Litter production plays an important role in the functioning of the ecosystem, providing several ecosystem services, such as nutrients cycling and carbon storage. We studied litter production patterns and its relationship with forest structure over a chronosequence of secondary forests in southern Bahia, Brazil. In the study area, 15 pairs of mature and secondary forest were used, in a chronological sequence, being 10, 25 and 40-year-old secondary forests and mature forests. Plots were created for the collection of aboveground biomass data, and within these plots, litter collectors were installed and monitored for 1 year. The results showed that litter production was lower in 10-year-old secondary forests when compared with older forests. On the other hand, in the 10-year-old forests, annual litter production represents 47.8% of the stored biomass, while in mature forests annual litter production represents only 4%. We found that structural variables (basal area, number of stems and canopy opening) influence significantly litter production, as well as litter as percentage of forest biomass. The study emphasizes the importance of biomass production through litterfall in regenerating tropical forests, and its importance for carbon storage and for the maintenance of ecosystem services.

To better understand the role of seed banks in ecological succession of dry forests, we compared similarities between vegetation and seed banks and assessed the relative contributions of seed dispersal and persistence in chronosequences in the Brazilian semi-arid region. To sample the standing vegetation and the seed bank, we collected data in three sites with three successional ages in each one (5 y, 25 y and 45 y). A total of 180 soil samples (three sites × three successional ages × 10 plots × two components) were collected. The composition of the seed bank was assessed by the seedling emergence method. Of 166 species identified in the standing vegetation, only 50 (30.1%) were also present in the seed bank, resulting in low similarity (Jaccard index = 0.02–0.21) and reflecting the rarity of woody species and the dominance of annuals (71% of richness). The relative importance of seed persistence and seed dispersal to seed banks composition were balanced in most cases (difference was not rejected in four out six comparisons). Those results suggest that seed banks in tropical dry forests are largely the result of high dispersal rates and the persistence of allochthonous annual species that contribute to decoupling seed bank and vegetation composition.

Trends in structural and chemical leaf traits along a chronosequence of semi-evergreen tropical forest and their correlation with litter production and decomposition and associated carbon (C) and nitrogen (N) fluxes were assessed. Leaves of 15 dominant species in each plot were collected to measure leaf area, specific leaf area (SLA), C and N concentration and C:N ratio. Litterfall was measured and litter decomposition experiments were set up in 16 experimental plots in a chronosequence of secondary and mature forest. All five leaf traits combined discriminated the secondary forests from mature forest. SLA, N and C:N were significantly correlated to litter decomposition rates. Litter decomposition was significantly slower in mature forest compared with secondary forests. The N concentration of litter was lowest during the dry season, when litterfall was highest. N concentration in fresh leaves was higher than in litter, indicating that N is re-absorbed before leaf abscission. Leaf dynamics and associated nutrient cycling differ significantly between secondary forests and mature forest. Ecosystem-level leaf structural and chemical traits are good predictors of the stage of the forest and explain well the differences in decomposition rates between secondary and primary forests.

The control of western juniper (Juniperus occidentalis Hook.) trees released shrub and herbaceous vegetation from dominance of the tree overstory. Revegetation of the woodland with desirable browse and forage species required weed control of both shrub and herbaceous species. The method of tree control (herbicidal, mechanical, or wood harvesting) influenced subsequent weed control-revegetation options in the understory. Physical restraints imposed by standing dead trees resulting from picloram (4-amino-3,5,6-trichloropicolinic acid) treatment limited the use of weed control and seeding equipment. Accumulation of litter interfered with the use of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] for annual grass control on both the picloram and wood harvest plots. Establishment of forage species was most successful on the mechanically cleared plots. Attempts to revegetate with browse species were largely foiled by native herbivores, and selective predation occurred on herbaceous species.

