Abstract:Reeves's Pheasant (Syrmaticus reevesii), endemic to China, is an endangered species of pheasants. The wintering habitat selection by the species was investigated at three scales (10, 115 m and 250 m) in Dongzhai National Nature Reserve from 2000 to 2002. At each scale, a range of habitat variables were compared between the used and the control sites. At the smallest scale (10 m), the variables influencing wintering habitat selection were slope, tree cover, and the interaction between the cosine of slope aspect and the shrub height. At the mid-scale (115 m), the area of shrub, the area of broad-leaved forest, and the area of conifer forest were the key factors. At the largest scale (250 m), broad-leaved and conifer forest coverages and their interaction were the key factors. According to the lowest AIC and AIC_c values at the mid-scale, the characteristics at this scale were stated as the ultimate factors influencing the habitat selection of the bird. When a range of habitat variables at all scales within a multivariate regression were considerred, the most important variables were conifer forest coverage at the mid-scale, broad-leaved forest coverage, and the interaction between the conifer forest and shrub coverages at the large-scale, and the distance to beach and farmland. These results highlight the importance of multiscale analyses when habitat selection by pheasants are considerred.

Abstract:To investigate the genetic resources and to clarify the classification status of the Chinese yak, the Maiwa yak, Jiulong yak, Datong yak, and Tianzhu White yak were intensively studied using microsatellite DNA, RAPD (random amplified polymorphic DNA), and AFLP (Amplified Fragment Length Polymorphism) DNA markers on the basis of the previous study work of the authors' on chromosomes and blood protein polymorphisms of the Chinese yak. The overall results showed that: (1) the genetic distance based on allele frequencies at the microsatellite loci between the Maiwa yak and Jiulong yak was the largest (1.506), and as expected, the two populations of the Maiwa yak had the smallest genetic distance (1.062). The four yak breeds were clustered into two groups: the first group comprised the Jiulong yak, and the second group comprised the remaining three breeds; (2) the genetic distance between the Datong yak and Tianzhu White yak was the smallest (0.0336), whereas the genetic distance between the Jiulong yak and Maiwa yak was the largest (0.0414) based on the data from the RAPD and RFLP analyses. The four yak breeds were again clustered into two groups with the Datong yak and Tianzhu White yak grouped together first, followed by the Maiwa yak; (3) analyses of the chromosomes and blood protein polymorphisms showed a similar pattern of relationship among the breeds. Therefore, it was concluded that the Chinese yak could be considered to be of two types with the Jiulong yak and Maiwa yak as their representatives, respectively. This conclusion was in accordance with the classification proposed later by professor Cai L and his colleagues, according to which the Chinese yak was classified into two types, the ‘Qinghai-Tibetan Plateau yak’ and the ‘Hengduan Mountain Alpine yak’, although this conclusion differed from the other classifications. Considering the geographic distribution, ecological factors, history and development of the Chinese yak, it was believed that this classification is reasonable.

Abstract:Field experiments were conducted on soybean Glycine max, yudou29, a major cultivated variety in the Henan Province of China to study the relationship between photosynthetic characteristics and other physioecological parameters of its leaves under soil drying and rewatering treatments. The study showed that the dawn water potential of soybean leaves under the drying treatment was very close to that of soybean leaves under well-watered treatments (CK) when soil water content was higher than 47% of field water capacity (FWC). But when soil water content dropped below 47% of FWC, the leaf water potential decreased rapidly, indicating a significant threshold reaction. The dawn water potential threshold of soybean leaves was about ?1.02 MPa. Below this, the leaf water potential and net photosynthesis ratio dropped rapidly. When the soil water content was 47%, the leaf water potential and net photosynthesis ratio were nearly as high as those in CK, but the transpiration ratio was 67% lower, indicating that transpiration was more sensitive to drought than photosynthesis. After rewatering, the water status of soybean leaves improved, the net photosynthesis ratio and transpiration ratio increased linearly, and leaf stomata conductance (Gs) also recovered quickly. These results showed that after stress removal, soybean had fast-growing characteristics.

