Forest Interior Research Articles

Response of birds to high biodiversity silvopastoral systems: Integrating food production and biodiversity conservation through applied nucleation in southern Brazil

The quality of a landscape’s matrix is a key condition for the conservation of biodiversity and affects the diversity and composition of bird assemblages in agricultural landscapes with forest remnants. In southern Brazil most agricultural landscapes are a mosaic of cultivated areas, treeless pastures and forest remnants. These landscapes must be planned and managed for food production while synergically enhancing ecological restoration and biodiversity conservation. In this study, we compared the diversity and composition of bird species in High Biodiversity Silvopastoral Systems (SPSnuclei), treeless pasture areas, forest edges and forest interiors. SPSnuclei is a type of silvopastoral system (SPS) whose design was inspired by applied nucleation reforestation techniques using multispecies agroforestry nuclei. In this study, we sought to understand the influence of the SPSnuclei on the diversity and composition of birds by comparing SPSnuclei to treeless pasture areas, forest edges and the forest interior. We hypothesize that multispecies agroforestry nuclei would restore some of the ecosystem biodiversity, and therefore resilience. To quantify bird diversity, sound recorders were installed simultaneously within these habitats during the spring and summer of 2016 and 2017 on three dairy farms. We identified calls from 108 bird species in 2400 min of recordings (600 min/habitat). The High Biodiversity Silvopastoral System increased the diversity of birds in the agroecosystem. Species richness was higher in the parcels with SPSnuclei compared to treeless pastures (P < 0,05). Although, species richness was smaller in the SPSnuclei than forest edge and interior of the forest remnants (P < 0,05). Eight species from the interior and forest edge were observed in the SPSnuclei, but not in the treeless pastures. This research presents evidence that SPSnuclei has positive effects on the diversity and composition of the avifauna in agricultural landscapes and could act as stepping stones that increase connectivity between forest remnants.

Effects of Adjacent Land Use Types on the Composition of Vascular Flora in Urban Forest Ecotones in the Southern Poland

The purpose of the research was the recognition of edge effects regarding similarities and differences of vascular flora in undergrowth layers in the urban forest ecotones. Four types of urban forest neighborhoods were analyzed: ecotones adjacent to the manor park, the agriculture field, housing estates and the road. The plant compositions in the forest ecotones were compared with the plant compositions in the urban forest interior and the forest nature reserve. The phytosociological type of studied forests was a subcontinental oak-hornbeam one (Tilio-Carpinetum). Diagnostic plant species (e.g., characteristic) for forests from the non-diagnostic ones were identified. Forest consistent plant species dominated in the ecotone adjacent to the manor park and in the interior of urban forests too, but the best conditions for these plants were inside the forest nature reserve, where native consistent forest plants showed the highest dominance when comparing all studied areas. A higher anthropogenic pressure from the adjacent areas results in supporting the growth of inconsistent plant species in the forests, and these plants are mostly represented by plants belonging to grass and synanthropic communities. Another conclusion drawn from our research is that the protected forest, represented by a nature reserve in the city, provides better “shelter” for native forest plants than the urban forest without any protection. Ultimately, a permanent challenge is to achieve and maintain the balance between nature and the impact of anthropogenic activities on urban forests in the city. The high quality of green areas, biodiversity, including forests, implicates possibilities of sustainable development in cities. The research results will be useful for local urban planners and ecologists during their work on strategies of city development, including shaping of green infrastructure.

Risk-Induced Foraging Behavior in a Free-Living Small Mammal Depends on the Interactive Effects of Habitat, Refuge Availability, and Predator Type

