Effects of converting natural grasslands into planted grasslands on ecosystem respiration： a case study in Inner Mongolia, China

With increasingly intensifying degradation of natural grasslands and rapidly increasing demand of high quality forages, natural grasslands in China have been converted into planted grasslands at an unprecedented rate and the magnitude of the conversion in Inner Mongolia is among the national highest where the areal extent of planted grasslands ranks the second in China. Such land-use changes（i.e., converting natural grasslands into planted grasslands） can significantly affect carbon stocks and carbon emissions in grassland ecosystems. In this study, we analyzed the effects of converting natural grasslands into planted grasslands（including Medicago sativa, Elymus cylindricus, and M. sativa＋E. cylindricus） on ecosystem respiration（F（eco）） in Inner Mongolia of China. Diurnal F（eco） and its components（i.e., total soil respiration（F（ts））, soil heterotrophic respiration（F（sh）） and vegetation autotrophic respiration（F（va））） were measured in 2012（27 July to 5 August） and 2013（18 July to 25 July） in the natural and planted grasslands. Meteorological data, aboveground vegetation data and soil data were simultaneously collected to analyze the relationships between respiration fluxes and environmental factors in those grasslands. In 2012, the daily mean F（eco） in the M. sativa grassland was higher than that in the natural grassland, and the daily mean F（va） was higher in all planted grasslands（i.e., M. sativa, E. cylindricus, and M. sativa＋E. cylindricus） than in the natural grassland. In contrast, the daily mean F（ts） and F（sh） were lower in all planted grasslands than in the natural grassland. In 2013, the daily mean F（eco）, F（ts） and F（va） in all planted grasslands were higher than those in the natural grassland, and the daily mean F（sh） in the M. sativa＋E. cylindricus grassland was higher than that in the natural grassland. The two-year experimental results suggested that the conversion of natural grasslands into planted grasslands can generally increase the F（eco） and the increase in F（eco） is more pronounced when the plantation becomes more mature. The results also indicated that F（sh） contributed more to F（eco） in the natural grassland whereas F（va） contributed more to F（eco） in the planted grasslands. The regression analyses show that climate factors（air temperature and relative humidity） and soil properties（soil organic matter, soil temperature, and soil moisture） strongly affected respiration fluxes in all grasslands. However, our observation period was admittedly too short. To fully understand the effects of such land-use changes（i.e., converting natural grasslands into planted grasslands） on respiration fluxes, longer-term observations are badly needed.

Vegetation recovery after fire in mountain grasslands of Argentina

Fire is a natural disturbance occurring every few years in many grasslands ecosystems. However, since European colonization, fire has been highly reduced or even suppressed in Argentinean grasslands, fostering ignitable material accumulation. This has led to occasional catastrophic controldemanding fire events, extended for larger areas. The aims of this work are to study vegetation recovery and change after a non-natural fire event in mountain grasslands. The study area is located in the Ventania mountain system, mid-eastern Argentina. We studied vegetation recovery after fire(January 2014) in two different communities: grass-steppes(grasslands) and shrub-steppes(open low shrublands). We measured vegetation cover, species richness and bare ground percentage in burned and unburned areas 1, 4, 8, 11 and 23 months after fire. Vegetation surveys were also performed at the end of the growing season(December) 11 and 23 months after fire. Data were analyzed using regression analysis, ANOVA and multivariate analysis(NMS, PERMANOVA). Both communities increased their vegetation cover at the same rate, without differences between burned and unburned areas after two years. Species richness was higher in shrublands and their recovery was alsofaster than in grasslands. Considering functional composition, besides transient changes during the first year after fire, there were no differences in abundance of different functional vegetation groups two years after fire. At the same time, shrublands showed no differences in species composition, while grasslands had a different species composition in burned and unburned plots. Also, burned grassland showed a higher species richness than unburned grassland. Data shown mountain vegetation in Pampas grassland is adapted to fire, recovering cover and richness rapidly after fire and thus reducing soil erosion risks. Vegetation in mountain Pampas seems to be well adapted to fire, but in grasslands species composition has changed due to fire. Nonetheless, these changes seem to be not permanent since prefire species are still present in the area.

Biomass of Natural Grassland under Different Enclosure Conditions

Taking natural grassland on the northern slope of the Qilian Mountain for example, this paper investigated and compared aboveground and belowground biomass of grassland in multi-year enclosure(20 years), one-year enclosure, control areas(natural grazing areas). The results showed that coverage and height of the enclosure sample plots were significantly higher than that of natural grazing area(P <0.05); mean aboveground biomass of grassland: multi-year enclosure(316.58 g/m^2) > one-year enclosure area(299.07 g/m^2) > multi-year enclosure control area(254.39 g/m^2) > one-year enclosure control area(187.37 g/m^2); belowground biomass: multi-year enclosure(2,906.90 g/m^2) > one-year enclosure area(2,587.26 g/m^2) > multi-year enclosure control area(2,378.93 g/m^2) > one-year enclosure control area(2,029.17 g/m^2); mean aboveground biomass of natural grassland was 263.60 g/m^2, mean belowground biomass 2,225.56 g/m^2; ratio of belowground biomass to aboveground biomass varied between 6.79 and 12.90, distribution of belowground biomass and aboveground biomass in each plot showed significant differences(P <0.05). Enclosure was favorable for improving the coverage and biomass of natural grassland plant communities in the Qilian Mountains.

