permanent forest inventory plots to support sustainable management and conservation of intact tropical forests. A key conclusion is that to maximize the use of data from such large international networks within policymaking, it is crucial that leadership is widely shared among participants. Such an approach helps to address ethical concerns surrounding international collaborations and also achieves greater policy impact.SummaryLong‐term data from permanent forest inventory plots have much to offer the management and conservation of intact tropical forest landscapes. Knowledge of the growth and mortality rates of economically important species, forest carbon balance, and the impact of climate change on forest composition are all central to effective management. However, this information is rarely integrated within the policymaking process. The problem reflects broader issues in using evidence to influence environmental management, and in particular, the need to engage with potential users beyond the collection and publication of high‐quality data. To ensure permanent plot data are used, (a) key “policy windows”—opportunities to integrate data within policy making—need to be identified; (b) long‐term relationships need to be developed between scientists and policy makers and policymaking organizations; and (c) leadership of plot networks needs to be shared among all participants, and particularly between institutions in the global north and those in tropical countries. Addressing these issues will allow permanent plot networks to make tangible contributions to ensuring that intact tropical forest persists over coming decades.

Trait Variation in Moths Mirrors Small-Scaled Ecological Gradients in A Tropical Forest Landscape

Simple SummaryTropical rainforests are still lost at alarming rates due to timber extraction or conversion into plantations. While losses of species diversity are well documented, less is known about how the functional integrity of insect communities changes with such interventions. Using light-trap samples taken from species-rich moth assemblages in one region in SW Costa Rica, we asked whether the body size of moths and the contribution of warningly colored species change from old-growth forest across disturbed forest toward oil palm plantations. Across three topographic types of old-growth forest, differences were small. Moth species occurring in plantations were substantially smaller than their relatives thriving in natural forest. Similarly, the incidence of warning coloration dropped massively in plantations. Two different types of mimicry (moths imitating wasps or poisonous beetles, respectively) showed their own patterns of variation across ecosystems, yet both color types were very rare in plantations. These results confirm that not only insect species diversity becomes greatly diminished when tropical forests are destroyed: the functional composition and integrity of the insect fauna that remains in plantations is eroding as well.Along environmental gradients, communities are expected to be filtered from the regional species pool by physical constraints, resource availability, and biotic interactions. This should be reflected in species trait composition. Using data on species-rich moth assemblages sampled by light traps in a lowland rainforest landscape in Costa Rica, we show that moths in two unrelated clades (Erebidae-Arctiinae; Geometridae) are much smaller-sized in oil palm plantations than in nearby old-growth forest, with intermediate values at disturbed forest sites. In old-growth forest, Arctiinae predominantly show aposematic coloration as a means of anti-predator defense, whereas this trait is much reduced in the prevalence in plantations. Similarly, participation in Müllerian mimicry rings with Hymenoptera and Lycidae beetles, respectively, is rare in plantations. Across three topographic types of old-growth forests, community-weighted means of moth traits showed little variation, but in creek forest, both types of mimicry were surprisingly rare. Our results emphasize that despite their mobility, moth assemblages are strongly shaped by local environmental conditions through the interplay of bottom–up and top–down processes. Assemblages in oil palm plantations are highly degraded not only in their biodiversity, but also in terms of trait expression.

Rapid recovery of phylogenetic diversity, community structure and composition of Bornean tropical forest a decade after logging and post-logging silvicultural interventions

