Abstract:Heihe River is the second largest inland river in northwest China which flows through Qinghai Province, Gansu Province and Inner Mongolia Autonomous Region. Because of the rapid development of social economy, the sharp increase of water utilization in the middle reaches and the aggravation of contradiction of supply and demand on water resources, the water to the lower reaches decreases and the ecological environment deteriorates constantly. According to the severe situation of ecology system depravation in Heihe River basin, Chinese government decided to invest 2.35 billion RMB to carry out 3 years ecological management in Heihe River basin from August in 2001. After 3 years ecological management, the depravation of ecological environment is controlled effectively. This paper researches the ecological management engineering in the upper reaches of Heihe River and evaluates the effect of the ecological management engineering. The methods of field sampling and measuring are used to obtain the index indicating the ecology change in the upper reaches of Heihe River in 2006. The effects of fencing grassland, fencing natural forest, and artificial afforestation to the ecology are evaluated. The result suggests that: Firstly, in fencing grassland area, the yield of grass had increased by 42–113%, average height of the grass had increased by 60–100%, and the degree of coverage had increased by 67–100%. Secondly, in fencing natural forests area, the degree of coverage had increased by 15–33%, the shade density had increased by 50–100%, average height had increased by 80–125%, and the crown size had increased by 63–186%. Thirdly, the growth increment of the trees in artificial afforestation area is bigger than that outside artificial afforestation area. In conclusion, ecological management leads to obvious ecological effect in the upper reaches of Heihe River.

Abstract:Meteorological data are scarce due to lack of meteorology stations in the Qinghai–Tibet Plateau. This often results in an imprecise estimation of air temperature. A linear estimation of air temperature of an alpine meadow on Northern Tibetan Plateau at heights of 1.5 m–2.1 m by using MODIS land surface temperature (LST) data was conducted in this study. The results showed that linear estimation of daily maximum and daytime mean air temperatures from MODIS LST data were not accurate enough (P > 0.01, R² < 0.10) during the growing season. In contrast, the linear relationships between daily maximum and daytime mean air temperature and MODIS LST during the non-growing season were both significant (P < 0.01, R² > 0.40). MODIS LST data were accurate enough to linearly estimate daily minimum and nighttime mean air temperatures (P < 0.01, R² > 0.55). Moreover, derived LST from MODIS/Terra platform (MOD11A2) had higher accuracies than derived LST from MODIS/Aqua platform (MYD11A2) in linearly estimating air temperatures mentioned above.

Abstract:Replacing mammals with birds has been tested successful in restoring degraded grassland ecosystem towards sustainable management. We pre-tested the effects of chicken litter (CL) on grassland productivity and soil quality in order to carry out free range chicken income generation practice in large areas. The amounts of 25 g m^-2 and 50 g m^-2 of CL, equaling 30 m² per chick and 60 m² per chick, were applied on Leymus chinensis (L. chinensis) communities at Hunshandak sandland, Inner Mongolia, China. Besides, urea was applied at same rate as comparison. The above ground production was increased to 107% and 148% by CL applied at 25 g m^-2 and 50 g m^-2 respectively but underground biomass was reduced to 64% and 68% by CL applied at 25 g m^-2 and 50 g m^-2, contributing to the reduction of total biomass and R/S ratio. L. chinensis production was enhanced by CL, with higher nitrogen use efficiency (NUE) being achieved than that of urea. N and P uptake in L. chinensis elevated to 202% and 280% respectively by CL; the N concentration was reduced to 87% on average. Nevertheless, CL’s favoring L. chinensis (p = 0.026) rendered potential question on biodiversity, calling for further study and cautious management to sustain ecosystem stability. CL amended soil showed better physical quality including lower soil bulk density, more soil moisture and soil organic matter. Besides, soil treated by CL was more resistant to nutrient leaching. Our results showed that CL benefited the production and soil quality of grassland ecosystem, with little side effect on its structure and function.

Abstract:Greenhouse experiments were conducted to assess the effects of supplemental calcium in salinised soil on the response of germination and seedling growth of Caesalpinia crista, L. (Fabaceae). NaCl and CaSO₄·2H₂O were added to the soil and 0:0, !:0, 1:0.25, 1:0.50, 1:0.75, 1:1, 1:1.25, and 1:1.50 Na/Ca ratios were maintained. Salinity significantly retarded the seed germination and seedling growth, but the injurious effects of NaCl on seed germination were ameliorated and seedling growth was restored with calcium supply at the critical level (1:0.50 Na/Ca ratio) to salinised soil. Calcium supply above the critical level further retarded the seed germination and seedling growth due to the increased soil salinity. Salt stress reduced N, P, K and Ca content in plant tissues, but these nutrients were restored by addition of calcium at the critical level to saline soil. The opposite was true for Na⁺. The results are discussed in terms of the beneficial effects of calcium supply on the seedling growth of C. crista grown under saline conditions.

