芨芨草群落土壤盐分特征

通过对内蒙古及青海9个样点芨芨草群落及其相邻地带性群落土壤电导率的研究,从区域大尺度及生境小尺度揭示了土壤盐分对芨芨草群落分布的影响,并基于土壤的盐分特征分析了芨芨草群落的植被属性。结果表明:在区域大尺度,芨芨草群落的分布与土壤盐分不存在直接的相关性,芨芨草既可以在低盐环境下形成群落,也可在盐分较高的环境下形成群落,是一个生态幅较宽的耐盐物种;而在相同地点的小尺度上,芨芨草群落的土壤含盐量总是比相邻地带性针茅群落的土壤含盐量高,地带性针茅群落的耐盐性不及芨芨草群落;青海地区大面积的芨芨草草原发育在含盐量较高的土壤环境,远高于相邻地带性针茅群落。土壤盐分特征分析结果表明,芨芨草群落表现出明显的非地带性植被特征,其分布与区域降水不存在直接的相关性。     

不同水分对白茎盐生草(Halogeton arachnoideus)根区土壤水盐动态及其生长的影响

为研究不同水分条件下白茎盐生草根区土壤水盐动态变化及生长规律,采用桶栽试验,以水分和植被生长为控制因素;探索了白茎盐生草生长对土壤水盐动态的影响及土壤水分对白茎盐生草生长的影响。结果表明:土壤含水率随土层深度增加而增大,呈“反S”型分布,土壤剖面电导率随土层深度呈递减趋势,为“S”型分布。与裸土相比,植被生长条件下的土壤水盐动态变化更加复杂;水分不足条件时更容易产生盐分表聚现象。特枯水年下的白茎盐生草生长受到严重抑制,但特丰水年和丰水年对植物生长的影响差异并不显著。因此,与裸土相比,白茎盐生草生长显著影响其根区土壤水盐动态。     

人工植被对崇明东滩滨海盐土水盐空间异质性的影响

运用经典统计学和地统计学相结合的方法,于2012年6月研究了上海市崇明东滩滨海盐土上3种人工植被表层土壤(0～20cm)水盐的空间异质性.结果表明:不同样地的土壤含水量大小顺序为:落羽杉林>狗牙根草丛>夹竹桃灌丛,其变异系数分别为13.9%、13.4%和12.9%;土壤电导率为:夹竹桃灌丛>落羽杉林>狗牙根草丛,其变异系数分别为79.2%、55.4%和15.9%;二者均属中等程度变异.不同样地土壤水盐的理论变异模型各不相同,其中土壤电导率的拟合效果更好,R2在0.97～0.99.当植被从夹竹桃灌丛→狗牙根草丛→落羽杉林,土壤含水量的空间异质性程度由弱变强,其中夹竹桃的变异性是随机的;植被从狗牙根草丛→夹竹桃灌丛→落羽杉林,土壤电导率的空间异质性由中等相关变为强相关.不同植被下土壤电导率空间自相关性多为正相关,土壤水分多呈负相关.狗牙根草丛的土壤水盐均呈条带状分布,落羽杉林地土壤水盐均呈大斑块连续状分布,而夹竹桃灌丛的土壤水分呈小斑块破碎状分布,盐分呈条带状分布.     

黄河三角洲垦利县夏季土壤水盐空间变异及土壤盐分微域特征

黄河三角洲作为我国重要的后备土地资源区,土壤盐渍化问题突出,切实掌握季节性土壤水盐状况及其微域特征是该区土壤盐渍化防控和土地资源高效利用的重要基础。选择黄河三角洲垦利县,通过野外调查实测与室内化验分析获取土壤水盐含量数据,利用统计分析、GIS空间插值、实地观测与数据分析对比等方法,分析了研究区夏季土壤水盐状况及其微域变异规律。结果显示:研究区夏季土壤水盐含量总体较高,含盐量以中度盐渍化为主,随着土层深度的增加含盐量呈上升趋势,且各层土壤含盐量呈显著正相关性;含盐量较高的地区主要分布在该区东北部和中东部,含盐量较低的地区主要分布在西南部和中部;土壤含盐量从大到小的植被类型依次为光板地→碱蓬→高粱→芦苇→茅草→水稻→棉花→玉米;土壤盐分微域变化特征明显,含盐量受距路边远近、不同耕作措施、地形部位、植被群落等因素影响较大,表现出微域规律性和复杂性。该研究基本摸清了研究区夏季时相的土壤水盐状况及其微域特征,为黄河三角洲农作物栽培管理及土壤资源可持续利用提供了科学依据。     