Predators have a major influence on prey populations and broader ecosystem dynamics through both their consumptive and non-consumptive effects. Prey employ risk-induced trait responses such as shifts in habitat use or changes in foraging behavior in response to the presence of predators. Risk-induced changes in foraging depend upon both the predator community and the environmental context; however, the influence of these factors have rarely been concurrently examined in free-living animals. We investigated the interactive effects of habitat, refuge availability, and predator type on the foraging behavior of free-living white-footed mice, accounting for the abiotic factor moonlight. We used auditory calls of a local terrestrial cursorial predator and a local avian ambush predator to simulate predation risk in both a forest edge and a forest interior habitat, and measured the foraging of mice under different experimental refuge types. We found that, while mice had reduced foraging when exposed to predation risk, the degree of this response depended on an interaction among habitat, refuge use, and type of predator. Prey had the greatest reduction in foraging and used refuges the most when exposed to cursorial-hunting foxes at the open forest edge. The risk-induced reduction in foraging and the use of refuges was much weaker in the forest interior, but even here foxes elicited a greater response as compared to owls. Generally, foraging tended to decrease with increasing moonlight, but this was not significant. We suggest that it is the temporal nature of cursorial vs. ambush predators in our system that drives such effects as opposed to their hunting mode, and that prey responses to temporal hotspots of risk need further examination. Generally, our results show that wild small-mammal prey species have variable responses to predation risk depending on the environmental context in which risk occurs.

Urban forest fragmentation can highly influence pollinator-plant interactions in close contrasting habitats of a local herb, Ajuga decumbens (Labiatae)

Frequent anthropogenic activities in urban regions may result in fragmentation, sequentially forming a variety of forest edges. The contrasting habitats (forest interior vs. edge) may differ in foster pollinator and plant diversity, but little is known about the influence of urban forest fragmentation on pollinator-plant interactions. Six patches of a local bee-pollinated herb, Ajuga decumbens (Labiatae) were used to detect the edge effect. The patches from both the forest edge (three patches) and interior (the other three patches) habitats were close to reduce the differences in pollinator fauna, in an urban fragmented forest in Wuhan city, China. We investigated the pollinator species richness and abundance as well as the reproductive success of the plant across the forest edge and interior habitats. Results revealed that the pollinator assemblage and fruit set of the plant differed between the forest edge and interior habitats, plants from the forest edge had higher pollinator abundance and yielded more fruits than those from the forest interior. Although the patches were close enough for the pollinating bees to fly over, forest edges resulting from fragmentation intensely changed the pollinator assemblage of the local herb. Where the fragmentation of urban forest is unavoidable, our results indicated that the forest edge should be a friendly urban matrix for the local herb and its bee pollinators. Thus, anthropogenic actions e.g. road hardening and introduction of ornamental flowers should be avoided in areas where the forest edges have already been generated by urban construction.

A comparison of the clinical, laboratory and epidemiological features of two divergent subpopulations of Plasmodium knowlesi

Plasmodium knowlesi, a simian malaria parasite responsible for all recent indigenous cases of malaria in Malaysia, infects humans throughout Southeast Asia. There are two genetically distinct subpopulations of Plasmodium knowlesi in Malaysian Borneo, one associated with long-tailed macaques (termed cluster 1) and the other with pig-tailed macaques (cluster 2). A prospective study was conducted to determine whether there were any between-subpopulation differences in clinical and laboratory features, as well as in epidemiological characteristics. Over 2 years, 420 adults admitted to Kapit Hospital, Malaysian Borneo with knowlesi malaria were studied. Infections with each subpopulation resulted in mostly uncomplicated malaria. Severe disease was observed in 35/298 (11.7%) of single cluster 1 and 8/115 (7.0%) of single cluster 2 infections (p = 0.208). There was no clinically significant difference in outcome between the two subpopulations. Cluster 1 infections were more likely to be associated with peri-domestic activities while cluster 2 were associated with interior forest activities consistent with the preferred habitats of the respective macaque hosts. Infections with both P. knowlesi subpopulations cause a wide spectrum of disease including potentially life-threatening complications, with no implications for differential patient management.

