Regeneration Of Tropical Dry Forest Research Articles

Diversity patterns along ecological succession in tropical dry forests: a multi‐taxonomic approach

Evaluating the diversity of multiple taxa is fundamental to understand community assembly and to assess the integrity and functionality of tropical secondary forests. In this study, we analyzed the natural regeneration of tropical dry forests (TDFs) in three regions of Brazil using Hill–Simpson diversity, abundance and β‐diversity of trees and five groups of insects (herbivores, fruit‐feeding butterflies, ants, culicid mosquitoes and dung beetles). Sampling was conducted in 39 0.1 ha plots using a chronosequence approach (13 plots in early, intermediate and old‐growth forests). We evaluated the contribution of three different levels to γ‐diversity: α (within plots), β1 (among plots) and β2 (among successional stages), and further determined the relative importance of turnover (species replacement) and nestedness (differences in species number among sites) to β2. Our results showed that, unexpectedly, the Hill–Simpson diversity was consistently higher in early than old‐growth stages for all regions, but varied more widely in the intermediate stages. For each group separately, the same trend was observed for butterflies, ants, dung beetles and herbivores and did not differ among stages for mosquitoes. Successional differences in abundance were only detected for trees (increasing along the gradient) and for mosquitoes (decreasing). According to our expectations, the additive partitioning analysis showed that β2‐diversity contributed more to γ‐diversity than β1‐diversity, when all taxa were considered together and for most of them separately (except for butterflies and dung beetles). Most of the β2‐diversity was due to species turnover, but this contribution varied among groups and regions, with the highest turnover for herbivores and the lowest for dung beetles. Our results suggest that the Hill–Simpson diversity and changes in species composition (as given by β2‐diversity) are better indicators of forest natural regeneration than raw species richness, corroborating previous studies with plants and animals.

Long‐term comparison of the orchid bee community in the tropical dry forest of Costa Rica

AbstractGlobal bee decline and its impact on pollination in agricultural and natural ecosystems have attracted public attention. However, more data are needed to show their generality and intensity in different ecosystems, especially in the tropics. For centuries, the tropical dry forest (TDF) of Costa Rica underwent intense deforestation, but in the last four decades, a large part of this forest has entered a recovery process. Using data of orchid bees generated by Janzen et al. (Ecology, 63, 66) in TDF in the Santa Rosa sector of the Guanacaste Conservation Area (ACG), we posed a general question: What changes have occurred in diversity, composition, and seasonality of the euglossine bee community in the TDF during the last 40 years and how are these changes related to the current recovery of this forest. We sampled euglossine bees during 2018–2019 using methods similar to those applied previously. To characterize the response of euglossine bees to habitat loss, we extended the sampling to pastures adjacent to the protected area. With the loss (n = 4) and gain (n = 3) of bee species, we did not find significant changes in overall species richness between now and 40 years ago. However, the composition of the euglossine community in the protected area in 1977 was more similar to that found in current pastures than to the current community in forests, where the presence of forest‐dependent species has been favored. It is possible that TDF regeneration in Santa Rosa has led to changes in the composition of the community of these bees.Abstract in Spanish is available with online material.

Woody species richness drives synergistic recovery of socio-ecological multifunctionality along early tropical dry forest regeneration

Secondary tropical forests offer critical ecosystem services such as regulation of climate, soil and water resources, which are frequently traded off against the provision of forest products for human use or repeated clearing for agriculture. While some evidence also suggests potential synergies between regulating and material contributions of regenerating forests to people, the ecological mechanisms of multiple synergies remain poorly understood. We assess tradeoffs and synergies by testing for cascading effects of tropical dry forest age and vegetation drivers on key ecosystem properties that underpin multiple regulating, material and non-material contributions to people. To do so we first compiled published evidence to propose a conceptual framework of the causal dependence among variables. Then, we tested which direct or indirect effects of this a priori conceptual model are supported by structural equation models of measured data from a chronosequence of secondary tropical dry forest plots. We tested whether individual density, taxonomic or functional diversity, community-weighted mean in wood specific gravity, or composition of the woody vegetation best explained synergies or tradeoffs among multiple key ecosystem properties. We show a synergistic, positive effect of observed woody species richness on all four key ecosystem properties, including total basal area, litter layer carbon stocks, soil penetration resistance and availability and versatility of socioeconomically useful plants. A similar synergistic effect of linear age-dependent changes in species composition suggests that the simultaneous recovery of multiple functions is not only driven by absolute woody species accrual, but also by temporal woody species turnover as secondary succession proceeds. However, local farmers reported uses of only a small fraction of available plant biodiversity that has previously been documented in the literature to be socioeconomically useful. In synthesis, we found that observed woody species richness and successional turnover along tropical dry forest regeneration are synergistic drivers of biodiversity, ecosystem functioning and the availability and versatility of currently underutilized plant products in Western Mexico. Such observed synergy between a range of key regulating, material and non-material contributions to people highlights untapped socioecological potential for multifunctional tropical forest restoration through sustainable use.

