Species diversity, regeneration and dominance as influenced by canopy gaps and their characteristics in tropical evergreen forests of Western Ghats, India

Canopy gaps play a significant role in maintaining structure and composition of tropical forests. This study was carried out in tropical evergreen forests of central Western Ghats in India to understand the influence of canopy gap size and the relationship of gap regime attributes to diversity measures and regeneration. The average gap size in the study area was found to be 396 m2 and around half of gaps were 4–8 years old. Gaps created by natural single tree fall were smaller in size but significantly higher in number. Diversity and regeneration of woody species were compared with canopy gaps and intact vegetation. Species richness and diversity was higher in gaps than in intact vegetation. Macaranga peltata, a shade intolerant species dominated gaps while intact vegetation was dominated by shade tolerant Kingiodendron pinnatum.Gap size significantly influenced species diversity and regeneration. Gap area and age were significantly and negatively correlated with diversity measures but positively correlated with regeneration. Among all the attributes of gaps, regeneration was significantly positively correlated with light intensity. Gaps maintained species diversity and favored regeneration of woody species. In addition to gap size and age, other gap ecological attributes also affected species diversity and regeneration.

Comparison of stem taper models for the four tropical tree species in Mount Makiling, Philippines

This study was conducted to evaluate the performance of six stem taper models on four tropical tree species, namely Celtis luzonica(Magabuyo),Diplodiscus paniculatus(Balobo), Parashorea malaanonan(Bagtikan), and Swietenia macrophylla(Mahogany) in Mount Makiling Forest Reserve(MMFR), Philippines using fit statistics and lack-of-fit statistics. Four statistical criteria were used in this study, including the standard error of estimate(SEE),coefficient of determination(R^2), mean bias( E),and absolute mean difference(AMD). For the lack-offit statistics, SEE, E and AMD were determined in different relative height classes. The results indicated that the Kozak02 stem taper model offered the best fit for the four tropical species in most statistics. The Kozak02 model also consistently provided the best performance in the lack-of-fit statistics with the best SEE, E and AMD in most of the relative height classes. These stem taper equations could help forest managers and researchers better estimate the diameter of the outside bark with any given height,merchantable stem volumes and total stem volumes of standing trees belonging to the four species of thetropical forest in MMFR.

Demographic variation and habitat specialization of tree species in a diverse tropical forest of Cameroon

Background： Many tree species in tropical forests have distributions tracking local ridge-slope-valley topography. Previous work in a 50-ha plot in Korup National Park, Cameroon, demonstrated that 272 species, or 63% of those tested, were significantly associated with topography. Methods： We used two censuses of 329,000 trees ≥1 cm dbh to examine demographic variation at this site that would account for those observed habitat preferences. We tested two predictions. First, within a given topographic habitat, species specializing on that habitat （＇residents＇） should outperform species that are specialists of other habitats （＇foreigners＇）. Second, across different topographic habitats, species should perform best in the habitat on which they specialize （＇home＇） compared to other habitats （＇away＇）. Species＇ performance was estimated using growth and mortality rates. Results： In hierarchical models with species identity as a random effect, we found no evidence of a demographic advantage to resident species. Indeed, growth rates were most often higher for foreign species. Similarly, comparisons of species on their home vs. away habitats revealed no sign of a performance advantage on the home habitat. Conclusions＂ We reject the hypothesis that species distributions along a ridge-valley catena at Korup are caused by species differences in trees _〉1 cm dbh. Since there must be a demographic cause for habitat specialization, we offer three alternatives. First, the demographic advantage specialists have at home occurs at the reproductive or seedling stage, in sizes smaller than we census in the forest plot. Second, species may have higher performance on their preferred habitat when density is low, but when population builds up, there are negative density-dependent feedbacks that reduce performance. Third, demographic filtering may be produced by extreme environmental conditions that we did not observe during the census interval.

Genetic Variation in Tropical Tree Species and Plantations: A Review

The global efforts to restore tropical forests and their productive and ecological functions through plantation forestry largely depend on the available genetic variation in the tree species used to establish the plantations. However, there is limited information on the levels and trends of the genetic variation and variability of different plantation tree species in the tropics. Therefore, this study reviews several marker-based studies that have investigated genetic variation. Most of the top economic species like Eucalyptus tereticornis and Mansonia altissima are attributed to low levels of genetic diversity, while others like Pinus caribaea and Swietenia macrophylla still exhibit high expected heterozygosity across different populations. However, the levels of genetic diversity assessed may depend on the markers used. Microsatellites, i.e., simple sequence repeats (SSRs), mostly give higher estimates when compared to other polymerase chain reaction-based markers. Other factors that typically contribute to the directional pattern of genetic variation in tropical tree species and populations include their distribution, density, seed dispersal, succession, and reproduction. Also, anthropogenic impacts like logging and fragmentation have contributed to the vast genetic base reduction of many tropical species and populations. Having adequate genetic variation within the plantation populations is significant in improving their fitness, resilience, fecundity, productivity, and other ecological functions. It also provides a basis for tree improvement and breeding in plantation forests. Although clonal forestry is becoming widespread and considered highly productive, it is attributed to specific economic, technical, and ecological risks, such as the increased spread of pests and diseases. Therefore, further discussions and recommendations to maximise genetic diversity in tropical (clonal) plantations are provided.

