本文選題：優(yōu)勢灌叢 + 松樹��； 參考：《陜西師范大學》2016年博士論文

【摘要】：毛烏素沙地東南緣的生態(tài)系統(tǒng)受自然和人為因素的影響,荒漠化嚴重,植被退化迅速,致使該沙區(qū)自然恢復的可能性大大降低。在人工植被恢復工程中幼苗的定居是關鍵階段,但沙區(qū)土壤水分含量低、養(yǎng)分貧瘠、溫差大、光照強、競爭、化感、捕食和多風等多種因素卻限制幼苗的定居。人們曾經(jīng)采用過許多不同的植被恢復方法,但由于代價大、風險高、有時甚至成為加速植被退化的原因,恢復效果甚微。因此,該沙區(qū)迫切需要發(fā)展一種新型的、低花費的、而且有效的恢復方法來維持生態(tài)系統(tǒng)功能的穩(wěn)定,提高植被恢復的速度。保育植物理論(nurse plant theory)是指利用植物間的保育作用,通過保育植物(nurse plant)促進目標物種(target species)的種子萌發(fā)或者幼苗定居,從而有效縮短恢復的時間。那該理論是否可應用在毛烏素沙地東南緣的植被恢復中,成為恢復沙地生態(tài)系統(tǒng)的一種新型而有效的方法?保育植物對目標物種存在顯著的保育作用是該理論能成功應用在植被恢復中的關鍵。毛烏素沙地東南緣的優(yōu)勢植被類型是灌叢,本研究根據(jù)灌叢種的密度和生物學特性選擇該沙區(qū)優(yōu)勢灌叢檸條(Caragana korsinskii)、沙柳(Salix psammophyila)、紫穗槐(Amorpha fruticosa)作為保育植物,(1)采用野外灌叢剪除試驗,通過研究剪除與未剪除優(yōu)勢灌叢冠層下植物群落總地上生物量和物種多樣性的差異,從群落水平上確定該沙區(qū)優(yōu)勢灌從對冠層下所有目標植物是否存在保育作用;(2)采用幼苗移栽試驗,通過選擇兩年生油松(Pinus tabulaeformis)和樟子松(Pinus sylvestris)幼苗作為目標物種,將其分別種植在開闊地、檸條、紫穗槐和沙柳4種微生境下,連續(xù)3a監(jiān)測油松和樟子松幼苗的存活率和主枝生長長度,從種群水平上研究優(yōu)勢灌叢冠層下和開闊地間兩種松樹幼苗存活和主枝生長長度的差異,確定優(yōu)勢灌叢對冠層下兩種恢復樹種幼苗的定居是否存在保育作用;(3)采用溫室因子控制試驗,模擬保育灌叢冠層下和開闊地間不同的光照及水分條件,研究兩種松樹幼苗的生長(苗高和基徑)和生物量(根、莖、葉及總生物量)特征對光照和水分的響應機制,揭示優(yōu)勢灌叢保育作用形成的機理。本研究不僅能充實保育植物理論,加深對植物間促進作用的方式及機理的了解,而且還為環(huán)境惡劣和退化地區(qū)發(fā)展有效的生態(tài)恢復方法提供理論依據(jù)和實踐支撐,從而加快該理論在我國植被恢復中的應用。主要研究結(jié)果和結(jié)論如下:研究結(jié)果:(1)未剪除檸條、沙柳和紫穗槐灌叢冠層下植物群落總地上生物量及物種多樣性顯著高于剪除優(yōu)勢灌從的(P0.05)。剪除優(yōu)勢灌從對冠層下植物群落生物量的影響要大于對多樣性的影響。固氮的檸條和紫穗槐灌叢冠層下植物群落總生物量均顯著高于非固氮的沙柳灌叢的(P0.05);鄉(xiāng)土種檸條和沙柳灌叢冠層下植物群落物種多樣性均顯著高于外來種紫穗槐灌叢的(P0.05)。優(yōu)勢灌叢對豆科、禾本科和雜草植物功能群均具有顯著的正效應(P0.05)。檸條和紫穗槐冠層下不同功能群間均存在顯著差異(P0.05);沙柳灌叢對豆科功能群的影響顯著高于禾本科和雜草功能群(P0.05)。(2)檸條、紫穗槐和沙柳冠層下油松幼苗總存活率均顯著高于開闊地的(P0.05),而樟子松幼苗總存活率僅紫穗槐冠層下顯著高于開闊地的(P0.05)。保育灌叢冠層下油松幼苗存活率顯著高于樟子松幼苗的(P0.05)。紫穗槐冠層下油松和樟子松幼苗總存活率均最高,而且其每年的年度存活率均顯著高于開闊地的(P0.05);檸條和沙柳冠層下松樹幼苗年度存活率在第二個生長季開始顯著低于開闊地(P0.05)。油松幼苗的主枝生長長度在優(yōu)勢灌叢冠層下和開闊地間無顯著差異,而樟子松幼苗主枝生長長度在開闊地和紫穗槐冠層下最大(P0.05)。除光照與油松主枝長度不相關外,光照和土壤濕度均與松樹幼苗的存活率和主枝長度顯著正相關(P0.05)。保育灌叢高度和冠幅面積與油松和樟子松幼苗存活率呈顯著正相關(P0.05)。沙柳浸提液對松樹幼苗生長影響的試驗證實,高濃度浸提液對松樹幼苗生長有顯著抑制作用(0.05)。(3)檸條、紫穗槐和沙柳冠層下光照強度、大氣溫度和土壤溫度都顯著低于開闊地(P0.05),同時優(yōu)勢灌叢的存在增加淺層土壤(0～20 cm)的有機質(zhì)、速效鉀、速效氮、pH值和土壤電導率。光照和水分對松樹幼苗生長和生物量特征的影響均顯示出顯著的交互作用(P0.05)。遮蔭條件下,松樹幼苗大多數(shù)的生長和生物量指標在不同水分條件下的差異基本不明顯;干旱條件下,松樹幼苗大多數(shù)的生長和生物量指標在不同光照條件下也無顯著差異。研究結(jié)論:(1)毛烏素沙地東南緣優(yōu)勢灌叢檸條、沙柳和紫穗槐在群落水平上顯著增加冠層下所有植物的地上總生物量及物種多樣性,在種群水平上增加冠層下油松和樟子松幼苗的存活率,而且松樹幼苗主枝生長也未受到抑制;因此優(yōu)勢灌叢對冠層下植物群落和兩種松樹幼苗的定居存在明顯的保育作用。(2)保育灌叢的化學效應(固氮和化感)、植株的高度、冠幅大小和結(jié)構不同時,其對冠層下植物的保育作用程度也不同。固氮灌叢(紫穗槐和檸條)對松樹幼苗存活有持續(xù)的保育作用,但檸條冠幅結(jié)構緊密,可能因為對光的競爭,減弱保育作用;化感灌叢沙柳大大減弱其對冠層下松樹幼苗的保育作用。因此保育植物盡可能選擇固氮灌叢,避免選擇化感灌叢。外來種紫穗槐植株最高、冠幅面積最大,對冠層下松樹幼苗的保育作用最強,但其對物種多樣性的影響卻較小。保育灌叢對豆科、禾本科和雜草植物功能群均存在保育作用,但不同功能群間和同一功能群內(nèi)不同物種間均存在著所受保育作用的程度差異。當保育和目標植物均是豆科固氮植物時保育效果不明顯。目標物種的光適應能力不同其所受保育作用程度也不同;油松幼苗對光的適應能力強,受保育作用程度大,更適合被選作為恢復樹種。(3)優(yōu)勢灌叢的保育作用主要是通過為冠層下植物提供適宜微環(huán)境的方式產(chǎn)生的,改善最明顯的是光照強度和土壤濕度,其次是土壤有機質(zhì)和速效氮。光照和水分間的交互作用影響著松樹幼苗的生長,而且遮蔭緩解了干旱的不利影響,干旱緩解了遮蔭的不利影響,這也是優(yōu)勢灌叢對兩種光適應能力不同的松樹幼苗均具有保育作用的原因�？偟膩碚f,保育植物理論是可以應用在毛烏素沙地東南緣的植被恢復中,成為恢復沙地生態(tài)系統(tǒng)的一種新型而有效的方法。但是保育灌叢的選擇要考慮鄉(xiāng)土種還是外來種,以及灌叢的高度、冠幅大小、冠幅結(jié)構及化學效應;恢復物種的選擇要考慮其自身的生物學特性及其與保育植物的相互作用;從而提高該理論應用在植被恢復中的成功率。