Rarity patterns and the conservation status of tree species in South American savannas

The interest in quantifying rare species has been increasing, but less attention has been paid to analysing their conservation status. Here, we used the Rabinowitz method based on geographical range, habitat specificity and population size to classify 2,203 tree species of South American savannas (SAS). We considered species with narrow (stenochoric) or wide (eurychoric) geographic range respectively occurring in up to 10% or over of the latitudinal belts in the SAS, specialist (stenoecious) or generalist (euryoecious) species occurring in one or more ecoregions, respectively, and locally scarce or abundant populations of species with low or high numbers of records within a grid cell of 1° latitude by 1° longitude, respectively. We then quantified species which only occur inside protected areas (PAs), in and outside PAs, or only outside PAs. Of the 2,203 species, 49.25% were rare, 40.35% stenochoric, 14.12% stenoecious and 56.15% had a scarce population. The Cerrado (433) followed by Caatinga (259), Campos Rupestres montane savanna (256), Bahia interior forests (189) and Guiana savanna (154) had the highest number of rare species. Only 6.44% species only occurred inside PAs, 83.79% in and outside PAs and 9.75% only outside PAs. Unprotected species are mostly geographically restricted with ecoregion specialists, and have small population sizes. The number of protected species are is positively correlated with the number of records within them. The establishment of PAs should focus on both core and disjunct savannas to encompass all ecoregions in order to ensure the conservation of species and the range of evolutionary processes in SAS.

How diverse is the chemistry and plant origin of Brazilian propolis?

Propolis is a honey bee product containing chiefly beeswax and resins originated from plant buds or exudates. Propolis resin exerts a diversity of biological activities, such as antitumoral, anti-inflammatory, antimicrobial, and defense of the hive against pathogens. Chemical standardization and identification of botanical sources is crucial for characterization of propolis. Types of Brazilian propolis are characteristic of geographical regions and respective biomes, such as savannas (Cerrado), mangroves, dry forest (Caatinga), rain forests (Amazon, Atlantic, and Interior forests), altitudinal fields (“Campos Rupestres”), Pantanal, and Araucaria forests. Despite the wide diversity of Brazilian biomes and flora, relatively few types of Brazilian propolis and corresponding resin plant sources have been reported. Factors accounting for the restricted number of known types of Brazilian propolis and plant sources are tentatively pointed out. Among them, the paper discusses constraints that honey bees must overcome to collect plant exudates, including the characteristics of the lapping-chewing mouthpart of honey bee, which limit their possibilities to cut and chew plant tissues, as well as chemical requirements that plant resins must fulfil, involving antimicrobial activity of its constituents and innocuity to the insects. Although much still needs to be done toward a more comprehensive picture of Brazilian propolis types and corresponding plant origins, the prospects indicate that the actual diversity of plant sources of honey bee propolis will remain relatively low.

Biological Aspects and Movements of Neotropical Fruit-Feeding Butterflies.

The patterns of insect movement are the cumulate product of many individual decisions and can be shaped by the way morphology and behaviour interacts with landscape structure and composition. Hence, the ongoing process of habitat fragmentation increases the distance among suitable habitats and changes those in such a way that it may favour some movement behaviour. Our study described some biological traits (sex ratio, age structure and individual permanence in a population), as well as the movements of fruit-feeding butterflies along the horizontal dimension (among habitats: forest interior, natural forest transition - ecotone and anthropogenic forest transition - edge) and the vertical dimension (between canopy and understory). We sampled butterflies monthly over 1year in the Atlantic rainforest, South-eastern Brazil, following a standardized design using bait traps. We found that sex ratio was male biased for five out of the six more abundant species and the age structure showed an increase in recruitment of new individuals in the dry season followed by a noticeable aging of the populations in the wet season. In general, our results revealed an aggregated spatial distribution, in which few individuals travelled long distances while most individuals were recaptured in the same trap, suggesting that all studied habitats currently provide the necessary conditions for the maintenance of butterfly populations, favouring fewer movements and narrow home ranges for both sexes and species. Conservation of a set of heterogeneous habitats it is especially important for the maintenance of sedentary butterflies and of those that move large distances.

Amphibians and reptiles of the Atlantic Forest in Recôncavo Baiano, east Brazil: Cruz das Almas municipality.

