本文選題：土壤線蟲(chóng) + 群落結(jié)構(gòu)�。� 參考：《南京農(nóng)業(yè)大學(xué)》2015年博士論文

【摘要】：土壤線蟲(chóng)廣布于各種類型的土壤中,在維持土壤生態(tài)系統(tǒng)的穩(wěn)定性、促進(jìn)物質(zhì)循環(huán)和能量流動(dòng)等方面發(fā)揮著重要的作用,而且還是理想的環(huán)境指示生物,因此,近些年來(lái),有關(guān)土壤線蟲(chóng)群落結(jié)構(gòu)特征及影響因素的研究受到重視。然而,到目前為止,有關(guān)西藏高原土壤線蟲(chóng)方面的研究極少。在西藏北部地區(qū),草地是面積最大,也是最重要的生態(tài)系統(tǒng)類型,其中,高寒草甸類草地廣泛分布,具有典型的區(qū)域代表性。為了解西藏高原高寒環(huán)境下植被對(duì)土壤線蟲(chóng)群落的影響,本研究選擇的研究區(qū)域位于西藏北部那曲地區(qū)那曲縣(N31 °31′38"～N31°32′02,E 92°04′03″～E92° 04′16″海拔4534 m～4567 m)。在研究區(qū)域內(nèi)選取有代表性的植物群落,分別為委陵菜、高山嵩草、藏北離草為主要建群種的高寒草甸。通過(guò)定期和土壤分層采樣,應(yīng)用線蟲(chóng)群落個(gè)體密度、種類組成、營(yíng)養(yǎng)結(jié)構(gòu)及其特征指數(shù),以及生物多樣性指數(shù)等,分析土壤線蟲(chóng)群落的時(shí)空變化特征。此外,選擇已實(shí)施圍欄封育措施3年的高山嵩草型高寒草甸,分別在圍欄內(nèi)外設(shè)置樣地,通過(guò)分析土壤線蟲(chóng)群落及土壤理化性質(zhì),在了解線蟲(chóng)群落變化及其與土壤環(huán)境之間關(guān)系的基礎(chǔ)上,探討自由放牧對(duì)藏北高寒草甸的影響,以及圍封對(duì)高寒草甸恢復(fù)的作用,以期為退化草地恢復(fù)以及西藏畜牧業(yè)發(fā)展提供理論依據(jù)。主要研究結(jié)果如下:(1)從西藏北部高寒草甸3種植物群落的土壤樣本中分離得到土壤線蟲(chóng)33038條,分屬于2綱6目51科93屬,個(gè)體密度23～4 109條100g-1干土。(2)土壤線蟲(chóng)個(gè)體密度以委陵菜植物群落最低,其次是藏北嵩草植物群落,高山嵩草植物群落最高;3種植物群落的土壤線蟲(chóng)個(gè)體密度均在返青期最大,盛長(zhǎng)期次之，枯草期最小,季節(jié)間差異顯著。土壤線蟲(chóng)類群屬數(shù)則以委陵菜群落為最高,高山嵩草群落次之,藏北嵩草群落最低,季節(jié)變化趨勢(shì)與個(gè)體密度一致。(3)委陵菜群落的土壤線蟲(chóng)多樣性及豐富度均最高,高山嵩草群落次之,藏北嵩草群落最低;藏北嵩草群落的均勻度和優(yōu)勢(shì)度均明顯高于其它兩種植物群落。一般地,從土壤表層往下,多樣性指數(shù)(H′)、豐富度指數(shù)(SR)隨著土層加深而減小,而均勻度指數(shù)(J′)、優(yōu)勢(shì)度指數(shù)(λ)則隨之增大,這種趨勢(shì)在高山嵩草群落和藏北嵩草群落比較明顯。(4)3種植物群落之間,土壤線蟲(chóng)營(yíng)養(yǎng)類群組成及分布特征差異顯著。植食性線蟲(chóng)和食細(xì)菌線蟲(chóng)是研究區(qū)域的主要營(yíng)養(yǎng)類群。不同植物群落間,植食性線蟲(chóng)和雜食/捕食性線蟲(chóng)的相對(duì)多度差異顯著。土壤線蟲(chóng)生活策略以r-對(duì)策為主,表現(xiàn)為cp2線蟲(chóng)類群在3種植物群落均為優(yōu)勢(shì)類群。通過(guò)食真菌線蟲(chóng)和食細(xì)菌線蟲(chóng)的比例(F/B)及線蟲(chóng)通道指數(shù)(NCR),說(shuō)明3種植物群落的土壤有機(jī)質(zhì)均以細(xì)菌分解途徑為主。在指示高寒草甸所受干擾方面,cp5對(duì)于來(lái)自于放牧等干擾表現(xiàn)的較為敏感,而PPI/MI的靈敏度較低。(5)在植物群落的盛長(zhǎng)期,土壤含水量、pH、電導(dǎo)率與土壤線蟲(chóng)個(gè)體密度均顯著相關(guān),食真菌性線蟲(chóng)明顯受到土壤pH的影響,食細(xì)菌性線蟲(chóng)僅在返青期受到pH的影響,雜食/捕食性線蟲(chóng)在枯草期的個(gè)體密度與土壤含水量顯著相關(guān)。從cp1到cp5,線蟲(chóng)各功能類群與土壤性質(zhì)之間的關(guān)系逐漸增強(qiáng),cp2和cp4在返青期受到土壤pH的影響;cp1及cp3類群跟土壤理化性質(zhì)間沒(méi)有表現(xiàn)出顯著的相關(guān)性;cp5類群在返青期和枯草期跟土壤含水量顯著相關(guān),在盛長(zhǎng)期則跟土壤pH間極顯著相關(guān)。(6)委陵菜群落一般被看做是高山嵩草型高寒草句發(fā)生嚴(yán)重退化的形式。高山嵩草型高寒草甸發(fā)生退化會(huì)導(dǎo)致土壤線蟲(chóng)個(gè)體密度下降,雖然線蟲(chóng)的類群屬數(shù)未發(fā)生明顯變化,但線蟲(chóng)群落種類構(gòu)成卻發(fā)生了較大的變化。退化還導(dǎo)致植食性線蟲(chóng)的個(gè)體密度增加,以及cp3、cp5類群在群落中所占的比重增大等。因此,土壤線蟲(chóng)群落對(duì)高山嵩草高寒草甸發(fā)生退化有明顯的響應(yīng)。(7)短期圍封提高了土壤線蟲(chóng)群落的物種多樣性和豐富度,優(yōu)勢(shì)類群種類及其個(gè)體數(shù)量均明顯增加。(8)圍封使土壤線蟲(chóng)群落的營(yíng)養(yǎng)結(jié)構(gòu)發(fā)生變化。自由放牧樣地土壤線蟲(chóng)群落不同營(yíng)養(yǎng)類群的個(gè)體密度:植食性線蟲(chóng)食細(xì)菌性線蟲(chóng)食真菌性線蟲(chóng)雜食/捕食性線蟲(chóng),而圍封樣地則為:食真菌性線蟲(chóng)植食性線蟲(chóng)占線蟲(chóng)食細(xì)菌性線蟲(chóng)雜食/捕食性線蟲(chóng),但2樣地間各營(yíng)養(yǎng)類群個(gè)體密度的差異并未達(dá)到顯著水平。圍封降低了植食性線蟲(chóng)在群落中所占的比重,使高寒草甸生態(tài)系統(tǒng)向更加穩(wěn)定的方向發(fā)展。(9)圍封樣地的多樣性指數(shù)H′、豐富度SR均高于放牧樣地;圍封樣地的優(yōu)勢(shì)度指數(shù)λ明顯低于放牧樣地;WI指數(shù)反映出在放牧強(qiáng)度最大的植被盛長(zhǎng)期(8月)高寒草甸的健康程度最差,若進(jìn)一步過(guò)載會(huì)將導(dǎo)致高寒草甸退化。本研究通過(guò)對(duì)西藏北部地區(qū)高寒草句土壤線蟲(chóng)群落與植物群落之間的關(guān)系進(jìn)行研究,提出了藏北高寒草甸土壤線蟲(chóng)個(gè)體密度、屬數(shù)、時(shí)空分布特點(diǎn)等方面的調(diào)查結(jié)果,揭示出青藏高原特殊氣候條件下高寒草甸土壤線蟲(chóng)群落結(jié)構(gòu)的基本特征。通過(guò)研究自由放牧對(duì)高寒草甸土壤線蟲(chóng)群落的影響,以及土壤線蟲(chóng)群落對(duì)圍封措施的響應(yīng)情況,獲得了圍封措施有利于藏北高寒草甸生態(tài)系統(tǒng)的正向演替,使之向更穩(wěn)定的方向發(fā)展的結(jié)論,為當(dāng)?shù)匦竽翗I(yè)發(fā)展提供了理論依據(jù)。
