青海云杉林更新及其幼苗幼树生长态势模拟研究

发布时间：2018-01-14 09:05

本文关键词：青海云杉林更新及其幼苗幼树生长态势模拟研究　出处：《兰州大学》2017年博士论文　论文类型：学位论文

【摘要】：青海云杉(Picea crassifolia)广泛分布于祁连山区,是该地区的优势乔木树种。青海云杉林承担着气候调节、生物多样性维持、固碳释氧和水源涵养的生态服务功能,是生态环境脆弱的西北地区的重要生态屏障。其中青海云杉林所承载的水源涵养功能对水资源贫乏的西北内陆来说乃是重中之重,这关系到甘肃河西走廊地区及部分内蒙古地区工农业用水问题,是有关国计民生的大事。目前,祁连山国家级自然保护区的生态环境安全已上升为国家生态安全战略层面。然而自上世纪60年代以来,森林砍伐、土地资源不合理利用以及青海云杉林经营管理不善导致青海云杉更新不良,对青海云杉林的可持续发展产生威胁,进而影响青海云杉林生态服务功能的发挥。为了理清影响青海云杉更新的因素,本文以青海云杉为研究对象,以影响青海云杉更新的生物因素和非生物因素为切入点,通过野外调查、室内实验以及模型模拟等方法揭示青海云杉更新的时空特征,主要研究结果如下:1.环境变量对青海云杉更新的影响(1)在坡面尺度上,青海云杉幼苗幼树的分布首先受海拔梯度的影响(约占总变异的34.3%),调查结果显示青海云杉幼苗幼树在中等海拔梯度(2900-3200 m)分布最多,其次受其他环境要素如坡度、坡向及距母树的距离(约占总变异的27.7%)的影响。(2)在样方尺度上,青海云杉幼苗幼树受苔藓层的影响。研究结果显示厚度约为5 cm和盖度约为50%的苔藓层是影响青海云杉更新的阈值;即当苔藓层厚度约为5 cm、盖度约为50%时,生长在苔藓层上的幼苗幼树最多。2.苔藓沿海拔梯度对青海云杉更新的影响(1)在相同海拔梯度薄苔藓层(5 cm)促进青海云杉更新,降低幼苗幼树死亡率,而厚苔藓层(10 cm)抑制青海云杉的更新。(2)去除地表苔藓层后(裸地)随着海拔梯度的升高青海云杉的更新能力下降;在未去除地表苔藓处理中,随着海拔梯度的升高,苔藓对青海云杉的更新产生积极的促进作用;该研究结果为“胁迫梯度假说”提供了直接证据,即随着胁迫梯度的增强,物种间的正相互作用在增强。(3)在较低海拔梯度上(2750 m),苔藓抑制了青海云杉幼苗幼树的存活,而随着海拔梯度的升高,苔藓降低了青海云杉幼苗幼树的死亡率,说明在环境条件较为恶劣的情况下苔藓对青海云杉产生了“保育作用”;暗示着苔藓植物潜在扩张了青海云杉幼苗幼树的生态位,在胁迫梯度的末端提高了幼苗幼树的存活率。3.苔藓化感作用对青海云杉种子萌发和湿度梯度对出苗的影响(1)高浓度(50 mg ml~(-1))苔藓水提液抑制青海云杉种子萌发,而低浓度(0.5 mg ml~(-1)和5 mg ml~(-1))苔藓水提液促进青海云杉种子萌发,在水提液浓度为0.5 mg ml~(-1)时,青海云杉种子的萌发率最高,约为70%。(2)在干燥(空气湿度50%)和中等湿度(空气湿度70%)的环境中,苔藓植物对青海云杉出苗具有积极的“保育作用”,而在潮湿(空气湿度90%)的环境中苔藓对青海云杉出苗产生抑制作用。该结果意味着苔藓对青海云杉更新具有双重影响。(3)苔藓层改变了青海云杉幼苗的形态学特征,导致生长在苔藓层中的青海云杉幼苗柔弱纤细(5.41×10~(-4)±6.7×10~(-5) g cm~(-1);幼苗干重/幼苗长度),而生长在裸土上的青海云杉幼苗较为粗壮(6.58×10~(-4)±8.5×10~(-5) g cm~(-1);幼苗干重/幼苗长度),但是苔藓层中的青海云杉出苗率高于裸土上的青海云杉出苗率,综合以上结果,苔藓对青海云杉更新起到积极的促进作用。4.不同时空尺度青海云杉幼苗幼树的生物量特征(1)FAREAST模型模拟显示,60年内青海云杉幼苗幼树的生物量在任何一个海拔梯度上随着时间的推移均呈显著的线性增长趋势。(2)青海云杉幼苗幼树的生物量与海拔梯度呈二次多项式关系,即生物蓄积量随着海拔梯度的增加而增加,达到峰值后再降低。(3)模拟结果显示青海云杉幼苗幼树的生物量在祁连山西、中和东段不同,幼苗幼树分布的海拔梯度的上限和下限有所差异,这与不同模拟站点的气候变量、土壤变量、地形变量以及生物环境变量密切相关。
[Abstract]:Qinghai spruce (Picea crassifolia) is widely distributed in the mountainous area of Qilian, is the area of the dominant tree species. The Qinghai spruce bear climate regulation, biodiversity conservation, carbon fixation and oxygen release and water conservation ecological service function, is the ecological barrier to the fragile ecological environment in Northwest China. The water conservation function of Qinghai spruce forest carrying on water resource poor inland Northwest is priority among priorities, which relates to the industrial and agricultural water problems in Hexi Corridor of Gansu area and Inner Mongolia area, is beneficial to the people's livelihood event. At present, Qilian Mountains National Nature Reserve, ecological security zone has risen to the level of national ecological security strategy. However, since the last century since 60s, deforestation, land resources and rational utilization of Qinghai spruce forest economic mismanagement of Qinghai spruce bad regeneration of Qinghai spruce forest A threat to sustainable development, thereby affecting Qinghai spruce forest ecosystem service function. In order to clarify the influence factors of Qinghai spruce renewal, this paper takes Qinghai spruce as the research object, the effect of biological factors of Qinghai spruce renewal and abiotic factors as the breakthrough point, through field investigation, laboratory experiment and simulation method to reveal the spatial and temporal characteristics of Qinghai spruce update, the main results are as follows: 1. effects of environmental variables on Qinghai spruce update (1) in the slope scale, the distribution of Qinghai spruce seedlings first by altitudinal gradient effect (accounting for about 34.3% of the total variance), the survey results show that Qinghai spruce seedlings in the middle altitude gradient distribution (2900-3200 m) the most, followed by other environmental factors such as slope, slope and distance from trees (about 27.7% of the total