內(nèi)蒙古溫帶疏林草地生態(tài)系統(tǒng)植被—土壤的空間分異特征研究
發(fā)布時間：2018-07-24 10:08
【摘要】：以榆樹(Ulmus pumila L.)為主要優(yōu)勢種的疏林草地是適應渾善達克沙地植被演替的頂極群落。榆樹疏林生態(tài)系統(tǒng)具有較高的生境多樣性、生物多樣性以及結構多樣性,在維護區(qū)域的生態(tài)穩(wěn)定和生態(tài)安全中發(fā)揮著不可替代的作用,對控制草地沙化具有重要意義。20世紀后期,在氣候變化以及人為活動(農(nóng)耕、放牧)等因素的影響下,渾善達克沙地榆樹疏林遭到破壞,榆樹種群的更新受到了極大的限制,整個榆樹疏林生態(tài)系統(tǒng)的植被蓋度、物種多樣性也隨之降低。榆樹疏林生態(tài)退化的問題已經(jīng)影響到了整個區(qū)域的生態(tài)格局和經(jīng)濟安全。因此,亟需對渾善達克沙地榆樹疏林生態(tài)系統(tǒng)的空間分布及其影響因素開展相關研究,并以此為渾善達克沙地榆樹疏林的保護和恢復工作提供理論支持。本研究以渾善達克沙地榆樹疏林為研究對象,通過研究天然狀態(tài)下榆樹疏林的空間分布特征,探討空間格局的形成原因,分析潛在生態(tài)過程以及干擾因子。主要結論如下:(1)榆樹種群的年齡結構呈現(xiàn)2個峰值,存在嚴重斷層問題,屬于衰退型種群。在東部區(qū)域,以第Ⅰ齡級(DBH5 cm)、第Ⅲ齡級(10 cm≤DBH15 cm)和第Ⅳ齡級(15 cm≤DBH20 cm)的榆樹較多;在北部、南部和西部區(qū)域,第Ⅰ齡級(DBH5cm)、第Ⅴ齡級(20 cm≤DBH25 cm)和第Ⅵ齡級(25 cm≤DBH30 cm)的榆樹數(shù)量較多。相對于東部區(qū)域,北部、南部和西部區(qū)域的種群衰退問題更加嚴重。榆樹種群呈現(xiàn)前期銳減、中期穩(wěn)定、后期衰退的動態(tài)特征。榆樹種群更新的關鍵時期處于第Ⅱ齡級(5 cm≤DBH10 cm),在避免對該齡級干擾的基礎上加強保護是促進榆樹種群良性發(fā)展的關鍵。(2)榆樹疏林中主要木本植物(榆樹、耬斗葉繡線菊(Spiraea aquilegifolia Pall.)和小葉錦雞兒(Caragana microphylla Lam.))在小尺度上呈現(xiàn)出顯著的聚集分布特征,相對于喬木,灌木具有更大的聚集尺度。種子擴散限制、萌蘗繁殖以及生境異質性可能是影響木本植物空間分布特征的主要作用因子。不同齡級的榆樹之間在小尺度上呈現(xiàn)出顯著相互促進的作用關系,成年榆樹與榆樹幼苗呈現(xiàn)“庇護與被庇護”的種內(nèi)關系。榆樹分別與耬斗葉繡線菊和小葉錦雞兒在所有尺度上(0-50 m)呈現(xiàn)出相互獨立的種間關系。榆樹與2種灌木各自占據(jù)不同的空間位置,未產(chǎn)生直接的種間競爭。(3)榆樹的種群密度在東部區(qū)域最高,在南部區(qū)域最低,北部和西部區(qū)域居中。這與該區(qū)域內(nèi)的年均溫度呈現(xiàn)出一致的空間分布規(guī)律,溫度可能是影響榆樹種群空間分布的重要環(huán)境因子。榆樹的種群密度分別與胸徑、樹高、冠幅呈現(xiàn)相反的空間分布規(guī)律,表明榆樹種群存在“自疏”現(xiàn)象,隨著榆樹個體的生長,種群密度逐漸降低。榆樹種群的密度和灌木群落的密度之間呈現(xiàn)出顯著的負相關關系,表明榆樹種群與灌木群落呈現(xiàn)相反的空間分布格局。草本群落與土壤理化性質的空間分布具有較好的一致性,土壤理化性質可能是影響草本群落空間分布的主要作用因子。(4)沙丘對榆樹疏林植被和土壤理化性質的空間分布具有顯著的影響,不同微地形間的喬木層、灌木層、草本層植被各指標具有顯著性差異,背風坡的植被最為豐富,迎風坡最為稀疏。土壤理化性質各指標從丘間地、背風坡、坡頂?shù)接L坡依次呈現(xiàn)逐漸遞減的梯度變化。丘間地的水分狀況、土壤結構和養(yǎng)分狀況最好,迎風坡最差。(5)放牧是導致林分結構退化的重要干擾因子,隨著放牧強度的增加,木本植物的數(shù)量逐漸降低。放牧活動對榆樹種群空間格局的影響主要體現(xiàn)在對幼樹和幼苗的破壞方面,放牧活動降低了榆樹種群的空間聚集尺度,加速了“自疏”過程。長時間過度放牧后,放牧壓力的降低可能是造成灌木入侵的重要影響因素。(6)榆樹顯著影響到了冠下草本群落和土壤理化性質的空間分布。榆樹疏林中榆樹與草本植物之間呈現(xiàn)良好的共生關系。榆樹可能通過調節(jié)土壤水分的再分配過程和冠下的光照環(huán)境對草本植物的生長和土壤理化性質的改善起到促進作用。以榆樹孤立木為中心的區(qū)域存在明顯的沃島效應。在目前氣候條件下,灌木的存在雖未對榆樹的生長造成直接影響,但研究發(fā)現(xiàn)隨著氣候干旱的加重,榆樹的數(shù)量可能會持續(xù)減少,灌木(如耐旱植物小葉錦雞兒)的數(shù)量則可能會持續(xù)增加。若不采取有效的保護措施,以榆樹為主導的疏林草地可能將逐步退化為以灌叢為主導的疏林草地類型。建議通過調控放牧強度、建立自然保護區(qū)等措施恢復整個榆樹疏林生態(tài)系統(tǒng)的活力。
[Abstract]:The sparse forest grassland with Ulmus pumila L. as the main dominant species is the top community adapted to the vegetation succession in Hun Sandan sandy land. The elm forest ecosystem has high habitat diversity, biodiversity and structural diversity, and plays an irreplaceable role in maintaining the ecological stability and ecological security of the region. The land desertification is of great significance in the late.20 century. Under the influence of climate change and human activities (farming, grazing), the elm trees in Hun DAQ sandy land have been destroyed, the population of elm trees has been greatly restricted. The vegetation coverage and species diversity of the elm tree sparse forest ecosystem are