A list of amphibian and reptile species that occur in open and forested areas of the Atlantic Forest in the municipality of Cruz das Almas, in the Recôncavo Baiano, eastern Brazil is presented. Field sampling occurred between January 2015 to March 2019, totalling 117 samples distributed in three areas: Parque Florestal Mata de Cazuzinha, Mata da Cascalheira, and Riacho do Machado. A total of 1,848 individuals of 69 species (31 anurans, 14 lizards, 19 snakes, two amphisbaenians, and three testudines) was recorded. Additionally, one individual of Ophiodesstriatus was found in Mata da Cascalheira after the end of sampling, totalling 15 lizard species and 70 herpetofaunal species. The prevalence of open-area species and the presence of Phyllopezuslutzae, Diploglossuslessonae, and Dryadosauranordestina in interior forest patches are discussed. Additionally, a new record of the invasive terrapin Trachemysdorbigni in the State of Bahia is reported.

Simplified Communities of Seed-Dispersers Limit the Composition and Flow of Seeds in Edge Habitats

Edge effects, driven by human modification of landscapes, can have critical impacts on ecological processes such as species interactions, with cascading impacts on biodiversity as a whole. Characterizing how edges affect vital biotic interactions such as seed dispersal by frugivores is important for better understanding potential mechanisms that drive species coexistence and diversity within a plant community. Here, we investigated how differences between frugivore communities at the forest edge and interior habitats of a diverse tropical rainforest relate to patterns of animal-mediated seed dispersal and early seedling recruitment. We found that the lemur communities across the forest edge-interior gradient in this system showed the highest species richness and variability in body sizes at intermediate distances; the community of birds showed the opposite pattern for species richness. Three large-bodied frugivores, known to be effective dispersers of large seeds, tended to avoid the forest edge. As result, the forest edges received a lower rate of animal-mediated seed dispersal compared to the interior habitats. In addition, we also found that the seeds that were actively dispersed by animals in forest edge habitats were smaller in size than seeds dispersed in the forest interior. This pattern was found despite a similarity in seed size of seasonally fruiting adult trees and shrubs between the two habitats. Despite these differences in dispersal patterns, we did not observe any differences in the rates of seedling recruitment or seed-size distribution of successful recruit species. Our results suggest that a small number of frugivores may act as a potential biotic filter, acting on seed size, for the arrival of certain plant species to edge habitats, but other factors may be more important for driving recruitment patterns, at least in the short term. Further research is needed to better understand the potential long-term impacts of altered dispersal regimes relative to other environmental factors on the successional dynamics of edge communities. Our findings are important for understanding potential ecological drivers of tree community changes in forest edges and have implications for conservation management and restoration of large-seeded tree species in disturbed habitats.

Interactive effects of elevation and newly paved road on avian community composition in a scientific reserve, Bioko Island, Equatorial Guinea

AbstractUnderstanding interactive effects between anthropogenic disturbance and abiotic factors on species turnover can help to identify and prioritize conservation of potentially vulnerable tropical bird communities. We investigated the potential factors influencing avian understory community composition along with a recently constructed road across three elevations (300, 800, and 1200 m), each with two sampling sites (road edge vs. interior forest), over a four‐year period on Bioko Island, Equatorial Guinea. Insectivorous species were the most abundant guild‐sampled accounting for 55% of total species diversity within the dataset followed by frequent mixed‐flock followers (48%). Habitat associated with elevation was the most significant factor influencing the composition of avian communities. Additionally, we identified species with clear statistical associations for each elevation: the yellow‐lored bristlebill (Bleda notatus), olive sunbird (Cyanomitra obscura), and white‐tailed warbler (Poliolias lopezi). We found evidence for significant community differences between the disturbance edge and interior forest transects at 300 m only. Likewise, understory insectivores were found at higher numbers within the interior forest transect at this elevation. Based on the data presented here, we suggest low elevation avian understory insectivores should be considered focal species for future assessment studies in this area. Furthermore, since many traditional protected areas focus on upland habitat containing high species endemism, our findings emphasize the importance of equally conserving lowland elevations as they may house commonly overlooked, yet important and diverse segments of the bird community.Abstract in Spanish is available with online material.

