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1.
《地理学报(英文版)》2019,(9)
In many arid ecosystems, vegetation frequently occurs in high-cover patches interspersed in a matrix of low plant cover. However, theoretical explanations for shrub patch pattern dynamics along climate gradients remain unclear on a large scale. This context aimed to assess the variance of the Reaumuria soongorica patch structure along the precipitation gradient and the factors that affect patch structure formation in the middle and lower Heihe River Basin(HRB). Field investigations on vegetation patterns and heterogeneity in soil properties were conducted during 2014 and 2015. The results showed that patch height, size and plant-to-patch distance were smaller in high precipitation habitats than in low precipitation sites. Climate, soil and vegetation explained 82.5% of the variance in patch structure. Spatially, R. soongorica shifted from a clumped to a random pattern on the landscape towards the MAP gradient, and heterogeneity in the surface soil properties(the ratio of biological soil crust(BSC) to bare gravels(BG)) determined the R. soongorica population distribution pattern in the middle and lower HRB. A conceptual model, which integrated water availability and plant facilitation and competition effects, was revealed that R. soongorica changed from a flexible water use strategy in high precipitation regions to a consistent water use strategy in low precipitation areas. Our study provides a comprehensive quantification of the variance in shrub patch structure along a precipitation gradient and may improve our understanding of vegetation pattern dynamics in the Gobi Desert under future climate change. 相似文献
2.
In this study the spatial patterns and dynamics of vegetation patches along a grazing gradient in the steppe ofLarrea divaricataandStipaspp. in NE Patagonia (Argentina) are described. A general effect of grazing is the reduction of total plant cover resulting from the decrease in cover of perennial grasses (Stipa speciosa, Poa ligularis, Stipa tenuis) and some tall shrubs (Chuquiraga hystrix, Bougainvillea spinosa, Lycium chilense). Dwarf shrubs (Nassauvia fueguianaandJunellia seriphioides) increase their cover under medium and/or high grazing pressures. Plant species are spatially grouped into patches which alternate with areas of bare soil. Eleven types of vegetation patch differing in the dominant plant functional type or species, floristic richness and size were identified with different relative frequency along the grazing gradient. Based on these results, it is postulated that grazing forces the replacement of large patches dominated by tall shrubs with high species richness, byLarrea divaricatapatches or small dwarf shrub patches with low species richness and the extinction of grass patches. This results from: (1) disruption of local balances of species deletions and additions; (2) fragmentation of large patches; and (3) formation of new vegetation patches. These changes lead to differing plant spatial organization and heterogeneity along the grazing gradient which may be described by characteristic arrays of vegetation patches. 相似文献
3.
地表径流对荒漠灌丛生境土壤水分空间特征的影响 总被引：3，自引：2，他引：1
土壤水分是干旱区多尺度生态水文过程的关键影响因素和驱动因子,其时空格局是生态、水文、气象、地形等自然过程研究的重要参数。笔者研究了降水径流事件后3种不同灌丛个体尺度土壤水分空间异质性特征,结果表明,珍珠灌丛个体尺度土壤水分空间分布特征表现为灌丛边缘>灌丛内部>灌丛间裸地,驼绒藜灌丛表现为灌丛内部>灌丛边缘>灌丛间裸地,而狭叶锦鸡儿灌丛不同微生境土壤水分差异不显著。珍珠和驼绒藜灌丛同一微生境土壤水分存在坡位梯度,珍珠灌丛3个微生境土壤水分均表现为上坡位大于下坡位,而驼绒藜灌丛边缘表现为上坡位小于下坡位,其他两个微生境无明显规律;狭叶锦鸡儿灌丛土壤水分无明显的坡位梯度。3种灌丛不同微生境土壤含水量随土层深度增加的变化不明显。这说明在降水径流事件中,不同斑块的反应差异引起了地表径流的形成以及随之发生的资源再分配,从而导致了景观内土壤水分的空间异质性。 相似文献
4.
