Abstract:An incubation method was used to investigate the nitrogen release characteristics from the residue of ten plant species which commonly grow in the northern part of the Loess Plateau. The effect of the residue on soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN) was also determined. There were significant differences in the total N content and the C/N ratios among the different types of plant residue. The total N content of the residues ranged from 6.61 to 32.78 g kg^-1. The C/N ratio of the residue ranged from 14 to 65. There was an immediate increase in soil N after alfalfa, erect milkvetch, and korshinsk peashrub residue was added to the soil. In contrast, soil N decreased after elm, sea buckthorn, and wild peach residue was added to the soil. The soil N content remained relatively low for 14–34 days and then increased. This indicated that N immobilization occurred during the early portion of the incubation period when elm, sea buckthorn and wild peach residue was added to the soil. Soil N levels were low during the entire incubation period when simon poplar, locust, Stipa bungeana, and old world bluestem residue were added to the soil. The addition of plant residue significantly increased SMBC and SMBN in all treatments. The SMBC and SMBN values were greatest in treatments containing plant residue with high total N content and low C/N ratios. The C/N ratios of korshinsk peashrub, sea buckthorn, and wild peach residues were similar, but the amount of N released from these residues and the effects of the residue on SMBC and SMBN in soil were significantly different. This indicates that not only the C/N ratio but also the chemical composition of the plant residue affected decomposition. It is important to consider C and N release characteristics from plant residue in order to adjust the C and N balance of soil when revegetating degraded ecosystems.

Abstract:The pygmy loris (Nycticebus pygmaeus) is a small prosimian living in Vietnam, Laos, eastern Cambodia and the south part of China. In China it is only found in Pingbian, Hekou, Jinping, Luchun of Yunnan. As N. pygmaeus is seriously threatened by hunting, trade and habitat destruction, it is listed in Appendix II of CITES, and in 2006 the IUCN classified it as “vulnerable”. In order to understand the characteristics of energy metabolism and thermoregulation of N. pygmaeus, the resting metabolic rate (RMR) and body temperature (T_b) at different ambient temperature (T_a) of pygmy lorises, as well as body mass, energy intake, digestable energy intake, digestability and the thermal conductance were measured in captivity. The results obtained mainly are as follows: (1) Pygmy loris feed dry food averaged 12.90 1.02 g/d. They could gain 214.87 16.65 kJ/d from food intake, and earned 200.15 16.36 kJ digestable energy intake per day with 90.13 1.34% of the digestability. (2) The T_b at room temperatures was a little low (35.23 0.16 C) and varied with T_a from 25 C to 35 C. There was a positive relationship between T_b and T_a, which was described as: T_b = 27.22 + 0.34T_a (r = 0.880). (3) The resting metabolic rate (RMR) of the pygmy loris was 0.3844 0.0162 mlO₂/g/h, which was 51.91 1.90% of the previous predicted rate by Kleiber (1961) [21]. (4) The average thermal conductance of the pygmy loris (N. pygmaeus) was 0.0449 0.0031 mlO₂/g/h/C. These characteristics of energy metabolism and thermoregulation of N. pygmaeus in Yunnan Daweishan Nature Reserve might be considered as the adaptive characteristics to their environment in tropical semi-evergreen forests and secondary forests.

Abstract:A study was conducted to investigate the impact of starvation on different sizes of Manila clam Ruditapes philippinarum (0.66 ± 0.11, 2.12 ± 0.38, and 11.65 ± 0.84 mm in shell length, respectively) in the summer of 2008. Different size clams were starved for 7, 15, 30, 45, and 60 d, respectively, and followed by refeeding for 30 d. During the study, the water temperature ranged 26.2–28.4 °C, salinity 22–24‰, and pH 7.80–8.12. Compensatory growth occurred in the smallest size-group after 7 and 15 d of starvation, respectively. The point-of-no-return (PNR₅₀) was determined to be 18.7 d. However, no compensatory growth was noted in the medium size-group, and the PNR₅₀ for this group was 25.2 d. The complete compensatory growth was observed for the largest size-group following food depravation for 7 and 30 d, respectively. In the same group, over-compensatory growth occurred 15 d post-starvation. The PNR₅₀ for the largest size-group was 46.3 d. The survival rate of different groups decreased as the starvation time prolonged. To discuss the change in body biochemical composition of individuals in the process of starvation and refeeding, the biochemical composition of the largest group individuals at different stages was determined. There were no significant differences in moisture and ash concentrations of the largest size-group during starvation and refeeding (P > 0.05). The relative body protein content increased as the starvation period prolonged and the level returned to normal after refeeding. The lipid content of the clam at the end of starvation was significantly lower than the initial level (P < 0.05), and remained below the initial level at end of the refeeding period.

