羔羊管护须把好“七关”

羔羊对外界环境的适应能力和疾病的抵抗能力较差,且易发生应激反应,因此要保证羔羊早吃初乳、吃好常乳、精心管理、减少应激和发病死亡,提高羔羊成活率,确保其健康地生长。1.把好初生关羔羊出生时用碘酒或酒精做好脐带消毒,并及时清理口。

仔猪的饲养管理

介绍了仔猪饲养管理需要紧抓的"三关",即初生关、开食补料关和断奶关,以期降低仔猪死亡率,提高断奶窝重,保证仔猪健康生长。

提高仔兔成活率的有效措施

本文主要从长毛兔仔兔的初生关、防病关、补饲关和断奶关等四道关口,总结提高仔兔成活率的有效措施,旨在更好地指导长毛兔的生产实践。

A significant carbon sink in temperate forests in Beijing: based on 20-year field measurements in three stands

Numerous efforts have been made to characterize forest carbon （C） cycles and stocks in various ecosystems. However, long-term observation on each component of the forest C cycle is still lacking. We measured C stocks and fluxes in three per- manent temperate forest plots （birch, oak and pine forest） during 2011-2014, and calculated the changes of the components of the C cycle related to the measurements during 1992-1994 at Mr. Dongling, Beijing, China. Forest net primary production in birch, oak, and pine plots was 5.32, 4.53, and 6.73 Mg C ha-1 a-1, respectively. Corresponding net ecosystem production was 0.12, 0.43, and 3.53 Mg C ha-1 a-1. The C stocks and fluxes in 2011-2014 were significantly larger than those in 1992-1994 in which the biomass C densities in birch, oak, and pine plots increased from 50.0, 37.7, and 54.0 Mg C ha-1 in 1994 to 101.5, 77.3, and 110.9 Mg C ha a in 2014; soil organic C densities increased from 207.0, 239.1, and 231.7 Mg C ha-1 to 214.8, 241.7, and 238.4 Mg C ha-l; and soil heterotrophic respiration increased from 2.78, 3.49, and 1.81 Mg C ha-1 a-1 to 5.20, 4.10, and 3.20 Mg C ha-1 a-l. These results suggest that the mountainous temperate forest ecosystems in Beijing have served as a carbon sink in the last two decades. These observations of C stocks and fluxes provided field-based data for a long-term study of C cycling in temperate forest ecosystems.

Satellite-based Estimation of Gross Primary Production in an Alpine Swamp Meadow on the Tibetan Plateau:A Multi-model Comparison

Alpine swamp meadows on the Tibetan Plateau,with the highest soil organic carbon content across the globe,are extremely vulnerable to climate change.To accurately and continually quantify the gross primary production（GPP） is critical for understanding the dynamics of carbon cycles from site-scale to global scale.Eddy covariance technique（EC） provides the best approach to measure the site-specific carbon flux,while satellite-based models can estimate GPP from local,small scale sites to regional and global scales.However,the suitability of most satellite-based models for alpine swamp meadow is unknown.Here we tested the performance of four widely-used models,the MOD17 algorithm（MOD）,the vegetation photosynthesis model（VPM）,the photosynthetic capacity model（PCM）,and the alpine vegetation model（AVM）,in providing GPP estimations for a typical alpine swamp meadow as compared to the GPP estimations provided by EC-derived GPP.Our results indicated that all these models provided good descriptions of the intra-annual GPP patterns（R〉20.89,P〈0.0001）,but hardly agreed with the inter-annual GPP trends.VPM strongly underestimated the GPP of alpine swamp meadow,only accounting for 54.0% of GPP_EC.However,the other three satellite-based GPP models could serve as alternative tools for tower-based GPP observation.GPP estimated from AVM captured 94.5% of daily GPP_EC with the lowest average RMSE of 1.47 g C m^（-2）.PCM slightly overestimated GPP by 12.0% while MODR slightly underestimated by 8.1% GPP compared to the daily GPP_EC.Our results suggested that GPP estimations for this alpine swamp meadow using AVM were superior to GPP estimations using the other relatively complex models.

Are regional precipitation-productivity relationships robust to decadal-scale dry period?