基于δD和δ18O的青海湖流域芨芨草水分利用来源变化研究

水分条件是限制干旱半干旱地区植物生长重要的生态因子,为了揭示青海湖流域典型生态系统下芨芨草植物的水分利用来源及其如何响应水分条件的变化,选择了自然和干旱控制条件下芨芨草植物,通过测定芨芨草植物茎水和各潜在水源(土壤水、地下水及降水)中δD、δ~(18)O组成,并利用直接比较分析法和多源混合模型计算芨芨草植物对土壤水的利用比例。研究结果表明:表层土壤水分和土壤水中δD、δ~(18)O值表征出较大波动范围,其直接受降水和蒸发作用影响,土壤蒸发线的斜率和截距明显小于大气水线斜率和截距,表明土壤水中同位素组成经历了强烈的蒸发分馏过程,而芨芨草茎水中δD、δ~(18)O值都集中分布土壤水蒸发线附近,说明芨芨草根系主要利用不同深度的土壤水。自然条件下芨芨草在生长季初期(6月)利用表层土壤水(0—10cm,45.1%),8—9月份大降水事件影响土壤含水量和同位素组成,降水入渗深度较深且芨芨草根系对土壤水分吸收的比例相差不大,表明根系在土壤含水量较高时均能吸水不同深度土壤水。在干旱控制条件下芨芨草在7月初主要利用表层土壤水(0-30cm),随着表层土壤水分的减少,根系吸收深度转向较深土壤层,而灌溉后表层土壤水分明显增加,其吸收深度又转向表层,表明芨芨草根系吸收深度能敏感地响应土壤水分的变化。另外还发现芨芨草在生长季内并未直接利用地下水。     

内蒙古典型草原区芨芨草群落适生生境

芨芨草群落是干旱与半干旱地区重要的植被资源,内蒙古典型草原区常在地形稍低的部位镶嵌有芨芨草群落,且芨芨草群落常与低洼湿草甸群落相连。为了探究芨芨草群落的适生生境,在锡林郭勒盟典型草原区选取了4个代表性调查区,从芨芨草群落及其相邻群落分布的地形特征、调查区的地下水埋深、1 m深土层的土壤电导率、土壤pH值和土壤质地等指标上对芨芨草适生生境进行探究,结果表明,芨芨草群落在内蒙古典型草原区常分布在河漫滩和丘间蝶形洼地地区,呈现出由高程梯度导致的与地带性针茅群落、湿草甸群落带状分布的特点,导致这种成带分布的原因与地下水埋深及地表径流有关,芨芨草群落生境的地下水埋深一般在1-3 m且有地表径流的补充;芨芨草群落耐盐碱性强,其生境也与反映土壤盐分含量的土壤电导率和土壤pH值有关;但芨芨草群落生境的形成不是由土壤机械组成所致。     

盐地碱蓬、柽柳和芦苇生长的水盐阈值对类圆形植被斑块形成机制的解释

山东省黄河三角洲离海向陆25 km左右的区域内分布着不同类型的类圆形植被斑块,其演替速度快、生物多样性高,是研究黄河三角洲水盐交互作用和植被演替的理想对象,揭示其形成过程和机制对于黄河三角洲盐碱滩地植被恢复有着重要的实践意义。基于类圆形植被斑块的盐地碱蓬(Suaeda salsa)、柽柳(Tamarix chinensis)、芦苇(Phragmites australis)生长发育的水盐阈值和生活习性,以及黄河三角洲缓平低地盐生植物群落的分布规律,对类圆形植被斑块形成过程和机制进行了解析。结果表明：缓平低地的积水地形导致的局部水盐再分配是类圆形植被斑块形成的基础。盐地碱蓬分布在类圆形植被斑块的最外缘,为局部高盐分(1.0%～2.1%)、湿润地带;向斑块中心,分布着矮小的芦苇,为局部中高盐分(0.12%～0.79%)、低水深地带;再向斑块中心,柽柳散落分布在积水线附近,为局部低水深、中等盐分(0.16%～0.70%)地带;斑块中心区分布着芦苇和白茅,为局部高水深、低盐分(0.1%～0.32%)区域。春季和冬季,灰白色的高含盐量盐斑出现在盐地碱蓬外侧,为局部高盐分(1.6%～3.4%)、干...     

