Tropical Semi-evergreen Forest Research Articles

Tree Diversity and Ecosystem Carbon Stock Assessment in Nambor Wildlife Sanctuary, Assam

A study was carried out to assess tree diversity, forest carbon stock and carbon dioxide (CO2) sequestration in Nambor tropical semi-evergreen forest. A total of 53 tree species from 47 genera and 32 families were recorded in the forest. Vatica lanceifolia was the dominant tree species with maximum 33.78 importance value index (IVI), 0.30 Shannon diversity index (H′) and 0.03 Simpson’s index (D) followed by Lagerstroemia reginae (20.75 IVI, 0.18 H′ and 0.004 D), Dysoxylum excelsum (17.70 IVI, 0.20 H′ and 0.006 D), Sterculia villosa (14.15 IVI, 0.09 H′ and 0.0007 D) and Toona ciliata (11.60 IVI, 0.07 H′ and 0.0004 D) as codominant species. Among the forest carbon pools, maximum 50.32% carbon was stored in soil followed by 39.42% in above ground biomass and 10.21, 0.03 and 0.02% in below ground, leaf litter and dead debris pools, respectively. Total ecosystem carbon stock in Nambor forest was estimated to be 244.78 Mg ha−1. The estimated carbon stock was extrapolated over 3700 hectare area and found to be 905186.50 Mg. The total forest carbon stock was also converted into CO2 equivalents and estimated as 3,322,034.46 Mg. The study observed that forest ecosystem offsets significant amount of atmospheric CO2; therefore, conservation and management of forest resources are imperative to combat global climate change.

Fine root growth and soil nutrient dynamics during shifting cultivation in tropical semi-evergreen forests of northeast India

Fine root growth and soil nutrient dynamics during shifting cultivation in tropical semi-evergreen forests of northeast India

Tree stem bases are sources of CH4 and N2 O in a tropical forest on upland soil during the dry to wet season transition.

Tropical forests on upland soils are assumed to be a methane (CH4 ) sink and a weak source of nitrous oxide (N2 O), but studies of wetland forests have demonstrated that tree stems can be a substantial source of CH4 , and recent evidence from temperate woodlands suggests that tree stems can also emit N2 O. Here, we measured CH4 and N2 O fluxes from the soil and from tree stems in a semi-evergreen tropical forest on upland soil. To examine the influence of seasonality, soil abiotic conditions and substrate availability (litter inputs) on trace greenhouse gas (GHG) fluxes, we conducted our study during the transition from the dry to the wet season in a long-term litter manipulation experiment in Panama, Central America. Trace GHG fluxes were measured from individual stem bases of two common tree species and from soils beneath the same trees. Soil CH4 fluxes varied from uptake in the dry season to minor emissions in the wet season. Soil N2 O fluxes were negligible during the dry season but increased markedly after the start of the wet season. By contrast, tree stem bases emitted CH4 and N2 O throughout the study. Although we observed no clear effect of litter manipulation on trace GHG fluxes, tree species and litter treatments interacted to influence CH4 fluxes from stems and N2 O fluxes from stems and soil, indicating complex relationships between tree species traits and decomposition processes that can influence trace GHG dynamics. Collectively, our results show that tropical trees can act as conduits for trace GHGs that most likely originate from deeper soil horizons, even when they are growing on upland soils. Coupled with the finding that the soils may be a weaker sink for CH4 than previously thought, our research highlights the need to reappraise trace gas budgets in tropical forests.

Spatial Distribution, Population Structure and Neighbour Relation of Trewia nudiflora within Forested Vegetation of North-Eastern U.P., India

