發(fā)布時(shí)間：2018-01-18 02:36

  本文關(guān)鍵詞：上海城市廢棄地雜草種子庫季相動(dòng)態(tài)與城鄉(xiāng)差異　出處：《華東師范大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 廢棄地 雜草種子庫 地上群落 季相動(dòng)態(tài) 城鄉(xiāng)差異

【摘要】：快速城市化引發(fā)的生境退化、外來種入侵等生態(tài)環(huán)境問題,對(duì)城市植物多樣性產(chǎn)生了諸多影響。雜草作為城市植被的三大組分之一,具有對(duì)異質(zhì)化生境敏感性高、可塑性強(qiáng)及適應(yīng)對(duì)策多樣的特點(diǎn),是研究城市化對(duì)植被影響及其響應(yīng)的模式對(duì)象。探究其土壤種子庫在城鄉(xiāng)梯度上的差異,及其與地上雜草群落間的關(guān)系,有助于揭示城市化對(duì)雜草物種多樣性的影響。本研究以上海廢棄地雜草土壤種子庫為研究對(duì)象,在城區(qū)-城郊-郊區(qū)城市化梯度上,選取24個(gè)樣地進(jìn)行春秋兩季的群落學(xué)調(diào)查,并采集土壤開展種子庫萌發(fā)實(shí)驗(yàn),進(jìn)而分析雜草土壤種子庫的種類、密度、物種多樣性的城鄉(xiāng)差異,比較其與地上雜草群落物種組成的相似性。主要研究結(jié)果如下:1)上海城市廢棄地雜草種子庫以一年生(尤其是夏季一年生)、低矮類型、鄉(xiāng)土種為主;秋季的種子密度(2675粒/m2)遠(yuǎn)高于春季(838粒/m2)。在城區(qū)-城郊-郊區(qū)梯度上,一年生比例、低矮類型比例均呈現(xiàn)增加趨勢(shì),而種子密度和外來種的比例(約40%)無明顯城鄉(xiāng)差異。2)上海城市廢棄地雜草土壤種子庫和地上雜草群落的豐富度和Shannon-Wiener 指數(shù)在城鄉(xiāng)梯度上均無明顯差異。其中地上群落春季的豐富度和Shannon-Wiener指數(shù)分別為32種和3.0,秋季分別為22種和2.6;土壤種子庫春季的豐富度和Shannon-Winener指數(shù)分別為11種和2.0,秋季分別為8種和1.7。3)上海城市廢棄地雜草土壤種子庫物種組成與地上群落間存在顯著差異。以Jaccard系數(shù)表征物種相似性,春季地上植被群落與地下土壤種子庫間,城區(qū)(0.14±0.06)顯著低于城郊(0.24±0.08);秋季地上植被與春季地下土壤種子庫間,城區(qū)(0.09±0.06)顯著低于郊區(qū)(0.17±0.06)。4)上海城市廢棄地雜草的物種組成,無論在土壤種子庫還在地上群落,均表現(xiàn)出明顯的春秋季節(jié)差異。春秋兩季間的相似性(Jaccard系數(shù))均在2.5以下,并且土壤種子庫春秋兩季的相似性(0.11±0.05)在城區(qū)顯著低于地上群落(0.20±0.03)。這表明高度的城市化導(dǎo)致了地下地上間在季相變化上的不同步。綜上所述,上海城市廢棄地雜草種子庫以低矮型和夏季一年生為主。人為干擾導(dǎo)致的較高外來種比例以及土壤種子庫與地上群落間的低相似性,使得城市化這一個(gè)綜合環(huán)境因子對(duì)廢棄地雜草土壤種子庫的影響并不顯著。
[Abstract]:Ecological and environmental problems, such as habitat degradation and alien species invasion, caused by rapid urbanization, have a lot of impacts on urban plant diversity. Weeds are one of the three major components of urban vegetation. It has the characteristics of high sensitivity to heterogeneous habitats, strong plasticity and various adaptive strategies. It is a model object to study the effects of urbanization on vegetation and its response. The difference of soil seed bank in urban and rural gradient is explored. The relationship between the weed community and the above ground weed community is helpful to reveal the effect of urbanization on weed species diversity. This study took the weed soil seed bank of Shanghai abandoned land as the research object. On the gradient of urbanization, 24 plots were selected for community investigation in spring and autumn, and seed bank germination experiments were carried out, and the species and density of weed soil seed bank were analyzed. The differences of species diversity between urban and rural areas were compared with the species composition of aboveground weed community. The main results were as follows: 1) the annual (especially summer annual) weed seed bank in abandoned land of Shanghai. Low type, native species mainly; The seed density of 2 675 seeds / m2 in autumn was much higher than that in spring (838 seeds / m2). The ratio of seed density to exotic species (about 40%) has no significant difference between urban and rural areas. Richness and Shannon-Wiener of Weed soil seed Bank and aboveground Weed Community in abandoned Land of Shanghai. There was no significant difference in the index between urban and rural areas, and the richness and Shannon-Wiener index of aboveground community in spring were 32 species and 3. 0 respectively. 22 species and 2.6 species in autumn; The richness and Shannon-Winener index of soil seed bank in spring were 11 and 2.0 respectively. There were significant differences between species composition of weed soil seed bank and aboveground community in Shanghai. Jaccard coefficient was used to characterize species similarity. Between the aboveground vegetation community and soil seed bank in spring, 0.14 鹵0.06 in urban area was significantly lower than that in suburban area (0.24 鹵0.08). The species composition of weeds in urban area was significantly lower than that in suburban area (0.17 鹵0.06) between autumn and spring soil seed bank (0.09 鹵0.06). No matter the soil seed bank is still in the aboveground community, there are obvious seasonal differences in spring and autumn, and the similarity of Jaccard coefficient between spring and autumn is below 2.5. The similarity of soil seed bank in spring and autumn was 0.11 鹵0.05) in urban area, significantly lower than that in aboveground community (0.20 鹵0.03). This indicates that the high degree of urbanization leads to the inconsistency of the seasonal changes between the ground and the ground. The weed seed bank in the abandoned land of Shanghai is dominated by low type and annual growth in summer. The proportion of exotic species caused by human disturbance and the low similarity between soil seed bank and aboveground community are higher. The effect of urbanization, a comprehensive environmental factor, on weed soil seed bank in abandoned land was not significant.
【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：S451

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本文編號(hào)：1439111