大凌河口湿地水盐梯度下翅碱蓬的生态阈值

基于大凌河口湿地翅碱蓬生物量、密度、株高、株重等生物指标之间极显著的相关性,选取生物量为指标,研究不同土壤理化因子条件下,翅碱蓬种群分布的变化规律。结果表明:翅碱蓬生物量自然对数分别与土壤盐分、水分含量之间具有极显著的一元二次曲线拟合关系,表明翅碱蓬群落分布受土壤水分、盐分的影响;用高斯模型求解出大凌河口湿地翅碱蓬随土壤水盐变化的生态阈值,翅碱蓬的最适土壤盐分为12.14 g·kg-1,生态阈值区间为5.02~19.26 g·kg-1,最适生态阈值区间为8.58~15.70 g·kg-1;翅碱蓬最适土壤水分为59.82%,生态阈值区间为22.02%~97.62%,最适生态阈值区间为40.92%~78.72%。上述研究结论为河口湿地翅碱莲生境保护与植被修复提供了科学依据。     

河西走廊荒漠盐碱地人工柽柳林土壤水盐分布

土壤盐碱化是一个全球性问题,植树造林是一种主要的改良措施.为了研究荒漠盐碱地10年人工柽柳林土壤水盐空间分布及生态改良效果,对2、4、6和8m行间距柽柳灌下和行间的土壤水盐进行分析,并构建结构方程模型量化土壤水盐对植被的影响程度.结果表明:林地浅层土壤(0~40 cm)可溶性盐明显低于林外(CK),灌下土壤含水率高于行间.且6m行间距柽柳的高度和冠幅及其灌下草本植物的盖度和生物量均大于其他行间距柽柳,阳离子在柽柳周围的富集程度为Na^+>K^+>Ca^2+>Mg2+,阴离子的富集程度为Cl^->HCO3^->SO4^2-.土壤盐分含量最高的是MgSO4,其次是CaCl2、NaCl和MgCl2,KHCO3含量最少.土壤水盐中影响植被生长的最大因素是土壤水分,其次是盐分,最小为pH,权重大小分别是50.6%、29.5%和19.9%.     

玛纳斯河流域农田土壤水盐空间分布特征及影响因素

采用传统统计学和地统计学相结合的方法,通过野外实地分层采集土样,分析干旱区典型内陆河玛纳斯河流域农田土壤水盐的空间分布特征及其影响因素,并探讨了土壤水盐在空间分布上所体现的耦合作用关系.结果表明:研究区农田土壤整体上水分含量较低(14.2%~20.9%),盐渍化程度较高(平均全盐量6.00~9.15 g·kg-1),土壤水盐的剖面分布均呈现出"底聚"现象;各层土壤水分均属于中等变异强度,土壤盐分变异强度较大;受结构性因素影响,各土层盐分和含水量均具有较强的空间相关性.各层土壤水盐的水平分布格局无规律,受地形、地貌等因素制约.在人类活动的干扰下,土壤水盐耦合作用的关系更趋复杂,但两者的空间分异呈现出一定程度的同步性.     

Relationships Between Plant Spatial Patterns, Water Infiltration Capacity, and Plant Community Composition in Semi-arid Mediterranean Ecosystems Along Stress Gradients