测定了荒漠地区超旱生小灌木红砂在3种生境(山前荒漠、山前戈壁和中游戈壁)下的叶片水分状态、抗氧化酶活性及渗透调节物质含量,以探讨荒漠植物在不同生境下的生理生化特征及对荒漠极端环境的适应机制。结果表明:在3种生境下,红砂叶片相对含水量和叶片水势随着土壤含水量的下降而下降,叶绿素含量随着土壤含水量的下降而升高。随着生境土壤干旱的加剧,超氧化物歧化酶(SOD)及过氧化物酶(POD)活性逐渐升高,而过氧化氢酶活性下降。在土壤含水量较少的戈壁生境,渗透调节物质含量上升。SOD和POD活性的升高是红砂抵御干旱环境的主要抗氧化保护机制;渗透调节在红砂叶片适应干旱胁迫的过程中发挥着重要作用,高的渗透调节能力使红砂在水分不足的条件下维持较低的渗透势,有利于植物吸水,从而增强其耐旱性。 相似文献
5.
Reaumuria soongorica is a short woody shrub widely found in semi-arid areas of China. It can survive severe environ- mental stress including high salinity in its natural habitat. Thus, we investigated the involvement of anti-oxidative enzymes, photosynthetic pigments and flavonoid metabolism in the adaptation of R. soongorica to saline environments. R. soon- gorica was treated with 0, 100, 200 and 400 mM NaC1 solutions for 14 days. Soil salt content increased significantly by watering with high content of NaC1 solution, and no variation between 8 and 14 days during treatment. The levels ofpe- roxidation of lipid membranes （measured by malondialdehyde content） and the activities of three antioxidant enzymes （superoxide dismutase （SOD）, peroxidase （POD） and ascorbate peroxidase （APX）） increased under salt stress. Chlorophyll and carotenoid content decreased with increasing salt content. The ratio of Chl a/Chl b and carotenoid/Chl exhibited sig- nificant increase under 400 mM NaC1. However, total flavonoid and anthocyanin contents and key enzyme activities in the flavonoid pathway including phenylalanine ammonialyase （PAL） and Chalcone isomerase （CHI） decreased under salt stress. These findings possibly suggest that R. soongorica has an adaptation protection mechanism against salt-induced oxidative damage by inducin~ the activity of antioxidant enzymes and maintaining a steady level of carotenoid/Chl. 相似文献
6.
7.
黄土高原半干旱区天然锦鸡儿灌丛对土壤水分的影响 总被引：13，自引：4，他引：13
本文选择黄土高原半干旱区定西地区的一种地带性植被,天然甘蒙锦鸡儿灌丛,将其0～99m深的土壤水分含量与人工柠条锦鸡儿灌丛、人工杏树林、天然草地、放牧荒坡和农地的土壤水分含量进行了比较。结果发现,天然锦鸡儿灌丛在1m以下土壤各层的水分含量均高于人工柠条灌丛和人工杏树林,而与放牧荒坡和农地的土壤湿度接近,略低于农地。天然锦鸡儿灌丛4m以上土层的土壤湿度还明显高于天然草地;天然锦鸡儿灌丛形成的难效—无效水层深度在2m土层以上,而人工柠条灌丛形成的难效无效水层则深达56m,人工杏树林42m,天然草地、放牧荒坡分别为36m和33m,农地1m。 相似文献
8.
Julio R. Gutiérrez Francisco López-Cortes Pablo A. Marquet 《Journal of Arid Environments》1998,40(4):383-399
Six sites between 0 m and 4000 m were sampled for plant and soil chemical characteristics along the Río Loa, Atacama Desert, Chile. Sites located between 0 m and 1500 m showed lower species richness, higher plant cover and higher herbaceous productivity than the upper part of the altitudinal gradient. The number of species varied non-linerly with precipitation along the altitudinal gradient. Plant cover and herbaceous productivity in the lowlands is characterized by thePluchea absinthioides Distichlis spicataassociation of anthropic origin. We propose that vegetation structure along the altitudinal gradient has been affected by past and present human activities, and climatic and edaphic factors. 相似文献
9.
