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古尔班通古特沙漠土壤种子库时空特征及其对积雪覆盖改变的响应
贾风勤
学位类型博士
导师张元明 ; 塔西甫拉提·特依拜
2017-05-01
学位授予单位中国科学院大学
学位授予地点新疆乌鲁木齐
学位专业理学博士
关键词土壤种子库 种子活力 时空格局 取样尺度 积雪覆盖变化 植物群落结 Soil Seed Bank Seed Vigor Spatial Distribution Pattern Sampling Scale Snow Variability Plant Community Structure
摘要古尔班通古特沙漠是我国最大的固定和半固定沙漠,自 80 年代以来沙漠油气资源开发、公路建设、过度放牧等对沙漠植被产生严重的干扰,使维持沙漠地表稳定的基本条件正趋于丧失,威胁着荒漠生态系统的稳定性。土壤种子库是植被更新和恢复的重要前提,深入了解该沙漠土壤种子库特征及其与地上植被的关系,对于指导受损植被的恢复实践具有重要意义。鉴于此,本文以古尔班通古特沙漠为研究区域,分析了沙丘 7 个地貌部位土壤种子库时空分布特征,解析了土壤种子库及其与地上植物关系,阐明了土壤种子库空间分布格局的尺度效应,探讨了积雪变化对土壤种子库种子萌发及种子活力的影响。主要研究结果如下:(1)沙丘冬季、春季和秋季沙丘土壤种子库密度在整体上(0-10 cm)分别为478.87 seeds/m2、97.87 seeds/m2 和 177.86 seeds/m2,呈显著差异;土壤种子库物种丰富度分别为 17、11 和 12 种,生活型均以短命植物占绝对优势;土壤种子库密度、物种丰富度、Shannon-Wiener 指数、Simpson 指数和 Pielou 均匀度指数均表现为从冬季土壤种子库到秋季土壤种子库呈“V”型变化即春季土壤种子库各数量特征均为最低。(2)沙丘0-10 cm土壤层次3种土壤种子库的密度、物种丰富度、Shannon-Wiener指数、Simpson 指数和 Pielou 均匀度指数受坡位影响显著,其中迎风坡底部、背风坡3 个坡位的冬季种子库和春季种子库间有显著差异。0-2 cm 土壤层次 3 种土壤种子库各数量指标也受坡位影响显著,其中在迎风坡坡底、背风坡上部和下部多表现出冬季土壤种子库显著高于春季,但个别坡位存在秋季显著高于春季。(3)沙丘植物种以菊科为主,生活型多为短命植物;迎风坡植物密度显著少于背风坡,且随季节变化两坡向植物密度变化均呈“V”型,共有种以背风坡相对较多。α 多样性指数在迎风坡及背风坡均为坡上部最大,坡底最小且有显著差异;从早春到秋季各坡位 α 多样性指数呈减少和“V”型两种变化趋势。β 多样性指数变化表明随坡位升高,迎风坡和背风坡物种替代性指数降低,相似性指数增加,两者在背风坡均表现为显著变化;从早春到秋季两坡向上物种替代指数增加,相似性指数降低,但替代性指数均无显著差异,沙丘坡向和坡位对草本植物α多样性和β多样性时空格局均产生显著影响。(4)沙丘 7 个坡位 0-10 cm 冬季、春季和秋季土壤种子库相似性关系中冬季土壤种子库相似性系数均较春季和秋季为高,但同一种子库在 7 个坡位间相似性系数无显著差异;7 个坡位 0-2 cm、2-5 cm 和 5-10 cm 土壤层次 3 种土壤种子库相似性均以0-2 cm 为最高。土壤种子库与地上植物组成的物种存在关系中以“只有地上植物但无土壤种子库”的物种数量始终为最高。土壤种子库及地上植物物种生活型均以短命植物为主。(5)相比与土壤种子库种子密度和物种丰富度,Shannon-Wiener 指数、Simpson指数和 Pielou 均匀度指数具有更为明显的空间尺度效应;Pielou 均匀度指数随取样面积增加呈线性负相关,最小取样面积不能确定;其余 4 个土壤种子库数量特征均随取样尺度增加呈现单峰分布特征,建议测定种子密度的取样尺度为 0.5 m×0.5 m,物种丰富度指数、Shannon-Wiener 指数和 Simpon 指数为 2 m×2 m。(6)积雪处理对不同植物种子萌发率影响为:抑制萌发、促进萌发、对种子萌发的影响不定;不同积雪处理还显著影响部分植物种子萌发。在积雪处理对种子萌发有促进作用的植物种中,短命植物最多,多年生植物最少;有抑制作用的植物种则主要以短命植物和多年生植物为主。未萌发种子复水萌发率表现出 4 种变化趋势:随积雪厚度增加,复萌萌发率呈单调增加或单调降低的变化趋势;呈“V”型或倒“V”型变化趋势,拐点均出现在自然降雪处理下。积雪处理导致 36.54%的植物所有未萌发种子失去活力。积雪处理对未萌发种子潜在活力均表现两种影响:正效应和负效应。尤其是在积雪处理对种子萌发有抑制作用的植物种中,去雪、自然降雪和加雪处理对短命植物种子萌发负效应高于一年生长营养期植物、多年生草本和灌木。
其他摘要Gurbantunggut Desert is the largest fixed and semi-fixed desert in arid and semi-arid regions of China. Stabilization is one of the major features of the sand dune systems in the Gurbantunggut Desert. However, in recent years, commercial activities in the Gurbantunggut Desert, such as oil exploitation, tourism, nomadic activities and tillage,have massively destroyed the aboveground vegetation, which significantly and negatively influenced the stabilization of sand dunes. It is urgent to implement ecosystem restoration to mitigate these negative effects. Up to now, several researchers described the disturbance of grazing, engineering activities, biological soil crust on soil seed banks characteristics and special pattern, and reviewed the strategies for restoring and reconstructing the destroyed vegetation. However, there are several questions puzzled in the process of vegetation restoration. (1) How change of soil seed bank on typical longitudinal sand dune (seed density, component and spatial pattern), (2) how change of scale-dependent spatial patterns of soil seed bank, (3) what and how change of characteristics of soil seed bank to snow variability. In order to explain those questions, the characteristics of soil seed banks in different soil depths at different geomorphic positions in the sand dunes, scale effect of spatial pattern of soil seed bank, and response of seeds in soil seed bank to snow variability was investigated in field and laboratory.The result showed:Seasonal difference of total soil seed banks density (0-10 cm) was significant in winter soil seed bank, spring soil seed bank and autumn soil seed bank. Total soil seed bank in winter was 478.87 seeds/m2, followed by autumn soil seed bank was 177.86seeds/m2, 97.87 seeds/m2 in spring soil seed bank. The major life forms of plant species in three types of soil seed bank were ephemeral. The density, species richness,Shannon-Wiener index, Simpson index and Pielou’s