The influence of timber harvest on the structure and composition of riparian forests in the Coastal Redwood region

The composition and structure of riparian forests in the coast redwood region were analyzed in relation to the length of time since timber harvest, and the width of riparian buffer zone. Ten sites were sampled in the central range of the coast redwood forest type within a variety of post-harvest age groups and riparian buffer zone widths. Data was collected using randomly selected sample plots adjacent to perennial coastal steams. Correlation Fisher's r to z tests and two-tailed t-test were used to examine the relationship between the sample variables and the experimental parameters “years since harvest”, and “width of buffer.” Results indicate that canopy cover was negatively correlated to “years since harvest” with the highest level of canopy cover found on the youngest sites and the lowest level found on the old-growth sites. The hardwood to conifer dominance ratio and the basal area of Alnus rubra (red alder) were correlated negatively to both “years since harvest” and “buffer width” indicating that timber harvest favored hardwood species. Late seral associates such as Oxalis oregana (redwood sorrel), Anthyrium filix-femina (lady fern), and Vaccinium parviflorum (billberry) were found preferentially in older forests and sites with wider buffer zones, while non-native species such as Hedera helix (English ivy), Pampas cortedaria (pampas grass), and Myosotis latifolia (forget-me-not) were found preferentially in younger forests and areas with smaller buffer zones.     

Effects of bamboo stands on seed rain and seed limitation in a rainforest

Bamboos often negatively affect tree recruitment, survival, and growth, leading to arrested tree regeneration in forested habitats. Studies so far have focused on the effects of bamboos on the performance of seedlings and saplings, but the influence of bamboos on forest dynamics may start very early in the forest regeneration process by altering seed rain patterns. We tested the prediction that the density and composition of the seed rain are altered and seed limitation is higher in stands of Guadua tagoara (B or bamboo stands), a large-sized woody bamboo native from the Brazilian Atlantic Forest, compared to forest patches without bamboos (NB or non-bamboo stands). Forty 1 m² seed traps were set in B and NB stands, and the seed rain was monitored monthly for 1 year. The seed rain was not greatly altered by the presence of bamboos: rarefied seed species richness was higher for B stands, patterns of dominance and density of seeds were similar between stands, and differences in overall composition were slight. Seed limitation, however, was greater at B stands, likely as a resulted of reduced tree density. Despite such reduced density, the presence of trees growing amidst and over the bamboos seems to play a key role in keeping the seeds falling in B stands because they serve as food sources for frugivores or simply as perches for them. The loss of such trees may lead to enhanced seed limitation, contributing ultimately to the self-perpetuating bamboo disturbance cycle.     

Effects of fitch odor (Mustila eversmanni) on behavior and breeding of root voles (Microtus oeconomus)

From April to December in 1997 at Northwest Plateau Institute of Biology, Chinese Academy of Science, the effect of predation risk on social behavior, feeding, reproduction and sexual hormones of the root voles (Microtus oeconomus) was studied when the root voles (Microtus oeconomus) were exposed to the odor of fitch (Mustila eversmanni). The results showed that the root voles delayed breeding period and the frequency of the copulation significantly lowered (P<0.01). Comparing with the control group, the accumulated time of amicable behavior in females, and general activity of both sexes increased significantly (P<0.01). The frequencies of general activity (P<0.01), investigating activity (females:P<0.05, males:P<0.01), and self-grooming (P<0.01) of both sexes were less significantly. At the same time, the amount of energy intake (P<0.05) and body weight (P<0.01) of the root voles decreased significantly. The litter weight and ovary index of females decreased (P<0.01). For males the sperm count in epididymides also decreased significantly (P<0.01). The progesterone in the blood serum of root voles females increased significantly under fitch odor (P<0.01). Biography: WANG Zhen-long (1971-), male, lecture in Department of Biology, Qufu Normal University, Qufu 273165, P.R. China Responsible editor: Zhu Hong     

Effects of Pinus massoniana bark extract on the adhesion and migration capabilities of HeLa cells

Pinus massoniana Lamb is a Chinese red pine species used in traditional medicine for the treatment of a variety of human health disorders. Recent studies have shown that P. massoniana bark extract (PMBE) has an anti-proliferation effect on cancer cells. However, it is not clear if PMBE affects cancer cell migration and/or invasion. We tested the effect of PMBE, which has B-type procyanidin as its main constituent, on the adhesion and migration capabilities of HeLa cells, a human cervical cancer cell line, cultured in vitro. Our results showed that PMBE has no significant effect on the adhesion capability of HeLa cells, but strongly inhibits their migration. This finding suggests that PMBE could be a potential therapeutic agent for metastatic cancer.