The architectural parameters of Reaumuria soongorica root system in different habitats of Gansu Province, China were analyzed to examine its ecological adaptability to arid environments. Results show that： （1） Topological indices of R. Soongorica root sys- tem are small in all habitats, and root branching pattem tends to be dichotomous. Also, the indices gradually increase in the Min- qin windblown sand region and the Zhangye Gobi region in Hexi Corridor, which indicates that drought tends to produce her- ringbone-like root branching pattems. （2） Fractal dimension values ofR. Soongorica root system are small and not obvious in the Minqin windblown sand region and the Zhangye Gobi region in Hexi Corridor, with values of 1.1778 and 1.1169, respectively. Fractal dimension values are relatively large in Jiuzhoutai semi-arid hilly and gully region of the Loess Plateau, which indicates that the R. Soongorica root system has better fractal characteristics in this region than in the other regions. （3） Total branching ra- tios of the R. Soongorica root system in arid regions of Hexi Corridor are smaller than that in the Jiuzhoutai semi-arid hilly and gully region of the Loess Plateau. This shows that root branching ability in the semi-arid region is stronger, and it decreases to some degree with increased drought. （4） The root connection lengths of R. soongorica root system are long in all habitats, but there are significant length differences between the different habitats. The root connection length at the Minqin windblown sand region is the longest. It is concluded that R. soongoriea adapts to arid environments by decreasing root branching, decreasing root overlap and increasing root connection length, which makes its root branching pattern tend to be herringbone-like to reduce com- petition in root internal environment for nutrients and to enhance root absorption rate of nutrients, and ensure effective nutrition space. Thus the roots can absorb enough water and nutrients in resource-poor settings to ensure normal physiological requirements. 相似文献
10.
Soil temperatures at 0, 5, 10 and 20 cm depths were monitored continuously at different microhabitats (beneath shrub canopy
(BSC); bare intershrub spaces (BIS)) induced by xerophytic shrub (Caragana korshinskii Kom.) canopy, respectively. We mainly
aimed to assess the effects of shrub canopy and precipitation on the spatial-temporal variability of soil temperature. Results indicate
that both precipitation and vegetation canopy significantly affect soil temperature. In clear days, soil temperatures within the
BSC area were significantly lower than in the BIS at the same soil depth due to shading effects of shrub canopy. Diurnal variations
of soil temperature show a unimodal sinusoidal curve. The amplitude of soil temperature tended to decrease and a hysteresis of diurnal
maximum soil temperature existed at deeper soil layers. Vertical fluctuations of soil temperature displayed four typical
curves. In the nighttime (approximately from sunset to sunrise), surface temperature within the BSC area was higher than in the
BIS. In rainy days, however, soil temperatures were affected mainly by precipitation and the shrub canopy had a negligible effect
on soil temperature, and little difference in soil temperature at the same soil depth was found between the BSC area and in the BIS.
Diurnal variations in soil temperature decreased exclusively as rainfall continued and the vertical fluctuations of soil temperature
show an increased tendency with increasing soil depth. 相似文献
11.