Abstract:Identifying the specific forces driving environmental impact is a hot topic in the field of sustainable development in the pasturing area. In the paper, the ecological footprint was taken as the index of environmental impact, and a series of index like population quality, prosperous, using intensity, livelihood tactics are considered as the main human factors. Using the STIRPAT model and temporal series data from 1980 to 2007, the author analyzes the effects of the human driving forces of environmental impact.
The ecological footprint method presents a simple framework for national natural capital accounting, and it has been used as a comprehensive index of human activity impact, which indirectly reflect human activity’s pressure on the environment. Our analyses showed that the ecological footprint increased from 238736.9 to 877716.1 ha and per capital ecological footprint also increased from 0.854 to 1.961 ha/per during 1980–2007 in Gannan pasturing area. However, in the meantime, the ecological footprint intensity was inclined from 25.396 to 3.025 ha/ten thousand yuan.
With a view of dismantling the human driving forces of ecological footprint, the modified IPAT-called STIRPAT has been employed as a common analytic framework. Our analyses showed that population quantity and using intensity was a major driver of ecological footprint, their coefficients were greater than 1.0 in model (1); In addition, promoting the prosperous lever and the primary industry proportion, the impact of environment will be increased, but their coefficients are less than 1.0 in model (1). At the same time, the technological eco-efficiency of sample regions was discussed in details, the range ability of the technological eco-efficiency was wider, and 15 years went beyond the average level, but the other was less than the average level. Another important finding in the empirical study is that there are some evidences of an environmental Kuznets curve for ecological footprint within the range of calculated data. Some potential improvements in some further researches and suggestions to alleviate the environment pressure, and it is put forward in the last section.

Abstract:To study the impact of nitrogen deposition on 1-year-old Chinese fir (Cunninghamia lanceolata) seedlings in pots, the dissolved NH₄NO₃ was sprayed on the seedlings every 3 days for 1 year. The simulated elevated N depositions were equivalent to N0(0), N1(6 gN/(m² a)), N2(12 gN/(m² a)), N3(24 gN/(m² a)) and N4(48 gN/(m² a)). The results indicated that medium N treatments (N2, N3) enhanced growth significantly. The height, stem base diameter and per-seedling biomass of Chinese fir seedlings increased with N loads and decreased in the high N treatments. Compared to N0, the height and per-seedling biomass were highest in N2 treatment and increased by 10.77% and 12.35%, respectively. The stem base diameter was highest in N3 treatment and increased by 8.81% compared to N0. The net photosynthetic rate (Pn) in treatments N1, N2, N3, N4 increased by 1.20%, 9.28%, 24.23% and 4.30%, and the highest photosynthetic rate by 67.09%, 125.32%, 148.10% and 51.90%, respectively. The N1–N3 treatments, especially N2, stimulated light compensation point (LCP) of the seedlings significantly, but N4 exhibited inhibitive effect. Compared with LCP, light saturation point (LSP) showed weaker response to N loads, positive to N2, but negative to all other N treatments. Low-to-medium N treatments (N1, N2) enhanced Chl (a + b) by 2.19% and 37.15%, while medium-to-high N treatments (N3, N4) reduced Chl (a b) by 7.95% and 15.56%, respectively. Water use efficiency (WUE) and stomatal conductance (C) decreased slightly with N loads.

