Consequences of plateau pika disturbance on plant-soil carbon and nitrogen in alpine meadows.

The presence of burrowing mammals can have extensive effects on plants and soils, creating bare soil patches in alpine meadows and potentially altering plant-soil carbon (C) and nitrogen (N). This study focuses on the plateau pika (Ochotona curzoniae) to examine the responses of plant-soil C and N to a small burrowing mammal from quadrat scale to plot scale. The density of active burrow entrances in disturbed plots was used as an indicator of the disturbance intensity of plateau pikas. The study found that the below-ground biomass (BGB) and its C and N, as well as soil C and N concentrations were significantly lower in bare soil areas than in vegetated areas and undisturbed plots. This shows that the quadrat scale limited the estimation of the C and N sequestration potential. Therefore, further research on the plot scale found that the disturbance by plateau pika significantly reduced plant biomass and BGB carbon stock. However, plateau pika did not affect soil C and N stocks or ecosystem C and N stocks. These findings suggest the bare soil patches formed by plateau pika caused plant and soil heterogeneity but had a trade-off effect on plant-soil C and N stocks at the plot scale. Nevertheless, moderate disturbance intensity increased the C and N sequestration potential in grassland ecosystems. These results provide a possible way to estimate how disturbance by small burrowing mammals affects C and N cycling in grassland ecosystems while accurately assessing the effects of small burrowing mammal densities on C and N in grassland ecosystems.

Small Semi-Fossorial Herbivores Affect the Allocation of Above- and Below-Ground Plant Biomass in Alpine Meadows.

Small semi-fossorial herbivores can affect plant aboveground biomass (AGB) in grasslands and possibly alter the allocation of AGB and belowground biomass (BGB). In this study, plateau pika (Ochotona curzoniae) was used to investigate such effects at three alpine meadow sites on the Eastern Tibetan Plateau, where pairs of disturbed vs. undisturbed plots were randomly selected and sampled. We also explored the relationships between soil properties and BGB/AGB across the plots in the presence and absence of plateau pikas, respectively. We found that BGB and BGB/AGB were 11.40 and 8.20% lower in the presence of plateau pikas than in their absence, respectively. We also found that the BGB/AGB was positively related to soil moisture and soil total nitrogen (STN) in the absence of plateau pikas. In contrast, BGB/AGB was positively related to STN, soil organic carbon (SOC), soil carbon/nitrogen (C/N), and soil total phosphorus in the presence of plateau pikas. These factors indicated plateau pika disturbance increased AGB allocation. The relationship between AGB and BGB of alpine meadow plants to soil variables was also different between sites with and without plateau pika disturbance. In conclusion, small semi-fossorial herbivore disturbance is likely to alter grassland carbon stock and should be well controlled for sustainable conservation and management of alpine meadows on the Tibetan Plateau.

Effects of Plateau Pika Disturbance on the Spatial Heterogeneity of Vegetation in Alpine Meadows.

Herbivory is one of the important factors that influence spatial heterogeneity of vegetation in grasslands. In this study, we focused on plateau pika (Ochotona curzoniae) to investigate the effects of the presence of small semi-fossorial herbivores and their disturbance intensity on the spatial heterogeneity of vegetation in alpine meadows across three sites in the Qinghai-Tibetan Plateau. A random stratified paired sampling method was used to collect vegetation data, and plant species richness at both fine and coarse scales were used to estimate the spatial heterogeneity of vegetation. This study showed that the presence of plateau pikas led to higher spatial heterogeneity of vegetation in alpine meadows, which increased linearly as the disturbance intensities of plateau pikas increased. The findings of this study demonstrate that small semi-fossorial herbivores have an important impact on the spatial heterogeneity of vegetation, and present a possible approach for estimating the effect of the presence of a small semi-fossorial herbivore and its disturbance intensity on the spatial heterogeneity of vegetation in grasslands.

Responses of plant productivity and soil nutrient concentrations to different alpine grassland degradation levels.

Although grassland degradation simultaneously affects plant productivity and soil nutrient concentrations, the relationship between plant productivity and soil nutrient concentrations during the process of grassland degradation is not yet well documented. A 4-year survey in the Qinghai-Tibetan Plateau was conducted to simultaneously investigate the relationships between plant productivity and soil nutrient concentrations in an alpine grassland at an overall degradation level and individual degradation levels. Our results showed that the total plant, sedge, and forb biomasses decreased, whereas the grass and legume biomasses first increased and then decreased as the level of alpine grassland degradation increased. Soil organic carbon (C), total nitrogen (N), total phosphorus (P), available N, and available P concentrations also decreased with the increase in degradation level. Our results also showed that plant productivity was positively correlated with soil nutrient concentrations (soil organic C, total T, total P, available N, available P) at an overall degradation level, whereas plant productivity was positively correlated with only the soil organic C concentration at each degradation level. Our findings suggested that the alpine grassland degradation conditions had different effects on the plant productivity of four functional groups (sedges, grasses, legumes, forbs) and affected the relationship between plant productivity and soil nutrient concentrations.