Trewia nudiflora Linn. (Euphorbiaceae) is a soft wooded, fast growing multipurpose dioecious tree which grows within the moist semi-evergreen tropical forests of north-eastern Uttar Pradesh. Its spatial distribution, population structure and neighbour relation were examined within eight plots located at six different sites differing in the light regimes and soil moisture status. Loose sub-populations of male and female trees were recognized at all the sites and the distance between any two female sub-populations was greater than that between two male sub-populations. The mean inter-sub-population distance for same sex and for opposite sex was lesser in shaded and high moisture environment. The number of male trees per sub-population was greater under open environment with average soil moisture while that of female sub-populations was greater under high moisture environment. Further, the inter-tree distances for any two adjacent female trees was significantly greater than for the two adjacent male trees. Further, female individuals generally occurred in highly moist soil of low bulk density while male individuals occurred more on relatively lesser moist soil of higher bulk density. As regards to the population structure, the proportional share of seedlings and saplings was quite high under exposed and high soil moisture conditions. The proportional share of young as well as mature trees of T. nudiflora was always higher in open as compared to shaded condition and the number of mature trees showed gradual decrease with decreasing light intensity. Further, the sites having better light and moisture regimes showed greater proportion of females and juveniles. The neighbourhood analysis showed that the density of neighbouring species of all the three life forms-herbs, undershrubs and shrubs was generally greater within the neighbourhood zone of target male trees than that for the target female trees of Trewia under all the light regimes. More than 60 species occurred within the neighbourhood zone of T. nudiflora, which shows quite stable population and niche occupancy to cope up with the prevailing forest environment of the region.

Trends in leaf traits, litter dynamics and associated nutrient cycling along a secondary successional chronosequence of semi-evergreen tropical forest in South-Eastern Mexico

Abstract: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.

Can the use of medicinal plants motivate forest conservation in the humid mountains of Northern Oaxaca, Mexico?

Background. Non-timber forest products are being integrated into conservation strategies. Medicinal plants are considered a reason to conserve the source forests.Question. Can the use of medicinal plants motivate forest conservation?Study site and dates. The study was conducted in Santiago Camotlán, Distrito Villa Alta, Oaxaca, a humid mountainous area in the Sierra Norte of Oaxaca, Mexico, from August 2011 to May 2013.Methods. Ecological Land Units were characterized, and the relative importance of medicinal plants was evaluated. The ethnobotanical methods included participatory mapping, open interviews, semi-structured interviews and free lists with local specialists, as well as members of 17 systematically selected households, collection of characteristic and medicinal plant species, and plant walks with local specialists. For each species, a newly proposed Knowledge, Use and Perception Index based frequency of mention in free lists, frequency of use and perceived importance was calculated.Results. Local people divided their territory primarily by physical geographic characteristics and utilization. Nine units were distinguished: village and roads, home gardens, pastures, cultivated fields (maize, beans, sugar cane and coffee), cloud forest, semi-evergreen tropical forest and evergreen tropical forest, secondary growth ( acahuales ), and riparian vegetation. The most important medicinal plants were Salvia microphylla , Lippia alba and Artemisia absinthium , all cultivated in home gardens; weedy vegetation provided the majority of all medicinal plants. Individuals interested in preserving medicinal species transplanted them into a home garden.Conclusion. For people in the study area, the presence and use of medicinal plants was not a decisive reason for forest conservation.

Native tree species diversity of Rampahar Natural Forest Reserve in Rangamati South Forest Division, Bangladesh

Tropical forests of Bangladesh are facing rapid loss in floristic diversity and resultant changes of vegetation necessitates the assessment of plant composition and diversity. The present study was conducted to assess the composition of native tree species of Rampahar Forest Reserve of Rangamati hill district, Bangladesh. Rampahar is a remnant tropical semi-evergreen natural forest extending to an area of 648 ha. Simple random sampling method with 20 m × 20 m sized 20 and 5 m × 5 m sized 10 samples plots were used to study both tree species composition and seedling status of tree species. A total of 50 tree species under 28 families and 15 regenerating tree species under 13 families were recorded in the study area. Family Moraceae possessed the highest number of tree species (6 species) while families Anacardiaceae and Sterculiaceae possessed the highest number (2 species) for regenerating tree species. The survey indicated that Protium serratum (Wall. ex Colebr.) Engl. is the most dominant tree species with the highest relative density (RD), relative frequency (RF) and importance value index (IVI). Basal area of all the tree species was 13.13 m 2 /ha where Ficus religiosa was represented by the highest basal area (1.14 m 2 /ha). Protium serratum was also a dominant regenerating tree species with highest RD (15.24%), RF (16.30%) and IVI (50.09). The native trees species of this remnant forest need attention for immediate conservation

