Ecology of a steppe-tundra gradient in interior Alaska

Abstract. Subarctic steppe is currently restricted in interior Alaska and the Yukon Territory to steep, south-facing river bluffs. Paleoecological and biogeographic evidence suggests that some steppe taxa may have been more widespread during the Full-Glacial. We examined factors controlling the distribution of steppe taxa on an elevation gradient across a steppetundra ecotone; such analyses may help define potential Full-Glacial distributions of these taxa. Multivariate analyses suggest that species can be divided into four spatially distinct groups, but individualistic species distributions create considerable overlap among these groups. The steppe-tundra ecotone comprises a broad zone of mixing between steppe taxa and drought-tolerant alpine tundra taxa, followed by an abrupt shift to alpine shrub tundra. The transition from low steppe to tundra vegetation is primarily associated with a gradient of decreasing soil temperature. The more abrupt transition from mixed steppe-tundra to alpine shrub tundra vegetation is primarily associated with changes in soil depth and soil moisture. Variation in vegetation within steppe is associated with gradients in soil phosphorus and moisture. Greenhouse experiments on drought tolerance of two steppe and two tundra taxa suggest that the individualistic distribution of species along the ecotone is partly a function of physiological differences among species. Our analyses of vegetation-environment relationships support the hypothesis that some components of the steppe community could have been more widespread during the colder Full-Glacial.     

松嫩平原草原植被分类系统的探讨

 本文在对松嫩平原的草原植被作了全面调查,记录了760多个样方以及对生境,特别是土壤的一些主要因子做了分析的基础上,采用植物与生境和定性与定量相结合的方法;确定以植物种类组成(特别是生态种组)、群落相似性的数量指标和动态特征为依据的分类原则。划分了4个群目、12个群属和40个群丛,建立了三级的分类系统,并阐明各等级分类单位的特征,揭示了松嫩平原草原植物的组合规律及其与环境的关系。不同等级分类单位的相似和差异,体现了分类系统是一个有机的整体和调查区植被的连续性和间断性．此外,分类系统的高级分类单位与立地类型的对应关系,为草原的经营管理提供了依据。     

The effects of micro-habitats and grazing intensity on the vegetation of burial mounds in the Kazakh steppes

Background: Burial mounds (kurgans) of Eurasian steppes are man-made habitat islands that have the potential to harbour rich plant diversity due to micro-habitats associated with their topography.

Aims: We assessed whether kurgan micro-habitats harboured different species pools and functional groups from those found on the surrounding steppes. In addition, we asked if these mounds were affected by different grazing intensities from those on the surrounding vegetation.

Methods: We surveyed kurgan micro-habitats (northern and southern slopes, surrounding ditch) and adjacent steppe plains in non-grazed, moderately grazed and heavily grazed sites in northern Kazakhstan. We analysed differences in species composition of four habitats under three grazing regimes using Generalised Linear Mixed Models, PCA ordination and indicator species analysis.

Results: Kurgan micro-habitats had diverse vegetation and supported the co-existence of plant species with different environmental needs. We identified 16 steppe specialists confined to kurgan micro-habitats. Steppe vegetation was well-adapted to extensive grazing, although heavy grazing supported ruderals and a decline in steppe specialists. There was a significant interaction between grazing intensity and habitat type: heavy grazing supported ruderals and suppressed steppe specialists especially on the slopes.

Conclusions: We highlighted that kurgans play an important role as maintaining high plant diversity locally in extensive steppe plains in Central-Asia by increasing environmental heterogeneity and supporting specialist species confined to these micro-habitats.     

样地尺度现代表土花粉与植物群落的定量关系

建立现代植被与表土花粉的精确关系,是基于孢粉记录定量重建古植被与古气候的基础与关键.截止目前,植物群落样方记录较少参与到现代植被与花粉的统计分析中,限制了其精确关系的定量表达.本文通过中国东北样带的森林、草甸草原、典型草原和荒漠草原33个表土样品分析及植被样方调查,基于Bray-Curtis相异系数,研究了东北样带现代...     