Understanding patterns in plant and herbivorous insect diversity across spatial and temporal scales is fundamental to ecology, but comparative multi-taxonomic studies in tropical seasonally dry forests remain scarce. In 36 sites, distributed over three forest age classes (5–10 y, 10–30 y, >100 y) and three seasonal forest types (dry, intermediate, humid), we sampled plants of different stem diameter classes while caterpillars were sampled across vertically distributed forest layers during three seasons over the year. We recorded 299 plant species and 485 caterpillar morphospecies. For large woody plants, species numbers showed a gradually increasing trend with forest age in the intermediate and humid forest types, while the main portion of explained variation in overall species turnover was accounted for by the forest type × forest age interaction (21.3–23.1% of 44.4–48.7%). Ordinations and multivariate pairwise comparisons suggested a faster but also very distinct successional development of species diversity of large plants in the driest compared with humid and intermediate forest types. In contrast, highest species numbers of small plants in the undergrowth was often found in the 5–10 y-old vegetation across forest types, whereas forest type was the major factor in overall species turnover (contributing 24.2% of 48.7% explained variation). Caterpillar species turnover was most correlated to species turnover of small plants; however, variation in caterpillar species diversity appears to be mostly regulated by seasonal cues, and to a lesser extent by patterns of regional turnover and local diversity of undergrowth plant species.

The aim of this study was to investigate the spatiotemporal variation in richness, abundance, structure and composition of phyllostomid bats over a successional gradient in a tropical dry forest in south-eastern Brazil. Four successional stages (pasture, early, intermediate and late) were sampled in the northern part of the state of Minas Gerais. Bats were sampled using mist nets at three sites for each of the four successional stages (12 sites in total) during eight periods between 2007 and 2009. A total of 537 individuals were captured (29 recaptured), distributed among four families and 22 species. Bat abundance and richness varied in space, being higher in the late-successional stage, and over time, being significantly lower during the dry season. When compared between guilds, only the abundance of omnivores varied significantly during the sampled months. Our results demonstrate that areas of late-successional stages showed higher bat richness and abundance in comparison with areas undergoing secondary succession. Our results also suggest the use of early-successional areas as flying routes by bats can lead to failure to detect differences in bat composition within successional gradients. We suggest future studies should assimilate landscape-level analyses into their studies to better evaluate the effects of successional gradients on bat assemblages.

Isolated pioneer trees have been shown to increase the deposition of animal-dispersed seeds. The effect of gender on seed rain has not yet been investigated, and this study aimed to evaluate whether female and male plants of a pioneer dioecious zoochoric tree differ with respect to the seed rain under their canopies. Seed rain was evaluated for 13 mo, from October 2009 to October 2010, in secondary vegetation of the Atlantic forest in southern Brazil. We used 60 seed traps (0.5 m2): 40 traps under the crowns of 40 Myrsine coriacea (Primulaceae) trees (20 male and 20 female individuals) and 20 at sites without trees. We found 365071 diaspores belonging to 115 morphospecies from 37 families, and 38.3% of the morphospecies were trees, most of them zoochoric. The female trees accumulated a greater number of diaspores and species richness than male trees. The male trees accumulated a higher number of seeds and species than areas without trees. This study shows that sites containing female and male trees of M. coriacea and sites without trees differed significantly in terms of seed rain, and there is a gender effect in this dioecious, pioneer tree species because female plants promote an increase in the richness and abundance of diaspores.

Vegetation and environment change mutually during secondary succession, yet the idiosyncrasies of the vegetation effect on the understorey environment are poorly understood. To test whether the successional understorey environment changes predictably and is shaped by the structure and seasonality of tropical dry forests, we estimated basal area and vegetation cover, and measured understorey temperature, light and moisture conditions, in 17 plots forming a 60-y chronosequence and a mature forest. Light and air and soil temperature decreased with time (75−15% of open-sky radiation, 31.7−29.3 °C, and +2.5 °C to −0.5 °C relative to ambient, respectively), whereas relative humidity increased (67−74%). Soil water availability increased with early-successional development (−45 to −1 kPa) but decreased afterwards (to −18 kPa). The first axis of a PCA of the rainy-season environment explained 60% of the variation and was strongly related to air temperature and relative humidity. During tropical dry-forest succession, such factors may be more important than light, the reduction in which is not extreme compared with taller and more vertically stratified wet forests. Seasonality significantly affected the successional environmental gradients, which were marked mainly during the wet season. Environmental heterogeneity was higher in the wet than in the dry season, and larger for resources (light and water) than for conditions (temperature and humidity). The wet-season increase in environmental heterogeneity potentially creates differential growing scenarios; the environmental harshness of the dry season would mostly challenge seedling survival.