Diversidad y carbono almacenado en el área forestal permanente de Álvaro Obregón, Calakmul, Campeche

El Área Forestal Permanente (AFP) del ejido Álvaro Obregón en Calakmul resguarda selvas subperennifolias que han estado expuestas al manejo forestal. Dada su importancia como reservorios de carbono y biodiversidad, el objetivo de este estudio fue analizar la diversidad arbórea, la acumulación de biomasa y la captura de carbono en diferentes comunidades de dicho tipo de vegetación (selva mediana – SMSP y selva inundable - SI) presentes en el AFP, las cuales están en periodo de recuperación desde hace más de 20 años. El trabajo se realizó en parcelas circulares de 1 000 m2, en donde se etiquetaron, midieron (altura y diámetro a la altura de 1.30 m), e identificaron los taxa arbóreos presentes. En las SMSP se determinó una riqueza de 90 especies, con densidades de 5 170 y 3 720 ind ha-1, con una diversidad (H) intermedia (2.8 a 2.65). En las SI se identificaron 75 especies, con una densidad (5 920 a 8 630 ind ha-1), y una diversidad (H) alta (3.02 a 3.06). La diversidad estructural promedio (Hsdh) fue baja para SMSP y SI, con valores de carbono de 16.6 a 37.17 Mg C ha-1, en SMSP; y 36.44 a 44.58 en SI. Se concluye que las selvas subperennifolias analizadas están en recuperación, con procesos de regeneración y captura de carbono importantes para la conservación de la diversidad.

Distribution and Abundance of Big-Leaf Mahogany (Swietenia macrophylla) on the Yucatan Peninsula, Mexico

Big-leaf mahogany ( Swietenia macrophylla King) is an economically important timber species in the Neotropics. For over three centuries, it has been selectively extracted from tropical forests, threatening its populations. We investigate the actual and potential distribution of big-leaf mahogany and assess its abundance on the Yucatan Peninsula based on the National Forest and Soils Inventory database. Furthermore, we evaluate environmental factors associated with its distribution, abundance, and tree size. The actual and potential distribution models show the presence of mahogany in a wide geographic area covering the southern and eastern portions of the Yucatan Peninsula. Abundance of mahogany in the landscape varies and in general is low. The spatial potential distribution model was best explained by the environmental variables of vegetation cover (medium- and high-stature semievergreen tropical forest) and elevation (upland areas). Results also indicate that mahogany remains relatively abundant and contain larger size classes in localities where the species has been harvested and managed for decades under community forest management. Furthermore, statistical analyses show greater tree density of mahogany mostly associated with low-stature semievergreen tropical forest having deep soils (gleysols and vertisols), while larger tree size (diameter at breast height) was associated with medium-stature semievergreen tropical forests in upland areas with moderately deep or shallow soils (mostly rendzinas or leptosols). Despite deforestation, land-use change and forestry activities on the Yucatan Peninsula, particularly in the past 20 years, the distribution and abundance of mahogany do not appear to be as drastically reduced as described in other neotropical regions.

Results of Study on Vegetation Diversity at Muong Nhe Nature Reserve, Dien Bien Province