Logged-over forests comprise a large proportion of tropical forest landscapes, but questions remain on how to fully describe and understand the regeneration of these forests and which selective logging and silvicultural interventions are best for maintaining biological diversity. We used a phylogenetic approach to capture changes on the evolutionary diversity, structure and composition of 72-one-hectare forest subplots in East Kalimantan that were logged using conventional (CL) and reduced-impact (RIL) techniques, including post-logging silvicultural interventions by reducing stem density (thinning), shortly after (on average 18 months) and 10 years after treatments. Both CL and RIL techniques initially decreased phylogenetic diversity, but after a decade of succession the phylogenetic diversity levels were no longer different from unlogged forests (Controls). Thinning through poison-notching non-commercial trees led to an increase in phylogenetic diversity after a decade of succession. Mean evolutionary relatedness, as measured by the Net Relatedness Index, initially decreased in logged forests, possibly because of harvest of closely related dipterocarp species, but returned to initial levels after a decade. Regardless of silvicultural interventions 10 years after logging had no effect on the mean evolutionary relatedness of the trees in the communities at both time intervals.Both CL and RIL techniques increased the phylogenetic composition dissimilarity with unlogged forest, with increasing logging intensity resulting in increasingly larger effects, although the changes were smaller for RIL. Phylogenetic composition only became dissimilar from unlogged forest after a decade of succession, when the logging intensity was above 4 m2 ha−1 for both CL and RIL, equivalent to 8 trees ha−1 or 68 m3 ha−1. Post-logging silvicultural interventions started to cause changes in phylogenetic composition when the basal area was reduced by thinning by more than 10 m2 ha−1. The rapid recovery of phylogenetic diversity, community structure and, to a lesser extent composition after logging and thinning confirms that tropical forests are resilient to a single logging cycle. With low-intensity logging of less than 4 m2 ha−1, RIL techniques appear to facilitate phylogenetic structure and compositional recovery to levels not different from unlogged forest after 10 years of succession, especially when combined with post-logging silvicultural intervention with a basal area reduction by thinning of less than 10 m2 ha−1. However, it remains to be seen whether forests will respond similarly to a second logging cycle.

Estructura poblacional de Morpho helenor peleides kollar, 1850 (lepidoptera: nymphalidae) en un paisaje de bosque seco tropical, departamento de Bolivar, Colombia.

Teniendo en cuenta la alta tasa de destrucción de los bosques en la región Caribe colombiana y la escasa información disponible sobre la ecología poblacional de las mariposas del género Morpho, se analizó la variación de estructura poblacional de Morpho helenor peleides Kollar, 1850 en un paisaje de Bosque seco tropical (BST) en los Montes de María, Caribe colombiano. Metodología. Para el estudio de la mariposa, se utilizó el método de captura-marca-recaptura (CMR) en siete estaciones, en las cuales se instalaron trampas Van Someren-Rydon cebadas con una mezcla de frutas fermentadas. Resultados. La abundancia total fue de 287 individuos, con 59 recapturas (20,5%). Se obtuvieron tamaños poblacionales entre 8 y 339 individuos. La proporción sexual macho-hembra fue 3:1. Se capturaron mayores porcentajes de mariposas nuevas (41,8%) e intermedias (38,6%). El tiempo de residencia máximo registrado fue de 38 días. Se calcularon distancias totales de vuelo entre 149 y 1,231m, aunque las hembras presentaron los mayores promedios (303.7±189.4m) de distancia recorrida; pero no se encontraron diferencias significativas entre las distancias recorridas entre sexos (U= 265,5, p&gt;0,05). Conclusiones: La estructura poblacional de M. helenor peleides presentó una variación espacial y temporal en el paisaje de bosque seco estudiado. Adicionalmente, se determinó que la cobertura de dosel natural juega un papel importante en la dinámica temporal y la distribución de la abundancia de este grupo de mariposas en el bosque seco tropical y se resalta la importancia de este ecosistema en la conservación de esta especie.

Functional trait representation differs between restoration plantings and mature tropical rainforest

The planting and attempted restoration of tropical forest landscapes is increasing rapidly across the globe. Two limiting aspects of large-scale forest restoration are the demand for appropriate quantities of seeds and seedlings of native species, and the ability to facilitate succession in planted sites. Species functional traits such as seed type, tree size, germination time, and wood density may influence the quantity of seedlings that can be produced for restoration, and the potential of these seedlings to persist and facilitate site succession. Therefore, it is important to understand the species composition and functional trait representation of restoration plantings. We explored the species composition and functional trait representation of 846 restoration plantings in the Australian Wet Tropics containing > 465,000 seedlings from 599 species, using seedling supply records from six nurseries over a six year period (2012–2017). Despite restoration plantings in the Australian Wet Tropics containing an impressive number of species, just 52 species contributed over half of all individual seedlings. We found that species with small animal-dispersed seeds and low wood density were more abundant, on average, and had greater representation in restoration plantings than in mature rainforest. Despite this, we did not find evidence that restoration plantings had a diminished capacity to grow tall or sequester carbon as there was no significant difference in the relative abundance of tall tree species or species with high wood density. Small seeded and fast growing species may be cheaper to produce in nurseries and may accelerate site succession as these characteristics are associated with pioneer and early successional species, however these traits are also associated with higher mortality rates. Understanding how functional trait representation influences the success of restoration plantings will require further insight into temporal aspects of site succession.