Forage Forest in Natural Grassland:Important Role and Development Recommendations

In order to increase the productivity of grassland animal husbandry,reduce natural disasters,curb grassland degradation and solve some problems of animal husbandry development in Inner Mongolia,we should actively develop feed shrubs.Forage forests can supplement the shortage of feed caused by seasonal difference and natural disasters in natural grasslands in winter and spring,solve the difficulties in storage and transportation of feed and shortage of funds,regulate the climate,improve the soil fertility,proof wind and fix sand,thereby promoting the benign cycle of grassland ecology.In the natural grasslands of Inner Mongolia,shrubs or small arbors such as Caragana microphylla,Caragana korshinskii Kom,Hedysarum scoparium Fisch et May,Hedysarum mongolicum Turcz,Lespedeza bicolor Turcz,Hippophae rhamnoides Linn,Ulmaceae macrocarpa Hance and Kochia prostrata(L.)Schrad can be used to create forage forests.Scientific research should be actively carried out on the harvesting and cutting period,planting scale,feeding methods and breeding of improved varieties of forage forests.

Current Distribution of Vegetation Resources in Yunnan-Guizhou Plateau and Mechanism Research of Its Effects on Rocky Desertification Process

Yunnan-Guizhou Plateau is the core area of the rocky desertification in the Chinese southwest Karst regions, and the existing studies are very limited to describe the process of rocky desertification quantitatively. The vegetation resources are applied as the key indicators in quantitative description of the degree of rocky desertification damage, and the previous methods using only remote sensing datasets are not competent to distinguish the detailed information of vegetation type, coverage and patch fragmentation on a large scale. Previous research shows that the technology of unmanned aerial vehicle and the estimation software of fraction vegetation coverages and patches could be accurately and rapidly to exploit vegetation resource information. In this project, current distribution of vegetation resources in Yunnan-Guizhou Plateau was clarified to reveal the influence mechanism of the rocky desertification. The control factors of rocky desertification distribution and the driving reasons of its dynamic changes were explained by the data of terrain, climate, population, economics and policy. Therefore, it could get the current distribution of vegetation resources in Yunnan-Guizhou Plateau, especially the grassland resources could be updated, which could not provide research foundations and scientific implications for resolving the rocky desertification, but also could provide valuable background information for the programs of restoring ecological environment and increasing local people's income in Yunnan-Guizhou Plateau.

Grazing Pressure and Plant Functional Types in Puna Highlands,Northwestern Argentina

The Puna grasslands support grazing systems that produce meat and wool in multi-species herds,especially from llama(Lama glama)and sheep.However,it is yet unknown whether grazing pressure can modify grassland structure and Plant Functional Types diversity and cover in Puna grasslands.We analyzed the relationship between grazing pressure and Plant Functional Types by comparing transects located near stockyards(high grazing pressure)and far from them(low pressure)and by evaluating the relationship between the Plant Functional Types cover to a Grazing Pressure Index(GPI).This index incorporates the heterogeneity of traditional pastoral management.At two ecological sites(Ciénego and Tolar),we sampled paired transects(near-far).Plots near and far from corrals were similar in all the variables measured except for plots in Tolar,which tend to have higher total cover,possibly due to fecal fertilization near stockyards.Furthermore,we recorded an increase in total cover and grass cover at higher GPI in Ciénego,while in Tolar we found lower values of total cover and herbaceous dicotyledonous cover at intermediate intensities of GPI.The only negative relationship found was the cover of clonal and non-clonal shrubs,possibly explained by the greater use of these shrubs as firewood near stockyards.In summary,our study does not show important changes in Plant Functional Types as a function of grazing pressure in the studied grasslands probably because grazing pressure is diluted or diminished when livestock rotates in different areas and grazing durations vary.Finally,the long grazing history with which the Puna has evolved could also contribute to the co-structuration between native vegetation and livestock farming.

A large forage gap in forage availability in traditional pastoral regions in China

Forage supply has been stressed due to the rapid increase in China's livestock consumption.However,the long-term dynamics of the relationships between forage demand and multi-sourced supply are not understood.Here,we examine the annual forage demand,or practical carrying capacity(PCC),and supply,or theoretical carrying capacity(TCC)from 2000 to 2019 in China.We construct a forage supply-demand index(FSDI)to represent the forage supply pressure using MODIS-derived net primary productivity products and provincial statistical datasets,and we consider two scenarios.First,natural grasslands are the sole source of forage.Second,natural grassland forage supply is supplemented with straw crops.We find an increase in PCC in northwestern China's major pastoral and agropastoral provincial regions,including Inner Mongolia,Gansu,Ningxia and Qinghai,at rate of 0.24-3.59 million sheep units(SU)a year.As the primary source of forage,the theoretical carrying capacity of natural grasslands(TCCgrass)expanded at a rate of 3 million SU/yr nationally.Crop straws fed 126.58 million SU nationally in 2019,which accounted for 11.3%of the total practical carrying capacity and alleviated the forage supply pressure by reducing FSDI by 26.56%.During 2000–2019,the theoretical carrying capacity of straw crops(TCCcrop)increased rapidly from 76.5 million SU to 126.6 million SU,which accounted for 10%-15%of the total forage supply at the national scale.We also discovered large carrying capacity gaps(TCCgap)in the northwestern pastoral provincial regions of Inner Mongolia,Xinjiang,Gansu,and some agricultural provinces such as Shandong and Henan,when we considered forage supply from both natural grasslands and straw crops.Our findings showed a large forage gap in the traditional pastoral regions,and we also discussed green fodder as a potential solution for balancing the supply of and demand for forage,which may shed light on crop and forage planning.