Abstract:In 2004 and 2005, we studied winter habitat use and selection by wapiti in Wandashan Mountains, Heilongjiang Province, China. Using Geographic Information System (GIS) and Remote Sensing (RS), we measured habitat availability in terms of the area of each habitat category in the study area. We compared winter habitats used by wapiti and their availability. The results showed that the habitats used by wapiti were disproportional to their availability. Wapiti preferred clear-cuttings, low vegetation coverage (No. 2, 3 NDVI classes), 200–300 m elevation range, south aspect, and 600–700 m distance range away from roads. They also showed different preferences for feeding and resting. The feeding sites tended to be located at broad-leaved stands and clear-cuttings, No. 2, 3 NDVI classes, and south slope, whereas the bedding sites tended to be clear-cuttings, and No. 2, 3, 4 NDVI classes. Using the logistic regression model to predict the probability of habitat use by wapiti in winter, we found that the overall prediction accuracy was 74.4% for the total habitat samples, with 84.2% for the habitat samples used by wapiti and 62.4% for the control samples correctly predicted by using this model.

Abstract:A field study was conducted to examine the relationships between the root-shoot ratio dynamics and the precipitation and temperature of the typical Leymus chinensis steppe recovering from grazing in Inner Mongolia, China. A former piece of pasture land that had been fenced off for 2 years was selected for the study, and aboveground and belowground biomass was collected from the study site along with local precipitation and temperature observations during the study period and was used in the analysis. The results indicated that 1) the seasonal change in both aboveground and belowground biomass in Leymus chinensis steppe demonstrated a pattern with a single peak occurring in August. 2) The root-shoot ratio showed a seasonal variation, with relatively high values at the beginning and the end of the growing season. The minimum ratio occurred in late August when the aboveground bio-mass reached its maximum. 3) The monthly root-shoot ratio was significantly correlated (p < 0.05) with the monthly precipitation two months ago, and with the mean temperature in the previous month. A regression model was built with the root-shoot ratio as the dependent variable, and precipitation and temperature as the independent variables. This regression could be used to model the monthly root-shoot ratio dynamics of Leymus chinensis steppe during the growing season.

Abstract:The morphological and physiological plasticity to 6 light conditions was investigated for seedlings of 4 tree species dominating at different successional serals in subalpine coniferous forests in eastern Qinghai-Tibet Plateau, China. Abies faxoniana is a late successional species, while Betula albo-sinensis is a pioneer tree species, with Picea asperata and Acer davidii among other mid-late successional species. To compare the responses of photosynthetic characters to different growth light conditions, the seedlings were potted and placed in artificially shaded chambers with gradients of 100%, 55%, 40%, 25%, 15% and 7% of the full sunlight, respectively. During two and a half years' cultivation, various morphological and photosynthetic parameters were measured and analyzed. The results were: 1) all seedlings of the four species under the low growth light conditions showed decrease in root collar diameter, relative growth rate, leaf thickness, root mass ratio, leaf area-based photosynthetic capacity, dark respiration rate, light saturation point and light compensation point, while showed increase in specific leaf area, above-ground to under-ground mass ratio, specific stem length, leaf mass ratio and stem mass ratio; 2) under most light conditions, A. faxoniana of the two conifers revealed lower values in both leaf area-based photosynthetic capacity and respiration rates than P. asperata; the same fact held true for the two broad-leaved trees with lower values observed in B. albo-sinensis; 3) under higher light conditions, relative growth rates of P. asperata and B. albo-sinensis got higher values than those of A. faxoniana and A. davidii, while contrary results were obtained under lower light regimes; 4) the means of phenotypic plastic indices of the eleven morphological and physiological parameters of P. asperata and B. albo-sinensis were higher than those of A. faxoniana and A. davidii, respectively. The findings indicate that A. faxoniana has better adaptation to low light regimes, but as a shade-tolerant species, it is not so adapted to low light regimes as the trees of earlier successional serals, especially P. asperata and B. albo-sinensis. Of the four tree species, physiological plastic indices were higher than morphological plastic indices, suggesting that morphological plasticity plays an important role in their adaptation to different growth light conditions. The results also support the hypothesis that ecophysiological traits of tree species determine their successional status and associate habitats of their seedlings.

Abstract:Aimed to estimate how forest floor cleaning affected the carbon budget and soil physical feature, a 2-yr (2005–2006) measurement on soil respiration, soil bulk density, capillary porosity, soil temperature and soil volumetric moisture was carried out in a larch plantation. Firstly, forest floor cleaning evidently decreased soil respiration. Annual cumulative soil CO₂ efflux decreased from 44.2 μmol·m^-2 a^-1 to 22.4 μmol·m^-2 a^-1. Secondly, cleaning practice slightly increased soil temperature at the growing season, but reduced it at the dominant winter season. It also made soil moisture higher in summer, but lower in spring and autumn. Moreover, the cleaning practice induced more compact soil compared with the uncleaned control. Thirdly, forest floor cleaning of litters and understory shrubs could cause non-respiratory carbon loss of about 175.0 mol·m^-2. This loss decreased from 175.0 mol·m^-2 to 137.4 mol·m^-2 when soil respiratory carbon loss decreased. However, the alteration of soil physical characters in the cleaned plots should be carefully considered since this alteration was not favorable to the growth of larch plantation in a long run.

Abstract:A total of 33 taxa, including 21 families, 8 classes and 7 phyla, were found at the eastern tidal flat of Lingkun Island, Wenzhou Bay. Most of them were mollusks, crustaceans and polychaetes. The species numbers found at 3 tidal flats (high, middle and low) were 25, 30 and 14, respectively. It was shown that the high tidal flat had the highest value of diversity indices, followed by middle and low tidal flats. The species belonged to 5 different trophic functional groups: Phytophagous, Camivorous, Omnivorous, Planktophagous and Detritivorous in qualitative samplings. Then 3, 8, 5, 3 and 2 species belonged to Planktophagous, Phytophagous, Camivorous, Omnivorous and Detritivorous groups, respectively, in quantitative samplings. The density and species number of each functional group did not display seasonal variation by the two-way ANOVA method. Regardless of seasonal variation, density of the Phytophagous group and Camivorous group had distinct difference among different zones of tidal flats, and the species number of the Phytophagous group and Omnivorous group had obvious difference among different zones of tidal flats. Results show that there was variation of functional groups among habitats. Change in components of the macrobenthic community reflected different food sources in different zones of tidal flats.