Abstract:To evaluate the tolerance of riparian plant Distylium chinense in Three Gorges Reservoir Region to anti-season flooding, a simulation flooding experiment was conducted during Autumn and Winter, and morphology and photosynthesis of D. chinense seedlings and their recovery growth after soil drainage were analyzed in different duration of flooding and flooding depth. The seedlings were submitted to four treatments: (1) 40 seedlings unflooded and watered daily as control (Unflooded, CK); (2) 120 seedlings flooded at 1 cm above the ground level (F-1 cm); (3) 120 seedlings flooded at 12 cm above the ground level (F-12 cm) and (4) 120 seedlings completely submerged with 2 m water depth (F-2 m, top of plants at 2 m below water surface). The flooding survival, plant height, stem diameter, adventitious roots, stem lenticels, epicormic shoots, chlorophyll content and photosynthesis parameters were determined at 0, 15, 30, 90 days in flooding stress and 15, 60 days after soil drainage. The results showed that the survival of the seedlings subjected to flooding was 100% for all repeated measurements in all treatments. Adventitious roots, hypertrophied lenticels and stem hypertrophy were observed in the seedlings flooded for more than 15 d, and increased with the prolonged flooding duration, while disappeared after the soil was drained. Flooding duration and flooding depth showed significant individual and interactive effects on leaf chlorophyll a (Chl a), chlorophyll b (Chl b), and their ratio, chlorophyll (a + b), the net photosynthesis rate (P_n), transpiration rate (T_r), stomatal conductance (C_s), and inter-cellular CO₂ concentration (C_i) of D. chinense seedlings (P < 0.01). After 15 days of flooding, there was no significant decrease in P_n of the flooded seedlings as compared with that of the control seedlings. P_n of the flooded seedlings was significantly lower than that of the control seedlings after 30 days of flooding (P < 0.05), whereas P_n showed no significant difference among seedlings from three flooding depths. After 90 days of flooding, P_n of the F-2 m flooded seedlings was significantly lower than that of the controls, F-1 cm and F-12 cm flooded seedlings (P < 0.05), but still maintained high photosynthetic capacity. P_n of the F-1 cm and F-12 cm flooded seedlings rose gradually after soil drainage, while, it was significantly lower than that of the control seedlings after 15 days of recovery (P < 0.05). After 60 days of recovery, P_n of all seedlings flooded with different depths showed no significant difference as compared with that of the control seedlings and new leaves grew out in the F-2 m flooded seedlings. The effect of all flooding treatments on Gs, T_r, Chl a, Chl b, Chl a/Chl b and chl (a + b) was basically the same as their effect on P_n, while the effect of all flooding treatments on C_i was quite the contrary. Correlation analysis showed that P_n was positively relative with G_s, T_r, Chl a, Chl b and chl (a b) (P < 0.05) and significantly negative with C_i (P < 0.05). Therefore, the present study demonstrates that D. chinense has high survival and good recovery growth after long-term flooding in anti-season flooding and could be taken as an excellent candidate species in the re-vegetation of water-level-fluctuation areas in Three Gorges Reservoir Region.

Abstract:As one of the most important crops in China, rice accounts for 18% of the country’s total cultivated area. Increasing atmospheric CO₂ concentration and associated climate change may greatly affect the rice productivity. Therefore, understanding the impacts of climate change on rice production is of great significance. This paper aims to examine the potential impacts of future climate change on the rice yield in the middle and lower reaches of the Yangtze River, which is one of the most important food production regions in China. Climate data generated by the regional climate Model PRECIS for the baseline (1961–1990) and future (2021–2050) period under IPCC SRES B2 scenario were employed as the input of the rice crop model ORYZA2000. Four experimental schemes were carried out to evaluate the effects of future climate warming, CO₂ fertilization and water managements (i.e., irrigation and rain-fed) on rice production. The results indicated that the average rice growth duration would be shortened by 4 days and the average rice yield would be declined by more than 14% as mean temperature raised by 1.5 °C during the rice growing season in 2021–2050 period under B2 scenario. This negative effect of climate warming was more obvious on the middle and late rice than early rice, since both of them experience higher mean temperature and more extreme high temperature events in the growth period from July to September. The significance effect of the enhanced CO₂ fertilization to rice yield was found under elevated CO₂ concentrations in 2021–2050 period under B2 scenario, which would increase rice yield by more than 10%, but it was still not enough to offset the negative effect of increasing temperature. As an important limiting factor to rice yield, precipitation contributed less to the variation of rice yield than either increased temperature or CO₂ fertilization, while the spatial distribution of rice yield depended on the temporal and spatial patterns of precipitation and temperature. Compared to the rain-fed rice, the irrigated rice generally had higher rice yield over the study area, since the irrigated rice was less affected by climate change. Irrigation could increase the rice yield by more than 50% over the region north of the Yangtze River, with less contribution to the south, since irrigation can relieve the water stress for rice growing in the north region of the study area. The results above indicated that future climate change would significantly affect the rice production in the middle and lower reaches of the Yangtze River. Therefore, the adverse effect of future climate change on rice production will be reduced by taking adaptation measures to avoid disadvantages. However, there is uncertainty in the rice production response prediction due to the rice acclimation to climate change and bias in the simulation of rice yield with uncertainty of parameters accompanied with the uncertainty of future climate change scenario.

