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The objective of this study was to explore the distribution of poisonous plants and soil quality in relation to grassland degradation in the Qinghai-Tibetan Plateau (QTP) by employing poisonous plants characteristics including diversity index, coverage and composition and the soil properties including soil physical, chemical, and biological indicators. The degraded grasslands (DGs) had significantly increased cover and diversity values of poisonous plants compared with the non-DGs (NDGs). Grassland use types had significant effects on the composition and characteristics of poisonous plants. The NDGs had increased levels of soil nutrients and soil enzyme activities, with decreased soil pH and bulk density (BD), indicating a higher and better soil nutrient status compared with DGs. The soil texture, soil pH, and soil BD were very important in affecting the structures of poisonous plants. We concluded that grassland degradation had significant effect on poisonous plants coverage and diversity; conversely, poisonous plants also aggregated the grassland degradation, decreasing the soil fertility in the QTP. [ABSTRACT FROM AUTHOR]

Land disturbances and management approaches can significantly alter the restoration of degraded grasslands. Therefore, understanding the carbon and nitrogen storage accompanying plant and soil physical and chemical properties due to anthropogenic disturbance and different management strategies is important, as it can help us understand not only how ecosystem responds to its dynamics but also the restoration effects of restoration methods. In our study, we investigated carbon, nitrogen storage, plant community alterations and other soil chemical and physical properties regarding artificial grasslands with different restoration years and native grasslands with different degradation levels. We found that artificial grassland establishment significantly increased above- and belowground biomass, but the richness, diversity and evenness indexes had a decreasing trend compared with extremely degraded grasslands. Grazing also had a negative effect on plant communities and diversity indexes. The soil organic carbon (SOC) was highest in non-degraded grasslands (ND). The SOC content had decreased 21.89%, 38.30% and 43.15% with the increase of the grassland degradation compared with ND. The total nitrogen (TN) content was also higher in the ND (0.955kg·m−2) than in either degraded grasslands (0.908kg·m−2, 0.786kg·m−2, and 0.769kg·m−2 for moderately, heavily and extremely degraded, respectively). The total carbon, SOC and TN content were concentrated on the 0–4cm depth, accounting for more than 50% of the total content. We also found that the soil nutrients substantially decreased with increasing restoration years. Furthermore, soil nutrients had a close relationship with plant and soil factors, as reflected by a correlation index. The above-mentioned results indicated that artificial grasslands can be used as an effective method to restore “black-beach” soil grassland. In the long term, however, management interventions should be implemented to prevent the degradation of artificial grasslands. [ABSTRACT FROM AUTHOR]

Understanding the complex effects of biotic and abiotic factors on the composition of vegetation is very important for developing and implementing strategies for promoting sustainable grassland development. The vegetation-disturbance-environment relationship was examined in degraded alpine grasslands in the headwater areas of three rivers on the Qinghai-Tibet Plateau in this study. The investigated hypotheses were that (1) the heterogeneity of the vegetation of the alpine grassland is due to a combination of biotic and abiotic factors and that (2) at a small scale, biotic factors are more important for the distribution of alpine vegetation. On this basis, four transects were set along altitudinal gradients from 3,770 to 3,890 m on a sunny slope, and four parallel transects were set along altitudinal gradients on a shady slope in alpine grasslands in Guoluo Prefecture of Qinghai Province, China. It was found that biological disturbances were the major forces driving the spatial heterogeneity of the alpine grassland vegetation and abiotic factors were of secondary importance. Heavy grazing and intensive rat activity resulted in increases in unpalatable and poisonous weeds and decreased fine forages in the form of sedges, forbs, and grasses in the vegetation composition. Habitat degradation associated with biological disturbances significantly affected the spatial variation of the alpine grassland vegetation, i.e., more pioneer plants of poisonous or unpalatable weed species, such as Ligularia virgaurea and Euphorbia fischeriana, were found in bare patches. Environmental/abiotic factors were less important than biological disturbances in affecting the spatial distribution of the alpine grassland vegetation at a small scale. It was concluded that rat control and light grazing should be applied first in implementing restoration strategies. The primary vegetation in lightly grazed and less rat-damaged sites should be regarded as a reference for devising vegetation restoration measures in alpine pastoral regions. [ABSTRACT FROM AUTHOR]

Abstract: To assess the role of soil seed banks in restoring degraded grasslands in the alpine region of the Qinghai-Tibetan Plateau (QTP), we studied the similarity of species composition between aboveground vegetation and soil seed banks in alpine grasslands at different degradation levels and in revegetated grasslands in different years since restoration across different seasons (spring, summer and autumn). One-way analysis of variance (ANOVA) was applied to compare differences in the soil seed bank among the native grasslands in different degraded states, in the revegetated grasslands across years since restoration and seasonal changes. The Sorenson similarity index and detrended correspondence analysis (DCA) were applied to examine the similarity of species composition in the soil seed bank and aboveground vegetation. It was found that the highest and lowest soil seed density occurred in autumn (October) and summer (July), respectively. We also explored the changes about transient and persistent soil seed banks. Basically, we found that all experimental plots were inclined to choose transient seed banks rather than persistent seed banks expect for non-degraded and 5 year restoration grasslands. There were significant differences in soil seed density among the degraded grasslands and among the different aged revegetated grasslands (P <0.05). Soil seed density increased with decreasing levels of degradation while it increased with age since restoration. We also explored the seed density among three functional groups (grasses, sedges and forbs) and found that forbs had the highest soil seed density. A low similarity of species composition between soil seed banks and aboveground vegetation in the degraded grasslands implied that the seed bank contributed little to the restoration of the aboveground vegetation in these degraded grasslands. A high similarity of species composition between soil seed banks and aboveground vegetation in the artificially restored grasslands indicated that the seed soil bank was important in maintaining the vegetation structure and cover in the established grasslands. [Copyright &y& Elsevier]