青海省芨芨草草原的群落特征及其分布规律

芨芨草(Achnatherum splendens)是一种旱生植物,广泛分布于欧亚草原和荒漠地区。它是一种生态可塑性很强的植物,可分布于草原、荒漠草原等植被带内。以其为优势种可以形成盐生草甸、草原、荒漠草原等多种植被类型。青海省共和盆地、青海湖盆地和柴达木盆地东部等地大面积分布有芨芨草群落,并和本区分布的其他草原类型形成基带植被。无论是其生境条件、生物生态学特性、群落的组成及分布规律均具有草原性质,应划归草原植被类型较为合适。     

Herbal vegetation in shelter belts composed of various species in Shira steppe, Khakasia

Shelter belts composed of various species were grown under arid conditions of the Shira steppe, Khakasia. The results of the investigation of species diversity, distribution of herbs over ecological groups, and regularities of species composition dynamics, structure and biomass of ground vegetation in shelter belts are reported. The influence of the ground vegetation on the tree growth in shelter belts is considered.     

Peculiarities of the biotopic distribution of orthoptera in the typical steppe of European Russia

The taxonomic composition, ecological and spatial distribution of orthopterans were studied in different vegetation types of the typical steppe on the left bank of the Volga River basin (Saratov Prov.). Some species showed clear selectivity with respect to specific features of the soil and vegetation, despite significant annual fluctuations in the taxonomic composition and abundance of local populations. Two groups can be distinguished: the polytopic species and those inhabiting intrazonal communities but not typical steppe habitats. The orthopteran complexes of the zonal and halophytic habitats show a relatively high similarity; they differ well from those of mesophytic plant communities, restricted to the lower mesorelief areas. Intrazonal habitats with mesophytic conditions comprise almost 45% of the species diversity of orthopterans in the typical steppe subzone, and reveal the greatest diversity of life forms of these insects. The data obtained are of interest for monitoring the successive changes in steppe ecosystems affected by both climatic and anthropogenic factors.     

内蒙古温带草原区植被盖度变化及其与气象因子的关系

利用1982-1999年内蒙古地区NOAA/AVHRR的NDVI数字遥感影像,对内蒙古温带草原区植被盖度进行了反演,探讨了近20a来温带草原植被盖度的变化情况,并对植被盖度与不同组合方式的降水及气温数据进行了相关分析,探讨了植被盖度与气象因子的关系。结果表明:①近20a来温带草原植被盖度呈上升趋势,占总面积72%的草原植被盖度发生了增长,3种不同草原类型中典型草原盖度上升趋势最为明显;②温带草原生长季平均盖度、逐月盖度与降水成正相关关系,与气温呈负相关关系,其中降水对盖度的影响存在着时滞及累积效应;③3种草原类型植被盖度对气象因子的敏感性不同,荒漠草原植被盖度与气温和降水相关性最强,其次为典型草原与草甸草原。     

Vegetation Patterns of the Irano-Turanian Steppe along a 3,000 m Altitudinal Gradient in the Alborz Mountains of Northern Iran

The Irano-Turanian floristic region is a major center of endemism in the Holarctic of Eurasia. The Alborz Mountains of northern Iran are a complex and heterogeneous environmental system with rich water resources and great habitat diversity. We have investigated steppe plant communities along an altitudinal gradient ranging from approximately 1,000 m a.s.l. in the semi-desert steppes near Tehran to a height of 3,966 m a.s.l. at the summit of Mount Tochal. Our two-way indicator species analysis of 1,069 vegetation samples resulted in classification of five major vegetation zones: (1) a semi-desert Artemisia steppe near Tehran, (2) a Stipa grassland in the alluvial undulating hills north and west of Tehran, (3) a submontane and steppe zone, (4) a subalpine cushion formation zone and (5) an alpine meadow and subnival zone of Mount Tochal. Annuals and ephemerals in the semi-desert vegetation decline as altitude increases and almost disappear in the alpine zone. Past human impacts of ancient Persian civilization and a traditional pastoral economy have affected the physiognomy of plant communities; thorny dwarf shrubs now dominate the treeless vegetation of the region. Lower competition for space, different phenology and the presence of edaphic and hydrological layers associated with anthropogenic impacts are major reasons for entanglement of different plant communities in the arid- and semi-arid steppe. The phytogeography of the region changes from omni-Irano-Turanian and Saharo-Sindian transgressive species at lower altitudes to a more limited range of western Irano-Turanian species and local endemics at higher altitudes.     