Ecosystem services supply and interactions along secondary tropical dry forests succession

Secondary forests will likely dominate future tropical landscapes, and the ecosystem services they provide to humanity will be particularly relevant. However, few empirical studies provide quantitative evidence of how the supply of ecosystem services change along secondary forest succession. The need for such information is particularly pressing for tropical dry forests because of their extensive global coverage and a high degree of disturbance. Here we examine the changes in the potential supply of ecosystem services and the interactions among them along secondary tropical dry forest succession for a site on the Mexican Pacific coast. Using data from a chronosequence of twelve sites followed over ten years, we characterized changes in five ecosystem services along a successional gradient from abandoned farmland to old-growth forests: forage, multiple forest resources, microclimate regulation, carbon storage and carbon sequestration. The long-term recovery trajectory for each service was modelled using linear and non-linear mixed models. Interactions among them were examined over different timeframes using Spearman correlations. The results showed rapid non-linear recovery of multiple forest resources provision, microclimate regulation and carbon storage within the first two decades of succession. Carbon sequestration increased slightly over time, while the supply of forage showed no clear trend. The strength of the interactions among pairs of services changed through successional time, being particularly higher in farmlands and old-growth forests. Our findings suggest that adaptive forest management practices that foster the natural regeneration of tropical dry forests are cost-effective mechanisms to recover the supply of critical ecosystem services for local actors by meeting their livelihood needs as well as those for the global community through climate change mitigation. Maintaining tropical dry forest resilience will highly depend on the maintenance of diversity in terms of species and ecosystem services.

Lepidoptera are Relevant Bioindicators of Passive Regeneration in Tropical Dry Forests

Most evaluations of passive regeneration/natural succession or restoration have dealt with tropical rain forest or temperate ecosystems. Very few studies have examined the regeneration of tropical dry forests (TDF), one of the most damaged ecosystem types in the world. Owing to their species diversity and abundance, insects have been widely used as bioindicators of restoration. Butterflies were among the most abundant and useful groups. We sampled four sites with different levels of anthropogenic disturbance in a Mexican TDF (Morelos State) and compared butterfly communities. A first goal was to examine whether adult butterflies were significant bioindicators owing to their specificity to restricted habitats. A second aim was to determine if differences exist in butterfly communities between some fields abandoned from 4–8, 8–15 and 15–30 years and a reference zone considered as primary forest. We found 40% to 50% of the species of butterflies were specifically related to a habitat and/or a level of anthropogenic disturbance. The time it takes for passive regeneration and recovery of the Mexican tropical dry forest is much higher than 25 years (our older zone), considering that almost none of the butterflies found in our conserved reference zone were present in our 25 year aged study zone.

Removal of cattle accelerates tropical dry forest succession in Northwestern Mexico

AbstractDomestic livestock influence patterns of secondary succession across forest ecosystems. However, the effects of cattle on the regeneration of tropical dry forests (TDF) in Mexico are poorly understood, largely because it is difficult to locate forests that are not grazed by cattle or other livestock. We describe changes in forest composition and structure along a successional chronosequence of TDF stands with and without cattle (chronic grazing or exclusion from grazing for ~ 8 year). Forest stands were grouped into five successional stages, ranging from recently abandoned to mature forest, for a total of 2.7 ha of the sampled area. The absence of cattle increased woody plant (tree and shrub) density and species richness, particularly in mid‐successional and mature forest stands. Species diversity and evenness were generally greater in sites where cattle were removed and cattle grazing in early successional stands reduced establishment and/or recruitment of new individuals and species. Removal of cattle from forest stands undergoing succession appears to facilitate a progressive and non‐linear change of forest structure and compositional attributes associated with rapid recovery, while cattle browsing acts as a chronic disturbance factor that compromises the resilience and structural and functional integrity of the TDF in northwestern Mexico. These results are important for the conservation, management, and restoration of Neotropical dry forests.

