Human disturbance may change dominance hierarchies of plant communities, and may cause substantial changes in biotic environmental conditions if the new dominant species have properties that differ from the previous dominant species. We examined the effects of bamboos (Bambusa tulda and Cephalostachyum pergracile) and their litter on the overall woody seedling abundance, species richness and diversity in a mixed deciduous forest in northeastern Thailand. These bamboo species are gaining dominance after human disturbance. Our results show that seedling abundance and species richness were reduced by bamboo canopies. Seedling abundance and species diversity under bamboo canopies were affected by bamboo litter, whereas seedling abundance and species diversity outside bamboo canopies did not respond to the mixed-tree litter manipulation. Removal of bamboo litter increased seedling abundance and species diversity. However, bamboo litter addition did not affect seedling abundance or species diversity compared to either control or litter removal. This may indicate that the effect of natural amount of bamboo litter is as high as for litter addition in preventing seedling establishment by woody species and hence in minimizing resource competition. We conclude that undergrowth bamboos and their litter affect tree seedling regeneration differently from mixed-tree litter, causing changes in plant community composition and species diversity. Increased human disturbance, causing a shift in dominance structure of these forests, may result in a concomitant reduction in their overall woody species abundance, richness and diversity. Thus, management of bamboos by controlling their distribution in areas of high bamboo density can be an important forest restoration method.

Variations in species richness and diversity at a local scale are affected by a number of complex and interacting variables, including both natural environmental factors and human-made changes to the local environment. Here we identified the most important determinants of woody species richness and diversity at different growth stages (i.e. adult, sapling and seedling) in a bamboo-deciduous forest in northeast Thailand. A total of 20 environmental and human disturbance variables were used to determine the variation in species richness and diversity. In total, we identified 125 adult, 111 sapling (within fifty 20 · 20-m plots) and 89 seedling species (within one hundred and twenty 1 · 1-m subplots). Overall results from stepwise multiple regression analyses showed that environmental variables were by far the most important in explaining the variation in species richness and diversity. Forest structure (i.e. number of bamboo clumps and canopy cover) was important in determining the adult species richness and diversity (R 2 = 0.48, 0.30, respectively), while topography (i.e. elevation) and human disturbance (i.e. number of tree stumps) were important in determining the sapling species richness and diversity (R 2 = 0.55, 0.39, respectively). Seedling species richness and diversity were negatively related to soil phosphorus. Based on our results, we suggest that the presence of bamboos should be incorporated in management strategies for maintaining woody species richness and diversity in these forest ecosystems. Specifically, if bamboos cover the forest floor at high densities, it may be necessary to actively control these species for successful tree establishment.

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The objective of this study was to investigate the duration of flowering and fruiting and the growth of riparian species in the natural forest along Phra Prong River, Watthana Nakhon District, Sa Kaeo province. The occurrence of flowering and fruiting was recorded every month from February 2015 to January 2016 (12 months) along a 7km distance of the riversides. Sixty six species belonging to 36 families were seen flowering and fruiting in this study. They were observed during February – April. The peak of flowering and fruiting occurred in March (early summer). Hydnocarpus anthelminthicus, Uvaria rufa, and Combretum latifolium had a long lasting flowering and fruiting period. Oxystelma esculentum, Capparis micracantha, Connarus cochinchinensis, Derris scandens, and Ficus racemosa produced flowers and fruits more than once a year. Those species may play an important role in availability of food resources for animals in the riparian forest. The appropriate time to collect seeds in Phra Prong riparian forest starts from February and lasts until August. The germination test indicated that Xanthophyllum lanceatum and Crateva magna had a high germination rate, about 70%. Growth of some riparian species, including Cinnamomum iners, Dipterocarpus alatus, Hydnocarpus anthelminthicus and Hopea odorata was monitored every three months from July 2015 to June 2016. Diameter growth of D. alatus was significantly higher during the wet season (Jul-Sep) than other seasons. In contrast, the rest of the species showed no significant differences among monitoring periods. Height growth rate of C. iners was significantly highest late in the dry period (Jan-Mar).

Disturbance and productivity may infl uence and alter community structure by aff ecting the partitioning of resources among species. Here, we examined how evenness in the relative abundance of growth stages (seedlings, saplings and adults) of woody species is related to measures of productivity (i.e. total diameter breast high (dbh) and tree volume) and aspects of human disturbance (i.e. number of tree stumps, area covered by charcoal making holes and trail length) in a bamboodeciduous forest, northeastern of Th ailand. Our results using stepwise multiple regressions showed that productivity (total dbh) explained a signifi cant part of the variation in evenness only at the adult stage where evenness decreased with productivity. We found a decreased evenness of saplings with the area covered by charcoal making holes. Evenness of seedlings was not related to productivity or human disturbance variables and other environmental variables contribute more to explain the variation in evenness at this stage. Evenness was correlated consistently between the growth stages but the strength of relationships diminishes across the stages. Our results suggest that high productivity and human disturbance may facilitate competitive dominant species, aff ecting evenness in woody communities.