evenness index of total soil seed bank was highest in winter, lowest in spring, and showed a trend of “ V ”pattern from winter soil seed bank to autumn soil seed bank.The difference of seed density, species richness, Shannon-Wiener diversity index,Simpson’s diversity index and Pielou evenness index of total soil seed banks in three seasons were significant in different positions of sand dune, such as there was significant difference between winter soil seed bank and spring soil seed bank on base of windward slope, base of leeward slope, low part of leeward slope and up part of leeward slope. The similar result was observed in 0-2 cm soil layer in three seasons.Among windward slope and leeward slope of sand dune, the main species of plant were Composite, and life form of ephemeral plants had the highest proportion; plant density on windward slope was significantly lower than leeward slope, but showed a same trend of “V” pattern from early spring to autumn. On both slope aspects, the highest α–diversity (Richness index, Shannon-Winer diversity index, Simpson’s diversity index and Pielou evenness index) was observed at upper slope, the lowest at base of slope; there was a decreasing trend or a “V” pattern in each terrain with seasonal change was delayed. β-diversity (indicated Cody index) was decreasing, and Sorenson index was increasing with the terrain rising on windward slope and leeward slope, and observed a significant change in leeward slope.The similarity coefficient between the soil seed banks and aboveground vegetations varied among three soil seed banks in seven positions of sand dune, and similarity coefficient in winter was obviously more than spring and autumn, but there was no significant difference in seven positions at the same soil seed bank. The vegetation was more similar to the soil seed bank in the sallow layer (0-2 cm) than to the soil seed bank in the deeper soil (2-5 cm and 5-10 cm), which showed that the vegetation contributed less to the soil seed bank as soil depth increased. The major life forms of plant species in soil seed bank were ephemeral, and the relationship between the soil seed banks and species presence proportion of aboveground was “Only the aboveground vegetation, no seeds”Spatial distribution patterns of Shannon-Wiener diversity index, Simpson’s diversity index, and Pielou evenness index obviously changed with the spatial scales than the seed density and species richness. Seed density, species richness, Shannon-Wiener and Simpson’s diversity indices of soil seed bank with the increase of spatial scales were unimodal, which had the maximum data at the 0.5 m×0.5 m for seed density,2 m×2 m for species richness, Shannon-Wiener and Simpson indices.There were three types of seed responses to snow variability: germination percentage increased, decreased, or undetermained; germination percentage of thirteen species seeds were significantly effect. The proportion of ephemeral was highest and perennial species was lowest when snow increased seed germination percentage; the major life forms were ephemeral and perennial species when snow decreased seed germination.There were four kinds of un-germinated seed responses to snow variability:re-germination percentage increased, decreased, a trend of “V” or inverted “V”pattern, but the change point of re-germination percentage always appeared under the natural snow thickness. About 36.54% un-geminated seed loss vigor and dead after snow treatments.Snow thickness had positive or negative effects on potential vigor of un-germinated seeds. Especially, in these species which snow treatment decreased seed germination percentage, the negative effects to ephemeral seed germination was higher than the annual plant species, perennial herbaceous and shrubs.
学科领域生态学
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14781
专题研究系统_荒漠环境研究室
作者单位1.中国科学院新疆生态与地理研究所
2.新疆大学
推荐引用方式
GB/T 7714
贾风勤. 古尔班通古特沙漠土壤种子库时空特征及其对积雪覆盖改变的响应[D]. 新疆乌鲁木齐. 中国科学院大学,2017.
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