The semiarid northeast coast of Brazil harbours just less than 44,300 ha of mangroves, 4% of Brazilian total. Notwithstanding this relatively small area, these forests have high ecological and economic importance, sustaining traditional fisheries and protecting biodiversity, including many threatened species. They present unique biogeochemical characteristics resulting in distinct ecosystem functioning compared to mangroves located in humid areas. Semiarid mangroves present lower aboveground biomass compared to humid region mangroves but show similar belowground biomass. Whereas mangrove soils in humid areas are strongly influenced by sulphate reduction, iron geochemistry is a primary driver of soil characteristics in semiarid mangrove soils, suggesting different responses to climate change drivers between them. Although legally protected, they have incurred continuous degradation due to regional drivers, mostly aquaculture and river damming, which differs from those in humid coast mangroves. Semiarid mangroves are also particularly sensitive to drivers associated with global climate change (high temperatures, reduced rainfall and sea level rise). These conditions occur at a global scale; however, the impacts are worsened by the natural conditions of semiarid coastlines, which already provide biologically stressful conditions for mangroves. This article compares the impacts of such drivers in semiarid mangroves with those of humid mangroves, focusing on their biogeochemical response and eventual rehabilitation.

Human-induced land-use change has resulted in substantial loss and degradation of habitat for forest-dwelling wildlife. The moor macaque Macaca maura, an Endangered primate endemic to Sulawesi, Indonesia, has been observed in a wide array of habitats, including heavily modified areas, but little is known about the quality of these habitats. Here we compared the habitat quality of two areas occupied by moor macaque populations: a previously human-modified karst forest now located within a national park and a heavily modified forest located in an unprotected area. We assessed habitat quality by measuring specific indicators of potential food availability derived from vegetation data and quantified the nutritional environment based on macronutrient analysis of fruit samples collected at the two sites. Although the species richness, diversity and overall stem density of macaque food trees were greater in the protected area forest, total basal area and mean diameter at breast height were greater in the heavily modified forest. Mean metabolizable energy concentrations of fruits eaten by macaques were similar between forests, as were the proportions of protein, lipids and total non-structural carbohydrates. These results provide further support for the notion that heavily modified habitats should not be overlooked for their potential conservation value. To further augment their value, conservation efforts should focus on forest restoration, specifically the planting of fast-growing species that are utilized by both wildlife and people.

Threats of forest degradation of the Tano Offin Globally Significant Biodiversity Area present the need to generate eco-information pertinent for its conservational purposes. Ten 50 m × 50 m plots (tree layer) were assessed for plant life forms with diameter ≥ 10 cm. A 10 m × 10 m plot (shrub layer) was located within each of the 50 m × 50 m plots where plant life forms with diameter < 10 cm were assessed. 1 m × 1 m quadrats (herb layer) were laid at the corners of the 50 m × 50 m plots and its centre for canopy closure and natural regeneration assessments. Plant species (240) belonging to 59 families were identified: 171 trees, 41 lianas, 11 shrubs, 7 herbs, 7 herbaceous climbers, 1 epiphyte, 1 grass and 1 fern. Species diversity (H´) of the tree, shrub and herb layers was 2.55, 2.54 and 2.48 respectively. The average maximum tree height was 46.19 m and the basal area was 28.36 m2/ha, which is below the 35 m²/ha conventional basal area value of tropical forests. Celtis mildbraedii and Rinorea welwitschii were the most structurally significant species at the tree and shrub layers, respectively, and a total of 75 tree species were regenerating.

Drivers of forest structure in central African rain forests are largely unknown. Using forest inventory data (3024 0.4-ha plots) in a forest concession of 154 456 ha in north-eastern Gabon covering an altitudinal gradient (from 485 to 1009 m asl), relationships between above-ground plot biomass and environmental variables (soil type, altitude, slope, aspect) and floristic composition (score given by an ordination method) were tested. After controlling for confounding variables, biomass was significantly related to altitude (with a modal response peaking at 346 Mg ha–1 on western slopes at an altitude of 707 m asl) and to aspect (additional 18.3 Mg ha–1 on eastern slopes) but not to floristic composition. Biomass and basal area responded differentially to the environment. Mean wood density was significantly related to soil, altitude and floristic composition, with a predicted minimum of 0.60 g cm–3 at an altitude of 1009 m asl in stands characterized by Scorodophloeus zenkeri and a maximum of 0.69 g cm–3 at an altitude of 458 m asl in monodominant Gilbertiodendron dewevrei stands. Variation in forest structure in the concession was primarily driven by altitude while floristic composition played a role in differentiating the variation in biomass and basal area.