FOXD1 promotes breast cancer proliferation and chemotherapeutic drug resistance by targeting p27.

Forkhead transcription factors are essential for diverse processes in early embryonic development and organogenesis. As a member of the forkhead family, FOXD1 is required during kidney development and its inactivation results in failure of nephron progenitor cells. However, the role of FOXD1 in carcinogenesis and progression is still limited. Here, we reported that FOXD1 is a potential oncogene in breast cancer. We found that FOXD1 is up-regulated in breast cancer tissues. Depletion of FOXD1 expression decreases the ability of cell proliferation and chemoresistance in MDA-MB-231 cells, whereas overexpression of FOXD1 increases the ability of cell proliferation and chemoresistance in MCF-7 cells. Furthermore, we observed that FOXD1 induces G1 to S phase transition by targeting p27 expression. Our results suggest that FOXD1 may be a potential therapy target for patients with breast cancer.

[Application of Narcotrend-assisted anesthesia in-depth monitor during escharectomy and skin transplantation in burn patients with target-controlled infusion of remifentanil hydrochloride and propofol].

OBJECTIVE: To evaluate the feasibility and efficacy of Narcotrend (NT) monitor in monitoring the depth of anesthesia in severely burned patients with target-controlled infusion (TCI) of remifentanil hydrochloride and propofol during perioperative period. METHODS: Eighty patients with severe burn hospitalized from February to November 2011, to whom eschar excision was performed within one week after injury, were enrolled. They were classified into II to III grade according to the American Society of Anesthetists classification, and their total burn area ranged from 31% to 50%TBSA, or full-thickness burn area from 11% to 20% TBSA. Patients were divided into trial group (monitoring depth of anesthesia with routine method and NT monitor) and control group (monitoring depth of anesthesia with routine method) according to the random number table, with 40 cases in each group. All patients received TCI of remifentanil hydrochloride and propofol to induce and maintain anesthesia. During the operation, the anesthesia level of NT monitor used in the trial group was maintained from grade D1 to E0, while the fluctuation of mean arterial pressure (MAP) and heart rate of patients in control group was maintained around the basic values within a range of 20%, and on the basis of which, concentrations of two narcotics were adjusted. Concentrations of remifentanil hydrochloride and propofol during maintenance of anesthesia were recorded. The duration from drug withdrawal to waking from anesthesia (including the duration from drug withdrawal to eye opening by calling and the duration from drug withdrawal to orientation recovery) of patients was recorded. Values of MAP and heart rate at admission into the operation room, loss of consciousness, 2 min after intubation, before operation, 2, 15, and 30 min after the beginning of operation, and the end of operation were recorded. The prediction probability (P(k)) of NT stage (NTS) and NT index (NTI) in trial group, and that of MAP and heart rate in control group for two durations from drug withdrawal to waking form anesthesia were recorded. The administration of vasoactive drugs and intraoperative awareness of patients in two groups were recorded. Data were processed with t test, analysis of variance, and chi-square test, and the relationship between NTS, NTI, MAP, heart rate and their corresponding P(k) for the duration from drug withdrawal to orientation recovery was processed with Spearman correlation analysis. RESULTS: Maintained target effect-site concentration of remifentanil hydrochloride and target plasma concentration of propofol of patients were obviously lower in trial group [(2.62 ± 0.35) ng/mL, (3.84 ± 0.22) µg/mL] than in control group [(2.95 ± 0.21) ng/mL, (4.16 ± 0.31) µg/mL, with t values respectively -5.113 and -5.324, P values all below 0.01]. The duration from drug withdrawal to eye opening by calling and the duration from drug withdrawal to orientation recovery were obviously shorter in trial group [(10.2 ± 0.7) min, (11.1 ± 1.0) min] than in control group [(11.3 ± 1.0) min, (13.1 ± 0.7) min, with t values respectively -5.740 and -10.806, P values all below 0.01]. The MAP (except for 2 min after intubation) and the heart rate of patients in both groups were lower at the time points from loss of consciousness to the end of operation than at the time of entering operation room (with F values respectively 12.074, 36.425, P values all below 0.01 in trial group and F values respectively 21.776, 35.759, P values all below 0.01 in control group). The statistically significant difference between two groups in MAP level was only observed at the time of loss of consciousness (t = 3.985, P < 0.01). MAP level was close in two groups at other time points. Heart rates of patients in two groups were close during perioperative period. P(k) values of NTS and NTI for the duration from drug withdrawal to eye opening by calling (0.937 ± 0.025, 0.899 ± 0.049) were obviously higher than those of MAP and heart rate for this duration (0.579 ± 0.057, 0.536 ± 0.039, F = 900.337, P < 0.01). P(k) values of NTS and NTI for the duration from drug withdrawal to the orientation recovery (0.901 ± 0.031, 0.868 ± 0.046) were significantly higher than those of MAP and heart rate for this duration (0.532 ± 0.060, 0.483 ± 0.044, F = 890.895, P < 0.01). NTS, NTI, MAP, and heart rate were respectively negative, positive, positive and positive in correlation with their P(k) values for the duration from drug withdrawal to the orientation recovery (with r values from -0.734 to 0.682, P values all below 0.01). There was no statistically significant difference between two groups in administration of vasoactive drugs. No intraoperative awareness occurred. CONCLUSIONS: Application of Narcotrend monitor in monitoring the depth of anesthesia in severely burned patients during perioperative period with TCI of remifentanil hydrochloride and propofol is beneficial to reducing dosage of narcotics and shortening duration of recovery from anesthesia, and it can accurately predict the level of consciousness of patients at the time of withdrawal of anesthesia.