The vegetation at Muong Nhe nature reserve has been described in 5 types: Tropical evergreen moist monsoon closed forest (only secondary sub-types formed by human activities including tropical evergreen moist monsoon secondary forests after selected logging, tropical evergreen moist monsoon secondary forests formed on abandoned upland fields, tropical evergreen secondary scrubs and grasslands); Tropical semi-evergreen semi-dry monsoon closed forest (only secondary sub-type formed by human activities); Sub-tropical evergreen moist monsoon closed forest (including secondary sub-types formed by human activities including sub-tropical evergreen moist monsoon secondary forest and sub-tropical evergreen secondary scrubs); Sub-tropical evergreen moist monsoon broad-leaved mixed with conifers forest; Sub-tropical semi-dry monsoon deciduous forest (only secondary sub-types formed by human activities including sub-tropical semi-dry monsoon deciduous secondary forest after selected logging, sub-tropical semi-dry monsoon deciduous secondary forest formed on abandoned upland fields, sub-tropical semi-dry secondary scrubs and grasslands) and cultivated communities. The results showed that closed forest is located at sub-tropical zone only. Based on species existed in each forest sub-type or community, the abundant species in tropical zone are fast-growing and photophilic plants while the abundant species in sub-tropical zone include both fast-growing plants and typical sub-tropical plants with monsoon moi climate or monsoon semi-dry climate. In the winter, tropical semi-evergreen forest and sub-tropical deciduous forest forms to North-Western regionalism. The non fast-growing and photophilic species are expected to be most abundant in the future based on currently vegetation succession indication, and there will be more and more closed forests in the near future at Muong Nhe nature reserve.

Genetic diversity and structure of the treeManilkara zapotain a naturally fragmented tropical forest

Abstract:Forest fragmentation, habitat loss and isolation may have a strong effect on biodiversity in tropical forests. This can include modification of the genetic diversity and structure of plant populations. In this study, we assessed the genetic diversity and structure of the treeManilkara zapotain 15 naturally formed fragments of semi-evergreen tropical forest, as well as in an adjacent continuous forest for comparison. Forest fragments were scattered within a matrix of wetlands and were highly variable in terms of size and degree of isolation. The naturally fragmented populations ofM.zapotahad slightly less allelic diversity (Ar: 3.4) than those of the continuous forest (Ar: 3.6), when corrected for sample size. However, populations in the fragments and continuous forest had very similar heterozygosity levels (HE: 0.59 in both cases). Low levels of genetic differentiation were observed among populations (FST: 0.026) and genetic structure was not consistent with isolation by distance, indicating high levels of gene flow. Genetic diversity was not explained by fragment size or degree of isolation. The relatively high genetic diversity and low inter-population genetic differentiation observed inM. zapotamay be the result of long-distance pollen and seed dispersal, as well as the high proximity among patches.

Estructura y composición arbórea de tres estadios sucesionales de selva mediana subperennifolia del municipio de Huautla, Hidalgo, México

Information on the taxonomic composition and conservation status of the semi-evergreen tropical forest in the state of Hidalgo is limited and descriptive, and disturbances caused by human activities are drastically affecting its structure and original physiognomy. For these reasons, the objectives of this study were: 1) to conduct an inventory of the tree flora, and 2) to provide quantitative data on the structure of the different semi-evergreen tropical forest successional stages. The floristic inventory and structural characterization were conducted in 9 localities of Huautla municipality, in the “Huasteca hidalguense”. In each locality, the basal area, frequency, density of individuals (normal diameter > 10cm) and relative importance value of each species were calculated. A total of 92 species, 76 genera and 31 families of trees were identified. The families Fabaceae, Malvaceae and Moraceae were the most representative for their species richness. The species with highest relative importance value were Adelia barbinervis and Cedrela odorata in early stages of succession, Bursera simaruba and Guazuma ulmifolia in intermediate stages and Brosimum alicastrum in mature stages. In few localities, mature vegetation was observed, and total tree species richness was comparable with that recorded in the same type of vegetation in other entities of Mexico.

Influence of functional traits on the demographic rates of 47 arboreal species in a tropical forest in northeastern Brazil

Influence of functional traits on the demographic rates of 47 arboreal species in a tropical forest in northeastern Brazil. Based on the premise that species use different strategies for acquiring and maintaining resources, it is possible to identify their similarities as determined by particular trade-offs between traits, the present work examined the specific leaf area (SLA), basic wood density (BWD), maximum height (Hmax) and seed shape (SS) of 47 arboreal species in a moist semi-evergreen tropical forest in northeastern Brazil and investigated the influence of those traits on plant mortality rates (MR) and growth (BAG). BWD and Hmax were the best predictors of mortality rates. The factorial analysis explained 70.4% of the total variability, distributed among three factors composed of traits and rates. MR and Hmax were found to be more readily observed when orthogonally rotated by the varimax method, with the first factor explaining 26.9% of the variance. Cluster analyses and principal component analyses, whose matrices contained the variables MR, BAG, SLA, and Hmax for each species, confirmed the discriminant analysis and allowed the identification of four functional groups. The fact that some of the correlations encountered differed from previously published results (such as the negative relationship between maximum height and mortality) may reflect regional climatic seasonality or indicate that this strategy benefits plant species that reach the upper canopy and thus become well-established.

