Tropical Seasonal Forest Research Articles

Resource use among sympatricCallosciurusspp. (Sciuridae) in tropical seasonal forests during the dry season in northeastern Thailand

Southeast Asia contains a diverse array of squirrels, with several species living sympatrically. However, limited data are available on how the squirrels coexist and share resources in the same habitat. Here, we examined resource-use variation between sympatric Callosciurus finlaysonii and C. caniceps in two habitats of northeastern Thailand: dry dipterocarp forest (DDF) and dry evergreen forest (DEF). Both species were bimodally crepuscular and did not differ in daily activity patterns. Callosciuruscaniceps was fewer in number than C. finlaysonii in DDF, but they had similar frequencies in DEF. The two species generally consumed different plant species, though some preferred fruits overlapped. Callosciurus finlaysonii from DEF remained higher in the trees than C. caniceps; all nests at elevated locations belonged to C. finlaysonii. When feeding, the preferred height of both species varied depending on food availability. In DEF, C. caniceps dominated C. finlaysonii during interactions. Together, our observations indicate that sympatry is possible because the two species differ in food choice and/or engage in vertical zonation.

Large-scale vegetation history in China and its response to climate change since the Last Glacial Maximum

Large-scale palaeovegetation reconstruction plays a critical role in improving our understanding of the response of vegetation to climate change and in reducing the uncertainty in predictions of vegetation change under global warming scenarios. Here, we present quantitative vegetation reconstructions for China since the Last Glacial Maximum (LGM), using 286 selected fossil pollen records analyzed using the biomization method. The results show that from 23 to 19 ka (1 ka = 1000 cal yr BP), steppe and desert expanded southeastwards, dominating northern China, whereas forest in eastern China shrank southwards to near the middle and lower reaches of the Yangtze River; the percentage of forested sites at this time was the lowest during the studied interval. Forest then developed gradually during 18–12 ka. During the early and middle Holocene, tropical seasonal forest, broad-leaved evergreen/warm mixed forest, and temperate deciduous forest shifted northwards by 2°, 4° and 5° in latitude, respectively, relative to today, and then declined in the late Holocene. In detail, forest flourished in the middle Holocene (9–4 ka) in semi-arid and semi-humid northern China, whereas it reached a maximum in the early and middle Holocene (11.5–6 ka) in humid southern China. Our results suggest that although forest throughout China exhibited the expected response to the evolution of the East Asian summer monsoon, precipitation exerted a more significant effect on vegetation change in northern China, whereas temperature and precipitation played a more important role in southern China. Our results are a potentially useful reference for assessing future vegetation dynamics under global warming scenarios.

Occurrence and distribution of Gigaspora under Cryptostegia madagascariensis Bojer Ex Decne in Brazilian tropical seasonal dry forest

The Brazilian tropical seasonal dry forest presents high abundance of arbuscular mycorrhizal fungal from Order Diversisporales, but the occurrence and distribution of Gigaspora species (Order Diversisporales) in invaded zones by exotic plant species in the Caatinga are not know yet. Here, we compare the occurrence and distribution of Gigaspora community in soils from invaded zone by the exotic plant species C. madagascariensis and soils from native zone by the native plant species M. tenuiflora from Brazilian tropical seasonal dry forest, Pombal, Paraiba, Brazil. We analysed and compared the number of spores and frequency of occurrence of Gigaspora species using 40 m transects and morphological analyses. In general, the most dominant Gigaspora species in the invaded zone was Gigaspora albida, whereas we did not find any dominance by Gigaspora species in the native zone. Differences in Gigaspora occurrence and distribution were associated with (1) the dominant plant species (C. madagascariensis vs. M. tenuiflora) that alter the occurrence and frequency of Gigaspora in field conditions from the Brazilian semiarid region, (2) the transition zone, where G. albida and G. margarita did not occur, and (3) specific plant-AMF pairing, where we identified G. gigantea as the most resilient AMF species occurring in all the studied sections into the 40 m transects. These results contribute to a deeper view about the Gigaspora occurrence and distribution in invaded and native zones of the Brazilian semiarid and open new perspective for ecological studies addressing specific AMF taxa and other exotic plant species in the Brazilian tropical seasonal dry forest.

ENSO Drives interannual variation of forest woody growth across the tropics.