[Abstract]:The ecological system in the southeastern margin of the Maowusu sandy land is affected by natural and artificial factors, desertification is serious, the vegetation degradation is rapid, and the possibility of natural recovery is greatly reduced. In the artificial vegetation restoration project, the settlement of the seedlings is the key stage, but the soil moisture content is low, the nutrient is poor, the temperature difference is large, the light intensity, competition and allelopathy are strong. Many different factors such as predation and windy restrict the settlement of the seedlings. People have used many different methods of vegetation recovery, but because of the high cost, high risk, and sometimes even the cause of accelerating vegetation degradation, the recovery effect is very little. Therefore, the sand area is urgently needed to develop a new, low cost, and effective recovery method. Maintaining the stability of the ecosystem function and improving the speed of vegetation recovery. The conservation plant theory (nurse plant theory) means to use the conservation function of the plant to promote the germination of the target species (target species) or the settlement of the target species (target species) by the conservation plant (nurse plant), thus effectively shortening the time of recovery. In the restoration of vegetation in the southeastern margin of Maowusu sandy land, it is a new and effective method to restore the sandy land ecosystem, which is the key to the successful application of the theory to the restoration of vegetation. The dominant vegetation types in the southeastern margin of Maowusu are shrubs. This study is based on the shrub species. The density and biological characteristics of the sand area were selected as the dominant shrub (Caragana korsinskii), Salix (Salix psammophyila), and Sophora japonica (Amorpha fruticosa) as a conservation plant. (1) the field shrub cutting test was used to study the differences in the total biomass and species diversity of plant communities under the crown layer of the predominant shrub. From the community level, it was determined whether the dominant irrigation in the sand area had a protective effect on all the target plants under the canopy. (2) the seedling transplanting test was used to select 4 young seedlings of Pinus tabulaeformis (Pinus tabulaeformis) and Pinus sylvestris (Pinus sylvestris) as the target species, and they were planted in open land, Caragana, Sophora japonica and Salix, respectively. Under the condition of continuous 3A monitoring of the survival rate and the growth length of the seedlings of Pinus tabulaeformis and Pinus sylvestris, the difference of survival and growth length of two species of pine seedlings under the dominant shrub canopy and open land was studied from the population level, and the conservation effect of the dominant shrubs on the settlement of the seedlings of the two species under the canopy was determined. (3) the greenhouse was used in greenhouse. Factor control test, to simulate the different light and water conditions between under canopy and open land, to study the response mechanism of the growth of two pine seedlings (Miao Gao and base diameter) and biomass (root, stem, leaf and total biomass) to light and water, and to reveal the formation mechanism of the predominant irrigation. This study not only enriches the conservation of the growth of the dominant shrub, but also enriches the conservation of the seedlings. Plant theory, to deepen the understanding of the ways and mechanisms of the promoting effect of plants, and to provide theoretical basis and practical support for