本文關(guān)鍵詞：青海云杉林更新及其幼苗幼樹(shù)生長(zhǎng)態(tài)勢(shì)模擬研究　出處：《蘭州大學(xué)》2017年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 青海云杉 更新 苔蘚 海拔梯度 化感作用 FAREAST模型

【摘要】：青海云杉(Picea crassifolia)廣泛分布于祁連山區(qū),是該地區(qū)的優(yōu)勢(shì)喬木樹(shù)種。青海云杉林承擔(dān)著氣候調(diào)節(jié)、生物多樣性維持、固碳釋氧和水源涵養(yǎng)的生態(tài)服務(wù)功能,是生態(tài)環(huán)境脆弱的西北地區(qū)的重要生態(tài)屏障。其中青海云杉林所承載的水源涵養(yǎng)功能對(duì)水資源貧乏的西北內(nèi)陸來(lái)說(shuō)乃是重中之重,這關(guān)系到甘肅河西走廊地區(qū)及部分內(nèi)蒙古地區(qū)工農(nóng)業(yè)用水問(wèn)題,是有關(guān)國(guó)計(jì)民生的大事。目前,祁連山國(guó)家級(jí)自然保護(hù)區(qū)的生態(tài)環(huán)境安全已上升為國(guó)家生態(tài)安全戰(zhàn)略層面。然而自上世紀(jì)60年代以來(lái),森林砍伐、土地資源不合理利用以及青海云杉林經(jīng)營(yíng)管理不善導(dǎo)致青海云杉更新不良,對(duì)青海云杉林的可持續(xù)發(fā)展產(chǎn)生威脅,進(jìn)而影響青海云杉林生態(tài)服務(wù)功能的發(fā)揮。為了理清影響青海云杉更新的因素,本文以青海云杉為研究對(duì)象,以影響青海云杉更新的生物因素和非生物因素為切入點(diǎn),通過(guò)野外調(diào)查、室內(nèi)實(shí)驗(yàn)以及模型模擬等方法揭示青海云杉更新的時(shí)空特征,主要研究結(jié)果如下:1.環(huán)境變量對(duì)青海云杉更新的影響(1)在坡面尺度上,青海云杉幼苗幼樹(shù)的分布首先受海拔梯度的影響(約占總變異的34.3%),調(diào)查結(jié)果顯示青海云杉幼苗幼樹(shù)在中等海拔梯度(2900-3200 m)分布最多,其次受其他環(huán)境要素如坡度、坡向及距母樹(shù)的距離(約占總變異的27.7%)的影響。(2)在樣方尺度上,青海云杉幼苗幼樹(shù)受苔蘚層的影響。研究結(jié)果顯示厚度約為5 cm和蓋度約為50%的苔蘚層是影響青海云杉更新的閾值;即當(dāng)苔蘚層厚度約為5 cm、蓋度約為50%時(shí),生長(zhǎng)在苔蘚層上的幼苗幼樹(shù)最多。2.苔蘚沿海拔梯度對(duì)青海云杉更新的影響(1)在相同海拔梯度薄苔蘚層(5 cm)促進(jìn)青海云杉更新,降低幼苗幼樹(shù)死亡率,而厚苔蘚層(10 cm)抑制青海云杉的更新。(2)去除地表苔蘚層后(裸地)隨著海拔梯度的升高青海云杉的更新能力下降;在未去除地表苔蘚處理中,隨著海拔梯度的升高,苔蘚對(duì)青海云杉的更新產(chǎn)生積極的促進(jìn)作用;該研究結(jié)果為“脅迫梯度假說(shuō)”提供了直接證據(jù),即隨著脅迫梯度的增強(qiáng),物種間的正相互作用在增強(qiáng)。(3)在較低海拔梯度上(2750 m),苔蘚抑制了青海云杉幼苗幼樹(shù)的存活,而隨著海拔梯度的升高,苔蘚降低了青海云杉幼苗幼樹(shù)的死亡率,說(shuō)明在環(huán)境條件較為惡劣的情況下苔蘚對(duì)青海云杉產(chǎn)生了“保育作用”;暗示著苔蘚植物潛在擴(kuò)張了青海云杉幼苗幼樹(shù)的生態(tài)位,在脅迫梯度的末端提高了幼苗幼樹(shù)的存活率。3.苔蘚化感作用對(duì)青海云杉種子萌發(fā)和濕度梯度對(duì)出苗的影響(1)高濃度(50 mg ml~(-1))苔蘚水提液抑制青海云杉種子萌發(fā),而低濃度(0.5 mg ml~(-1)和5 mg ml~(-1))苔蘚水提液促進(jìn)青海云杉種子萌發(fā),在水提液濃度為0.5 mg ml~(-1)時(shí),青海云杉種子的萌發(fā)率最高,約為70%。(2)在干燥(空氣濕度50%)和中等濕度(空氣濕度70%)的環(huán)境中,苔蘚植物對(duì)青海云杉出苗具有積極的“保育作用”,而在潮濕(空氣濕度90%)的環(huán)境中苔蘚對(duì)青海云杉出苗產(chǎn)生抑制作用。該結(jié)果意味著苔蘚對(duì)青海云杉更新具有雙重影響。(3)苔蘚層改變了青海云杉幼苗的形態(tài)學(xué)特征,導(dǎo)致生長(zhǎng)在苔蘚層中的青海云杉幼苗柔弱纖細(xì)(5.41×10~(-4)±6.7×10~(-5) g cm~(-1);幼苗干重/幼苗長(zhǎng)度),而生長(zhǎng)在裸土上的青海云杉幼苗較為粗壯(6.58×10~(-4)±8.5×10~(-5) g cm~(-1);幼苗干重/幼苗長(zhǎng)度),但是苔蘚層中的青海云杉出苗率高于裸土上的青海云杉出苗率,綜合以上結(jié)果,苔蘚對(duì)青海云杉更新起到積極的促進(jìn)作用。4.不同時(shí)空尺度青海云杉幼苗幼樹(shù)的生物量特征(1)FAREAST模型模擬顯示,60年內(nèi)青海云杉幼苗幼樹(shù)的生物量在任何一個(gè)海拔梯度上隨著時(shí)間的推移均呈顯著的線性增長(zhǎng)趨勢(shì)。(2)青海云杉幼苗幼樹(shù)的生物量與海拔梯度呈二次多項(xiàng)式關(guān)系,即生物蓄積量隨著海拔梯度的增加而增加,達(dá)到峰值后再降低。(3)模擬結(jié)果顯示青海云杉幼苗幼樹(shù)的生物量在祁連山西、中和東段不同,幼苗幼樹(shù)分布的海拔梯度的上限和下限有所差異,這與不同模擬站點(diǎn)的氣候變量、土壤變量、地形變量以及生物環(huán)境變量密切相關(guān)。
[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.

【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：S791.18

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