A chronosequence was used to study seed-bank communities during the first 12 y of tropical-dry-forest regeneration in abandoned pastures in Chamela, Mexico. Prediction that seeds of woody species replace those of herbaceous species during succession was tested and mechanisms of species replacement (facilitation, tolerance, inhibition) were assessed. Four successional categories (three sites each) were considered: pasture (0–1 y since abandonment), early (3–5 y), intermediate (10–12 y), and old-growth forest. At the end of the dry season, 20 cylindrical soil samples (10 cm diameter, 15 cm depth) were randomly obtained within a 20 × 50-m plot in each site. Seeds ≥1 mm were counted and identified. Overall, 2941 seeds and 102 morphospecies (52 taxonomically identified) were recorded. Seed bank density reduced, species diversity remained fairly constant and seeds of herbaceous species were replaced by those of woody species over the chronosequence. A clear species-by-species replacement pattern was detected, as expected under a mechanism of succession by facilitation. Twelve years after abandonment, a diverse seed bank of woody species did exist, indicating a fast recovery of the tropical-dry-forest regenerative potential; nonetheless, the structure and composition of the seed bank was still different from that in the old-growth forest.

The ecological importance of trees lasts much longer than their life spans. Standing dead trees (snags) and fallen trunks and branches are an important component of above-ground carbon stocks and nutrient reserves, provide habitat for wildlife, and interact with disturbance regimes (e.g. by serving as fuel for fires) (Clark et al. 2002, Harmon et al. 1986, Pyle et al. 2008). Despite these diverse functions, woody debris stocks remain poorly quantified in tropical forests in general (Brown 1997), and in tropical dry forests in particular (Harmon et al. 1995). More empirical studies of the patterns of woody debris and processes that control its dynamics are needed to understand its role in global biogeochemical cycles and for ecosystem simulation models, many of which do not represent coarse woody debris (CWD) as a separate pool (Cornwell et al. 2009).

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.

Community patterns along a successional sequence of abandoned fields within a tropical rain forest environment are described in terms of floristic composition and structure. Temporal patterns were summarized and main axes of variation extracted by multivariate methods.

External factors – length of cropping period, regrowth age, and proportion of the perimeter occupied by forest communities or remnants (here called forested perimeter) – were related to floristic and structural data on 40 sites. Multivariate direct gradient analysis showed overall floristic development to be positively related to regrowth age and forested perimeter, and negatively related to length of cropping period.

Structural development was shown by multiple regression to be positively related to regrowth age and negatively to length of cropping period; but forested perimeter had no significant relation to site structure. The type of crop grown showed no significant relation with floristic or structural development of the regrowth.

These results indicate that the conditions of the vegetation around a site have a great effect on community recovery, particularly in its species composition, whilst structure seems to be affected more directly by parameters which imply time.

The effects of herbivory by the leaf-cutting ant Atta laevigata Fr. Smith on the re-establishment of forest trees in an abandoned farm near Manaus, central Amazonia, were investigated. Experimental seedling transplants and observations on seedlings which emerged naturally in the study area showed that damage by leaf-cutting ants negatively affected tree seedling survival and growth. However, excluding leaf-cutting ants from experimental plots for 20 mo did not significantly increase tree seedling densities. The number of seedlings emerging varied considerably between plots and this obscured any effect the ants may have had on seedling survivorship. Taller seedlings, and seedlings attacked only once, suffered less mortality than smaller seedlings and seedlings attacked twice or more. In general, mortality was greater for those species preferred by the ants, indicating that selective herbivory by leaf-cutting ants affects tree species composition. The number of seedlings attacked by A. laevigata remained approximately constant throughout the period of this study in spite of the fact that the number available for attack increased. Thus, the chance of any individual seedling being attacked declined with time, suggesting that the effect of Atta herbivory on tree establishment is stronger during the first few years of forest regeneration.

We developed allometric relationships between tree size parameters (stem diameter at breast height (dbh), at ground surface (D0) and tree height) and leaf, stem, small-root (diameter <5 mm) and total root biomass in various tropical secondary-forest trees in Sarawak, Malaysia. In total, 136 individuals from 23 species were harvested to measure above-ground parts. Root systems of 77 individuals of 16 species were also excavated. The coefficients of correlation for the obtained allometric relationships between tree diameter and plant-part biomass showed high values, ranging from 0.83 to 0.99. In addition, there were few interspecific differences in relationships for all biomass parts, except for leaves. We also found relatively high coefficients of allometric relationships between tree height and plant-part biomass ranging from 0.83 to 0.94. Comparison of above- and below-ground biomass equations for various tropical rainforests implies that our allometric equations differ largely from the equations for tropical primary forests. Thus, choosing both above- and below-ground allometric equations for biomass estimation in tropical secondary forests of South-East Asia requires careful consideration of their suitability.