the development of effective ecological restoration methods in poor and degraded areas, and thus accelerate the application of this theory in the restoration of vegetation in China. The total aboveground biomass and species diversity of the plant community under the canopy of Salix and Sophora japonica were significantly higher than that of the predominant irrigation (P0.05). The effect of the removal of dominant irrigation on the biomass of plant community under the canopy was greater than that on the diversity. The species diversity of the plant communities under the crown of the native Caragana and Salix shrub was significantly higher than that of the foreign species (P0.05). The dominant shrubs had significant positive effects on the functional groups of legumes, Gramineae and weed plants (P0.05). There were significant differences between different functional groups under the canopy of Caragana and Sophora japonica. The difference (P0.05); the effect of Salix shrub on the functional group of legume was significantly higher than that of the functional group of Gramineae and weeds (P0.05). (2) the total survival rate of Pinus tabaci seedlings under the canopy of panicle and Salix was significantly higher than that in open land (P0.05), while the total survival rate of the seedlings of Pinus sylvestris was significantly higher than that in the open area (P0.05). The survival rate of Pinus tabulaeformis seedlings was significantly higher than that of Pinus sylvestris seedlings (P0.05). The total survival rate of Pinus tabulaeformis and Pinus sylvestris seedlings under the crown layer of Sophora japonica were the highest, and the annual survival rate was significantly higher than that in open land (P0.05). The annual survival rate of the seedlings under the Caragana and Salix canopy began to be significantly lower than the open land in the second growing seasons (P0.05 The growth length of the main branch of Pinus tabulaeformis seedlings had no significant difference between the dominant shrub canopy and the open area, while the growth length of the main branches of the seedlings of Pinus sylvestris seedlings was the largest under the open land and the crown of the Sophora japonica (P0.05). The light and soil moisture were significantly correlated with the survival rate and the length of the main branch of pine seedlings except for the light and the length of the main branch of Pinus tabulaeformis (P 0.05) there was a significant positive correlation between the height and canopy area of the conserved shrub and the seedling survival of Pinus tabulaeformis and Pinus sylvestris (P0.05). The effect of Salix leaching solution on the growth of pine seedlings confirmed that the high concentration extracts had a significant inhibitory effect on the growth of pine seedlings (0.05). (3) the light intensity under the canopy of the Caragana Caragana, the Sophora japonica and the Salix, and the soil temperature and soil The temperature was significantly lower than that of open land (P0.05). At the same time, the presence of dominant shrubs increased the organic matter of shallow soil (0~20 cm), available potassium, available nitrogen, pH value and soil conductivity. The effects of light and water on the growth and biomass of pine seedlings showed significant interaction (P0.05). Under shading conditions, most