also reduced. Elm tree sparse forest ecology is also reduced. The problem of degradation has affected the ecological pattern and economic security of the whole region. Therefore, it is urgent to carry out a study on the spatial distribution of the elm tree and its influencing factors in Hun Sandan sandy land and provide theoretical support for the protection and recovery of elm trees in Hun DAQ sandy land. By studying the spatial distribution characteristics of elm trees in natural elm trees, the reasons for the formation of the spatial pattern, the potential ecological processes and the interference factors are discussed. The main conclusions are as follows: (1) the age structure of the elm population presents 2 peaks, and there is a serious fault, which belongs to the decline population. In the eastern region, The elm trees of the first age class (DBH5 cm), the third age class (10 cm < DBH15 cm) and the fourth age class (15 cm < DBH20 cm) are more; in the north, the southern and western regions, the first instar (DBH5cm), the 5th instar (20 cm < < DBH25 cm) and the sixth instar of the elm are more. The population decline is more serious. The population of Ulmus elm has the dynamic characteristics of sharp decline, mid term stability and later decline. The key period of the elm population regeneration is stage II (5 cm < DBH10 cm). The key to promote the development of elm population is the key to promote the development of elm population. (2) the main woody plants in elm tree sparse forest. Elm, columbine (Spiraea aquilegifolia Pall.) and Caragana microphylla (Caragana microphylla Lam.) showed significant aggregation characteristics on small scales, and shrubs had larger aggregation scales relative to trees. Seed diffusion restriction, tillering reproduction and habitat heterogeneity may affect the spatial distribution of woody plants. The main function factor of the sign is that the elm trees of different ages show a significant mutual promotion on the small scale, and the adult elm and elm seedlings present the intraspecific relationship of "asylum and sheltered". The elm have an independent interspecific relationship with the Columbine and the Caragana microphylum on all scales (0-50 m) respectively. The elm and 2 shrubs occupy different spatial positions and do not produce direct interspecific competition. (3) the population density of elm is the highest in the eastern region, the lowest in the southern region and the middle in the northern and western regions. This has the same spatial distribution as the annual average temperature in the region, and the temperature may affect the spatial distribution of the elm population. Important environmental factors. The population density of elm tree has the opposite spatial distribution with the breast diameter, the tree height and the crown, indicating that the elm population has a "self sparse" phenomenon. With the growth of the elm individual, the population