[Abstract]:Soil nematodes are widely distributed in various types of soil, playing an important role in maintaining the stability of the soil ecosystem, promoting material circulation and energy flow, and is an ideal environmental indicator. Therefore, in recent years, the research on the structure characteristics and influencing factors of soil nematode community has been paid much attention. So far, there are few studies on soil nematodes in the Tibet plateau. In northern Tibet, the grassland is the largest and most important ecosystem type. Among them, the alpine meadow is widely distributed and has typical regional representation. In order to understand the effect of vegetation on the soil nematode community in the alpine environment of Tibet Plateau, this study has been studied. The selected research area is located in Nagqu County Nagqu county (N31 31 '38 "~ N31 degree 32' 02, E 92 degree 04 '03" to E92 degree 04' 16 "altitude 4534 m ~ 4567 m). In the study area, the representative plant communities are selected as the alpine meadow, which are the main group species of Potentilla, Alpine Kobresia and North Tibet. By stratified sampling, the spatial and temporal characteristics of soil nematode communities were analyzed by the individual density, species composition, nutritional structure, characteristics index and biodiversity index of nematode communities. In addition, the alpine kobrex Alpine alpine meadow, which had been enforced for 3 years, was set up inside and outside the fence, and the soil line was analyzed. On the basis of understanding the change of the nematode community and the relationship between the nematode community and its soil environment, the influence of free grazing on the alpine meadow in northern Tibet, and the effect of enclosure on the alpine meadow restoration, were discussed in order to provide a theoretical basis for the restoration of degraded grassland and the development of Tibet animal husbandry. The main results are as follows: (1) 33038 species of soil nematode were isolated from the soil samples of 3 plant communities in the northern alpine meadow of Tibet. It was divided into 2 classes, 6 orders, 51 families and 93 genera, and the individual density was 23~4109 100g-1 dry soil. (2) the individual density of the soil nematode was the lowest in the plant community of Potentilla, followed by the northern Kobresia Kobresia plant community, and 3 species of plant communities. The individual density of soil nematode was the largest in the period of returning to green. The minimum in the period of withered grass was the lowest. The number of soil nematode groups was the highest, the highest in the Alpine Kobresia community, the lowest in the northern Kobresia kobreus, and the seasonal trend was the same as the individual density. (3) the diversity and richness of the soil nematode in the community of Potentilla Potentilla The degree is the highest and the Alpine Kobresia community is the lowest. The evenness and dominance of Kobresia kobrei are obviously higher than those of the other two plant communities. Generally, the diversity index (H ') and the richness index (SR) decrease with the depth of the soil layer, and the evenness index (J'), dominance index ([lambda) (lambda) Ze Suizhi This trend is more obvious in the Alpine Kobresia and Kobresia kobreus communities. (4) there are significant differences in the composition and distribution of soil nematode nutrient groups among the 3 plant communities. The soil nematode life strategy was dominated by the r- strategy, which showed that the CP2 nematode group was the dominant group in 3 plant communities. Through the proportion of fungi nematodes and bacterial nematodes (F/B) and the nematode channel index (NCR), the soil organic matter in the 3 plant communities was dominated by the bacterial decomposition pathway. In the area of interference, cp5 is more sensitive to the interference from grazing, and the sensitivity of PPI/MI is low. (5) in the long term of the plant community, soil water content, pH, electrical