In stable populations with constant demographic rates, size distributions reflect size-dependent patterns of growth and mortality. However, population growth can also affect size distributions, which may not be aligned with current growth and mortality. Using 25 y of demographic data from the 50-ha Barro Colorado Island plot, we examined how interspecific variation in diameter distributions of over 150 tropical trees relates to growth–diameter and mortality–diameter curves and to population growth rates. Diameter distributions were more skewed in species with faster increases/slower decreases in absolute growth and mortality with diameter and higher population growth rates. The strongest predictor of the diameter distribution shape was the exponent governing the scaling of growth with diameter (partial R2 = 0.20–0.34), which differed among growth forms, indicating a role of life history variation. However, interspecific variation in diameter distributions was also significantly related to population growth rates (partial R2 = 0.03–0.23), reinforcing that many populations are not at equilibrium. Consequently, although fitted size distribution parameters were positively related to theoretical predictions based on current size-dependent growth and mortality, there was considerable deviation. These analyses show that temporally variable demographic rates, probably related to cyclic climate variation, are important influences on forest structure.

Climate is one of the most important factors determining variation in forest structure, but whether soils have independent effects is less clear. We evaluate how climate and soil independently affect forest structure, using 89 200 stems ≥ 10 cm dbh from 220 1-ha permanent plots distributed along environmental gradients in lowland Bolivia. Fifteen forest structural variables, related to vertical structure (forest height and layering), horizontal structure (basal area, median and the 99th percentile of the stem diameter and size-class distribution) and density of life forms (tree, palm and liana), were evaluated. Environmental variables were summarized in four multivariate axes, related to rainfall, temperature, soil fertility and soil texture. Multiple regression indicates that all structural variables were affected by one or more of the environmental axes, but the explained variation was generally low (median R2 = 0.15). Rainfall and soil texture affected most forest structural variables (respectively 87% and 80%) and had qualitatively similar effects. This suggests that plant water availability, as determined by rainfall and soil water retention capacity, is the strongest driver of forest structure, whereas soil fertility was a weaker driver of forest structure, affecting 53% of the variables. Maximum forest height, palm density, total basal area and liana infestation showed the strongest responses to environmental variation (with R2 ranging from 0.31–0.82). Forest height, palm density and total basal area increased with plant water availability, while liana infestation decreased with plant water availability. Therefore, multiple rather than single environmental factors must be used to explain the structure of tropical forests.

Sprouting may play a significant role in maintenance of plant diversity where prevailing disturbance frequency and severity allows. When disturbance frequency and severity decrease, strong sprouters may be outcompeted. As a result, species composition and diversity may change. This study was carried out to investigate the relationship between sprouting, succession and species diversity in a coastal dune forest that currently suffers from low-severity, chronic disturbance due to sea winds and loose sand substrate. Historically, the site was occupied by shifting cultivators who left the site about 80 y ago. Data on trees that were at least 1.3 m tall from 42 sample plots measuring 20 × 20 m were used. The plots were ranked in order of advancement of succession using the first axis of Principal Components Analysis of forest structural variables. Regeneration pattern was examined using analysis of stem diameter frequency distribution. Abundance and regeneration of strong basal sprouters, incidence of basal sprouting and species diversity decreased with advancement of succession. Only a few species could regenerate under the canopy of late-successional sites. Basal sprouts decreased with advancement of succession whereas trunk sprouts increased. These results suggest that maintenance of high species diversity may need a level of disturbance that allows regeneration and maintenance of strong basal sprouters.

The neotropical terrestrial insectivore Henicorhina leucosticta (Troglodytidae) maintains long-term territories through vocalizations and forages among leaf litter trapped in the understorey vegetation and ground litter. The relationship between forest structure and H. leucosticta territory size was studied in La Selva Biological Station, Costa Rica, during the non-breeding season in 2009. Forest structure was measured by assessing canopy openness and leaf area index (LAI) using hemispherical photography, while territory size was estimated with the playback technique using local conspecific vocalizations. Mean territory area was 3.8 ± 2.8 ha (mean ± SD, n = 10). Territory radius length was similar in old-growth forest and abandoned agro-forest plantations. We found that H. leucosticta territory size decreased as median LAI increased. We propose that LAI is related to territory size through the amount of leaf fall and subsequent leaf litter accumulation over the understorey plants, which constitutes an important reservoir of arthropod prey and nest materials for H. leucosticta. The long-term supply of food resources is likely to affect territory size in this species, as well as other insectivorous birds with similar foraging behaviour. These results are congruent with the structural cues hypothesis.