Topsoil for restoration: Resprouting of root fragments and germination of pioneers trigger tropical dry forest regeneration

Topsoil translocation has been effective for the restoration of plant communities, but until recently this method had not been used for tropical dry forest restoration. We tested different methods of topsoil deposition for restoring a dry forest on an abandoned limestone quarry. We also tested the effects of irrigation during the first dry season after topsoil deposition. The study was conducted in the Federal District of Brazil. A 2.1-ha area was cleared of vegetation, and the topsoil from that site was deposited on an exotic pasture field 1.4km away. First, a secondary forest was clear-cut, and the first 30cm of topsoil were removed and translocated. The soil was transported in dump trucks to the deposition site, which had been scarified in advance, and deposited by either forming 1.25-m-tall mounds or by leveling the soil into a 40-cm or 20-cm deep layer using a hydraulic excavator. The seed bank and the availability of root and stem fragments in the soil were both surveyed. The origin of the regenerants was categorized as either from seed or resprouting. We estimated vegetation cover for each life form, and measured all trees and lianas. After six months, 74% of the tree individuals and 60% of the liana individuals came from resprouting. Ruderal herbs and shrubs germinated from seeds. After 28 months, there were 51 species of trees, 8 species of lianas, 12 species of shrubs, and 34 species of herbs in the deposition treatments. The three deposition treatments were thickly covered with herbaceous/shrubby species, and had nine times the number of species (44 vs. 5) and five times the tree density (1.17 ind./m2vs. 0.25 ind./m2) as the non-deposition control. Tree survival was relatively high in both the non-irrigated and irrigated treatments. The total cost of topsoil translocation was 9604 USD, and the output was 0.43ha deposited/ha excavated when forming mounds of soil, 5951 USD and output of 0.75 when leveling to a 40-cm layer, and 3551 USD and 1.5 for a 20-cm layer of deposited material. However, deposition and transportation costs are fixed costs of establishing a new quarry that can be deducted from the total cost of restoration. Topsoil translocation was effective in kick-starting the succession process of a tropical dry forest.

PHYSIOGNOMY AND NATURAL REGENERATION OF DRY DECIDUOUS FORESTS AT SIGIRIYA, SRI LANKA

Although, poor natural regeneration of tropical dry forest has been observed in Sri Lanka.India. Africa and in Latin America. the factors affecting this have not been well studied.In this paper. the physiognomy of dry deciduous forests at Sigiriya in the northern dry zoneof Sri Lanka and some major factors which affect their natural regeneration wereestimated.The vegetation was enumerated in six 20x20m experimental plots. The diameter 01' trees25cm at breast height (dhh) was measured. Seed rain was detected hy collecting seedsusing wooden trays. allowing them to he germinated and enumerating the germinants overa period of eleven months. The seed bank was examined by collecting ten soil samplesfrom each plot three times within a year. Seedlings were recorded in 2x2m quadrates ineach plot and their growth and survival was recorded throughout an year. Soiltemperature, soil moisture and the canopy openness were also detected.The species composition and dominant species were identified for dry deciduous forest inthe arca. The beta diversity of forests is high implying the importance of conserving largeareas of dry forests. Seasonality of seed production. seed predation. lack of a persistentseed bank, unfavourahle environmental factors arc found to be affecting the regeneration ofdry deciduous forest. Possibilities of sustainable timber production in dry deciduous forestand the participation of local people in forest management arc also discussed.