Water redistribution from bare soil to vegetation patches is a key feature of semi-arid ecosystems, and is responsible for their patchy vegetation patterns. The magnitude of water redistribution depends on the properties of the bare soil (which determine the amount of water run-off) and the capacity of vegetation patches to trap water run-on. We examined the relationships between plant spatial patterns, water infiltration into bare soil, and plant community composition in semi-arid sites with different hydro-physical properties (silty and gypseous soils) in NE Spain. We also studied the effect of two stressors, aridity and grazing, on water infiltration and plant spatial patterns. Our results indicate a negative correlation of bare soil sorptivity (the capacity to absorb water by capillarity) and vegetation aggregation. There was a strong positive correlation between perennial grass cover and the spatial aggregation of vegetation, but aggregation was not associated with positive associations of different plant types. The aggregation of vegetation was positively correlated with species richness and the overall extent of vegetation cover. Grazing reduced water infiltration into silty soils, which are prone to compaction. In contrast, soil crust affected the hydrology of gypseous soils, especially in the most arid sites, where grazing increased infiltration, reducing surface sealing due to breaking of the soil crust. Together, our results suggest that biotic and abiotic factors affect the hydro-physical properties of soils in the semi-arid ecosystems of NE Spain, which is linked to the plant communities through the spatial distribution of plants.     

Clustered animal burrows yield higher spatial heterogeneity

An understanding of the relationships between spatial heterogeneity and disturbance regime is important for establishing the mechanisms necessary to maintain biodiversity. Our objective was to examine how the configuration of disturbance by burrowing rodents (Siberian marmot) affected the spatial heterogeneity of vegetation and soil nutrient properties. We established three 2500-m² (50 m × 50 m) isolated-burrows plots and three 2500-m² clustered-burrows plots in a Mongolian grassland. Each plot was subdivided into 4-m² quadrats, and the plant species richness, percent coverage, and soil nutrient properties in the quadrats were surveyed. Spatial heterogeneity was calculated for vegetation using the mean dissimilarity of species composition among sample quadrats, and geostatistical analysis was used to calculate soil properties. Heterogeneous patches of plants such as Achnatherum splendens and higher nutrient concentrations were found only near the clustered burrows. As a result, spatial heterogeneities of vegetation and soil nutrient properties were higher in the clustered colony than those in the isolated colony. The configuration of disturbance patches affected the spatial heterogeneity at the landscape level through the spatial pattern of disturbance frequency.     

Characteristics of the Achnatherum splendens community along the Qinghai-Tibet Railway, China

The Achnatherum splendens community is an important type of warm steppe vegetation which plays a very important role in environmental protection in the area along the Qinghai-Tibet Railway. In order to understand its dynamic features, the characteristics of the A. splendens community, such as spatial distribution pattern, species richness and biomass, were examined near Haiyan County, Qinghai Province. Results showed that the A. splendens community consisted of two types of mosaic patches, the microaggregation dominated by A. splendens and the microaggregation dominated by Stipa sp. The number and size of the two patches showed an interesting distribution pattern. The A. splendens patch decreased with increasing distance away from the railway, while species diversity increased. The total coverage of A. splendens was significantly higher than that of Stipa sp. The number and size of patches may indicate the degradation of the A. splendens community, which could be accelerated by human activities. Based on the characteristics and status quo of the A. splendens community, we suggest that some measures be taken to control human activities and rodents to conserve the A. splendens community. __________ Translated from Acta Ecologica Sinica, 2007, 27(2): 497–503 [译自:生态学报]     

青藏铁路沿线温性草原区芨芨草（Achnatherum splendens）群落特征

芨芨草群落是青藏铁路沿线一类重要的温性草原植被类型,对青藏铁路两侧及其四周的水土保持起着非常重要的作用。对青藏铁路西格段海晏县附近的芨芨草草原的空间分布特征、物种丰富度和生物量等特征进行了分析。结果显示,研究地区芨芨草群落由芨芨草斑块和针茅斑块镶嵌而成,两类斑块的数量、大小和斑块间大小变化幅度等特征在空间上表现出一定的规律;芨芨草斑块大小在样线上所占的比例比针茅斑块为小,且有随远离铁路而减小的趋势,而物种丰富度则出现相反的变化趋势;芨芨草斑块的盖度和单位面积上地上生物量显著高于针茅斑块。斑块的大小和数量在一定程度上反应了芨芨草群落的退化状况。人为活动往往会加剧芨芨草群落的斑块片段化。针对芨芨草群落的特征和现状,建议加强对这些区域内人为活动的限制力度以减少对芨芨草群落的干扰。     

Assessing long‐term hydrological and ecological responses to drainage in a raised bog using paleoecology and a hydrosequence