Meteorological extreme events such as El Niño events are expected to affect tropical forest net primary production (NPP) and woody growth, but there has been no large-scale empirical validation of this expectation. We collected a large high-temporal resolution dataset (for 1-13 years depending upon location) of more than 172 000 stem growth measurements using dendrometer bands from across 14 regions spanning Amazonia, Africa and Borneo in order to test how much month-to-month variation in stand-level woody growth of adult tree stems (NPPstem) can be explained by seasonal variation and interannual meteorological anomalies. A key finding is that woody growth responds differently to meteorological variation between tropical forests with a dry season (where monthly rainfall is less than 100 mm), and aseasonal wet forests lacking a consistent dry season. In seasonal tropical forests, a high degree of variation in woody growth can be predicted from seasonal variation in temperature, vapour pressure deficit, in addition to anomalies of soil water deficit and shortwave radiation. The variation of aseasonal wet forest woody growth is best predicted by the anomalies of vapour pressure deficit, water deficit and shortwave radiation. In total, we predict the total live woody production of the global tropical forest biome to be 2.16 Pg C yr-1, with an interannual range 1.96-2.26 Pg C yr-1 between 1996-2016, and with the sharpest declines during the strong El Niño events of 1997/8 and 2015/6. There is high geographical variation in hotspots of El Niño-associated impacts, with weak impacts in Africa, and strongly negative impacts in parts of Southeast Asia and extensive regions across central and eastern Amazonia. Overall, there is high correlation (r = -0.75) between the annual anomaly of tropical forest woody growth and the annual mean of the El Niño 3.4 index, driven mainly by strong correlations with anomalies of soil water deficit, vapour pressure deficit and shortwave radiation.This article is part of the discussion meeting issue 'The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications'.

Studies on forest ecosystem physiology: marginal water-use efficiency of a tropical, seasonal, evergreen forest in Thailand

Marginal water-use efficiency plays a critical role in plant carbon–water coupling relationships. We investigated the ecosystem marginal water-use efficiency (λ) of a tropical seasonal evergreen forest to (1) determine the general pattern of λ across time, (2) compare different models for calculating λ, and (3) address how λ varies with soil water content during different seasons. There was a U-shaped diurnal pattern in λ, which was higher in the early morning and late afternoon. At other times of the day, λ was lower and remained constant. Ecosystem λ was higher in the wet season than in the dry season. All three models successfully captured the diurnal and seasonal patterns of λ but differed in the calculated absolute values. The idea that λ is constant on a subdaily scale was partly supported by our study, while a constant λ was only true when data from the early morning and late afternoon were not included. The λ increases with soil water content on a seasonal scale, possibly because early morning λ remained low in dry conditions when the soil water content was low.

Complementarity of gymnosperms and angiosperms along an altitudinal temperature gradient

In seasonal tropical forests, evergreen–deciduous mixtures are more productive than monocultures because they intercept more light throughout the year, reflecting complementary resource use by functional groups possessing different traits. This suggests that temperate and boreal forests may also exhibit overyielding, due to the difference in phenology between gymnosperms and angiosperms. However, complementarity could also arise from differences in morphology between needle leaves and broad leaves, or facilitation by N‐fixing species. Alternatively, mixtures may be more productive simply because interspecific competition is less intense than intraspecific competition. We used forest inventory data to assess the complementarity of the main functional groups in Switzerland. We employed a trait‐based analysis of competition to determine whether: 1) trait differences reduce the intensity of competition between complementary functional groups, 2) complementarity is observed along a broad altitudinal temperature gradient. N‐fixing species facilitated the growth of non‐fixing species, such that 50/50 mixtures were 50% more productive than monocultures, though half the overyielding was due to the alleviation of intraspecific competition. In contrast, we found no evidence of complementarity between evergreen and deciduous species. For example, in stands where larch was mixed with other gymnosperms, there was no reduction in heterospecific competition among evergreen species, even though evergreens cast shade on one another throughout the year. In cold montane forests, broadleaf species reduced the suppression of needleleaf species, and vice versa. Thus, 50/50 mixtures of needleleaf and broadleaf species were 15% more productive than needleleaf monocultures. However, in warm lowland forests, broadleaf species exacerbated the suppression of needleleaf species, completely offsetting the positive effect that needleleaf species had on broadleaf species. In summary, we found no evidence of complementarity between evergreen and deciduous species, but needleleaf–broadleaf mixtures exhibited overyielding in cold montane forests, which is consistent with the stress gradient hypothesis, though the underlying mechanisms remain uncertain.