density gradually decreases. The density of the elm population and the density of the shrub community shows a significant negative correlation, indicating the elm species. The spatial distribution patterns of the herd and the shrub communities were in the opposite direction. The herbaceous community and the spatial distribution of soil physical and chemical properties were in good agreement. The physical and chemical properties of the soil may be the main factors affecting the spatial distribution of the herbaceous community. (4) the sand dunes have significant influence on the spatial distribution of the vegetation and soil physical and chemical properties of elm trees. There are significant differences in the indexes of the tree layer, shrub layer and herbaceous layer among the micro terrain. The vegetation of the leeward slope is the most abundant and the windward slope is the most sparse. The soil physical and chemical properties of each index are gradually decreasing gradually from the mound, the leeward slope, the top to the upwind slope. The water status of the hills, the soil structure and the nutrient status are the most. Well, the upwind slope is the worst. (5) grazing is an important disturbance factor that leads to the degradation of the stand structure. With the increase of grazing intensity, the number of woody plants gradually decreases. The effect of grazing activities on the spatial pattern of elm population is mainly in the destruction of young trees and seedlings, and the grazing activities reduce the spatial aggregation scale of the elm population and accelerate the grazing activities. "Self thinning" process. After long overgrazing, the reduction of grazing pressure may be an important factor in the invasion of shrubs. (6) the elm trees significantly affect the spatial distribution of the soil and soil physical and chemical properties under the crown. Elm trees and herbs have a good symbiotic relationship. Elm may adjust the soil by adjusting the soil. In the process of water redistribution, the light environment under Wacom can promote the growth of herbaceous plants and the improvement of soil physical and chemical properties. There is an obvious fertile island effect in the area centered on the isolated elm tree. Under the present climate conditions, the existence of shrubs has not made a direct impact on the growth of elm trees, but the study found that the climate is dry with the climate. The number of elm trees may continue to decrease, and the number of shrubs (such as drought resistant Caragana Caragana) may continue to increase. If no effective protection measures are taken, the elm dominated sparse forest grassland may gradually degenerate into a shrub based forest land type. It is suggested that the natural conservation should be established by regulating grazing intensity. Protective measures and other measures to restore the vitality of the whole elm sparse forest ecosystem.