Soil water deficit and vegetation restoration in the refuse dumps of the Heidaigou open-pit coal mine, Inner Mongolia, China 总被引：1，自引：0，他引：1
The sustainability of ecosystem restoration of refuse dumps in open-pit coal mines depends on plant species selection, their configuration, and the optimal usage of water resources. This study is based on field experiments in the northern refuse dump of the Heidaigou open-pit coal mine in Inner Mongolia of China established in 1995. Eight plant configurations, including trees, shrubs, grasses, and their combinations, as well as the adjacent community of natural vegetation, were selected. The succession of the revegetated plants, soil water storage, the spatiotemporal distribution of plant water deficits degree and its compensation degree were also studied. Results indicated that the vegetation cover (shrubs and herbaceous cover), richness, abundance, soil nutrients (soil organic matter, N and P), and biological soil crust coverage on the soil surface are significantly influenced by the vegetation configurations. The average soil water storage values in the shrub+grass and grass communities throughout the growing season are 208.69 mm and 206.55 mm, which are the closest to that of in the natural vegetation community (215.87 mm). Plant water deficits degree in the grass and shrub+grass communities were the lowest, but the degrees of water deficit compensation in these configuration were larger than those of the other vegetation configurations. Differences in plant water deficit degree and water compensation among the different configurations were significant (P<0.05). Plant water deficit degrees were predominantly minimal on the surface, increased with increasing soil depth, and remained stable at 80 cm soil depth. The soil moisture compensation in the natural vegetation, shrub+grass, and grass communities changed at 10%, while that in other vegetation communities changed between 20% and 40%. Overall, we conclude that the shrub+grass and grass configuration modes are the optimal vegetation restoration models in terms of ecohydrology for future ecological engineering projects. 相似文献
12.
Ecological patterns and processes in dune ecosystems have been a research focus in recent years, however information on how dune stabilization influences vegetation and soil at different spatial scales... 相似文献
13.
Effects of drought stress on antioxidant enzyme, photosynthetic
pigment and flavonoid pathway in two desert shrubs 总被引：1，自引：0，他引：1
Antioxidant enzyme activity, photosynthetic pigment content, and free malondialdehyde (MDA), as well as flavonoid content and
the key enzyme activity in the flavonoid pathway were determined in two desert shrubs, Caryopteris mongolica Bunge and
Reaumuria soongorica (Pall.) Maxim. under drought stress. The free MDA content was enhanced during the experimental period,
which may be an indicator of oxidative stress. Superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX)
activities in C. mongholica showed a significant increase during the experiment, but catalase (CAT) activity was slightly decreased.
On the other hand, POD and APX activities showed a significant increase and SOD and CAT activity data had no significant
changes in R. soongorica. APX, SOD, and CAT activities were higher in R. soongorica than in C. mongholica, but MDA content
was lower, indicating that the lower values of MDA were attributed to higher activities of antioxidant enzyme in R. soongorica.
Chlorophyll content decreased significantly in the two shrubs during the experiment, which indicated that there was a photoprotection
mechanism through reducing light absorbance by decreasing pigments content. Caretonoids content increased in C.
mongholica and decreased in R. soongorica. The ratio of Chla/Chlb decreased significantly but caretonoids/Chl revealed a significant
increase in the two shrubs, which could be explained as no decrease of peripheral light-harvesting complexes and a higher
tolerance to drought. Total flavonoid content and the activities of phenylalanine ammonialyase (PAL) and chalcone isomerase
(CHI) showed different changes between C. mongholica and R. soongorica after treatment. These values decreased in R.
soongorica and increased in C. mongholica except for PAL activity. However, anthocyanin content increased in the two shrubs,
indicating that there was a different regulation response in the flavonoid pathway in the two shrubs under drought stress, and anthocyanin
should be an important antioxidant both in the shrubs. Our results demonstrated the different responses of antioxidant
defense and drought tolerance ability between the two shrubs. 相似文献
14.
《寒旱区科学》2021,13(3)
Nebkhas, discrete mounds of sand and vegetation, are a common landscape feature critical to the stability of desert ecosystems and supported by limited precipitation. Nebkha morphology and spatial pattern vary in landscapes, but it is unclear how they change along precipitation gradients in arid and semi-arid regions. In this study we determined morphology and soil nutrient patterns of nebkha from different regions of northwestern China. The objective of this study was to understand zonal differences among nebkhas and how morphological characteristics and soil nutrient patterns of nebkha change along a precipitation gradient in northwestern China. Our results shows that mean annual precipitation(MAP) had significant effects on morphological characteristics of nebkhas such as height, area, and volume which significantly decreased with an increase in MAP. MAP had significant positive effects on shrub cover and species richness of nebkha. Soil nutrients such as soil organic matter(SOM), total carbon(TC), total nitrogen(TN), and total phosphorus(TP) in the 0-10 cm layer increased with an increase of MAP, and soil nutrient content within nebkhas was higher than in inter-nebkha areas.We concluded that nebkhas are "fertile islands" with an important role in ecosystem dynamics in study regions. Further,MAP is a key factor which determined zonal differences, morphological, and soil nutrients patterns of nebkhas. However,disturbance, such as animal grazing, and planted sand-stabilizing vegetation accelerated the degeneration of nebkha landscapes. We recommend implementation of protective measures for nebkhas in arid and semi-arid areas of China. 相似文献
15.