conductivity and soil nematode individual density are significantly correlated, and fungus eating nematodes are obviously affected by soil pH, and the bacterial nematode is only affected by pH during the green period. The individual density of omnivorous / predatory nematodes was significantly correlated with soil moisture content during the period of withered grass. From CP1 to cp5, the relationship between the functional groups of nematodes and soil properties gradually increased, and CP2 and CP4 were affected by the soil pH during the return period; there was no significant correlation between CP1 and CP3 groups and the physical and chemical properties of soil; cp5 groups were in the green period. There is a significant correlation between the soil moisture content and the soil water content of the dead grass period. (6) (6) the community of Potentilla is generally regarded as a form of severe degeneration of Alpine Kobresia humus. The degradation of Alpine Kobresia alpine meadow will lead to the decrease of individual density of soil nematode, although the number of nematode groups does not occur. The species composition of the nematode community changed significantly, but the degeneration also resulted in the increase of the individual density of the herbivorous nematode, and the increase in the proportion of CP3 and cp5 groups in the community. Therefore, the soil nematode community had a significant response to the degradation of Alpine Kobresia humilis meadow. (7) the short-term enclosure improved the soil nematode community. Species diversity and richness, dominant group species and their individual numbers increased significantly. (8) the nutrient structure of soil nematode communities was changed by enclosure. The individual density of different nutrient groups in soil nematode communities in free grazing plots: herbivorous nematode eating nematode omnivores / predatory nematodes, and enclosure samples The site was as follows: fungal nematode phytophagous nematodes were dominated by bacterial nematode omnivus / predator nematode, but the individual density differences between the 2 types of vegetative groups did not reach a significant level. The enclosure decreased the proportion of herbivorous nematodes in the community and made the alpine meadow ecological system develop in a more stable direction. (9) enclosed plots The diversity index H 'and richness SR were higher than grazing plots; the dominance index of enclosure plots was significantly lower than that of grazing plots; the WI index reflected the worst degree of health in the alpine meadow with the largest grazing intensity in the long term (August), if further overload would result in the degradation of the alpine meadow. This study passed to the northern region of Tibet high The relationship between the soil nematode community and the plant community was studied. The results of the investigation on the individual density, the number and the spatial and temporal distribution of the soil nematode in the northern Tibetan alpine meadow revealed the basic characteristics of the knot structure of the soil nematode community in the alpine meadow soil under the special climate of the Qinghai Tibet Plateau. The influence of the nematode community in the meadow soil and the response of the soil nematode community to the enclosure measures, the enclosure measures have been obtained for the positive succession of the alpine meadow ecosystem in the north of Tibet, and the conclusion that it develops in a more stable direction provides a theoretical basis for the development of the local animal husbandry.
【學(xué)位授予單位】：南京農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：S812.2

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