Edge effects caused by forest fragmentation may impact the growing environment of both seedlings and maternal trees. Early regeneration stages are of special concern but how maternal origin, edge effects, light environment, and distance from reproductive conspecific trees, as expected from the Janzen-Connell hypothesis, may affect seedling performance, has rarely been studied simultaneously. The goal of this study was to experimentally assess the relative importance of the aforementioned factors for seedling performance of an animal-dispersed, pioneer tree species Ficus tonduzii (Moraceae) in premontane wet forest fragments in Costa Rica. Seedlings from known maternal origins were grown in a screen house before being transplanted at two distances from focal trees in forest fragments. Both maternal trees (home) and non-maternal reproductive conspecific (away) were used as focal trees. In the screen house, seedling size and inherent growth differed by maternal origin. In the forest, distance from the nearest forest edge was the primary factor affecting survivorship and growth of transplants. Additionally, inconsistent maternal effects were observed. While seedlings from a particular maternal origin showed reduced growth in the screen house, those same seedlings showed enhanced growth once they were transplanted in the forest. In contrast, light environment or distance from the reproductive conspecific tree did not predict seedling performance. Home disadvantage was observed for one tree, which underlined the significance of seed dispersal. The results from this case study emphasize the importance of considering both edge effects and stage-specific maternal effects for successful species regeneration and restoration practices in fragmented landscapes.

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Weather-tolerant Interferometric Synthetic Aperture Radar (IFSAR) is expected to generate data for biomass estimation in tropical rainforests. We tested this prediction by examining the performance of X-band IFSAR data in estimating total biomass (TB), i.e., the sum of aboveground and belowground biomasses, in a selectively logged tropical rainforest. Our explorations incorporated the effects of topographic conditions on the accuracy of the procedure used. TB was estimated by a rectangular prism procedure, an original method developed for this study, using IFSAR-derived canopy height data and revised biomass density data (i.e., apparent density of total aboveground biomass [AGB] under a canopy tree). For gentle terrain conditions such as alluvial place, we found a significant correlation between TB estimates provided by IFSAR and field measurement data. Through application of a correction procedure, we were also able to adequately estimate the mean value and frequency distribution of TB. Estimation of TB in complex landscape topographies was restricted by the bias in IFSAR data.

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Assessing the effects of nutrient addition on organic matter decomposition in tropical tree plantations is essentially important because of the increasing importance of the afforestation along with the increases in the intensified management practices and fertilizer use. We tested the effects of phosphorus (P) addition on microbial respiration during the decomposition of Acacia mangium litters and leaves by using an incubation experiment. Following hypotheses were examined: (i) P addition reduces microbial respiration during the litter decomposition if labile carbon (C) and nitrogen (N) are little; while (ii) the effect is not clear in the fresh leaf decomposition due to the large amount of labile C and N. P addition significantly reduced the rates of microbial respiration during the litter decomposition, with the following possible mechanisms; (i) decrease in C or N investment in phosphatase due to the reduced P requirement makes microbes decompose fewer litters to get C or N, (ii) P addition improved microbial respiratory efficiency and reduced energy required to maintain microbial activity. Meanwhile in high-quality leaf, such decrease in microbial respiration rates during the decomposition by P addition did not occur. We suggested that P fertilization in fast-growing tree plantations in tropics may reduce organic matter decomposition. Since the present study is a short-term incubation study, longer studies or field experiments are required to fully understand the effects of P addition on the organic matter decomposition in P-limited tropical forests.

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This article explores changes in the traditional use of forests and their relationship with belief in tiger spirits in the Cardamom Mountains in southwest Cambodia. Locals inhabiting the mountains believe that spirits associated with tigers bite those who violate taboos on forest use. However, the tiger population has declined due to the wildlife trade, which experienced rapid growth during the civil war of the 1990s. The article examines the impact of the war and wildlife trade on the traditional use of the forest by analyzing the relationships among traditional beliefs, changes in the tiger population caused by the growth of the wildlife trade, and war-related changes in the social order. Before the war, beliefs associating tigers with forest use could be observed on several societal levels. The belief that tigers punish violators was practiced on village and inter-village levels, while another form of belief was also practiced on family and individual levels. However, the tiger’s disappearance from the region because of the wildlife trade made such beliefs ineffective. A new belief arose that violators were punished by crop damage caused by wild pigs and other animals. Nevertheless, those who practiced the belief at the individual and family levels still believed in the association between the tiger and spirits and their role in forest use. Therefore, the impact of the aforementioned factors on tiger beliefs differed according to societal level; the extinction of living tigers does not necessarily result in the disappearance of belief at all levels of society.

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