Estructura y composición florística de la selva mediana subperennifolia en Bethania, Campeche, México

We characterized the vegetation structure and the floristic composition of the semi evergreen tropical forest in the locality of Bethania, Campeche, Mexico. We marked ten 10 m x 10 m (1 000 m2) plots, where all individuals with a diameter at breast height (DBH) of ≥ 2 cm were measured. The structural analysis of the vegetation is based on the species importance values (IV). We found 490 woody individuals belonging to 34 species, grouped into 33 genera and 23 families. The Fabaceae was the plant family with more species (7). Terminalia buceras was the species with the highest relative dominance, followed by Metopium brownei , Coccoloba barbadensis and Zygia sp . These four species accounted for almost half (43.5%) of the relative importance value. Our results indicate that the medium semievergreen forest is characterized by floristic elements subtect to flooding. The number of woody individuals is concentrated in three families ( Fabaceae, Ochnaceae and Polygonaceae ). Finally, Bravaisia berlandieriana form a competitive hierarchy in the shrub layer that colonizes clearings of semi evergreen tropical forest of the locality of Bethania.

Plant Community Structure of Tropical Semi-Evergreen Forest of Reiek in Mamit District of Mizoram

Ecological study of tropical semi-evergreen forest of Reiek in Mizoram was carried out to determine the stratification of the forest as well as to prepare life form spectrum of the plant communities. Mizoram is a part of Indo- Myanmar region which falls under one of the 35 biodiversity hotspots identified worldwide and therefore has a rich biodiversity. A detailed floristic survey was carried out. Plant species were collected, mounted in herbarium sheets and identified. Structural analysis was carried out and profile diagram was drawn. The forest was found to be composed of three layers in both the disturbed and undisturbed areas of the forest. The life form spectrum has been compared with Raunkiers normal spectrum to find out the phytoclimate of the region. The study area was found to have an abundance of phanerophytes indicating a phanerophytic climate

Changes in soil carbon and nutrients following 6 years of litter removal and addition in a tropical semi-evergreen rain forest

Abstract. Increasing atmospheric CO2 and temperature may increase forest productivity, including litterfall, but the consequences for soil organic matter remain poorly understood. To address this, we measured soil carbon and nutrient concentrations at nine depths to 2 m after 6 years of continuous litter removal and litter addition in a semi-evergreen rain forest in Panama. Soils in litter addition plots, compared to litter removal plots, had higher pH and contained greater concentrations of KCl-extractable nitrate (both to 30 cm); Mehlich-III extractable phosphorus and total carbon (both to 20 cm); total nitrogen (to 15 cm); Mehlich-III calcium (to 10 cm); and Mehlich-III magnesium and lower bulk density (both to 5 cm). In contrast, litter manipulation did not affect ammonium, manganese, potassium or zinc, and soils deeper than 30 cm did not differ for any nutrient. Comparison with previous analyses in the experiment indicates that the effect of litter manipulation on nutrient concentrations and the depth to which the effects are significant are increasing with time. To allow for changes in bulk density in calculation of changes in carbon stocks, we standardized total carbon and nitrogen on the basis of a constant mineral mass. For 200 kg m−2 of mineral soil (approximately the upper 20 cm of the profile) about 0.5 kg C m−2 was “missing” from the litter removal plots, with a similar amount accumulated in the litter addition plots. There was an additional 0.4 kg C m−2 extra in the litter standing crop of the litter addition plots compared to the control. This increase in carbon in surface soil and the litter standing crop can be interpreted as a potential partial mitigation of the effects of increasing CO2 concentrations in the atmosphere.