Seasonality of the gut microbiota of free-ranging white-faced capuchins in a tropical dry forest

Research on the gut microbiota of free-ranging mammals is offering new insights into dietary ecology. However, for free-ranging primates, little information is available for how microbiomes are influenced by ecological variation through time. Primates inhabiting seasonal tropical dry forests undergo seasonally specific decreases in food abundance and water availability, which have been linked to adverse health effects. Throughout the course of a seasonal transition in 2014, we collected fecal samples from three social groups of free-ranging white-faced capuchin monkeys (Cebus capucinus imitator) in Sector Santa Rosa, Área de Conservación Guanacaste, Costa Rica. 16S rRNA sequencing data reveal that unlike other primates, the white-faced capuchin monkey gut is dominated by Bifidobacterium and Streptococcus. Linear mixed effects models indicate that abundances of these genera are associated with fluctuating availability and consumption of fruit and arthropods, whereas beta diversity clusters by rainfall season. Whole shotgun metagenomics revealed that the capuchin gut is dominated by carbohydrate-binding modules associated with digestion of plant polysaccharides and chitin, matching seasonal dietary patterns. We conclude that rainfall and diet are associated with the diversity, composition, and function of the capuchin gut microbiome. Additionally, microbial fluctuations are likely contributing to nutrient uptake and thehealth of wild primate populations.

Does Wood Fuel Gathering for Household Use Follow an Optimality Model? A Study from Kakamega Forest, Western Kenya

Successful management of forests, especially in the context of subsistence wood fuel use, can be improved by the application of theoretic models that predict patterns of use. A first step in this approach is understanding the decision rules of people using forests. While optimal foraging theory is normally applied to foraging for food, it also makes sense to apply it in the context of “foraging” for wood fuel. In this study, we applied a time allocation model of optimal foraging theory to wood gathering decisions in communities around Kakamega Forest, a mid-altitude seasonal tropical rain forest. The model predicts that the amount of wood gathered should increase with the distance to the wood source. We found that the predictions of OFT are supported, but only for adults and more strongly on a weekly scale. Based upon the results, we then discuss future improvements of the model to better understand and predict human use.

Hydrological niche segregation defines forest structure and drought tolerance strategies in a seasonal Amazon forest

AbstractThe relationship between rooting depth and above‐ground hydraulic traits can potentially define drought resistance strategies that are important in determining species distribution and coexistence in seasonal tropical forests, and understanding this is important for predicting the effects of future climate change in these ecosystems.We assessed the rooting depth of 12 dominant tree species (representingc. 42% of the forest basal area) in a seasonal Amazon forest using the stable isotope ratios (δ18O and δ2H) of water collected from tree xylem and soils from a range of depths. We took advantage of a major ENSO‐related drought in 2015/2016 that caused substantial evaporative isotope enrichment in the soil and revealed water use strategies of each species under extreme conditions. We measured the minimum dry season leaf water potential both in a normal year (2014; Ψnon‐ENSO) and in an extreme drought year (2015; ΨENSO). Furthermore, we measured xylem hydraulic traits that indicate water potential thresholds trees tolerate without risking hydraulic failure (P50and P88).We demonstrate that coexisting trees are largely segregated along a single hydrological niche axis defined by root depth differences, access to light and tolerance of low water potential. These differences in rooting depth were strongly related to tree size; diameter at breast height (DBH) explained 72% of the variation in the δ18Oxylem. Additionally, δ18Oxylemexplained 49% of the variation in P50and 70% of P88, with shallow‐rooted species more tolerant of low water potentials, while δ18O of xylem water explained 47% and 77% of the variation of minimum Ψnon‐ENSOand ΨENSO.We propose a new formulation to estimate an effective functional rooting depth, i.e. the likely soil depth from which roots can sustain water uptake for physiological functions, using DBH as predictor of root depth at this site. Based on these estimates, we conclude that rooting depth varies systematically across the most abundant families, genera and species at the Tapajós forest, and that understorey species in particular are limited to shallow rooting depths.Our results support the theory of hydrological niche segregation and its underlying trade‐off related to drought resistance, which also affect the dominance structure of trees in this seasonal eastern Amazon forest.Synthesis. Our results support the theory of hydrological niche segregation and demonstrate its underlying trade‐off related to drought resistance (access to deep water vs. tolerance of very low water potentials). We found that the single hydrological axis defining water use traits was strongly related to tree size, and infer that periodic extreme droughts influence community composition and the dominance structure of trees in this seasonal eastern Amazon forest.