Precipitation(PPT)is the primary climatic determinant of plant growth and aboveground net primary productivity(ANPP)for many of the world’s major terrestrial ecosystems.Thus,relationships between PPT and productivity can provide insight into how changes in climate may alter ecosystem functions globally.Spatial PPT–ANPP relationships for grasslands are found remarkably similar around the world,but whether and how they change during periods of extended climatic anomalies remain unknown.Here,we quantifed how regional-scale PPTANPP relationships vary between an extended wet and a dry period by taking advantage of a 35-year record of PPT and NDVI(as a surrogate for ANPP)at 1700 sites in the temperate grasslands of northern China.We found a sharp decrease in the strength of the spatial PPT–ANPP relationship during an 11-year period of below average PPT.We attributed the collapse of this relationship to asynchrony in the responses of different grassland types to this decadal period of increased aridity.Our results challenge the robustness of regional PPT–productivity if aridity in grasslands is increased globally by climate change.

Carbon-water coupling and its relationship with environmental and biological factors in a planted Caragana liouana shrub community in desert steppe,northwest China

The carbon and water cycle,an important biophysical process of terrestrial ecosystems,is changed by anthropogenic revegetation in arid and semiarid areas.However,there is still a lack of understanding of the mechanisms of carbon and water coupling in intrinsic ecosystems in the context of human activities.Based on the CO,and H,O flux measurements of the desert steppe with the planted shrub Caragana liouana,this study explored the carbon and water flux coupling of the ecosystem by analyzing the variations in gross primary productivity(GPP),evapotranspiration(ET)and water use efficiency(WUE)and discussing the driving mechanisms of biological factors.The seasonal variation in climate factors induced a periodic variation pattern of biophysical traits and carbon and water fluxes.The GPP and ET fluctuated in seasons,but the WUE was relatively stable in the growing season.The GP,ET and WUE were significantly driven by global radiation(R,),temperature(T,and T),water vapor pressure deficit,leaf area index and plant water stress index(PWSI).However,R,temperature and PWSI were the most important factors regulating WUE.R,and temperature directly affected WUE with a positive effect but indirectly inhibited WUE by rising PWSl.Plant water stress inhibited photosynthesis and transpiration of the planted shrub community in the desert steppe.When the plant water stress exceeded a threshold(PWSI>0.54),the WUE would decrease since the GPP responded more quickly to the plant water stress than ET.Our findings suggest that policies related to large-scale carbon sequestration initiatives under afforestation must first fully consider the status of water consumption and WUE.

Assessing the Ecological Carrying Capacity of Countries along the Belt and Road

The Belt and Road Initiative(B&R Initiative)is a crucial strategy to promote regional sustainable development in the new era.However,the realization of the B&R Initiative faces huge challenges because of the dual characteristics of a fragile eco-environment and strong dependence on ecological resources for economic development in the Belt and Road(B&R)countries.The ecological carrying capacity(ECC)is a crucial indicator for evaluating regional sustainable development.From the perspective of the relationship between the supply and consumption of ecological resources,this study uses net primary productivity data to measure the supply capacity of ecological resources,and it uses the agricultural production and trade data provided by the United Nations Food and Agriculture Organization to measure the level of ecological resource consumption.These supply and consumption data are then used to assess the ECC and ecological carrying status(ECS)of the B&R countries in 2017.The results show that:(1)The ECC of the B&R is 11.097 billion people;the ecosystem can also support 6.433 billion people,and the ECC is in a state of rich and surplus.(2)The ECS is polarized among the regions and countries along the B&R.Of the 65 countries,the ECC of 40 countries is in a rich and surplus state,mainly in Mid-East Europe and Southeast Asia,while the ECC of 19 countries is in severe overload,mainly in West Asia/Middle East.(3)Although the ecosystems still have ample carrying space in countries along the B&R,ecological protection is still facing enormous challenges during the implementation of the B&R Initiative combined with the internationally recognized ecological protection standards as well as the forecasts of the population and economic development.As the core content of building a new international trade network,the B&R Initiative will help to solve the spatial mismatch between the supply and consumption of ecological resources,which provides a new opportunity to coordinate the contradiction between the ecological protection and social demands of the B&R countries.