Question: We studied vegetation succession after drainage in a bog, as an analogue for potential persistent water table drawdown due to climate change. We asked: (1) how does bog vegetation change following a long‐term water table lowering and (2) how are effects of drainage on hydrology and vegetation distributed temporally and spatially? Location: Mer Bleue peatland, Ontario, Canada (45.41°N, 75.48°W). Methods: Analyses of changes in vegetation and hydrology associated with drainage were examined spatially along a hydrosequence and temporally using paleoecological reconstructions from peat cores (testate amoebae, pollen) in a drained portion of a peatland untouched for 85 years following drainage. Relationships between modern vegetation and water table were assessed through clustering and ordination analyses of vegetation relevés. Results: Post‐drainage increases in tree cover, especially Betula and Larix, decreases in Sphagnum cover and shifts in species composition of dominant shrubs were observed. Present‐day vegetation patterns along the hydrosequence were primarily related to seasonal variability of water table depth. Paleoecological records reveal that where the present‐day vegetation has been impacted by drainage, persistent water table lowering occurred in response to drainage. However, in an area with relatively natural vegetation, a transient drop in water table depth occurred at the time of drainage. Conclusions: Temporal and spatial patterns revealed that the bog response to drainage was spatially and temporally heterogeneous, and probably mediated by feedbacks among vegetation, peat structure and hydrology. Spatial patterns along the hydrosequence were similar to those observed in paleoecological reconstructions, but the use of the two complementary techniques provides additional insights.     

荒漠草原区4种植物群落土壤种子库特征及其土壤理化性质

土壤种子库作为地上植被更新的潜在种源,在植被自然恢复和演替过程以及生态系统建设中起着重要作用。以宁夏盐池县荒漠草原区4种植物群落为研究对象,通过对封育16年后植物群落土壤理化性质的变化与其土壤种子库的特征之间的关系的探讨,揭示荒漠草原植物群落的土壤种子库分布特征和演替趋势,以及土壤质量的改变如何影响土壤种子库特征。研究结果表明：（1）不同植物群落土壤种子库物种组成及种子密度不同,同一物种在不同植物群落土壤种子库中出现时种子密度也存在差异;禾本科、菊科、藜科植物种在4种植物群落土壤种子库中出现比例均较高,分别占到26.19%、21.43%和19.05%,占总物种数的66.7%;灰绿藜、冰草、碱蓬在4种植物群落土壤种子库中均有出现。（2）4种植物群落土壤种子库中多年生植物和一年生植物种子居多,灌木、半灌木植物种较少。（3）4种植物群落土壤种子库中物种数和种子密度均表现为：芨芨草群落 > 苦豆子群落 > 油蒿群落 > 盐爪爪群落;且随着土层的加深,4种植物群落土壤种子库中物种数和种子密度均呈递减趋势。（4）4种植物群落土壤种子库中Shannon-Wiener指数、Simpsin指数、Pielou指数和Patrick指数均表现为芨芨草群落 > 苦豆子群落 > 油蒿群落 > 盐爪爪群落。此外,芨芨草群落土壤种子库与油蒿群落土壤种子库相似性最高,油蒿群落与盐爪爪群落的最低。（5）土壤种子库物种多样性特征指数与土壤pH、含水量、碱解氮呈正相关,与土壤电导率呈负相关,其中土壤pH和电导率对种子库物种多样性的影响较大。荒漠草原封育以后,土壤种子库中植物种数、种子密度和物种多样性均呈增加趋势,且以多年生植物和一年生植物种子居多;禾本科和豆科植物的物种数和种子密度大于菊科和藜科,这表明围封后牧草品质改善,植物群落正向演替。     

Spatial patterns of ground vegetation, soil microbial biomass and activity in a mixed spruce-birch stand