Early Regeneration of Tropical Dry Forest from Abandoned Pastures: Contrasting Chronosequence and Dynamic Approaches

ABSTRACTOld field secondary succession of tropical dry forests (TDFs) is poorly understood, particularly regarding the dynamics of seedlings, saplings, and sprouts (regenerative communities). We used chronosequence and dynamic approaches to: (1) document successional trajectories of regenerative communities during the first dozen years of regeneration in abandoned pastures at Chamela, Mexico; (2) test the usefulness of chronosequences to predict the dynamics of regenerative communities along time; and (3) assess the influence of surrounding forest matrix, stand density, and understory light availability (in the rainy season) as driving factors of such dynamics. More than 1000 plants and 95 species of shrubs and trees 10–100 cm tall were monitored between 2004 and 2007 in nine abandoned pastures (0–12 yr since abandonment) and two old‐growth forest (OGF) sites; gain and loss rates of plants, species, and plant cover were obtained. Chronosequence predicted a rapid and asymptotic increase of plant density, species density, and plant cover toward the OGF values. Such prediction did not match with dynamic data that showed negative or neutral net community rates of change, independently of fallow age. Recruitment and species gain rates increased with the amount surrounding forest matrix. No other effect of the explored factors was detected. Strong rainfall shortenings could be responsible for the high loss and low gain rates of plants and species recorded in most sites. We highlight the critical role of supra‐annual rainfall variability on the dynamics of TDF regenerative communities and the poor predictive value of chronosequences in forest systems subjected to strong environmental temporal variation.Abstract in Spanish is available at http://www.blackwell‐synergy.com/loi/btp.

Ecology and regeneration of tropical dry forests in the Americas: Implications for management

Dry forests represent the most endangered ecosystem in tropical regions and continue to be one of the most sought after environments for human colonization, development and production. In spite of this, dry forests are one of the least well studied tropical habitats. This special issue is dedicated to reviewing much of the information that exists about tropical dry forest in the Americas. The introduction summarizes the articles presented herein, highlighting management strategies that are suggested throughout the special issue that may be useful for conserving tropical dry forest environments.

Critically Endangered Fijian Crested Iguana (Brachylophus vitiensis) Shows Habitat Preference for Globally Threatened Tropical Dry Forest

Tropical dry forests are a unique and threatened ecosystem in the Pacific and globally. In Fiji, the endangered Fijian crested iguana (Bracbylopbus vitiensis) is endemic to tropical dry forests. Yadua Taba Island contains one of the best remaining stands of tropical dry forest in the Pacific along with the largest (and only secure) population of B. vitiensis in Fiji and has been proposed as a translocation source for iguana conservation. In this study we determined the major vegetation types on Yadua Taba and identified forest habitat preferences of B. vitiensis to (1) characterize the island's habitats for tropical dry forest regeneration monitoring and (2) understand which forest types are preferred by iguanas for future translocation projects. Vegetation data were collected using reconnaissance, entitation, line transects, and aerial photos. Iguana abundance data were collected by nocturnal surveys of permanent transects. Six major vegetation types were identified of which tropical dry forest was the largest (46% of the island), followed by a combination of rocky cliff-shrubland/grassland vegetation (26%). Our conservative estimate of B. vitiensis population size on Yadua Taba is 12,000 iguanas, the majority of which occur in tropical dry forest. Superabundance of the dry forest understory tree Vavaea amicorum, the favorite fruit species of iguanas, may help account for the high density of iguanas observed. These results highlight the ecological link between tropical dry forest and B. vitiensis and emphasize the importance of rehabilitation or conservation of tropical dry forest habitat in potential iguana translocation sites as part of the management plan for B. vitiensis throughout the Fiji Islands.

Cronología de la regeneración del bosque tropical seco en Santa Rosa, Guanacaste, Costa Rica. I. Características edáficas

We characterized soil chemical and physical properties in eight tropical dry forest (TDF) successional sites along a time sequence (10, 15, 20, 40, 60 and >100 years) in Santa Rosa, Costa Rica. Seventeen soils were identified, described, and classified in six orders. Most soils were classified as Entisols and Vertisols, but Mollisols, Alfisols, Inceptisols and Ultisols were also present. All soils showed good fertility that did not constrain species richness. High edaphic variation seemed the result of complex interactions among the pyroclastic origin of Santa Rosa ignimbritic plateau (SRIP), the lithological composition and acidity of ignimbritic rocks, the strong seasonality in rainfall, intense hydric and aeolic erosion, topographic variations within the SRIP, and past human intervention. Correlations performed on soils classified as Entisols (<60 cm deep) showed a depletion of soil cations (Ca, Mg, K, Na and CEC) during the first 20 years of forest regeneration, that later recovered in mature TDF sites. Organic matter content did not change significantly along the TDF chrono-sequence. Substantial increments in macro-pores and soil hydraulic conductivity were observed, probably resulting from higher root biomass and turnover in older successional sites. Soil available water and meso-pore abundance were negatively correlated with TDF successional age. Our results indicate that edaphic changes observed along TDF regeneration might have been due to annual fires in pastures and young TDF sites, addition of decaying litter and fine roots as regeneration progressed, milder microclimate conditions during late regeneration in mature TDF sites, increased nutrient cycling, and the predominance of sandy loam textures among the soils examined. These changes in the soil environment with succession may have physiological and phenological consequences on the species appearing at different stages of TDF regeneration.