横断山区产水服务空间异质性及归因分析 总被引：2，自引：1，他引：2
包括产水服务在内的生态系统服务已被纳入区域土地利用规划以及可持续发展决策中,识别其空间分异特征及影响因素是进行决策的基础,而空间分异的定量归因研究仍需进一步加强。以空间异质性明显的中国横断山区为研究区,借助InVEST模型模拟产水服务空间分布,选择气候、地形、土壤、植被、土地利用等因子,采用地理探测器开展产水服务空间异质性归因分析。结果表明,① 气候类因子是产水服务空间异质性的主要控制因子,其中以降水量和蒸散量为主。② 在不同地貌及气候分区中,各因子对产水的空间分异的解释能力存在显著差异：平缓地区,蒸散量解释能力远高于降水量,随着起伏度的增大,降水量解释能力逐步增强,最终成为主要因子;在高原气候区,以蒸散量解释能力最强,而在中亚热带气候区,降水量为主要的控制因子。③ 值得注意的是,平缓地区土地利用类型因子的解释能力较为突出,在山区发展中应注意土地利用的合理规划,以减轻土地利用变化对产水服务空间变化的影响。④ 风险探测识别的产水服务重要区主要为初育土及人为土分布区、灌木林区以及坡度在≤ 5°和25°~35°区域,而其对应的高程值则在不同区域之间存在差异,因此,在横断山区产水服务的维持与保护工作中应充分考虑不同分区的具体情况。 相似文献
16.
不同植被类型的土壤水分对黄土高原的影响 总被引：9，自引：0，他引：9
Water stored in deep loess soil is one of the most important resources regulating vegetation growth in the semi-arid area
of the Loess Plateau, but planted shrub and forest often disrupt the natural water cycle and in turn influence plant growth.
The purpose of this study was to examine the effects of main vegetation types on soil moisture and its inter-annual change.
Soil moisture in 0–10 m depth of six vegetation types, i.e., crop, grass, planted shrub of caragana, planted forests of arborvitae,
pine and the mixture of pine and arborvitae were measured in 2001, 2005 and 2006. Soil moisture in about 0–3 m of cropland
and about 0–2 m of other vegetation types varied inter-annually dependent on annual precipitation, but was stable inter-annually
below these depths. In 0–2 m, soil moisture of cropland was significantly greater than those of all other vegetation types,
and there were no significant differences among other vegetation types. In 2–10 m, there was no significant moisture difference
between cropland and grassland, but the soil moistures under both of them were significantly higher than those of planted
shrub and forests. The planted shrub and forests had depleted soil moisture below 2 m to or near permanent wilting point,
and there were no significant moisture differences among forest types. The soil moisture of caragana shrub was significantly
lower than those of forests, but the absolute difference was very small. The results of this study implicated that the planted
shrub and forests had depleted deep soil moisture to the lowest limits to which they could extract and they lived mainly on
present year precipitation for transpiration. 相似文献
17.