An index of canopy closure was used to estimate closure above the crowns of all trees ≥ 10 cm dbh in 11.11 ha of undisturbed lowland tropical forest at La Selva, Costa Rica. To correct for the efFects of tree size on canopy closure, we used the residual of the regression of the canopy closure index on tree size. Analyses were carried out for the 104 species which had ≥ individuals; a total of 3224 trees were included. Nine species were found to have their crowns in significantly more open conditions than expected by chance and five species were found to have their crowns in significantly more closed conditions than expected by chance (P < 0.05). The remaining 90 species (86.5% of the assemblage) were distributed at random with respect to canopy closure, occupying the available light conditions indiscriminately. Species occurring under higher light levels did not show a narrower range of tolerance than did other species. Most species were found to occur over a substantial proportion of the canopy closure continuum present in the stand; overlap among the great majority of species in the assemblage is extensive. The results support the view that tropical forests comprise assemblages of generalist tree species, and raise questions about the classic notions of gap-phase dynamics.

Natural forests on Java have been generally cleared and remnants are now confined to mountain areas Although legally protected, these forests are used by local people for products like firewood, timber and fodder Locally, such exploitation is carried out daily by hundreds of people, whose livelihood depends on forest products Using a landscape-guided approach, a 15,500 ha area of montane forest in East Java has been sampled and analysed at the sylvatic mosaic level Vegetation types, sociologic species groups and vegetation structure are described for landscape units The most accessible landscape units have the most degraded forest with basal area values < 15 m2 ha−1 and a canopy closure of < 20% The least accessible units have relatively undisturbed forest with basal area values of > 45 m2 ha−1 and a canopy closure of > 60% Human activities such as tree cutting have altered species composition and modified forest structure to such an extent that large stretches of forest have been replaced by woodland or shrubland Forest degradation is described as a human induced process in which basal area and canopy closure are ultimately reduced, in spite of regrowth Comparison with other forest areas on Java shows that degradation as a result of tree cutting is a widespread phenomenon

Changes in structure of a Costa Rican upper montane Quercus forest were studied in twelve 0.1 ha plots along a chronosequence including 8- to 20-year-old Early Secondary Forest (ESF), 25- to 32-year-old Late Secondary Forest (LSF) and mature Primary Forest (PF). In 1.2 ha 2854 stems ≥ 3.0 cm dbh belonging to 42 tree species were recorded. Tree species richness per 0.1 ha ranged from 15 to 30. Diversity indices did not change significantly during succession. Stem density did not differ significantly among successional phases, while basal area was significantly higher in PF than in ESF and LSF. Maximum canopy height and basal area increased linearly during the first three decades of recovery. Height and dbh showed a significant, logarithmic regression for all forest phases. A period of 84 y was estimated as the theoretically minimum time needed for structural recovery. The maximum canopy height and basal area recovered two to five times slower in upper montane than in lower montane or lowland Neotropical forests.

A comparative study of the damage caused by Hurricane Hugo on the three main types of forest in the lesser Antilles was carried out in the mangrove forest, the semi-evergreen forest and the rainforests of Guadeloupe. Hurricane impact on these forests showed at first that high canopy trees generally prevented understorey trees from heavy direct damage (shield effect). In the species-poor, structurally homogeneous stands, in the mangrove forest, species' susceptibility was the major determinant in both intensity and type of damage. Damage was heavy in places and showed a certain spatial uniformity. In the rainforest, the high structural complexity of the vegetation generally induced a great variability in the spatial distribution of damage even at a small scale. Due to the presence of tall trees, indirect damage was locally very heavy. Clumps of large trees formed resistant structures which diminished lethal damage below the main canopy (cluster effect). In such a highly structured, species-rich forest, species' susceptibility was concealed at the local scale by the prevailing influence of vertical structure. Because of its relatively rich flora but low stature, the semi-deciduous forest exhibited intermediate patterns of damage. It was concluded that floristic composition and forest structure help to explain, and to predict, hurricane damage to forest cover.

