Abstract:The composition of the diet and the foraging ecology of the Asian elephant in its natural habitat were studied from 1998 to 2000 in the Shangyong National Natural Reserve located at Xishuangbanna, China, using field observation and dung analysis. A total of 106 plant species were recorded as being eaten by Asian elephants, 83 of which were identified in the elephants' dung. The plant families that contributed to a major proportion of the elephants' diet in the study area were: Gramineae (8 spp., 10.0%), Moraceae (7 spp., 9.9%), Papilionaceae (4 spp., 8.4%), Araliaceae (3 spp., 6.6%), Vitaceae (3 spp., 5.7%), Apocynaceae (3 spp., 4.6%), Musaceae (1 spp., 4.2%), Zingiberaceae (3 spp., 3.7%), Myrsinaceae (3 spp., 3.6%), Rosaceae (3 spp., 3.6%), Euphorbiaceae (5 spp., 3.3%), Ulmaceae (2 spp., 3.0%) and Mimosaceae (4 spp., 2.9%). The most important plants in the elephants' diet were Ficus spp. (Moraceae, 9.0%), Dendrocalamus spp. (Gramineae, 4.5%), Musa acuminata (Musaceae, 4.2%), Microstegium ciliatum (Gramineae, 3.5%) and Amalocalyx yunnanensis (Apocynaceae, 3.1%). Asian elephants consumed a variety of plants in terms of life forms, including trees, vines, shrubs and herbs. Early successional plant species constitute a higher proportion of the diet than late successional plants (42 spp. taking 59% vs. 32 spp. taking 37%). Browsing species accounted for a larger proportion of the diet compared to grazing species (77 spp. taking 91% vs. 6 spp. taking 9%). The number of plant taxa (species, genus, family) in elephants' diet each month negatively correlated with monthly rainfall and mean temperature. The study may help to develop proper strategies for wildlife management especially with regard to the human-elephant conflict, which is now a serious issue in the conservation of Asian elephants in this area.

Abstract:The total nitrogen, phosphorus, biomass, pH, dissolved oxygen in and temperatures of three eutrophic waters were investigated in the rapid-growth season of phytoplankton (July-October). Chloromonas rosae was cultivated in water samples from three eutrophic waters and diluted water samples from Lake Donghu to determine the effect of N and P concentrations on the growth rate. The relationship between the biomass and the N and P concentrations, analyzed by regression, showed that phosphorus was the limiting factor for algae growth in eutrophic water. The relationship between the growth rate and the P concentration can be described with the regression equation y=0.0806ln(x) 0.4658, (R²=0.889). The growth rate increased linearly with the increase of P concentration when it was below 0.05 mg/L. It increased less when the P concentration was above 0.05 mg/L, and was almost unchanged when the P concentration exceeded 0.2mg/L. The P concentration corresponding to the growth rate “0” (deduced from the regression equation) was 0.003mg/L, close to the minimal P concentration of poorly nutrient lakes. This indicated that the regression equation was representative. The average values for plankton cellular N and P in the three eutrophic waters were 53% and 85%, respectively. To evaluate the levels of eutrophy, N and P, both in the water and in the plants, must be considered. The biomass of phytoplankton is controlled by concentrations of both dissolved and cellular N and P. The following linear regression equations describe the relationship between biomass and N: y=10.687x-7.8304, (R²=0.950), and between biomass and P, y=122.11x-12.069, (R²=0.991). They exemplify the absolute and relative aspects of growth-limiting factors with Redfield values. We conclude that the only way to prevent eutrophication is to maintain a balance between the input and output of nutrients and to remove excessive dissolved N and P in the water.