Abstract:Net ecosystem carbon dioxide exchange (NEE) above a desert steppe in Inner Mongolia was measured with eddy covariance technique in growing season of 2008. Environmental factors were also observed during the same period. Our results show that the minimum of growing season daily cumulative NEE appeared on August 26 (-1.6 g Cm^-2), while the maximum appeared on June 11 (0.9 g Cm^-2). Monthly cumulative NEE distributed in the growing season unevenly. The minimum of monthly cumulative NEE appeared in June (0.74 g Cm^-2); the maximum appeared in September (-14.94 g Cm^-2). The sum of the growing season NEE was -45.5 g Cm^-2. The most important environmental factor affecting the half-hour average NEE was photosynthetically active radiation. The most important environmental factor affecting the daily cumulative NEE was 20–30 cm soil water content.

Abstract:Silver pomfret (Pampus argenteus) is an important fish species in China, whose fatality is strongly affected by marine salinity. To better understand the tolerance of sliver pomfret to varying environmental salinity at its early developmental stages, the influence of salinity on the activities of five antioxidant enzymes – superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione-S-transferase (GST), and glutathione reductase (GR) – in the kidney and muscle of juvenile silver pomfret was investigated in this study. Divided groups A, B, C, D at random, the juvenile silver pomfrets were then treated with different salinity levels of 25, 20, 15, and 10 with time periods of 24, 48, 96, and 120 h respectively. Generally speaking, the results show that the renal and muscular SOD as well as the renal CAT activities first rise then drop (P < 0.05), while the muscular CAT activity increases with the elapse of treatment time (P < 0.05) and peaked at 96 h, then decreased at 120 h, while the muscular CAT activity in group D increased consistently and peaked at 120 h. The renal GPX activity decreases significantly (P < 0.05) as the salinity drops and treatment time prolongs with its lowest level occurring at 96 h in group D, while the muscular GPX activity increases first then decrease (P < 0.05); moreover the renal and muscular GPX activities vary reversely in compensation. On a whole, the renal and muscular GST and GR activities first rise then drop (P < 0.05) with the drop of salinity and elapse of time. To sum up, the results acquired from study indicate that the salinity decrease could effectively stimulate and enhance the antioxidant enzyme activity in the kidney and muscle of the juvenile silver pomfrets, thus effectively eliminating the excessive reactive oxygen species (ROS) and minimizing the body damage. Characterized by certain sequentiality and tissue specificity, the activation of the antioxidant enzymes could also be inhibited when the salinity varies beyond the tolerance range of the body.

Abstract:The spatial and temporal variability of the spring phytoplankton bloom (SPB) in the central Yellow Sea is studied, using SeaWiFS surface chlorophyll remote-sensing data, AVHRR sea surface temperatures (SST), QuikSCAT sea surface wind speed (SSW) from 1998 to 2009 and the cruise survey data in 2007 and 2009. The influences of the hydrological conditions on the SPB are significant. (1) The rising SST and low SSW in spring play an important role in the development of the SPB. The SPB in the central Yellow Sea occurs primarily in April (from April 3 to April 24) and at this period the mean SST is generally greater than 10 °C, and 24 h averaged SSW is less than 5.4 m/s. The 99% of the SPB occurs when the SST is 9–14 °C and SSW is 0–7.9 m/s. (2) Specifically, the development of the SPB is from April 4 to April 7 and from April 4 to April 22 in 2007 and 2009 respectively. The longer duration of the SPB in 2009 than that in 2007 is related to the high SST in 2009, which is approximately 2 °C greater than that in 2007, and the weak SSW in 2009, which is much lower than that in 2007, which further indicate that these two factors are critical to the duration of the SPB. (3) The horizontal distribution of surface chlorophyll a in 2007 is found to be greater and located more northward than that in 2009. Comparing the spatial coverage of the SPB, the path of the Yellow Sea warm current, which is warmer and salty, and the location of maximum SST reveals that the spatial coverage of the SPB locates in the warmer temperature (>9 °C) and higher salinity (>33) waters in March and this warm and salty water was much more evident in 2007 than that in 2009 because a stronger warm current of the Yellow Sea in winter. (4) The vertical depths of the maximum chlorophyll layer (MCL) appear at three levels: surface, 10 m and 30 m in 2007, whereas the MCL occurs only at a sub-surface level in 2009 which is related to vertical stability of the water column, i.e., the water is vertically mixed in 2007 while vertically stratified in 2009.