Soil microbial community responding to moderately elevated nitrogen deposition in a Japanese cool temperate forest surrounded by fertilized grasslands

ABSTRACT To examine the hypothesis that the soil microbial community in a nitrogen (N) limited forest responds to moderately elevated N deposition (< 10 kg ha−1 yr−1), correlations between N deposition and soil microbial properties were analyzed in a cool temperate forest surrounded by normally fertilized pasture grasslands in northern Japan. Three experimental plots were established in forest edges adjacent to the grasslands, and the other three plots were in forest interiors at least 700 m away from the grasslands. N deposition in each plot was measured from May to November 2018. In August 2018, we collected litter and surface soil samples from all plots to measure net N mineralization and nitrification rates as indicators of microbial activity, and microbial biomass and various gene abundances (i.e., bacterial 16S rRNA gene, fungal ITS region, and bacterial and archaeal amoA genes) as indicators of microbial abundance. N deposition in forest edges was 1.4-fold greater than that in forest interiors, whereas maximum N deposition was 3.7 kg ha−1. N deposition was significantly correlated with net N mineralization and nitrification rates and 16S rRNA and bacterial amoA gene abundances. Microbial community structures analyzed for bacterial 16S rRNA gene and fungal ITS region amplicons were different between litter and soil samples but were similar between the forest edge and interior, although this analysis was made only for single pair of the two plots in the forest edge and interior. N deposition was also correlated with the soil C/N ratio and nitrate and ammonium contents. Thus, it was suggested that some soil microbial activities and abundances in an N limited forest likely responded to moderately elevated N deposition. These findings provide primary information on soil microbial response to moderately elevated N deposition.

Effect of transportation infrastructure on forest plant diversity and soil properties in Lawachara National Park, Bangladesh

Transportation infrastructure has bought many blessings for human civilization, although its negative influences, especially on a forested landscape should be heeded with prime concerns. In this study, we studied, how railway track perforating through Lawachara National Park affecting the nearby vegetation alpha (α) and beta (β) diversity and composition and soil properties, and whether the effects are active until a certain distance into the forest interior. Total 32 plots in 8 transect lines perpendicular to the railway are laid with 4 plots at 10 m, 40 m, 70 m and 100 m distances. Tree and tree regeneration α and β-diversity and composition, and soil organic matter and pH were assessed at each of these plots. Our results showed that, soil organic matter and pH, as well as α-diversity indices were significantly (P < .05) higher in plots near the railway track than forest interior parts in case of both tree and tree regenerations. But the β-diversity did not vary significantly (P > .05) with distances. High amount of organic matter in outermost plots was maybe due to the decomposition of litterfall and debris where increased pH value was due to presence of high amount of calcareous substances and plant residue. As the α-diversity of plant decreased with increasing distance from the railway track and in most cases the value decreased until 70 m distance, indicated that the influence of the railway tracks maybe prominent up to 70 m. So, to minimize this effect of vegetation structure proper steps such as careful planning in road building, afforestation using the native species and evaluation of the necessity of infrastructure and possible alternatives to it should be assessed.

Response of avian communities to edges of tropical montane forests: Implications for the future of endemic habitat specialists

Tropical montane landscapes harbor diverse flora and fauna, and many species there are ecological specialists with narrow elevational distributions, limited geographic ranges, and small global populations. Along elevational gradients, environmental conditions and community composition change dramatically over small spatial scales. As forests are disturbed and edges formed with modified habitat, natural communities could be affected differently across elevations by the many physical and biotic changes at edges. We asked whether forest edges produced altered patterns of avian species composition along a cloud forest - dry forest gradient on the Pacific slope of the Tilarán mountains in Monteverde, Costa Rica. A strong moisture gradient produces cloud forests near the ridgetops, with a concentration of species endemic to the Costa Rica – Panama highlands that are habitat specialists. We conducted 552 point counts across 110 locations from 1100 to 1800 m elevation, yielding 6586 detections of 115 species in 10 km2 of montane forest. We analyzed differences in species composition and single-species abundances between interior and near-edge forest habitats for species grouped by geographic range size. Species composition changed markedly from forest edge to interior in cloud forest habitats, but not in drier forests downslope. Endemic species, especially in cloud forest, were detected less frequently in mature forest near edges than in mature forest interior, and this difference was more pronounced than for cosmopolitan species. On tropical mountainsides, we can expect habitat-specialist endemic species to be more sensitive to further habitat modification. This sensitivity could limit the resilience of tropical bird communities.

