Experimental evaluation of the sustainability of dwarf bamboo (Pseudosasa usawai) sprout-harvesting practices in Yangminshan National Park, Taiwan.

Sustainable harvest of natural products that meets the needs of local people has been viewed by many as an important means for sustaining conservation projects. Although plants often respond to tissue damage through compensatory growth, it may not secure long-term sustainability of the populations because many plants enhance individual well-being at the expense of propagation. Sustainability may further be threatened by infrequent, large-scale events, especially ill-documented ones. We studied the impacts of sprout harvesting on sprout growth in a dwarf bamboo (Pseudosasa usawai) population that has seemingly recovered from an infrequent, large-scale masting event. Experimental results suggest that although a single sprout harvest did not significantly alter the subsequent abundance and structure of sprouts, culm damage that accompanied sprout harvesting resulted in shorter, thinner, and fewer sprouts. Weaker recovery was found in windward, continually harvested, and more severely damaged sites. These findings suggest that sprout growth of damaged dwarf bamboos is likely non-compensatory, but is instead supported through physiological integration whose strength is determined by the well-being of the supplying ramets. Healthy culms closer to the damage also provided more resources than those farther away. Sustainable harvesting of sprouts could benefit from organized community efforts to limit the magnitude of culm damage, provide adequate spacing between harvested sites, and ensure sufficient time interval between harvests. Vegetation boundaries relatively resilient to infrequent, large-scale events are likely maintained by climatic factors and may be sensitive to climate change. Continual monitoring is, therefore, integral to the sustainability of harvesting projects.

Estimation of nested spatial patterns and seasonal variation in the longitudinal distribution of Sicyopterus japonicus in the Datuan Stream, Taiwan by using geostatistical methods.

This study attempts to determine the scale-dependent hierarchical spatial variation and longitudinal distributions of Sicyopterus japonicus year round. The distribution of S. japonicus in the Datuan Stream in northern Taiwan was surveyed during the fall and winter 2007, as well as the spring and summer of 2008. The spatial structure of S. japonicus density was modeled using geostatistics. The longitudinal distributions of S. japonicus density were then estimated using kriging and hydrology distance with nested variogram models. Variography results indicate that nested variogram models could reflect the hierarchical structure in the spatial variation of seasonal S. japonicus density, with the small, median, and large ranges representing three nested scales. Models for the four seasons were consistent in that they shared the same shape of variogram models with various ranges and sill values. This model shape consistency implies stationary spatial correlations in the longitudinal fish distribution across the four seasons. The Kriging geostatistical method based on the multiple scales nested variogram models also provided robust estimates of S. japonicus densities at unsampled sections. We conclude that S. japonicus densities exhibit hierarchical patterns and variation in the four seasons along the study stream. Geostatistical methods with a nested variograms and hydrological distance are a highly effective means of delineating the hierarchical structure in longitudinal patterns of S. japonicus density in each season, providing estimates of the S. japonicus density for hierarchically structured spatial distributions and expanding knowledge of S. japonicus beyond the limits imposed by spatial and temporal scales.