Patterns of Loss and Regeneration of Tropical Dry Forest in Madagascar: The Social Institutional Context

Loss of tropical forests and changes in land-use/land-cover are of growing concern worldwide. Although knowledge exists about the institutional context in which tropical forest loss is embedded, little is known about the role of social institutions in influencing regeneration of tropical forests. In the present study we used Landsat images from southern Madagascar from three different years (1984, 1993 and 2000) and covering 5500 km2, and made a time-series analysis of three distinct large-scale patterns: 1) loss of forest cover, 2) increased forest cover, and 3) stable forest cover. Institutional characteristics underlying these three patterns were analyzed, testing the hypothesis that forest cover change is a function of strength and enforcement of local social institutions. The results showed a minor decrease of 7% total forest cover in the study area during the whole period 1984–2000, but an overall net increase of 4% during the period 1993–2000. The highest loss of forest cover occurred in a low human population density area with long distances to markets, while a stable forest cover occurred in the area with highest population density and good market access. Analyses of institutions revealed that loss of forest cover occurred mainly in areas characterized by insecure property rights, while areas with well-defined property rights showed either regenerating or stable forest cover. The results thus corroborate our hypothesis. The large-scale spontaneous regeneration dominated by native endemic species appears to be a result of a combination of changes in precipitation, migration and decreased human population and livestock grazing pressure, but under conditions of maintained and well-defined property rights. Our study emphasizes the large capacity of a semi-arid system to spontaneously regenerate, triggered by decreased pressures, but where existing social institutions mitigate other drivers of deforestation and alternative land-use.

Tropical dry-forest regeneration from root suckers in Central Brazil

Seed dispersal, predation, desiccation and seedling survival are strong bottlenecks that impede tropical forest recovery on abandoned agricultural lands (reviewed in Holl 2002). The ability to resprout after disturbances overcomes these barriers, as those individuals bypass the seed stage and have more vigorous shoots than seedlings (Bond &amp; Midgley 2001, Kammesheidt 1999, Kennard et al. 2002). Resprouting is a particularly important recovery mechanism in tropical dry forests (reviewed in Vieira &amp; Scariot 2006). There are a number of reasons why resprouting may be more important in dry forests than in rain forests, including slower decay rates of trunk bases (Ewel 1980), or adaptation of plants to drought (Bond &amp; Midgley 2001, Sampaio et al. 1993).

Principles of Natural Regeneration of Tropical Dry Forests for Restoration

Abstract Tropical dry forests are the most threatened tropical terrestrial ecosystem. However, few studies have been conducted on the natural regeneration necessary to restore these forests. We reviewed the ecology of regeneration of tropical dry forests as a tool to restore disturbed lands. Dry forests are characterized by a relatively high number of tree species with small, dry, wind‐dispersed seeds. Over small scales, wind‐dispersed seeds are better able to colonize degraded areas than vertebrate‐dispersed plants. Small seeds and those with low water content are less susceptible to desiccation, which is a major barrier for establishment in open areas. Seeds are available in the soil in the early rainy season to maximize the time to grow. However, highly variable precipitation and frequent dry spells are important sources of mortality in seeds and seedlings. Collecting seeds at the end of the dry season and planting them when soil has sufficient moisture may increase seedling establishment and reduce the time they are exposed to seed predators. Germination and early establishment in the field are favored in shaded sites, which have milder environment and moister soil than open sites during low rainfall periods. Growth of established seedlings, however, is favored in open areas. Therefore, clipping plants around established seedlings may be a good management option to improve growth and survival. Although dry forests have species either resistant to fire or that benefit from it, frequent fires simplify community species composition. Resprouting ability is a noticeable mechanism of regeneration in dry forests and must be considered for restoration. The approach to dry‐forest restoration should be tailored to this ecosystem instead of merely following approaches developed for moister forests.