Climate change may increase the intensity of hurricanes (Emanuel 1987, 2003), and thus the size of disturbance in tropical forests. As a consequence, disturbance-specialist plants, such as lianas, may increase in abundance there (Phillips & Gentry 1994). Putz (1984) hypothesized that lianas create larger treefall gaps by connecting trees together and pulling down multiple trees during storms. This positive-feedback cycle may increase the prevalence of lianas in disturbed tropical forests (Schnitzer & Bongers 2002, Schnitzer & Carson 2001). Alternatively, Putz (1984) proposed that lianas tie and stabilize canopies together, resulting in less disturbance. Forest age may determine the role of lianas during disturbance because liana abundance and composition vary through secondary succession (De Walt et al. 2000, Schnitzer et al. 2000). To test the two hypotheses of Putz (1984), we evaluated the effect of liana cutting between forests of different successional ages on tree damage by hurricane Wilma.

This paper examines the composition and density of soil seed banks under a mature seasonal rain forest (>150 years old), three secondary forests (4 yr Trema orientalis forest, 9 yr Macaranga denticulata forest and 25 yr Mallotus paniculatus forest) and in a slash-and-burn field of Xishuangbanna, southwest China. Seeds in the secondary forests germinated most rapidly in the first week, while the seeds of the seasonal rain forest and the slash-and-burn field soils germinated slowly over the first 6 weeks and peaked in the seventh and eighth weeks. Seed densities were 4585–65,665 seeds m−2 for forest sites and 1130 seeds m−2 for the slash-and-burn field in the top 10 cm of the soils. The seed density decreased with soil depth in the forest sites and tended to decline during succession. Herbs accounted for the largest proportion of seeds at all five sites. The importance of woody species, however, increased as forests became older. Slash and burn eliminated a large number of seeds in the upper soil and, consequently, reversed the vertical distribution of seeds in the soil and had a negative impact on family, genus and species richness of the soil seed bank as well.

Stand structure dynamics during early secondary forest succession were related to mortality, growth and recruitment rates, and the dependence of these demographic processes on fallow age and initial stand structure attributes was evaluated. In 11 secondary tropical rain-forest sites (1.5–19 y) in Chiapas, Mexico, one plot of 10 × 50 m was established. Diameter and height were measured for all trees ≥ 1 cm dbh, and their survival, growth and recruitment was monitored over a 2-y period. Changes in stand structure were especially fast in the first 5 y of succession, and decreased rapidly afterwards, which resulted from similar stand-level changes in relative mortality, growth and recruitment rates. Demographic processes were negatively related with initial stand basal area, but independent of initial tree density. Basal area was a better explanatory variable of the among-stand variability in these rates than fallow age. Results suggest that asymmetric competition and resulting patterns of tree-thinning are major driving forces determining secondary forest successional pathways. Fallow age per se is a compound variable reflecting community organization at a certain point along the successional axis, while community structure drives succession. Sudden mass mortality among dominant species in some stands showed that early secondary forest succession is not always a gradual and unidirectional process.

Secondary succession was studied in a Mexican cloud forest region along a chronosequence of 15 abandoned pastures (0.25–80 y). Our objective was to determine the effects of distance from the forest border on successional vegetation structure and woody species richness along the chronosequence. Vegetation structure similar to that of mature forests recovered over 40–50 y, both close to (0–10 m) and away from (40–50 m) the border. Total woody species richness was similar for both distances but species composition differed significantly. When primary forest species were analysed separately, basal area, height, abundance and richness were all significantly higher close to the forest border. Primary species such as Quercus spp. (barochorous-synzoochorous) and Carpinus caroliniana (anemochorous) had lower basal area, density and height away from the border than close to it. Secondary species such as Lippia myriocephala (anemochorous) and Myrsine coriacea (endozoochorous) did not differ in their rate of colonization between distances. The limitation of seed dispersal and establishment for primary woody species away from forest borders suggests that propagules need to be introduced to accelerate forest restoration.