本文選題：草原生態(tài)系統(tǒng) + 降水格局　； 參考：《內(nèi)蒙古大學(xué)》2015年碩士論文

【摘要】：當(dāng)前人類活動的加劇顯著地影響著全球大氣循環(huán)的格局。多個大氣循環(huán)模型預(yù)測：年際間降水波動增大、極端降水事件(如：極端干旱和強(qiáng)降雨)發(fā)生頻率增加將是未來全球水分循環(huán)變化的主要特征。水分是干旱、半干旱區(qū)草原植物生長發(fā)育的限制性資源。而草原生態(tài)系統(tǒng)是陸地生態(tài)系統(tǒng)中對降水變化非常敏感的系統(tǒng)。迄今為止,關(guān)于降水變化對我國草原生態(tài)系統(tǒng)會產(chǎn)生怎樣的影響,我們的認(rèn)識還相當(dāng)有限。研究群落與物種對降水變化的響應(yīng),對于我們深刻認(rèn)識生態(tài)系統(tǒng)的響應(yīng)至關(guān)重要。本實(shí)驗依托中國科學(xué)院內(nèi)蒙古草原站完全控水防雨棚實(shí)驗平臺,利用控制實(shí)驗的手段,探討了生長季不同降水總量和降水分布格局對內(nèi)蒙古典型草原群落與物種水平的影響。取得的主要結(jié)論如下：(1)土壤平均含水量隨著生長季降水量的增加而升高,表層(0-20cm)土壤水分的波動減小,總體水分波動增加；降水分配格局的改變雖然對土壤平均含水量沒有顯著影響,但是卻增加了土壤水分的總體變異。(2)群落地上生產(chǎn)力隨著生長季降水量的增加而增加,和土壤平均含水量之間存在顯著的線性關(guān)系。生長季前期和中期的降水量比值為1：1時,群落地上生物量顯著低于其他格局的處理。生長季降水量和降水格局的改變對地下生物量沒有顯著影響。(3)群落蓋度隨著生長季降水量的增加而升高,尤以增加生長季中期降水量的效果最為顯著。生長季降水總量和降水格局對群落多樣性沒有顯著影響；功能群之間比較發(fā)現(xiàn),多年生叢生禾草和多年生根莖禾草生物量隨著降水總量的增多而增加；多年生雜類草和一、二年生植物對降水總量的變化響應(yīng)不顯著。降水格局的改變對多年生叢生禾草、多年生根莖禾草、多年生雜草和一、二年生植物四個功能型組成均沒有顯著影響。(4)物種水平上,西伯利亞羽茅和大針茅的高度、蓋度和多度隨著降水總量的增加先增加后減小,生物量與土壤平均含水量之間存在著較好的線性關(guān)系；苔草的高度、蓋度和多度和生物量在整個降水范圍內(nèi)并沒有顯著差異；羊草的高度、蓋度、多度和生物量均隨降水量的增加而增加,生物量與土壤平均含水量之間存在較好的線性關(guān)系。降水分配格局的變化對四個物種的高度、蓋度、和密度沒有顯著影響,降水格局變化對西伯利亞羽茅和羊草的生物量均無顯著影響。苔草和大針茅的生物量在前期與中期降水量之比為1：8的處理下顯著高于其他處理水平。降水格局處理中四個物種的生物量與土壤平均降水量之間均無顯著的線性關(guān)系。
[Abstract]:The aggravation of human activities has significantly affected the pattern of global atmospheric cycle. Several atmospheric cycle models predict that the increase of interannual precipitation fluctuation and the increase of the frequency of extreme precipitation events (such as extreme drought and heavy rainfall) will be the main characteristics of global water cycle changes in the future. Water is a restricted resource for the growth and development of grassland plants in arid and semiarid areas. Grassland ecosystem is very sensitive to precipitation change in terrestrial ecosystem. So far, our understanding of the impacts of precipitation changes on grassland ecosystems in China is rather limited. It is very important for us to study the response of communities and species to precipitation changes. Based on the experimental platform of the Inner Mongolia steppe station of the Chinese Academy of Sciences, the effects of different precipitation amount and precipitation distribution pattern on the level of typical grassland communities and species in Inner Mongolia were studied by means of control experiments. The main conclusions are as follows: (1) the average water content of soil increases with the increase of precipitation in growing season, but the fluctuation of soil moisture decreases and the fluctuation of total water increases with the increase of precipitation in the growth season. Although the change of precipitation distribution pattern had no significant effect on the average soil water content, it increased the total variation of soil water content. 2) the aboveground productivity of the community increased with the increase of precipitation in the growing season. There was a significant linear relationship between soil moisture content and soil water content. When the precipitation ratio of the early and middle growing season was 1:1, the aboveground biomass of the community was significantly lower than the treatment of other patterns. The change of precipitation and precipitation pattern in growing season had no significant effect on the underground biomass. The coverage of community increased with the increase of precipitation in growing season, especially in the middle of growing season. The total precipitation and precipitation pattern in growing season had no significant effect on community diversity. The results of functional group comparison showed that the biomass of perennial herbage and perennial rhizomatous grasses increased with the increase of total precipitation, and that of perennial hybrid grasses and I. The response of biennial plants to the change of total precipitation was not significant. The change of precipitation pattern had no significant effect on the height of the four functional types of perennial herbaceous grasses, perennial rhizomatous grasses, perennial weeds and first and second year plants. Coverage and abundance increased first and then decreased with the increase of total precipitation, and there was a good linear relationship between biomass and soil average water content, but there was no significant difference in height, coverage and abundance and biomass of Carex spp in the whole precipitation range. The height, coverage, abundance and biomass of Leymus chinensis increased with the increase of precipitation, and there was a good linear relationship between biomass and soil water content. The change of precipitation distribution pattern had no significant effect on the height, coverage and density of four species, while the change of precipitation pattern had no significant effect on the biomass of Siberian fescue and Leymus chinensis. The biomass of Carex lanceolata and Stipa grandis was significantly higher than that of other treatments when the ratio of precipitation was 1:8. There was no significant linear relationship between the biomass of the four species and the average precipitation in the precipitation pattern treatment.
【學(xué)位授予單位】：內(nèi)蒙古大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：S812

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本文編號：2035811