Abstract:During June, August and October 2006, there were three multi-disciplinary surveys carried out in the Changjiang River estuary and its adjacent waters (122°00′–125°00′E, 27°50′–34°00′N) by R/V Beidou to study the species composition and abundance of ichthyoplankton (including fish eggs, larvae and juveniles), the spatial distribution of fish spawning ground and their relationship with habitat factors. There were 29, 29 and 25 grid stations sampled in the three cruises, respectively. The ichthyoplankton samples were collected by horizontally towing with a macro-plankton net (mouth diameter 80 cm, length 270 cm, mesh size 0.50 mm) at the sea surface, and the towing speed was 3.0 n mile/h at each sampling station. The towing lasted for 10 min. After hauling for each station, habitat factors including temperature and salinity were measured by Sea Bird-25 CTD. Samples were preserved in 5% formaldehyde solution immediately after sampling for analysis in laboratory. Since the trawl speed could not be accurately evaluated due to the effects of ocean currents and wind-induced wave, the amount of ichthyoplankton was evaluated by actual number of the sampling haul in each station. Ichthyoplankton collected were divided into three categories: dominant species, important species and main species by the index of relative importance (IRI). There are 71 species (including 1200 fish eggs and 2575 fish larvae and juveniles) collected during 3 cruises and 59 species have been correctly identified to species level, which belongs to 50 genera, 37 families and 9 orders; while 5 species can only be identified to genera level, 1 species only identified to family level and 6 species identified to order level. These 59 species identified to species level and 5 species identified to genera level are divided into three ecological patterns, i.e., brackish water species, neritic water species and coastal water species. Warm water species have 34 species in those 59 species identified to species level, accounting for 57.63%, warm temperature species have 25 species, accounting for 42.37%. According to the analysis of IRI, the dominant species are Engraulis japonicus (in June and August, that is important species in October), Scomber japonicus (in August), and Johnius grypotus (in October) during the survey; important species are Cynoglossus joyneri (in June and August), Trichiurus lepturus (in June, August and October), Gonorhynchus abbreviatus (in August), Stolephorus commersonii (in October), Saurida undosquamis (in October) and Saurida elongate (in October), and main species have 12 species in June, 9 species in August and 10 species in October, respectively. The amount of fish eggs and larvae of the dominant species, important species and main species (28 species) are 97.50% and 97.13% of the total amount of fish eggs and larvae, respectively, which are the important composition of fish eggs and larvae in the Changjiang River estuary and its adjacent waters.
In June and August of 2006, if compared with that in corresponding months in 1986, there are great changes in the habitat factors especially for temperature and salinity in the investigating areas: high salinity water from off-shelf is much closer to the coastal areas which results in the dramatic increase of sea surface salinity during all three surveys. Sea surface temperature, on the other hand, decreases distinctively in June, but significantly increases in August. The run-off of the Changjiang River greatly reduced due to the long-term drought in summer 2006, which is responsible for the great changes of habitat factors in the Changjiang River estuary and its adjacent waters. The habitat of the Changjiang River estuary is greatly changed, which consequently has significant influences on the spawning, breeding and the spatial distribution of spawning ground of neritic water species, such as Sardinella zunasi, Thryssa kammalensis, Thryssa mystax, Setipinna taty and S. commersonii ect, and coastal water species, such as Ilisha elongate and Konosirus punctatus ect.

Abstract:Elymus nutans Griseb. is a typical important plant species in the alpine meadow of Qinghai-Tibetan plateau. To examine the effects of temperature elevation on its physiological and chemical characteristics, a simulation study was conducted in situ with open-top chambers (OTC) followed the method of International Tundra Experiment (ITEX) from November 2002 to September 2007, and these OTCs were designed five kinds of size with bottom diameters of 0.85, 1.15, 1.45, 1.75, 2.05 m so as to rise different air temperatures. The air temperature inside OTCs increased by 2.68, 1.57, 1.20, 1.07 and 0.69 °C with increase of OTC diameter compared with ambient air. We found that with increase of air temperature, the soluble sugar content and SOD (superoxide dismutase) activity in leaves of E. nutans increased first, and then decreased, whereas, the soluble protein content and GSH (Glutathione) content decreased first and increased then, the chlorophyll a and total chlorophyll contents were decreased, but the contents of chlorophyll b were higher than that of control. Increased temperature enhanced the above-ground biomass and blade height of E. nutans. These results indicated that elevated temperature had significant and complicated effects on physiological–biochemical characteristics of E. nutans on Qinghai-Tibet plateau, when the temperature increased within the range of 0.69–1.57 °C, it may have positive effects on plant growth and development, and E. nutans could adapt even develop defensive strategy to the changes of a certain ecological environment changes.