The Monteverde Cloud Forest Reserve protects a variety of primary montane forest communities on volcanic parent materials. We describe the structure and composition of the forest to provide background information for epiphyte and nutrient cycling studies and for comparison with other tropical montane forests. In a 4-ha study plot in leeward cloud forest, density of stems (2062 individuals ha−1 for stems >2 cm dbh, 555 individuals ha−1 for stems > 10cm dbh) and stem basal area (73.8 m2 ha−1 for stems >2 cm, 62.0 m2 ha−1 for stems >10 cm dbh) were high relative to other montane forests. Stems in a subset of the plot (c. 1/3 of the area) were identified and assigned to 47 families, 83 genera and 114 species, which is rich compared with other montane forests. Large stems had a higher spatial variability of structural and floristic characteristics than small stems.

To investigate the implications of forest fragmentation for conservation of leaf-litter lizards the importance of fragment size, corridors and forest structure was examined in 20 forest fragments and six localities within a continuous forest in the Atlantic Plateau of São Paulo state, Brazil. The fragments were 2–276 ha in area and had different degrees of connectivity depending on the presence or absence of corridors. Two species of lizards were dominant, Ecpleopus gaudichaudii and Enyalius perditus. Variation in forest structure among sites was important only in explaining the abundance of E. perditus. Regardless of variation in forest structure, lizard species composition, total lizard abundance, number of species and abundance of E. perditus were sensitive to fragmentation per se but not to fragment size or corridor linkage. The inhospitable matrix surrounding fragments is probably what determines the presence and abundance of E. perditus and the higher lizard richness in continuous forests. These conditions may have prevented lizard species from recolonizing the forest fragments. Our results emphasize that the conservation of this leaf-litter fauna depends on the maintenance of large tracts of continuous forests and not on the size of fragments or on the presence of forest connections. Strategies for conservation of leaf-litter lizards in such highly fragmented Atlantic Forest landscapes should consider the enlargement of landscape connectivity between fragments and continuous forest, allowing the latter areas to act as a source of individuals for fragments.

This study provides a community-level analysis of how regeneration requirement and adult stature are related to tree allometry (diameter, height and crown size) throughout post-seedling ontogeny on Barro Colorado Island, Panama. Comparing 65 species, gap species are taller, have higher diameter growth rates and occupy more low-canopy sites (≤10 m canopy height) than shade species at small diameters (≤10 cm dbh). For trees >10 cm dbh, diameter-height relationships and growth rates no longer differ between gap and shade species, but shade species have larger, particularly deeper, crowns than gap species. Species with tall adult stature have more slender stems with larger crowns compared with treelet and mid-canopy species starting at 5 cm dbh. From 10 to 40 cm dbh, diameter growth rate is also significantly greater for tall species. The consistent allometric differences between functional groups on a community level will, in part, determine vertical and horizontal stand structure.

Stand structure, species richness and population structures of tree species were characterized in 12 stands representing 50 y of succession following slash-and-burn agriculture in a tropical dry forest in lowland Bolivia. Estimates of tree species richness, canopy cover and basal area reached or surpassed 75% of mature forest levels in the 5-, 8-, and 23-y-old stands respectively. Total stem density of the 50-y-old stand was almost twice that of the mature forest stand. This rapid recovery may be due to a high percentage of sprouting tree species, potentially high seed fall into abandoned fields, or the disturbance history of the mature stand. The even-aged size-class structures, dominance of long-lived pioneers, and presence of charcoal and pottery shards in soils of the mature forest stand suggest it formed after a severe disturbance, possibly fire of anthropogenic origin.

Swamp forest covers c. 2600 ha of coastal wetlands in Guadeloupe. An inventory of all vascular plants was conducted together with a characterization of the main abiotic descriptors within seventeen 10-m × 40-m plots, systematically sampled throughout the forest. Girth at breast height (GBH) was measured for all trees ≥10 cm GBH. Four forest types were discriminated according to pH, clay content and redox potential of the soils. Among the 107 species recorded, lianas and epiphytes were as much represented as tree species (28%). However, no epiphytes were encountered at the canopy level where Pterocarpus officinalis (Papilionaceae) was the evenly dominant tree. Local hummock-hollow topography was responsible for an aggregated distribution of P. officinalis. This species exhibits several adaptative traits which may explain its dominance over all of the lowland swamp forests subjected to permanent waterlogging in the hurricane-prone Caribbean islands.