Experimentally assessing the effect of search effort on snare detectability

Reducing threats to biodiversity is the key objective of ranger patrols in protected areas. However, efforts can be hampered by rangers' inability to detect threats, and poor understanding of threat abundance and distribution in a landscape. Snares are particularly problematic due to their cryptic nature and limited selectivity with respect to captured animals' species, sex, or age. Using an experimental approach, we investigated the effect of search effort, habitat, season, and team on rangers' detection of snares in a tropical forest landscape. We provide an effort-detection curve, and use our findings to make preliminary predictions about snare detection under different scenarios of patrol effort. Results suggest that the overall probability of a searcher detecting any given snare in a 0.25/km2 area, assuming 60 min (or approximately 2 km) of search effort is 20% (95% CI ± 15–25%), with no significant effect of season, habitat or team. Our models suggested this would increase by approximately 10% with an additional 30mins/1 km of search effort. Our preliminary predictions of the effectiveness of different patrolling scenarios show that detection opportunities are maximised at low effort levels by deploying multiple teams to a single area, but at high effort levels deploying single teams becomes more efficient. Our results suggest that snare detectability in tropical forest landscapes is likely to be low, and may not improve dramatically with increased search effort. Given this, managers need to consider whether intensive snare-removal efforts are the best use of limited resources; the answer will depend on their underlying objectives.

UAV-based canopy textures assess changes in forest structure from long-term degradation

Degraded tropical forests dominate agricultural frontiers and their management is becoming an urgent priority. This calls for a better understanding of the different forest cover states and cost-efficient techniques to quantify the impact of degradation on forest structure. Canopy texture analyses based on Very High Spatial Resolution (VHSR) optical imagery provide proxies to assess forest structures but the mechanisms linking them with degradation have rarely been investigated. To address this gap, we used a lightweight Unmanned Aerial Vehicle (UAV) to map 739 ha of degraded forests and acquire both canopy VHSR images and height model. Thirty-three years of degradation history from Landsat archives allowed us to sample 40 plots in undisturbed, logged, over-logged and burned and regrowth forests in tropical forested landscapes (Paragominas, Pará, Brazil). Fourier (FOTO) and lacunarity textures were used to assess forest canopy structure and to build a typology linking degradation history and current states. Texture metrics capture canopy grain, heterogeneity and openness gradients and correlate with forest structure variability (R2 = 0.58). Similar structures share common degradation history and can be discriminated on the basis of canopy texture alone (accuracy = 55%). Over-logging causes a lowering in forest height, which brings homogeneous textures and of finer grain. We identified the major changes in structures due to fire following logging which changes heterogeneous and intermediate grain into coarse textures. Our findings highlight the potential of canopy texture metrics to characterize degraded forests and thus be used as indicators for forest management and degradation mitigation. Inexpensive and agile UAV open promising perspectives at the interface between field inventory and satellite characterization of forest structure using texture metrics.

Examining Trajectories of Change for Prosperous Forest Landscapes in Cambodia.

Tropical forest landscapes are undergoing rapid transition. Rural development aspirations are rising, and land use change is contributing to deforestation, degradation, and biodiversity loss, which threaten the future of tropical forests. Conservation initiatives must deal with complex social, political, and ecological decisions involving trade-offs between the extent of protected areas and quality of conservation. In Cambodia, smallholders and industrial economic land concessions drive deforestation and forest degradation. Rural economic benefits have not kept pace with development aspirations and smallholders are gradually expanding agriculture into protected forests. We examine the drivers and effects of rural forest landscape transitions in Cambodia to identify trade-offs between conservation and development. Using historical trends analysis and information gathered through key informant interviews, we describe how local communities perceive social and ecological changes, and examine the implications of local development aspirations for conservation. We explore three scenarios for the future of conservation in Cambodia, each with different conservation and community development outcomes. We contend that conservation efforts should focus on strengthening governance to meet social and environmental requirements for sustainable forest landscapes. We suggest potential entry points for governance improvements, including working with local decision-makers and fostering collaboration between stakeholders. There is a need for realistic priority setting in contested tropical forest landscapes. Prosperous rural economies are a necessary but not sufficient condition for conservation.