Controlling hyperhydricity in micropropagated plants of Lippia grata Schauer (Verbenaceae), a native species of a dry seasonal tropical forest with pharmacological potential

The present study is to assess the morphophysiological development in vitro of Lippia grata Schauer, an endemic “Caatinga” species that shows pharmacological properties. Young cuttings containing nodal segments were divided into three explant types, namely E1 (apical bud), E2 (nodal segment below the apical bud) and E3 (nodal segment below E2); the explants were inoculated in MS medium supplemented with antioxidant compound (polyvinylpyrrolidone) or adsorbing agent (activated charcoal). The survival index, the occurrence of oxidation, contamination and the number of leaves and sprouts were assessed. The explants were cultivated in MS medium supplemented with polyethylene glycol 6000 (0, 0.5 and 1 g L−1) and closed with aluminum foil (total sealing) or with aluminum foil containing one hole (partial sealing), in the multiplication stage, due to hyperhydricity in vitro. Histological and biometric analyses were performed at the 45th cultivation day, as well as the analyses of antioxidative enzyme, and hydrogen peroxide and malondialdehyde levels. Normal leaves have presented greater organization and cellular development than hyperhydric leaves. The use of antioxidants was not efficient to control the oxidation of inoculated apical buds (E1), only. The lowest hyperhydricity rates in the multiplication stage were found in the partial sealing treatments; however, the total sealing of tubes, in combination with the PEG addition, has led to increased lipid peroxidation. In view of the results, it is concluded that the explant types, as well as the suitability of a functional gas exchange system in vitro, have favored the growth and development of cells and tissues, thus attenuating the hyperhydricity symptoms. In addition, this study demonstrates the suitability of the culture system through the facilitation of gas exchange allows the use of the protocol for in vitro propagation without compromising the leaf morphoanatomy.

Assessment of Plant Diversity of a Seasonal Tropical Wetland Forest Ecosystem in Bangladesh

The quantitative analysis of plant diversity was explored on a seasonal tropical wetland forest ecosystem at Ratargul Swamp Forest. The simple random sampling protocol was adopted, and 30 plots (10 m×10 m) each with one subplot (2 m×2 m) was investigated for the vegetation survey. The study found about 539 individuals of 48 species belonging to 36 families. Poaceae was the dominant among all family. The upper (trees with all size) and lower (shrubs, herbs, climbers, grasses) stratum was dominated by Pongamia pinnata and Clinogyne dicotoma, respectively. The taxonomic diversity was moderate in both lower and upper strata. The value of floristic quality index was calculated at 19.92, which represents moderate vegetative quality. The outcome also revealed the disturbances which influenced the plant community, mostly due to branch cutting by human (<30%). The findings will be useful for the conservation and scientific management of biodiversity as a hotspot in seasonal tropical wetland forest system.Keywords: Biodiversity, conservatism, disturbance, hotspot, wetland

Revisiting the hypothesis for increasing liana abundance in seasonal forests: a theoretical review

A decade ago, to address the question, “Why are lianas most abundant in seasonal tropical forests across the globe?”, the Mechanistic Explanation of Liana Global Abundance (MELGA) relied on the assumption that lianas have deeper roots than trees and are able to tap water from relatively deeper soil layers, giving them a competitive advantage during drought. We assess whether the assumption that lianas have deep roots is corroborated by the literature. We accessed the initial MELGA paper and evaluated all papers citing it. To date, we found that two papers tested the MELGA, and only one corroborated it. Deeper roots in lianas are not the single mechanism explaining liana success, due to limited empirical support. Instead, we propose that while liana success in seasonal forests may relate to deep roots for some species, it should not be viewed as the exclusive result of a single trait but as the possible result of multiple traits such as hydraulic redistribution, multifocal growing, drought resilience, higher water storage capacity, and acquisitive resource syndrome. Additional hypotheses should be evaluated along with predicted changes in plant community structure. These hypotheses should stimulate research on the mechanisms driving liana success in tropical forests.