Abstract:Leaf is one of the most sensitive organs that response to atmospheric environment changes. In arid region, especially under water stress conditions, water from foliar uptake is one of the main water subsidy sources, which plays an important role in plant survival, growth and ecosystem sustainable development. Foliar water uptake attracts more attention in physiological and ecological research all over the world. This essay summarized the main measurement methods of foliar water uptake at home and abroad in detail: vessel control method, stable isotope technology and heat ratio method. And analyzed the significance of foliar water uptake from physiological and ecological aspects; and discussed the influence factors of foliar water uptake from water condition perspective, water absorption and leaf structure aspects. The following aspects should be paid more attention in future researches: (1) measure the amount of foliar water uptake by using stable isotope technology and heat ratio method; (2) the relationship among foliar uptake of fog, dew, rain and water vapor in arid region; (3) the foliar uptake amount and rate should be simulated by models; (4) the mechanisms of foliar water uptake should be researched; (5) study foliar water uptake of different plants at ecosystem scale.

Abstract:This study was conducted to assess the effectiveness of phytoremediation on a tailing dam located in Shimen County, Hunan Province. Quadrat survey method was employed to investigate and sample the dominant plant species growing on the rehabilitated tailing dam. The fertilities of the soils were assessed, and concentrations of arsenic and other heavy metals in the plant and soil samples were measured. The results showed that no difference was found on the effect of soil capping with top and non-topsoils for rehabilitation of plants on the tailing dam. After rehabilitation, stable vegetation coverage types were established, 39 plant species were found to grow on the tailing dam, and the minimal area for plant communities was 30 m². The dominant plant species were planted Pteris vittata and natural colonizing Miscanthus sinensis. The contents of organic matter, nitrogen and phosphorus in the soils were low, while the potassium content was at a middle level; however, plots where Legumina plants grew were found to have higher level of nitrogen and phosphorus in the growing soils. Arsenic (As) and Cadmium (Cd) concentrations in the soils were 8 and 7 times of the grade III value of the National Standard for Soil Quality (GB15618-1995), respectively; while in tailings these were 81 and 68 times. The available As concentration in the soils ranged as 3.7–29.5 mg kg^-1, whereas the available As concentration in tailings was as high as 61.1 mg kg^-1. Concentrations for most of the heavy metals were in the normal range of terrestrial higher plants, except As and Cd in P. vittata and M. sinensis, and As in the roots of M. sinensis. It is concluded that phytoremediation project has reduced the ecological and health risks caused by the tailing dam to the ambient environment. However, the plants growing on the tailing dam which contained high As and Cd should be kept from entering into food chain in order to protect the health of local residents.

Abstract:A variety of studies on the impact of fire disturbance on ecosystems has shown that the physical and chemical properties of soil after fire disturbance change notably. Meanwhile, little is known about the effects of different fire intensities on the soil properties and vegetation after fire disturbance, especially in the south subtropical area. In this paper, we analyzed the soil physical and chemical properties, vegetation species and species diversity of fire center, fire edge (which was burned a year ago) and non-burned Pinus massoniana plantation in Gaoyao, Guangdong province, China. The results showed that the soil conductivity, water content, total nitrogen, total potassium, and available potassium content of fire center were significantly higher than those of the non-burned land, and pH was higher than that of fire edge, whereas the available nitrogen, total phosphorus and organic matter content were much lower, which were generally existed in 0–10 cm soil layer and 10–30 cm soil layer. Changes of the soil properties of fire edge were similar with those of fire center, but less significant, and seemed to be more complex. Effects of burning on the vegetation of fire disturbance plots were found to be notable, species number and average height of plants of fire disturbance plots were lower than those of the non-burned plots, a difference of species diversity and uniformity were also shown, and finally, the composition of plant community also changed, e.g., pioneer species such as D. dichotoma, etc., dominated, and drought-resistant plants, heat-resistant plants and positive plants increased after burning.