Inclusive Landscape Governance for Sustainable Development: Assessment Methodology and Lessons for Civil Society Organizations

Landscape governance refers to the combination of rules and decision-making processes of civic, private, and public actors with stakes in the landscape, that together shape the future of that landscape. As part of the Green Livelihoods Alliance, a program that supports civil society organizations (CSOs) to strengthen the governance of tropical forested landscapes, we developed and implemented a method that facilitates stakeholders to assess the status of governance in their own landscape and to identify options for improvement. In this article, we aim to reflect on landscape governance, based on our work within the Green Livelihoods Alliance. We present the method, summarize the results of its implementation, and draw practical lessons regarding the role of CSOs to improve landscape governance. We conducted workshops with stakeholders in 17 forested landscapes across 10 countries in Asia, Africa, and Latin America. During each workshop, participants scored and discussed a set of governance indicators, developed a common vision for landscape governance, and identified the practical steps that would need to be taken to achieve that vision. Analyzing the results from the workshops, we found that landscape stakeholders tend to perceive that: opportunities to influence decision-making are unequal; integrated landscape planning efforts remain noncommittal; and implementation and enforcement of regulations is weak. To improve governance in the future, it is common to call for the development of multi-stakeholder processes, to allow different actors to discuss, negotiate, and develop collaborative action to address landscape-level challenges. CSOs can support such processes, by helping to develop a shared understanding of landscape governance, differences in interests, and possibilities for collaborative action. CSOs can also help stakeholders to develop multi-stakeholder procedures, and build trust and capacity among stakeholders to take an active role in such processes.

Tree diversity and timber productivity in planted forests: Pinus patula versus mixed cloud forest species

Planted forests contribute to maximizing timber production but their role as valuable habitat for diversity is of increasing concern, particularly in tropical montane cloud forest (TMCF) landscapes, which present extremely high diversity and endemism. We compared tree diversity, potential timber productivity and estimated net revenues in planted forests of Pinus patula and mixed TMCF species in southern Mexico. These planted forests were 21 years-old and established under similar environmental conditions in abandoned pastures previously occupied by TMCF. Adult tree height and density were similar between planted forests, but sapling and seedling density were reduced in P. patula in comparison to the mixed forest (0.05 and 0.28 sapling m−2 and 0.08 and 0.56 seedling m−2, respectively). The diversity of adults was similar, but that of saplings and seedlings was lower in P. patula than in the mixed forest (saplings: 3.39 and 9.14 effective species; seedlings: 2.85 and 9.59, respectively). Timber volume was similar between planted forests; however, due to higher establishment costs and lower market price, the net present value (NPV) of the mixed forest was considerably lower than that of P. patula. The mixed forest only achieved a positive NPV with subsidies and an interest rate < 5% under a 30% harvesting intensity. To ameliorate biobiodiversity loss, TMCF landscapes require alternative measures; e.g., a supply of a diverse mix of native seedlings, stimulation of the market for native species, compensatory mechanisms for mixed plantations of native species and landscape approaches that combine economically profitable and ecologically desirable species.

Extinction–immigration dynamics lag behind environmental filtering in shaping the composition of tropical dry forests within a changing landscape