[Changes of plant community structure and species diversity in degradation process of Shouqu wetland of Yellow River].

Shouqu wetland of Yellow River plays important roles in the ecological security of the lower reaches of Yellow River. By the method of replacing time series with spatial sequence, an investigation was made on the changes of plant species diversity in the process of the natural degradation of the wetland. A comparison was also made to study the effects of artificial drainage on the plant species diversity. The results indicated that in the degradation process of Shouqu wetland, i.e., from swamp to swamp meadow, to alpine meadow, and to steppe meadow, the dominant plants followed the pattern of hygrophytes being gradually replaced by mesophytes and xerophytes, richness index and diversity index were increasing while dominance index was decreasing, and evenness index decreased first and increased then. The species diversity had an overall increasing trend. After artificial drainage, the proportion of poisonous weeds in the plant community increased, resulting in the increase of richness index and diversity index, slight decrease of evenness index and dominance index, and gradual decrease of Sorensen index. Artificial drainage made the habitat drying, which provided a chance for some mesophytes to invade, resulting in the increase of diversity index and richness index and the decrease of evenness index. On the whole, artificial drainage increased the plant diversity in the community, but the increase accompanied with increasing poisonous weeds, and thus, led the Shouqu wetland degraded into weed type wetland.

[Early warning and risk assessment of snow disaster in pastoral area of northern Xinjiang].

Based on the analysis of animal husbandry production and of distribution characteristics of snow disaster in northern Xinjiang, and by using RS and GIS techniques and field survey data, 9 early warning factors were selected from the three subsystems of grassland' s disaster-resistant capability, livestock's disaster-bearing capacity, and disaster-causing potential, and the death rate of livestock caused by snow disaster was used as a factor of risk assessment. An index system of snow disaster' s early warning and risk assessment for completely grazing grassland was established, and the early warning model of snow disaster, its distinguishing model, and risk assessment model were built by using multi-hierarchical synthetic and multi-objective linear weight function methods to predict the resistant capability of grassland and livestock against snow disaster, and to assess the potential risk loss from snow disaster in northern Xinjiang. The accuracy of the early warning model and risk assessment model was 85% and 72% , respectively.

[Assessment on vegetation restoration capacity of several grassland ecosystems under destroyed disturbance in permafrost regions of Qinghai-Tibet Plateau].

Vegetation restoration capacity of disturbed grassland ecosystem is one of the important components in assessing the influence of human engineering activities on the grassland ecosystems in permafrost region of Qinghai-Tibet Plateau. After comparing the features of vegetation communities, plant species diversity, grassland primary productivity, and economic group between disturbed and undisturbed communities, the comprehensive vegetation restoration capacity of several grassland communities under destroyed disturbance was assessed by using comprehensive assessment index. The results showed that the restoration of cover and community composition was obvious after 26 years natural restoration, being better for alpine steppes than for alpine meadows. However, the cover of disturbed communities was less than that of undisturbed communities. The restoration of plant species diversity in Stipa purpurea steppe was better than that in other grassland types. The biomass of standing plants restored from 0 to 148.8-489.6 g x m(-2), and that of Kobresia tibetica meadow was the highest (489.6 g x m(-2)). The palatable plants of disturbed communities were lower than those of undisturbed communities except for K. tibetica meadow, in which, the palatable plants were not changeable between disturbed and undisturbed communities. The comprehensive vegetation restoration capacity of alpine steppes was better than that of alpine meadows.