Investigation of phytosociological parameters and physico-chemical properties of soil in tropical semi-evergreen forests of Eastern Himalaya

The study of floral diversity in forest and its development are incomplete without taking consideration of plant-soil interactions. So with this view in mind, the present study was conducted in tropical semi-evergreen forests of the Mokukchung district, Nagaland, in eastern Himalaya. The aim of the study was to investigate the phytosociological parameters in relation to soil properties. Seven sites were randomly selected to study the soil properties at up to one meter in depth and a phytosociological study was carried out in nearby areas via the quadrate method. In the studied sites, the richness of tree species varied from 4 to 15 ha−1, with Gmelina arborea and Duabanga grandifloras being the common species. The highest total basal area was recorded in 10 mile village (47,998.16 cm2 ha−1) followed by Minkong village site (32,704.66 cm2 ha−1). Soil physical and chemical properties—i.e. bulk density (BD), soil pH, organic carbon (OC), available nitrogen (N), available phosphorus (P), and available potassium (K) were analyzed using standard procedures. Significant differences were observed in the soil properties. The basal area of species showed significant positive correlation in terms of available K (0.754) and OM (0.302) content in soil, and the Shannon–Wiener diversity index (H) is also positively correlated with the available N content (0.402). The undisturbed nature of the sites played an important role in maintaining the soil fertility and floral diversity of the sites. Moreover, sites with maximum productivity and soil fertility are considered as potential carbon sequestration areas in the region while sites with the low soil fertility need restoration.

Zonas ecológicas de Brosimum alicastrum Sw. en la costa del Pacífico mexicano

Se llevó a cabo una revisión de información biofísica existente sobre Brosimum alicastrum Sw. en la costa del Pacífico mexicano, con la finalidad de identificar y caracterizar zonas, de acuerdo con sus principales atributos ecológicos, así como relacionar algunas variables ambientales con la densidad y área basal de esta especie arbórea. Se determinaron 22 zonas ecológicas dentro de cinco tipos de vegetación y fue en la selva mediana subperennifolia donde Brosimum alicastrum presentó su mayor abundancia y desarrollo. La precipitación, altitud y capacidad de almacenamiento de agua en el suelo fueron las variables que mejor explicaron la variación ecológica de la especie en su área de distribución.

Effects of patch size, disturbances on diversity and structural traits of tropical semi-evergreen forest in the lowland Indo Burma hotspot: implication on conservation of the threatened tree species

Information on geographic distribution, population and threat status of most globally red listed species in the Indo Burma zone are inadequate. Given the increase in the prevalence of isolated forest patches in the part of this hotspot, evaluation is necessary on how size of the remnant forest patches and on-going disturbances affects structure and diversity of remaining habitats including the population of some globally threatened tree species. Quantitative vegetation inventory by 500 m long and 10 m wide (0.5 ha) line transects were randomly set in nine fragmented tropical semi-evergreen forest patches in Tripura, Northeast India. The studied forests patches grouped into small, medium and large based on their respected sizes. Spatial variability was analysed in woody species diversity and structure along the patch size gradients and their response to both patch size and anthropogenic disturbances. Out of 167 species, 13 identified as red-listed species by IUCN under the present inventory. Most of the diversity and structural parameters showed statistically significant positive response with the forest patch size, except for stand dominance, disturbance, sapling density and number of aggregated distribution pattern decreased when patch size increased. In addition, most of the diversity and structural attributes showed negative response with disturbances. Present baseline data would serve as an effective tool for management and protection of this important forest type. Future habitat restoration programme and strategies for relocation of additional population and re-introduction of those globally threatened trees are recommended.

A Novel Ant Species of the Genus <I>Anochetus</I> (Hymenoptera:Formicidae) from India with a Remarkable Nest Entrance Architecture

A novel ant species, Anochetus daedalus , is described based on worker caste collected from a nest in secondary tropical semi-evergreen forest from Sirsi, Karnataka, India, part of the Western Ghats biodiversity hotspot. It is very similar to Anochetus nietneri Roger, but is distinctly different in shape of the petiole. The species is notable for constructing elaborate nest entrance which resembles 'fort nests' constructed by some Pheidole spp.