Nitrogen fixer abundance has no effect on biomass recovery during tropical secondary forest succession

Abstract Nitrogen‐fixing trees (N2 fixers) provide new nitrogen critical for rapid biomass accumulation of tropical forests during early secondary succession, but it remains unclear how the abundance of N2 fixers in the forest community affects the growth of non‐fixers or the primary productivity of the whole forest. On the one hand, N2 fixers may enhance forest productivity by providing a facilitative effect through the provision of plant‐available nitrogen to non‐fixing trees. On the other hand, N2 fixers may suppress the growth of non‐fixers by growing faster and competing more vigorously for light and other resources. A third alternative is that the growth of N2 fixers themselves accumulate biomass rapidly, while having a neutral effect on non‐fixers, leading to an overall increase in forest biomass. We examine these alternative hypotheses using 5‐year tree census data from 88 plots in 44 seasonal tropical moist secondary forests (3–32 years old) across a human‐modified landscape in central Panama. We examined whether N2 fixers accumulated biomass more rapidly than non‐fixers, and how relative biomass of N2 fixers as a functional group and as individual species influenced the growth of non‐fixer and whole stand primary productivity. Surprisingly, we found no evidence for either a net competitive or a facilitative effect of N2 fixers as a functional group or individual species on the biomass recovery in these young forests. N2 fixers did not grow faster than non‐fixers. Individual mortality rates were lower among N2 fixers, but biomass losses due to mortality were similar between the two groups. Overall, we found no relationship between the relative abundance of N2 fixers and stand primary productivity during succession. Synthesis. Nitrogen‐fixing trees may be critical for reducing nitrogen limitation and accelerating biomass growth during tropical secondary forest succession, thereby impacting the global carbon cycle. However, our findings indicate that, in early successional seasonal tropical moist forests, nitrogen fixers provide neither a net competitive nor a facilitative effect on non‐fixing trees or the whole forest stand, likely because tropical nitrogen fixers utilize facultative fixation and hence abundance poorly approximates the ecosystem function of fixation. Our results indicate that models should not simply scale symbiotic fixation and its effects from nitrogen‐fixing tree abundance.

Fruit traits and temporal abundance shape plant-frugivore interaction networks in a seasonal tropical forest.

Interactions between fleshy fruited plants and frugivores are crucial for the structuring and functioning of biotic communities, particularly in tropical forests where both groups are diverse and play different roles in network organization. However, it remains poorly understood how different groups of frugivore species and fruit traits contribute to network structure. We recorded interactions among 28 plant species and three groups of frugivores (birds, bats, and non-flying mammals) in a seasonal forest in Mexico to determine which species contribute more to network structure and evaluate the importance of each species. We also determined whether fruit abundance, water content, morphology traits, and fruiting phenology are related to network parameters: the number of interactions, species contribution to nestedness, and species strength. We found that plants did not depend on a single group of frugivores, but rather on one species of each group: the bird Pitangus sulphuratus, the bat Sturnira parvidens, and the non-flying mammal Procyon lotor. The abundance, size, and water content of the fruits were significantly related to the contribution to nestedness, number of interactions, and species strength index of plant species. Tree species and birds contributed mainly to the nested structure of the network. We show that the structure of plant-frugivore networks in this seasonal forest is non-random and that fruit traits (i.e., abundance, phenology, size, and water content) are important factors shaping plant-frugivore networks. Identification of the key species and their traits that maintain the complex structure of species interactions is therefore fundamental for the integral conservation of tropical forests.

Persistence of Coffea arabica and its relationship with the structure, species diversity and composition of a secondary forest in Brazil.

Understanding the relationships between Coffea arabica L. and the native tree community of secondary forests regrowing after the abandonment of coffee plantations is important because, as a non-native species in the Neotropics, coffee can outcompete native species, reducing diversity and forests ecosystem services. We aimed to answer three questions: 1) Does coffee regeneration in secondary forests differ between shaded and unshaded abandoned plantations?; 2) How is coffee basal area related to structural attributes, species diversity and composition of the native community?; and 3) Do the relationships between coffee and native community differ between tree and sapling components? We sampled the tree and sapling components in a seasonal tropical dry forest that were previously used as shaded and unshaded coffee plantations. Coffee was the most important species in the sapling component of shaded systems, but was almost absent in unshaded ones. Coffee basal area was negatively related with the native density and absolute species richness of the sapling component; and was negatively related with tree density, and positively related with the percentage of pioneer individuals of the native tree component. Our results indicate that coffee persists in secondary forest communities even after more than 70 years of shaded-coffee plantations were abandoned, potentially reducing density and diversity of native species. Despite limitations, which hinder more general conclusions on coffee invasiveness in Brazilian secondary tropical forests, our results indicate that coffee is a strong competitor in the studied secondary forests and provide important insights for future research on this topic.