of the seedlings of pine seedlings were born. The difference of length and biomass under different water conditions was not obvious; under the drought conditions, most of the growth and biomass of pine seedlings had no significant difference under different light conditions. (1) the dominant shrub of the southeast margin of Maowusu sandy land, Salix and Sophora japonica increased significantly under the canopy level. The total biomass and species diversity of the plants increased the survival rate of the seedlings of Pinus tabulaeformis and Pinus sylvestris under the canopy level, and the growth of the main branches of the pine seedlings was not suppressed. Therefore, the dominant shrubs had obvious conservation effects on the settlement of the plant community and the two kinds of pine seedlings. (2) the chemical effects of the conservation shrubs (solid). Nitrogen and allelopathy, the height of the plant, the size of the crown and the structure of the plants are different. The nitrogen fixing shrubs (Sophora japonica and Caragana) have a continuous conservation effect on the survival of the pine seedlings, but the structure of the Caragana is tight, which may be due to the competition of light and weaken the conservation effect; the Salix of the alleloplastic shrub is greatly weakened. The conservation effect on the seedlings of the pine trees under the canopy. Therefore, the conservation plants should choose the nitrogen fixing shrubs as much as possible to avoid the choice of the allelopathic shrubs. The plants of the foreign species are the highest, the largest canopy area, and the best conservation effect on the seedlings under the canopy, but the effect on the species diversity is smaller. There is a conservation effect in all the groups, but there is a difference in the degree of conservation among the different functional groups and the same functional groups. When the conservation and the target plants are all nitrogen fixing plants in the leguminous family, the effect of conservation is not obvious. It has strong adaptability and high degree of conservation, and is more suitable to be selected as a restoration tree. (3) the conservation effect of dominant shrubs is mainly produced by providing suitable microenvironment for plants under canopy, and the most obvious improvement is light intensity and soil moisture, followed by soil organic matter and available nitrogen. Interaction between light and water. The growth of pine seedlings was affected, and shading alleviated the adverse effects of drought, and drought relieved the adverse effects of shading. This was the reason why the dominant shrub had a protective effect on the seedlings of two kinds of pine trees with different light adaptation ability. It is a new and effective method to restore the sandy land ecosystem. However, the selection of conservation shrubs should consider the native or exotic species, the height of the shrub, the size of the crown, the structure of the crown and the chemical effect, and the selection of the restoration species should consider its own biological characteristics and the interaction with the conserved plants. The success rate of the theory applied to vegetation restoration.
【學位授予單位】：陜西師范大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：Q948

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