| 摘要: |
| 和田河下游绿色走廊植被具有极为重要的涵养水源、防风固沙、保护土壤、维持生物多样性、净化环境污染等功能。且在减缓自然灾害、维护生态安全和社会经济发展中的不可替代的天然屏障和保障作用。为了研究荒漠河岸林植被分布及生理指标对水分条件的响应，文章在野外监测数据的基础上，
全面分析和田河下游植被分布情况及植物丰富度变化规律；选取代表性建群植物胡杨Populus euphratica，分析其相对含水量（RWC）、叶绿素（Chl）、可溶性糖（SS）、游离脯氨酸（Pro）和过氧化物酶(POD) 活性等生理指标对水分条件的响应机理。结果表明，胡杨是和田河下游主要建群植物，林下植被包括属于17 科的45 种灌木和草本植物；垂直河道方向的河漫滩、林下灌草地、灌丛草地和荒漠林地等不同样地的植物多样性变化来看，在河漫滩水分条件较好，一年生草本成为主要的优势物种，林下草地表现为较为完整的乔、冠、草3 层结构群落，因此这两种样地的物种丰富度较高，分别为6.1 和5.2。随着距河道距离的增加，灌丛草地内多年生草本、灌木物种增多，一年生草本逐渐消失，在荒漠林地是以耐旱、耐盐的灌木为主，同时物种丰富度也减小，这两种样地物种丰富度较低，分别为2.5 和1.3，说明在和田河干流绿色走廊距离河道越近物种数越多；从胡杨各生理指标的变化来看，胡杨长势等级“中等”的情况下，其相对含水量（RWC）、叶绿素（Chl）、可溶性糖（SS）、游离脯氨酸（Pro）和过氧化物酶(POD) 活性等生理指标达到了最高值，因为胡杨叶含水量减少和脯氨酸积累的增加是胡杨对水分亏缺的一种生理反应，即随着地下水位的降低，胡杨通过体内脯氨酸的积累，提高渗透调节能力，保持其原生质与环境的渗透平衡，说明胡杨在对水分亏缺时发生了生理上的变化以适应环境的变化。从胡杨各类生理指标对水分条件的响应可以看出，水分条件是决定荒漠河岸林植被分布的重要因素。 |
| 关键词: 胡杨 生理指标 水分条件 响应机理 和田河下游 |
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| Responses of Vegetation Distribution and Physiological Indexes to Water Condition in the Lower Reaches of Hetian River |
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Aikeremu ABULA1, DONG Zong wei1, Aishajiang AILI2, ZHAO Xinfeng2
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1.Management Bureau of Tarim River Basin,Kuerle;2.State Key Laboratory of Desert and Oasis Ecology,Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences,Urumqi
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| Abstract: |
| The green corridor vegetation in the lower reaches of the Hotan River has extremely important functions such as water conservation, windbreak and sand fixation, soil protection, biodiversity maintenance, purifying environmental pollution and other functions. Natural barriers in the desert play an irreplaceable role in the mitigation of natural disasters, the maintenance of ecological security, and social and economic development. To study the response of vegetation distribution and physiological indexes of desert riparian forest
to water conditions, on the basis of field monitoring data, this paper comprehensively analyzed the distribution of vegetation and the variation of plant richness in the lower reaches of the Hotan River. The response of relative water content (RWC), chlorophyll (Chl), soluble sugar (SS), free proline (Pro) and peroxidase (POD) activities of Populus euphratica to water condition was analyzed. The results showed that P. euphratica was the main constructive plant in the lower reaches of the Hotan River, and the understory vegetation included 45 species of shrubs and herbs belonging to 17 families. According to the changes of plant diversity in different places such as a floodplain, shrub grassland under forest, shrub grassland and desert forest land in the direction perpendicular to the river channel, the water condition of the floodplain is good, the annual herb has become the main dominant species, and the grassland under forest shows a relatively complete three-layer structure community of tree, crown and grass. Therefore, the species richness of these two kinds of plots is high, which are 6.1 and 5.2 respectively. With the increase of the distance from the river channel, the species of perennial herbs and shrubs in the shrub grassland increase, and the annual herbs gradually disappear. In the desert forest land, it is mainly drought and salt-tolerant shrubs, and the species richness also decreases. The species richness of the two sample plots is lower, which are 2.5 and 1.3 respectively, indicating that the closer to the river channel in the green corridor of the mainstream of the Hotan River, the more species there are. From the changes in physiological indexes of P. euphratica, when the growth grade is “medium”, the physiological indexes such as relative water content (RWC), chlorophyll (Chl), soluble sugar (SS), free proline (Pro) and peroxidase (POD) activity reach the highest value. The species richness of floodplain and understory shrub grassland was higher, while that of shrub grassland and desert forest land was lower, which indicated that the closer the green corridor was to the river, the more species there were. The variation trends of physiological indexes of P.euphratica indicated that the decrease of leaf water content and the increase of proline accumulation is a physiological response to P. euphratica water deficit. That is, with the decrease of groundwater level, P.euphratica improve its osmotic adjustment ability and maintains the osmotic balance between protoplasm and environment through proline accumulation in vivo, which indicates that P. euphratica has physiological changes to adapt to the changes in environment. From the response of physiological indexes of P.euphratica water conditions, it can be concluded that water conditions are the decisive factor for the growth and development of vegetation in desert riparian forests. |
| Key words: Populus euphratica physiological index water condition response mechanism lower reaches of Hotan River |