Abstract:Pinus tabulaeformis Carr. forest, the dominant community in Ziwuling Mountain lying in the hilly loess region, was studied for its nutrient distributions and bio-cycle characteristics in both natural and artificial forms. The results showed that the changes in the nutrient contents for different components in the same Pinus tabulaeformis Carr. forest stood in the order of needles > branches > bark > roots > bole. The aboveground nutrient elements in needles, branches, bark bole and litterfalls stood in the order of Ca > N > K > Mg > P, but the nutrients stored in the soil stood in the order of Ca > K > Mg > N > P. The accumulated amounts of nutrients increased first and then decreased with the increased age of the forest. The nutrient amounts reached their maximum when the stand was 30 years old, and decreased greatly when it was 50 years old. The 30-year-old artificial Pinus tabulaeformis Carr. forest had the highest annual accumulated amount of nutrients, and different stands stood in the order of II > III > IV > I. Comparatively, annual accumulated nutrients in different components stood in the order of needles > branches > roots > bark > bole. It was also suggested that the amounts of nutrients annually taken in from and retained in the natural Pinus tabulaeformis Carr. forest were significantly higher than those in artificial forests. The coefficients of nutrient use in various Pinus tabulaeformis Carr. stands stood in the order of Ca > Mg > N > K > P, but the nutrient use efficiency (NUE) of the same element decreased with increased age of the forest. There were no differences in the utilization coefficient and the turnover period of nutrients in both natural and artificial matured Pinus tabulaeformis Carr. forests.

Abstract:The current situation of the animal species biodiversity of macrobenthic fauna in the Jiaozhou Bay (South Shandong Peninsula, Yellow Sea) is reported in the present paper, based on the data from 15 investigation cruises carried out from February 1998 to November 2001. In analyzing the data, the Shannon-Wiener index, and species evenness and richness indices were used to study the trends of variation of the community structure, the species assemblages in the macrobenthic community, the dominant species, and the abundance of macrobenthic fauna in Jiaozhou Bay. A total of 322 species of macrobenthic animals were found in the bay, of which 133 species belong to 44 families of Polychaeta, while 92 species belong to 42 families of Crustacea. The average number of species per sample station ranged from 8 to 26. The Shannon-Wiener indices were very different among the samples, with the highest being recorded from Station 8 in November 2001, and the lowest from Station 9 in August 2001. The number of species, the Shannon-Wiener indices, and the species richness indices from Stations 7 and 9 were generally lower than those from other stations. This is because both the stations are situated at areas with a strong current and where the sediment is coarse sand. Although the richness index of species and the Shannon-Wiener index were high in Station 3, the Pielou evenness index was the lowest of all the sampling stations. This is because the station is located near the culture area of Ruditapes philippinarum, where a high abundance of clams caused low evenness. The results also revealed that the number of species and abundance greatly affected the biodiversity, and some environmental factors such as temperature, salinity, and primary productivity were also closely interrelated with biodiversity. Pollution and overexploitation caused by human activities were very important factors affecting macrobenthic biodiversity. In order to find the best way to enhance and protect living marine resources, the relationship between human activities and the biodiversity of macrobenthos in the Jiaozhou Bay should be studied further.

Abstract:Using limited-areas methods, the ability of several arbor and shrub species to endure and survive extreme aridity under field conditions in Horqin Sandy Land was studied, and the lowest critical soil water content that was endurable for each of these species was determined. By limiting the horizontal distribution range of the plant roots system, the limited-areas methods could decrease the spatial heterogeneity of soil water content and improve the accuracy of the determination of soil water content. This method also had the advantage of worsening the aridity endured by the plant species, proving helpful in testing the ability of these species to endure aridity. Our results showed that Prunus sibirica L., Caragana microphylla Lam., Artemisia halodendron Turcz. ex Bess., Salix gordejevii Cheng et Skv., Ulmus pumila L., and Populus pseudo-simonii Kitag. could endure critical soil water contents of 0.82%, 0.87%, 1.61%, 1.89%, 2.04% and 2.27%, respectively. The results were useful in evaluating the ability of these species to endure aridity, and had some important implications for the rational use of these species in accelerating the revegetation of sandy desertified lands.