variance). The effects of (2) in the square of Qinghai spruce seedlings, young The affected tree moss layer. The results show that the thickness of about 5 cm and about 50% of the coverage of moss layer is Qinghai spruce update threshold; when the moss layer is about 5 cm, the coverage is about 50%, affecting the growth of the seedlings in the moss layer up to.2. moss along an altitudinal gradient in Qinghai spruce update (1) at the same altitude gradient thin moss layer (5 cm) to promote Qinghai spruce seedlings to reduce mortality, update, and thick moss layer (10 cm) inhibited Qinghai spruce renewal. (2) after removal of moss layer (bare) decreased with the increase of the altitude of Qinghai spruce regeneration in the removal of moss; processing, with the increase of elevation gradient, moss update on Qinghai spruce has a positive role in promoting; provide direct evidence for the results of the study for the "stress gradient hypothesis", with the increase of stress gradient, species positive The interaction is enhanced. (3) at low altitudes (2750 m), Qinghai spruce moss inhibited the survival of seedlings and saplings, and with the increase of elevation gradient, moss reduced Qinghai spruce seedling and sapling mortality, that moss in environmental conditions are harsh conditions resulting in a "conservation" in Qinghai spruce; ecological bryophytes imply potential expansion of Qinghai spruce seedlings were, at the end of stress gradient improves the survival rate of the seedlings of.3. moss allelopathy on Seed Germination and seedling emergence of Qinghai spruce seed moisture gradient effect (1) and high concentration (50 mg ml~ (-1)) moss water extract inhibition of seed germination of Qinghai spruce, while low concentrations (0.5 mg and 5 mg ml~ (-1) ml~ (-1)) moss water extract to promote germination of Qinghai spruce seeds in the concentration of water is 0.5 mg ml~ (-1), Qinghai spruce seed germination rate is about 70%. (2 in) dry Dry (air humidity and humidity (50%) secondary air humidity 70%) environment, bryophytes of Qinghai spruce seedling has positive "conservation effect", and in the wet moss (air humidity 90%) environment has inhibitory effect on Qinghai spruce seedling. The results imply that the moss has dual influence on Qinghai spruce regeneration. (3) changed the moss layer morphology of Qinghai spruce seedlings, leading to growth in moss layer in Qinghai spruce seedlings slender (5.41 * 10~ (-4) + 6.7 * 10~ (-5) g cm~ (-1); seedling dry weight / seedling length), the growth in the bare soil on Qinghai spruce a sturdy seedling (6.58 * 10~ (-4) + 8.5 * 10~ (-5) g cm~ (-1); seedling dry weight / seedling length), but the moss layer in Qinghai spruce seedling emergence rate was higher than that of bare soil on Qinghai spruce seedling rate, based on the above results, the moss to promote.4. in Qinghai spruce regeneration Biomass characteristics with temporal and spatial scales of Qinghai spruce seedlings (1) FAREAST model simulations showed that the biomass of 60 years of Qinghai spruce seedlings at any altitude gradient over time showed a significant linear growth trend. (2) Qinghai spruce seedlings biomass with altitude gradient is two polynomial relationship, is the biological volume increases with increasing altitude, to a peak and then decreased. (3) the simulation results show that the biomass of Qinghai spruce seedlings in Qilian and Shanxi, the eastern section of different upper and lower altitude gradient of seedlings distribution is different, and the simulation of different site climate variables soil variables, topographic variables and biological environment variables are closely related.

【学位授予单位】：兰州大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S791.18

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