Research Priorities for Neotropical Dry Forests1

ABSTRACTOur understanding of the human and biophysical dimensions of tropical dry forest change and its cumulative effects is still in the early stages of academic discovery. The papers in this special section on Neotropical dry forests cover a wide range of sites and problems ranging from the use of multispectral and hyperspectral remote sensing platforms to the impact of hurricanes on tropical dry forest regeneration. Here, we present to the scientific community the results of a workshop on which research priorities for tropical dry forests were discussed. This discussion focuses on the need to develop linkages between remote sensing, ecological, and social science research. The incorporation of social sciences into ecological research could contribute dramatically to our understandings of tropical dry forests by providing important contextual information to ecologists, and by helping to develop an important science–policy–public nexus on which environmental management can succeed.

Effects of Nutrient Limitation on Aboveground Carbon Dynamics during Tropical Dry Forest Regeneration in Yucat�n, Mexico

Tree growth (as diameter increment), litterfall production, and litter biomass were studied in two secondary tropical dry forests of the Yucatan Peninsula under four treatments of nutrient addition. The study’s objective was to assess how variations in the nutrient supply affect aboveground net primary production and carbon (C) accumulation on the floor of two forests in different stages of regeneration. The study included an area of young forest (10 years old) with phosphorus (P)-poor soils and an area of old forest (around 60 years old) where soil P was comparatively less limiting. Four replicate plots (12 × 12 m) at each forest were either left intact (controls) or fertilized with nitrogen (N), P, or N plus P during 3 consecutive years. After 3 years of fertilization, relaxation of the constraints on nutrient limitation resulted in increased trunk growth rates at both the young and old forests. This effect was more pronounced with the addition of P or N plus P (trunk growth doubled with respect to controls), whereas N addition increased tree growth by 60% in comparison to trees in plots without nutrient supplements. In both forests, there were no significant differences in litterfall production among treatments during the first 2 years after fertilization. In the 3rd year of nutrient addition, litterfall production was significantly higher in plots fertilized with N plus P compared to control plots at both forest sites; however, changes in litterfall were not accompanied by litter accumulation in the floor of the two forests. The results of this study support the hypothesis that there is nutrient limitation during tropical dry forest regeneration. They further show that it may be maintained in the long term during secondary succession.

Distribution of three monkey species along a gradient of regenerating tropical dry forest

Only 2% of tropical dry forest in Central America remains undisturbed; consequently habitat regeneration is the best option to provide adequate areas of habitat for wildlife. This study examined the influence of a forest regeneration gradient (0–180 years since pasture abandonment) on the densities of white-faced capuchins ( Cebus capucinus), howling monkeys ( Alouatta palliata), and spider monkeys ( Ateles geoffroyi) in the tropical dry forest of Santa Rosa National Park, Costa Rica. Monkey densities and tree characteristics were sampled using 600 m transects within each of 14 sites from February to June 1996. Densities of all three monkey species were higher in older forests and in forests with greater food biomass estimates. The results indicate that monkey habitat, and consequently viable monkey populations, can be regained through protection and natural regeneration of tropical dry forest.

Regeneration of tropical dry forests in Central America, with examples from Nicaragua

. This paper focuses on the management potential of natural forests in the tropical dry zones of Central America, particularly Nicaragua. Distribution and status of dry forest formations are reviewed. Two case studies from the Pacific coast of Nicaragua are presented to illustrate the disturbance created by traditional utilization, and to show the relatively high potential for natural forest management, with many of the tree species having economic value. Natural forest management, together with conservation and reforestation, is viewed as the main management option for the tropical dry forest areas. In spite of its importance, this option has received little attention or promotion from the governmental forestry sector. Four complementary options which can be devised for silvicultural work in production forests are: encouragement of advanced growth of desirable tree species, inducement of natural regeneration, coppice management, and compensatory planting. These options form different strategies for rehabilitation of the production and conservation functions of the forest and may well be combined in the same area. Research applied to better utilization of the forest resources should form an intrinsic part of rural development programs. Research work in tropical dry forest areas should focus on ecological, as well as socio-cultural and economical aspects related to the management options. Experimental sites are important enabling and securing long-term basic and applied biological research. They may also serve as units for demonstration, training and extension.