Trees directly and indirectly influence the above- and below-ground environment, and can be expected to modify the spatial patterns of organisms associated with the forest floor. This study aimed to examine the effects of a coniferous (Picea abies) and a broad-leaved (Betula pubescens) tree species on the spatial pattern of ground vegetation and soil microbial properties in a mixed stand in central Sweden. I have characterised the species composition of ground vegetation, soil microbial biomass and activity, photosynthetic active radiation (PAR), soil water content and soil pH in the stand, and tested whether the spatial patterns of these variables were related to the positioning of trees. Geostatistics were used to describe the spatial variation in ground vegetation, soil mirobiological properties and the soil surface environment. PAR, soil water content and the cover of the moss Brachytecium reflexum and associated herb species decreased with the influence of spruce trees. Microbial biomass, measured as the amount of phospholipid fatty acids, decreased with spruce influence but increased with the influence of birch trees. Microbial respiration was not affected by spruce but increased with the influence of birch. Ground vegetation and microbial respiration, which were influenced by one tree species only, aggregate on a scale of 4-5 m, corresponding fairly well with patches of a single tree species. Soil microbial biomass, which was affected by both tree species, aggregated on a scale of 7-8 m. roughly corresponding to the distance between patches of spruce and birch trees respectively. I suggest that spruce trees influenced vegetation mainly through shading, and that a difference in the availability of organic matter under birch and spruce trees caused spatial variation in microbial biomass and activity. Thus, spatial patterns in ground vegetation and soil microbial properties may develop in a mixed forest of coniferous-broad leaved trees, as a result of the difference in influence of tree species and nested variation associated with the arrangement of the trees.     

Environmental control and spatial structures in peatland vegetation

Question: What are the relative influences of environment and space in structuring the plant composition in a peatland complex? Location: Lakkasuo, southern boreal zone, Finland. Method: We used principal coordinates of neighbour matrices (PCNM) to model spatial structures in the plant composition of a peatland complex comprising ombrotrophic and minerotrophic, open and forested areas. We used redundancy analyses (RDA) and variation partitioning to assess the relative influences of chemical variables (peat and water characteristics), physical variables (hydrology, soil properties, shade), as well as broad‐scale (>350 m) and medium‐scale (100–350 m) spatial structures on vegetation assemblages. Results: We identified five different significant spatial patterns circumscribing (1) the minerotrophic–ombrotrophic gradient; (2) dry ombrotrophic and wet minerotrophic areas; (3) open and shaded areas; (4) dry open/shaded and wet patches within the ombrotrophic areas; and (5) dry open patches and dry forested patches. With spatial structures and environmental variables, we were able to model 30% of the variability in plant composition in the peatland complex, 13% of which was attributable to spatial structures alone. Conclusions: We demonstrated that in the peatland complex, the spatial dependence processes were more important at the broadest scale, and found that patterns at a medium scale might reflect finer‐scale patterns that were not investigated here. Spatial autocorrelation in vegetation composition in the peatland complex appeared to be driven by Sphagnum species. Our results emphasize that spatial modelling should be routinely implemented in studies looking at species composition, since they significantly increase the explained proportion of variance.     

三峡库区澎溪河消落带植物群落分布格局及生境影响

三峡消落带是一条特殊的水—陆交错带,其生境的特殊性及对整个三峡库区的影响逐渐成为地学、环境科学、生态学等学科的研究热点。植被是消落带各项生态功能的载体。然而,三峡水库的运行使消落带原有植被遭到破坏。通过对澎溪河消落带植物群落及其生境的实地调查,采用双向指示种法(TWINSPAN)划分植物群落类型,并结合方差分解和CCA排序法研究4类生境影响因素组14个生境影响因子与植物群落空间分布的关系,探讨生境对消落带植物群落组成、结构及多样性的影响。结果表明:(1)消落带植物群落包括5种类型:狗牙根+雀稗群落、狗尾草+狗牙根群落、黄荆群落、白茅+鬼针草群落、苔草群落;(2)CCA排序中,第1排序轴对消落带植被空间变化的累计解释量为6.83%,占生境条件总解释量的44.73%,能很好地解释消落带植物群落与生境的相互关系,植物群落类型沿排序轴呈梯度分布;(3)土壤是影响消落带植被空间分布格局的主要影响因素组,各影响因素组间交互作用明显。淹水时间、海拔、土壤含水量是植物群落空间分布的主要影响因子,解释量分别为5.3%、3.0%、2.9%;(4)4类影响因素组共解释消落带植物群落空间格局变化的14.6%,未解释部分所占比例较大,可能是由于消落带内生境条件复杂,影响其群落组成及空间分布的潜在因素较多,如各种土地利用政策、人类活动干扰及景观组成等因素也可能对消落带植物群落构成有影响。研究消落带植物空间分布及其与生境的关系,以期为科学认识消落带、保护水库环境提供依据。