中国戈壁针茅草原的分布、群落特征和分类

戈壁针茅(Stipa tianschanica var. gobica)草原主要分布于荒漠草原区的石质丘陵或石质山坡, 向东可以分布在典型草原区的石质丘陵或山地, 向西也可以分布在荒漠区的石质山坡上。该研究调查了中国戈壁针茅草原的主要植被类型, 通过对115个样地的样方数据分析, 量化描述了这一草原类型的主要植物群落特征。结果表明, 中国戈壁针茅草原共有维管植物272种, 隶属于38科127属; 其中裸子植物3种, 隶属于1科1属; 被子植物269种, 隶属于37科126属, 物种数大于等于10种的科为: 菊科、禾本科、豆科、蔷薇科、百合科、藜科、石竹科; 戈壁针茅草原植物区系的生活型谱以地面芽植物为主, 共178种植物, 占总种数的65.44%; 水分生态类型以旱生植物为主, 共120种, 占总种数的44.12%; 植物区系地理成分上以东古北极分布种和亚洲中部分布种(含其变型)最多, 分别为82种和80种, 占总种数的30.14%和29.41%; 盖度等级划分上以0.1%-1.0%的盖度最多, 共174种, 占总种数的63.97%; 恒有度等级划分上以I级(0-20%)的物种数最多, 共258种植物, 占所有植物种数的94.85%。基于群落调查数据, 按照群落-外貌分类原则, 将戈壁针茅群系划分为8个群丛组106个群丛。     

内蒙古荒漠草原植被盖度的空间异质性动态分析

利用半方差函数分析法对内蒙古荒漠草原生长盛期(6—8月)的植被盖度时空变异特征的研究表明,荒漠草原生长盛期的植被盖度半方差函数形态符合指数模型,但函数曲线的形态和各参数在不同月份变化较大。其中,6月的植被盖度变程最大,达到100 m;7月植被盖度的半方差函数形态具有巢式等级结构;8月植被盖度的变程最小,仅为15 m,但空间变异程度最高。3个月的结构比介于72%—85%,具有较强的空间自相关。各向异性分析表明,6月植被盖度在135°方向的半方差函数值明显低于其它3个方向(0°、45°、90°),具有各向异性特征;而7月和8月植被盖度的各向异性比接近于1,表现为各向同性。研究结果表明,荒漠草原植被盖度空间异质性的时间动态不容忽视,在野外采样或制图时,要根据时间合理控制采样范围。     

Cultural monuments and nature conservation: a review of the role of kurgans in the conservation and restoration of steppe vegetation

Steppe is among the most endangered biomes of the world, especially in Eastern Europe, where more than 90 % of original steppes have been destroyed due to conversion into croplands, afforestation and other human activities. Currently, steppe vegetation is often restricted to places unsuitable for ploughing, such as ancient burial mounds called kurgans. The aim of our study was to collect and synthesise existing knowledge on kurgans by a review of research papers and grey literature. The proportion of kurgans covered by steppe vegetation increases from west to east and from lowlands to uplands. Despite their small size, kurgans act as biodiversity hotspots and harbour many red-listed species. High overall species richness and a high proportion of grassland specialists are maintained by a pronounced fine-scale environmental heterogeneity. The main factors threatening the biodiversity of kurgans are intensified agriculture and construction works. We conclude that kurgans can play a crucial role in preserving steppe vegetation, especially in intensively used agricultural landscapes in the western part of the steppe zone. Despite the vital role of kurgans in sustaining steppe vegetation, we identified serious knowledge gaps on their distribution, vegetation, flora and fauna and their potential role in steppe restoration.     