Composition, diversity and distribution of tree species in response to changing soil properties with increasing distance from water source – a case study of Gobind Sagar Reservoir in India

Construction of big dams on rivers develops artificial lakes or water reservoirs which conceive alterations in soil properties of the upstream catchment area. An undulating topography and freckly soil properties cause ups and downs in tree diversity, composition and distribution. The study aimed to evaluate the effect of Gobind Sagar reservoir on soil properties relative to the distance from it and assess its effect on tree diversity, evenness and their distribution in tropical and subtropical forests. Based on data analysis it was found that the soil moisture and organic carbon decreased along with increasing distance from the reservoir. It played a significant role in varying tree diversity. The sites distributed within0-2 km showed significantly higher α and β-diversity indices. Tree species richness and diversity indices showed a strong correlation（p ＆lt; 0.05） with soil moisture and organic carbon content. Simpson＇s and Mc Intosh evenness indices showed a strong negative correlation with soil bulk density. Indirect Detrended Correspondence Analysis（DCA） identified soil moisture and soil organic carbon as two major environmental gradients that influenced tree diversity and their distribution in five tropical and four subtropical forests in an upstream catchment of the reservoir. Mixed forests inhabited moist sites andAcacia-Pinus forests showed an inclination to dry areas. Canonical Correspondence Analysis（CCA）revealed that the tree species in tropical forests were mainly affected by driving forces such as soil moisture,organic carbon and bulk density whereas, in subtropical forest tree species were influenced by elevation, soil p H, EC and clay content.

Vegetative propagation of Apuleia leiocarpa(Vogel)J.F.Macbr

Apuleia leiocarpa is an environmentally and economically significant Atlantic Forest species threat-ened by ongoing exploitation.The vegetative propagation of the species could be a step forward to enable implanta-tion of clonal seed orchards and multiplication of selected trees but remains unknown to date.This study assessed the mini-cutting technique for propagation of A.leiocarpa and determined the time required for rooting and viable mini-cutting type and sizes.The results show that it is possible to propagate A.leiocarpa with mini-cuttings derived from mini-stumps produced with seeds;the mini-stumps pre-sented regrowth capacity and remained constantly produc-tive for 1 year;10-cm A.leiocarpa mini-cuttings should remain under misting conditions for at least 40 days,and the vegetative propagation of A.leiocarpa with intermediate 7-to 10-cm mini-cuttings resulted in more vigorous clonal seedlings than smaller mini-cuttings.

Antinecrotic and Antiapoptotic Effects of Different Concentrations of Copaiferalangsdorffii Essential Oil in Macrophages and Lymphocytes of Mice

Purpose： to evaluate the in vitro influence of Copaiferalangsdorffii essential oil on the antinecrotic activity in macrophages, and on the antiapoptotic activity in macrophages and lymphocytes of Swiss mice. Methods： lymphocytes and macrophages were obtained from ten 60-day-old male mice weighing 42-45 g, and then cultured in 24-well plates. Cells were treated with concentrations of 2%, 5%, 10% and 20% of oil from Copaiferalangsdorffii before or after induction of apoptosis with ultraviolet light. We used positive and negative controls. Hoechst staining was performed, and then images of cells under fluorescence microscope were captured and digitalized. We used Image J_1.46o to quantify the fluorescence intensity/brightness of condensation of the chromatin ofapoptotic cells. We used one-way ANOVA with Bonferroni＇s and Tukey＇s multiple comparison tests. Results are expressed as the means of relative densities after adjustment and 95% confidence intervals; P 〈 0.05 was considered statistically significant. Results： oil from Copaiferalangsdorffii at different concentrations has decreased necrosis and apoptosis of both lymphocytes and macrophages from mice, when compared to C＋ （all P 〈 0.05）. Discussion： Copaiferalangsdorffii is typically Brazilian and found in the Amazon region, with anti-inflammatory, antioxidant and antineoplastic effects due to its oil compounds, such as xyloglucans and kaurenoic acid. Its potential therapeutical usage was demonstrated in a national study. The present study showed that its oil has significant in vitro antiapoptotic and antinecrotic activity and it should be tested experimentally in vivo.

The Growth and Species-by-site Interaction of 18 Central American Multipurpose Tree Species Grown at 15 Tropical Sites World-wide

From a world-wide plant introduction trial series utilising 25 central American species planted at over 100 sites in nearly 60 countries, eighteen species planted at 15 sites in the tropics were chosen for further study of the factors determining site productivity and site by species interactions. The species were Acacia pennatula, Acacia farnesiana, Albizia guachapele, Ateleia herbert-smithii, Caesalpinia coriaria, Caesalpinia eriostachys, Caesalpinia velutina, Enterolobium cyclocarpum, Gliricidia sepi...