Water stored in deep loess soil is one of the most important resources regulating vegetation growth in the semi-arid area of the Loess Plateau, but planted shrub and forest often disrupt the natural water cycle and in turn influence plant growth. The purpose of this study was to examine the effects of main vegetation types on soil moisture and its inter- annual change. Soil moisture in 0–10 m depth of six vegetation types, i.e., crop, grass, planted shrub of caragana, planted forests of arborvitae, pine and the mixture of pine and arborvitae were measured in 2001, 2005 and 2006. Soil moisture in about 0–3 m of cropland and about 0–2 m of other vegetation types varied inter-annually dependent on annual precipitation, but was stable inter-annually below these depths. In 0–2 m, soil moisture of cropland was significantly greater than those of all other vegetation types, and there were no significant differences among other vegetation types. In 2–10 m, there was no significant moisture difference between cropland and grassland, but the soil moistures under both of them were significantly higher than those of planted shrub and forests. The planted shrub and forests had depleted soil moisture below 2 m to or near permanent wilting point, and there were no significant moisture differences among forest types. The soil moisture of caragana shrub was significantly lower than those of forests, but the absolute difference was very small. The results of this study implicated that the planted shrub and forests had depleted deep soil moisture to the lowest limits to which they could extract and they lived mainly on present year precipitation for transpiration. 相似文献
18.
古尔班通古特沙漠纵向沙垄植被空间异质性 总被引：5，自引：3，他引：2
在古尔班通古特沙漠南部纵向沙垄上按5 m×10 m的网格测度植被样方100个,采集浅层风沙土样品184件。调查发现,乔灌木层片和草本层片的分布及相互关系明显受沙垄地形影响,并且在干旱环境下种群间的竞争和空间上的互补使两层片生态优势度具有显著的相关性。地统计分析结果显示,纵向沙垄上植被空间异质性表现为木本层片的物种多样性呈斑块状分布,草本层片物种多样性呈现平行沙垄的带状结构和斑块结构叠加的特点,而植被盖度则在垂直沙垄走向的方向上具有强烈的梯度性变化。和沙垄土壤理化性质空间格局特征相对比,植被盖度及物种多样性与风沙土浅层含水量在自相关空间（变程）及空间异质性程度上比较接近。这是纵向沙垄小生态系统中草本植物和浅层土壤水分耦合关系在空间上的反映,也是木本植物对水分和土壤资源在小尺度（m）上竞争及中小尺度（10～100 m）上互补的结果。 相似文献
19.
HaiYan Zhou HuiJuan Tan ZhiShan Zhang XiaoHong Ji HengWen Fan JianLi Yuan 《寒旱区科学》2010,2(5):0455-0463
Reaumuria soongorica and Salsola passerina have significant differences in ecophysiological characteristics, which change with the environmental variations. Although they live together for a long period of time, their adaptive mechanisms to environmental stresses are very different. As two extreme xerophytes, Reaumuria soongorica and Salsola passerina differ significantly from other psammophytes in ecophysiological characteristics; they can survive in lower water potential, and can even grow in piedmont areas. Low water potential may be related to the existence of osmosis-regulating substance, such as praline, which can strengthen the capacity of water absorption. Compared to other psammophytes, Reaumuria soongorica and Salsola passerina have a higher degree of photo-inhibition under the same condition, and the photo-inhibition can lead to destruction of the photosynthetic pigment, nevertheless, this photo-inhibition can be repaired under suitable conditions in the morning and evening. 相似文献
20.
内蒙古高原东南部森林-草原交错带的地形-气候-植被格局和植被恢复对策 总被引：8，自引：6，他引：2
探讨内蒙古高原东南缘森林-草原交错带地形-气候-植被格局,表明植被分布受气候和地形综合影响,在区域尺度上,随降水量减少阔叶林逐步由桦林向栎林、山杨林转变,针叶林更为接近森林旱极;在局地尺度上,阔叶林多分布在蒸发微弱、土壤容重较小的陡阴坡,草原分布在对应的阳坡上,非地带性榆树疏林分布在毛管作用微弱、蒸发小的沙地上。交错带植被建设应在降水量允许范围内优先考虑针叶树;其次要考虑坡向、坡位对土壤水分条件的影响,森林应尽量栽植在坡度10°~40°的阴坡;在区域和局地尺度上都应注意造林密度以及乔灌草结合,沙地不宜栽植密林。 相似文献