Abstract:To understand levels of population differentiation in Pallas’s squirrel (Callosciurus erythraeus) in fragmented habitats, we collected 83 samples from three patches of artificial forest in Hongya County, Sichuan Province, China. Sample numbers from each patch were as follows: 16 from Hanwang (HW), 27 from Muchansi (MCS) and 40 from Yanyandong (YYD). The mitochondrial DNA control region was sequenced and 18 haplotypes were observed. Our results showed that haplotype diversities of the three C. erythraeus populations were similar (0.771, 0.791 and 0.733). Fixation indices (F_st) of pairwise populations were between 0.21 and 0.31, and the estimated gene flow (Nm) was between 1 and 2. Analysis of molecular variance (AMOVA) showed that most molecular variation occurred within populations (74.82%); variances among populations were small but there was significant genetic differentiation. In addition, the neighbour-joining (NJ) tree showed three clades in the phylogenetic tree for population genetic structure. This was confirmed by the median-joining haplotype network. Furthermore, analysis of isolation by distance (IBD) showed that genetic differentiation among the three populations was positively related to geographical distance. However, tests of neutrality and the observed mismatch distribution of pairwise differences between sequences indicated that C. erythraeus populations were relatively stable in the past.

Abstract:Seasonal changes of thermogenic capacity in Melano-bellied oriental voles (Eothenomysmelanogaster) were studied by measurements of body mass, basal metabolic rate (BMR), non-shivering thermogenesis (NST), thermogenic properties of brown adipose tissue (BAT), relative weight of liver mass, mitochondrial protein (MP) content, and activities of mitochondrial cytochrome C oxidase (COX) in autumn (October), winter (December), spring (April) and summer (July), respectively.
Results showed that: (1) Body mass of E.melanogaster was the highest in autumn, and the lowest in summer. The seasonal change in body mass was subject not only by environment temperature but also to other factors such as reproduction, feeding habit and climate in the habitat. Reproductive periods of E.melanogaster were in early spring (February–March) and late autumn (September–October), and therefore, the body mass was higher in spring and autumn. In addition, E.melanogaster feeds on leaves and stems of plants in spring and summer, whereas mainly on fruits in autumn and winter as they contain more energy. The difference in the feeding habit could result in higher body mass in the late half of the year, but lower body mass in winter. The lower body mass in winter provides E.melanogaster with an advantage in motility. (2) The BMR and NST of E.melanogaster was higher in winter than in other seasons, which suggests that the regulating thermogenic capacity is an important adaptive strategy for E.melanogaster. However, there was no difference in relative oxygen consumption (NST–BMR/BMR), suggesting that the regulative capacity of BMR is approximately equal to NST in E.melanogaster. This is different from some small mammal species in north China, which have higher regulative capacity in NST than E.melanogaster. Melano-bellied oriental voles live in mountainous area with subtropical zone monsoon climate and abundant food resource, and therefore have lower regulative capacity in NST, which can reduce an absolute request for energy. The low regulative capacity in NST can also help E.melanogaster to maintain energy balance and stable body temperature. (3) The relative mass of BAT in winter was significantly higher than that in summer. Different seasons significantly affected the MP content of BAT. The MP content of BAT was in the following order: winter > fall > spring > summer. The trend as following was observed for the mitochondrial COX activity of BAT: winter > spring > fall > summer. In experimental conditions, the thermogenic rate of many small mammal species increased under cold acclimation. Short photoperiod alone could also induce E.melanogaster to increase NST and mitochondrial COX activity of BAT. Therefore, ambient temperature and photoperiod are important environmental cues to induce seasonal changes in thermogenic capacity in E.melanogaster. (4) The relative mass of liver in summer was higher than that in other seasons, but no seasonal changes were found among other seasons. The MP contents of liver showed highest level in winter and lowest in spring and summer. Significant seasonal changes were also observed in the mitochondrial COX activity of liver. It increased significantly in winter, but not in other seasons. This indicates that liver participate in adjustment of thermogenesis. These data indicate that both increasing whole-animal thermogenesis rate and thermogenic capacity at the cells of BAT and liver play an important role in the adaption of E.melanogaster to seasonal changes, and they are also closely correlated with the habitat condition and their life habit.