Defoliated trees die below a critical threshold of stored carbon

Abstract Carbon starvation posits that defoliation‐ and drought‐induced mortality results from drawing down stored non‐structural carbohydrates (NSCs), but evidence is mixed, and few studies evaluate mortality directly. We tested the relationships among defoliation severity, NSC drawdown and tree mortality by measuring NSCs in mature oak trees defoliated by an invasive insect, Lymantria dispar, across a natural gradient of defoliation severity. We collected stem and root samples from mature oaks (Quercus rubra and Q. alba) in interior forests (n = 34) and forest edges (n = 47) in central Massachusetts, USA. Total NSC (TNC; sugar + starch) stores were analysed with respect to tree size, species and defoliation severity, which ranged between 5% and 100%. TNC stores declined significantly with increasingly severe defoliation. Forest edge trees had higher TNC stores that were less sensitive to defoliation than interior forest trees, although this may be a result of differing defoliation history. Furthermore, we observed a mortality threshold of 1.5% dry weight TNC. Our study draws a direct link between insect defoliation and TNC reserves and defines a TNC threshold below which mortality is highly likely. These findings advance understanding and improve model parametrization of tree response to insect outbreaks, an increasing threat with globalization and climate change. A free Plain Language Summary can be found within the Supporting Information of this article.

Small-scale environmental variations drive vegetation structure and diversity in Amazon riverine forests

Riverine forests in the Brazilian Amazon provide a series of ecosystem services and harbor one of the world's most diverse floras, but the main drivers of variation in small spatial scales in such tropical forests are not well understood. Our aim was to evaluate tree community structure and diversity patterns in the Teles Pires River to identify the main drivers of small-scale variations in the area. We sampled 4,180 individuals from 49 botanical families, 164 genera and 347 species by using six transects of five pairs of 50 m x 40 m permanent plots totalizing 60 permanent plots in a 12-hectare area. We utilized generalized linear mixed models to assess whether the effects of the environmental variables in the vegetation structural parameters. Altitude and groundwater depth were the main drivers influencing species diversity patterns. The trees had similar total biomass in areas within the same distance from the river margins. There was a lower species richness and tree density closer to the river margins. Otherwise, we found larger trees (higher individual biomass) closer to the river margins when compared to areas distant from the margins. Our results indicate a high species turnover from the river margins to the forest interior, which highlights the importance of assessing local effects on biological communities in tropical forests, especially in the Brazilian Amazon where several high-impact dams are planned.

Effects of stand edges on the structure, functioning, and diversity of a temperate mountain forest landscape

AbstractHuman land use is fragmenting forests around the globe, increasing the edge density in forest landscapes. More frequent natural disturbances also increase the presence of edges in forest ecosystems. Studying a mountain landscape in the Eastern Alps, we contrasted 661 plots situated at varying distances from a stand edge with 615 plots sampled in forest interiors. Our objectives were (1) to analyze the strength of edge effects on forest structure, functioning, and diversity; (2) to determine the penetration depth of edge effects into the forest interior; and (3) to quantify the difference between permanent edges (i.e., to a different land cover type) and transient edges (as created e.g., by natural disturbances). Edges affected forest biomass accumulation negatively (basal area, litter depth, live tree carbon), but had positive effects on diversity (variation in tree diameter, effective plant species number, plant species richness, number of red‐listed plant species). Biodiversity indicators responded most strongly to the presence of edges. The maximum distance of a significant edge effect was &lt;50 m across all indicators. Effects on forest structure and functioning were generally stronger at transient edges compared to permanent edges. Our findings highlight that both permanent and transient edges have a considerable influence on forest ecosystems and should be considered more explicitly in the analysis and management of forest landscapes.