The impact of rapid habitat loss and fragmentation on biodiversity is a major issue. However, we still lack an integrative understanding of how these changes influence biodiversity dynamics over time. In this study, we investigate the effects of these changes in terms of both niche‐based and neutral dynamics. We hypothesize that habitat loss has delayed effects on neutral immigration–extinction dynamics, while edge effects and environmental heterogeneity in habitat patches have rapid effects on niche‐based dynamics.We analyzed taxonomic and functional composition of 100 tree communities in a tropical dry forest landscape of New‐Caledonia subject to habitat loss and fragmentation. We designed an original, process‐based simulation framework, and performed Approximate Bayesian Computation to infer the influence of niche‐based and neutral processes. Then, we performed partial regressions to evaluate the relationships between inferred parameter values of communities and landscape metrics (distance to edge, patch area, and habitat amount around communities), derived from either recent or past (65 yr ago) aerial photographs, while controlling for the effect of soil and topography.We found that landscape structure influences both environmental filtering and immigration. Immigration rate was positively related to past habitat amount surrounding communities. In contrast, environmental filtering was mostly affected by present landscape structure and mainly influenced by edge vicinity and topography.Our results highlight that landscape changes have contrasting spatio‐temporal influences on niche‐based and neutral assembly dynamics. First, landscape‐level habitat loss and community isolation reduce immigration and increase demographic stochasticity, resulting in slow decline of local species diversity and extinction debt. Second, recent edge creation affects environmental filtering, incurring rapid changes in community composition by favoring species with edge‐adapted strategies. Our study brings new insights about temporal impacts of landscape changes on biodiversity dynamics. We stress that landscape history critically influences these dynamics and should be taken into account in conservation policies.

Changes in the Abundance and Composition of a Microbial Community Associated with Land Use Change in a Mexican Tropical Rain Forest

Land use change (LUC) has important effects on the aboveground biota, mainly by altering richness and diversity, as well as ecosystem functioning. However, the effects of LUC on abiotic and biotic soil properties need to be assessed to determine recovery potential when the original vegetation is restored. The Los Tuxtlas tropical rain forest landscape in Veracruz, Mexico, offers a suitable framework for testing this. To assess the effect of LUC on the microbial community of this tropical rain forest landscape, we analyzed the whole-cell fatty acid profile of the microbial community and physicochemical properties of soils from four types of land use: crops, pastures, secondary forest, and primary tropical rain forest for the dry and rainy seasons. Regardless of season, the microbial data grouped according to land use. The composition of the microbial community was correlated with soil pH in the dry season, and with nitrate, soil organic matter, and available phosphorus concentration in the rainy season. Land use affects the abundance of the microbial community as a function of seasonal variation. In comparison with the microbial community in primary and secondary forest, that of crops and pastures was more greatly affected by seasonal variation. In fact, there were no significant differences between the primary forests or among secondary forests of different ages. These results may indicate a capacity for fast recovery (5 years or less) by the microbial community upon forest regeneration.

Biodiversity and carbon storage are correlated along a land use intensity gradient in a tropical montane forest watershed, Mexico

Tropical montane cloud forest landscapes are changing, and forest conversion to other land uses is a major driver of biodiversity loss. Land use intensification can lead to significant losses in biodiversity and carbon storage (C); however, the impacts may vary greatly depending on land use type, management practices, and environmental context. We investigated how biodiversity and C are related along a gradient of land use intensification characterized by four dominant land uses in the upper part of Antigua River watershed, Mexico. The land uses were montane cloud forest, secondary forest, and traditional and intensive shade coffee plantations. We determined tree species composition, diversity, ecosystem structure, wood density and C content in dominant tree species to assess aboveground biomass (AGB) and C storage within eight study sites across the land use intensity gradient. A total of 83 tree species was recorded. A canonical correspondence analysis indicated that land uses are separated by particular tree species assemblages. Forests had higher basal area, density, and biomass than coffee plantations, however, the traditional shade coffee plantation had values similar to secondary forest. Calculating C using the standard estimate of 50% of AGB resulted in an overestimation of stored C by 5.8 to 4.1% compared to calculations based on actual measurements. Carbon storage in AGB and biodiversity were strongly and positively related across the land use intensity gradient, although the distinction between the two different intensities of coffee plantation management was not consistently as clear as we had expected. Carbon was highest in forest, but secondary forests and traditional shade coffee plantation had similar C, while intensive coffee had the lowest C content. These results highlight the importance of considering the potential of low intensity land uses such as traditional coffee plantations to mitigate biodiversity loss and preserve ecosystem functions as part of conservation efforts.

Learning from Local Perceptions for Strategic Road Development in Cambodia’s Protected Forests

Road development in tropical forest landscapes is contentious. Local preferences are often subordinated to global economic and environmental concerns. Opportunities to seek solutions based on local...