Abstract:With randomized complete block design, long-term water use efficiency (WUE_L), photosynthetic parameters (net photosynthetic rate Pn, transpiration rate Tr, stomatal conductance Gs, instantaneous water use efficiency WUE_i, maximum photosynthetic rate P max, light saturation pointLSP, carboxylic efficiency Ce), stomatal properties (frequency, size, superior/inferior stoma amount ratio) and root/shoot ratio of twelve Populus deltoids clones were studied under water stress in a greenhouse. Four water treatments were designed, namely, well-watered condition, slight water stress, moderate water stress, and severe water stress. Although the volumes of irrigated water for different treatments were the same, the irrigation intervals were strictly controlled. The results showed that long-term water use efficiency (WUE_L) differences among tested clones were obvious and became greater with the increase in water stress. J₂, J₆, J₇, J₈, and J₉ were excellent clones with high WUE_L. Stomatal frequency, stomatal size, Gs, Tr, Pn, and root/shoot ratio of J₂et al were moderate, whereas the superior/inferior ratio, P_max, LSP, Ce of J2et al were higher than other clones. The interrelations between WUE_L and the physiological parameters were analyzed. The results revealed that the WUE_L differences were induced by a series of physiological parameters, and clones with higher WUE_L always had strong photosynthetic capacity, higher WUE_i, and optimum root/shoot ratio.

Abstract:Pinus tabulaeformis carr. and Hippophae rhamnoides are widely planted in the low mountainous upland and loess plateau and are the main species for afforestation in the semiarid region. To expound their roles in controlling severe soil and water losses and the mechanism of their roles, a study on the hydro-ecological effects of the woods was carried out during 2002–2004, using the runoff plot method set up in different woods and conducting a physical and chemical analyses of the soil. The experimental woods are located in the low mountainous upland of Western Liaoning Province, China where the annual average air temperature is 5.4–8.7C, the annual precipitation is 450–580 mm, of which June averages 238.9 mm, and the annual average humidity is 38%–82%. The coverage rate of vegetation is 28%. The age of Pinus tabulaeformis carr. is 28 a, its distribution density is 2825 ind.·hm², and its coverage rate is 0.75, while those of Hippophae rhamnoides are 11a, 8950 ind.·hm² and 0.90, respectively. The results showed that the intercepting rates of canopy in Pinus tabulaeformis carr. and Hippophae rhamnoides were 23.08% and 32.28%. The litter intercepting rate averaged 14.17% in the Pinus tabulaeformis carr. woods and 20.8% in the Hippophae rhamnoides woods, respectively. The runoff depths in Pinus tabulaeformis carr. and Hippophae rhamnoides were 2.516 mm and 0.893 mm, while erosion amounts were 15.57 t·km^-2 and 0.76 t·km^-2, respectively. Under the comprehensive action in the artificial woods, the runoff depth and erosion amount from the woodland were 1/20 and 1/50 of those from the wasteland, respectively, which indicated the immense hydro-ecological functions of Pinus tabulaeformis carr. and Hippophae rhamnoides woods Litter and dead roots would decompose into organic matter and nutrient substances with the help of microbes, and would thus distinctly improve the physical and chemical properties of the soil. In comparison with the wasteland, the bulk density of soil decreased in the woodland, while the content of organic matter, total N, total K, and available K significantly increased. The physical properties of soil in the woodland, such as total porosity, noncapillary porosity, saturated moisture content, noncapillary water-holding capacity, were distinctly higher in surface soil (0–20 cm) than those in the soil at the depth of 20–40 cm. There was no significant difference of pH, total P, and available P among different land types or at different soil depths. The noncapillary water-holding capacities in Pinus tabulaeformis carr. and Hippophae rhamnoides were 182.1% and 275.9% times those of wasteland, respectively.