【學位授予單位】：中國林業(yè)科學研究院
【學位級別】：博士
【學位授予年份】：2017
【分類號】：S718.5
[Abstract]:The sparse forest grassland with Ulmus pumila L. as the main dominant species is the top community adapted to the vegetation succession in Hun Sandan sandy land. The elm forest ecosystem has high habitat diversity, biodiversity and structural diversity, and plays an irreplaceable role in maintaining the ecological stability and ecological security of the region. The land desertification is of great significance in the late.20 century. Under the influence of climate change and human activities (farming, grazing), the elm trees in Hun DAQ sandy land have been destroyed, the population of elm trees has been greatly restricted. The vegetation coverage and species diversity of the elm tree sparse forest ecosystem are also reduced. Elm tree sparse forest ecology is also reduced. The problem of degradation has affected the ecological pattern and economic security of the whole region. Therefore, it is urgent to carry out a study on the spatial distribution of the elm tree and its influencing factors in Hun Sandan sandy land and provide theoretical support for the protection and recovery of elm trees in Hun DAQ sandy land. By studying the spatial distribution characteristics of elm trees in natural elm trees, the reasons for the formation of the spatial pattern, the potential ecological processes and the interference factors are discussed. The main conclusions are as follows: (1) the age structure of the elm population presents 2 peaks, and there is a serious fault, which belongs to the decline population. In the eastern region, The elm trees of the first age class (DBH5 cm), the third age class (10 cm < DBH15 cm) and the fourth age class (15 cm < DBH20 cm) are more; in the north, the southern and western regions, the first instar (DBH5cm), the 5th instar (20 cm < < DBH25 cm) and the sixth instar of the elm are more. The population decline is more serious. The population of Ulmus elm has the dynamic characteristics of sharp decline, mid term stability and later decline. The key period of the elm population regeneration is stage II (5 cm < DBH10 cm). The key to promote the development of elm population is the key to promote the development of elm population. (2) the main woody plants in elm tree sparse forest. Elm, columbine (Spiraea aquilegifolia Pall.) and Caragana microphylla (Caragana microphylla Lam.) showed significant aggregation characteristics on small scales, and shrubs had larger aggregation scales relative to trees. Seed diffusion restriction, tillering reproduction and habitat heterogeneity may affect the spatial distribution of woody plants. The main function factor of the sign is that the elm trees of different ages show a significant mutual promotion on the small scale, and the adult elm and elm seedlings present the intraspecific relationship of "asylum and sheltered". The elm have an independent interspecific relationship with the Columbine and the Caragana microphylum on all scales (0-50 m) respectively. The elm and 2 shrubs occupy different spatial positions and do not produce direct interspecific competition. (3) the population density of elm is the highest in the eastern region, the lowest in the southern region and the middle in the northern and western regions. This has the same spatial distribution as the annual average temperature in the region, and the temperature may affect the spatial distribution of the elm population. Important environmental factors. The population density of elm tree has the opposite spatial distribution with the breast diameter, the tree height and the crown, indicating that the elm population has a "self sparse" phenomenon. With the growth of the elm individual, the population density gradually decreases. The density of the elm population and the density of the shrub community shows a significant negative correlation, indicating the elm species. The spatial distribution patterns of the herd and the shrub communities were in the opposite direction. The herbaceous community and the spatial distribution of soil physical and chemical properties were in good agreement. The physical and chemical properties of the soil may be the main factors affecting the spatial distribution of the herbaceous community. (4) the sand dunes have significant influence on the spatial distribution of the vegetation and soil physical and chemical properties of elm trees. There are significant differences in the indexes of the tree layer, shrub layer and herbaceous layer among the micro terrain. The vegetation of the leeward slope is the most abundant and the windward slope is the most sparse. The soil physical and chemical properties of each index are gradually decreasing gradually from the mound, the leeward slope, the top to the upwind slope. The water status of the hills, the soil structure and the nutrient status are the most. Well, the upwind slope is the worst. (5) grazing is an important disturbance factor that leads to the degradation of the stand structure. With the increase of grazing intensity, the number of woody plants gradually decreases. The effect of grazing activities on the spatial pattern of elm population is mainly in the destruction of young trees and seedlings, and the grazing activities reduce the spatial aggregation scale of the elm population and accelerate the grazing activities. "Self thinning" process. After long overgrazing, the reduction of grazing pressure may be an important factor in the invasion of shrubs. (6) the elm trees significantly affect the spatial distribution of the soil and soil physical and chemical properties under the crown. Elm trees and herbs have a good symbiotic relationship. Elm may adjust the soil by adjusting the soil. In the process of water redistribution, the light environment under Wacom can promote the growth of herbaceous plants and the improvement of soil physical and chemical properties. There is an obvious fertile island effect in the area centered on the isolated elm tree. Under the present climate conditions, the existence of shrubs has not made a direct impact on the growth of elm trees, but the study found that the climate is dry with the climate. The number of elm trees may continue to decrease, and the number of shrubs (such as drought resistant Caragana Caragana) may continue to increase. If no effective protection measures are taken, the elm dominated sparse forest grassland may gradually degenerate into a shrub based forest land type. It is suggested that the natural conservation should be established by regulating grazing intensity. Protective measures and other measures to restore the vitality of the whole elm sparse forest ecosystem.
【學位授予單位】：中國林業(yè)科學研究院
【學位級別】：博士
【學位授予年份】：2017
【分類號】：S718.5
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