Edge effects on the realised soil seed bank along microclimatic gradients in temperate European forests

Despite the crucial role of the seed bank in forest conservation and dynamics, the effects of forest edge microclimate and climate warming on germination responses from the forest seed bank are still almost unknown. Here, we investigated edge effects on the realised seed bank and seedling community in two types of European temperate deciduous forest, one in the Oceanic and one in the Mediterranean climatic region. Responses in terms of seedling density, diversity, species composition and functional type of the seed bank at the forest edge and interior were examined along latitudinal, elevational and stand structural gradients by means of soil translocation experiments. Moreover, we translocated soil samples from high to low elevation forests in the two regions, thus performing a warming simulation. Density, species diversity and mortality of the seedlings varied with region and elevation. Seedling density also differed between forest edge and interior position, while seedling cover mainly depended on forest structure. Both the edge and interior forest seed bank contained a high proportion of generalist species. In Belgium, a more homogeneous seed bank was found at the forest edge and interior, while in Italy compositional and ecological differences were larger: at the forest edge, more light and less moisture demanding seedling communities developed, with a higher proportion of generalists compared to the interior. In both regions, the upland-to-lowland translocation experiment revealed effects of warming on forest seed banks with thermophilization of the realised communities. Moreover, edge conditions shifted the seedling composition towards more light-demanding communities. The establishment of more light and warm-adapted species from the seed bank could in the long term alter the aboveground vegetation composition, with communities becoming progressively richer in light-demanding generalists and poorer in forest specialists.

Drivers of tree community assembly during tropical forest post-fire succession in anthropogenic savannas

In the context of global change, tropical forests are increasingly affected by fires. Understanding the ecological processes driving forest recovery in fire-modified landscapes is a critical issue.We analyzed spatial and temporal (8 years) changes in functional and phylogenetic composition of tree communities during forest post-fire recovery in anthropogenic savannas. We used null models to infer the main assembly processes driving forest succession along three 90-m transects running from an advancing savanna-forest edge to forest interior in New Caledonia. We also evaluated if successional changes differed between large and small trees, or depended on the demography of remnant savanna trees.We found coordinated shifts from drought- and fire-resistance towards shade-tolerance strategies, involving leaf, stem, and architectural traits along transects. Our results indicate stronger environmental filtering and faster temporal changes in composition of young edge communities. In forest interior, our results suggest slower compositional changes, with an important role of light limitation in community assembly. These non-random patterns depended on both the decline of savanna trees and compositional changes among forest species. We also found contrasting community patterns depending on tree size, supporting a stronger influence of environmental filtering on small trees.Our work emphasized the dominance of deterministic assembly processes driving tropical forest post-fire succession. Our study suggests that fire and drought drive environmental filtering during early succession at the forest edge, entailing constraints on multiple functional dimensions. As succession progresses, light-limitation becomes a stronger driver of community assembly, and community composition becomes more stable in time. Our study provides insights for a better understanding of the processes guiding tropical forest succession in the particular context of post-fire forest recovery.

Three- and Four-Dimensional Topographic Measurement and Validation

This paper reports on the activities carried out in the context of “Dragon project 32278: Three- and Four-Dimensional Topographic Measurement and Validation”. The research work was split into three subprojects and encompassed several activities to deliver accurate characterization of targets on land surfaces and deepen the current knowledge on the exploitation of Synthetic Aperture Radar (SAR) data. The goal of Subproject 1 was to validate topographic mapping accuracy of various ESA, TPM, and Chinese satellite system on test sites in the EU and China; define and improve validation methodologies for topographic mapping; and develop and setup test sites for the validation of different surface motion estimation techniques. Subproject 2 focused on the specific case of spatially and temporally decorrelating targets by using multi-baseline interferometric (InSAR) and tomographic (TomoSAR) SAR processing. Research on InSAR led to the development of robust retrieval techniques to estimate target displacement over time. Research on TomoSAR was focused on testing or defining new processing methods for high-resolution 3D imaging of the interior of forests and glaciers and the characterization of their temporal behavior. Subproject 3 was focused on near-real-time motion estimation, considering efficient algorithms for the digestion of new acquisitions and for changes in problem parameterization.