Direct seeding reduces costs, but it is not promising for restoring tropical seasonal forests

Direct seeding is a potential technique to restore forests; however, further studies are needed before its application on a large scale. We carried out a field experiment in a deforested area in southern Brazil to test the technical and economic feasibility of a direct seeding system with high tree species diversity to restore the tropical seasonal forest. We also compared species performances and tested the effects of seed size and successional group on tree seedling emergence and development. The trial was established at two different sowing times using 31 tree species. For two years after sowing we evaluated seedling emergence, establishment, survival and early growth of tree species, weed competition and costs for plantation establishment and early maintenance. Most species had low seedling emergence and establishment, but high survival rates, implying that low seedling emergence is the main barrier to community assembly that must be overcome. The most successful species had larger seeds, belonged to non-pioneer categories and had slower growth rates. Final costs after two years were lower than has been reported in the literature for most restoration planting using seedlings both in Brazil and elsewhere; however, seedling density was low. Although direct seeding may be a feasible alternative to decrease planting costs, the poor species performances and low seedling density may reduce its applicability. Thus, we recommend direct seeding only in association with the planting of pioneer species seedlings.

Assessments of preprocessing methods for Landsat time series images of mountainous forests in the tropics

ABSTRACTMonitoring forest changes based on numerous satellite images has been recently conducted in the tropics. Preparation of a time series of satellite images, sometimes referred to as preprocessing, is essential for conducting robust detection of forest change. To create consistent and stable conditions in satellite images, the best methods have to be used in each step to correct various sources of noise. This study assessed three atmospheric correction methods, six topographic correction methods, and eight gap-filling methods to produce the best possible time series of Landsat images of tropical seasonal forests. The results showed that the best methods for atmospheric and topographic correction were relative corrections using a Landsat Ecosystem Disturbance Adaptive Processing System (LEDAPS), which is based on a 6S radiative transfer model, and the C-correction, respectively. Weighted linear regression and multiple linear regression models were selected as the best models for the filling of data gaps associated with Scan Line Corrector-off and clouds, respectively. This study provided the best possible image preprocessing for trajectory-based change detection using annual Landsat images. Although the best possible preprocessing methods might vary depending on the change detection methods used in different study areas, the results highlight the preferable preprocessing methods, even for different types of time series analysis.

Composition and Diversity of Soil Fungi in Dipterocarpaceae-Dominated Seasonal Tropical Forests in Thailand.

Although fungi play essential roles in nutrient cycles and plant growth in forest ecosystems, limited information is currently available on the community compositions of soil fungi in tropical forests. Few studies have examined fungal community structures in seasonal tropical forests, in which forest fires potentially have a large impact on above- and belowground community processes. Based on high-throughput sequencing technologies, we herein examined the diversity and community structures of soil fungi in dry seasonal tropical forests in Sakaerat, northeast Thailand. We found that fungal community compositions diverged among dry evergreen, dry deciduous, and fire-protected dry deciduous forests within the region. Although tree species diversity did not positively correlate with soil fungal diversity, the coverage of an understory bamboo species (Vietnamosasa pusilla) showed a strong relationship with fungal community structures. Our community ecological analysis also yielded a list of fungi showing habitat preferences for either of the neighboring evergreen and deciduous forests in Sakaerat. The present results provide a basis for managing soil fungal communities and aboveground plant communities in seasonal tropical forests in Southeast Asia.

Effects of large aboveground biomass loss events on the deadwood and litter mass dynamics of seasonal tropical forests in Cambodia

Effects of large aboveground biomass loss events on the deadwood and litter mass dynamics of seasonal tropical forests in Cambodia

Shift in Abundance From Seedling to Juvenile Gives Lianas Advantage Over Trees: A Case Study in the Atlantic Forest Hotspot

The Atlantic Forest has been threatened by frequent human disturbances that affect its ecological processes. Lianas are an important component of tropical forest dynamics and, under chronic disturbance, may proliferate vigorously, potentially arresting secondary succession and hindering forest recovery. Our study aims to analyze abundance and diversity of liana and trees in different life stages in a disturbed semidecidual seasonal tropical forest fragment in southeast Brazil. We sampled the species richness and relative abundance in the following life stages of lianas and trees: I—seed (as seed arrival and seed bank processes), II—seedling, III—juvenile, and IV—adult. Lianas are more abundant than trees after the seedling stage, while trees showed more rarefied species richness only at the seed rain stage. Our results show that dispersal does not seem to be a bottleneck for either liana or tree community in disturbed fragments, but competition at the seedling stage may give lianas advantage over trees. Lianas may proliferate abundantly in forest fragments, even decades after disturbance. We recommend interventions for the management and restoration of disturbed forest fragments dominated by lianas to target this life form in life stages where they suppress the forest community, such as after the seedling stage.