Distribution,community characteristics and classification of Stipa tianschanica var. gobica steppe in China

戈壁针茅(Stipa tianschanica var. gobica)草原主要分布于荒漠草原区的石质丘陵或石质山坡, 向东可以分布在典型草原区的石质丘陵或山地, 向西也可以分布在荒漠区的石质山坡上。该研究调查了中国戈壁针茅草原的主要植被类型, 通过对115个样地的样方数据分析, 量化描述了这一草原类型的主要植物群落特征。结果表明, 中国戈壁针茅草原共有维管植物272种, 隶属于38科127属; 其中裸子植物3种, 隶属于1科1属; 被子植物269种, 隶属于37科126属, 物种数大于等于10种的科为: 菊科、禾本科、豆科、蔷薇科、百合科、藜科、石竹科; 戈壁针茅草原植物区系的生活型谱以地面芽植物为主, 共178种植物, 占总种数的65.44%; 水分生态类型以旱生植物为主, 共120种, 占总种数的44.12%; 植物区系地理成分上以东古北极分布种和亚洲中部分布种(含其变型)最多, 分别为82种和80种, 占总种数的30.14%和29.41%; 盖度等级划分上以0.1%-1.0%的盖度最多, 共174种, 占总种数的63.97%; 恒有度等级划分上以I级(0-20%)的物种数最多, 共258种植物, 占所有植物种数的94.85%。基于群落调查数据, 按照群落-外貌分类原则, 将戈壁针茅群系划分为8个群丛组106个群丛。     

青藏高原植物群落样方数据集

为便于了解青藏高原植被特殊物种组成、群落特征及分布格局, 该文利用2018-2021年在青藏高原不同区域内调查的338个样地、共758个样方的数据, 分析了高原植物群落的物种组成、区系特征和植被分类, 整合形成青藏高原植物群落样方数据集。结果表明: 青藏高原高寒和温性植物群落758个样方中, 共有植物65科279属837种; 其中, 物种数最多的5个科依次是菊科(134种)、禾本科(88种)、豆科(75种)、蔷薇科(43种)和莎草科(40种), 物种数最多的5个属依次是蒿属(Artemisia, 29种)、马先蒿属(Pedicularis, 27种)、风毛菊属(Saussurea, 25种)、黄耆属(Astragalus, 23种)和早熟禾属(Poa, 23种)。植物区系主要由温带(145属)和世界广布(36属)的成分所组成。物种的生长型以草本(83.51%)和灌木(10.87%)为主, 草本和木本的生活型分别以多年生草本(88.23%)和落叶灌木(83.67%)为主。338个样地可以划分为4个植被型组, 10个植被型, 20个植被亚型, 78个群系组和117个群系, 其中草原群系34个, 草甸群系33个, 荒漠群系33个, 灌丛群系14个和针叶林群系3个。该数据集覆盖青藏高原绝大部分高寒灌丛、高寒草原、高寒草甸、高寒荒漠、温性草原和温性荒漠植被区域, 可为研究高原植被特征和地带性分异规律, 气候变化和人类活动对高原植被的影响及其生态恢复提供坚实的数据基础, 同时为下一代中国植被图的更新提供参考。     

Relationship of different feeding groups of true bugs (Hemiptera: Heteroptera) with habitat and landscape features in Pannonic salt grasslands

Eastern European grasslands are still inhabited by a rich arthropod fauna, but the drivers and mechanisms influencing their communities have to be understood to ensure their future survival. Heteroptera communities were studied in 20 plot-pairs in Pannonic salt steppe–salt marsh mosaics in Hungary. The effects of vegetation characteristics, landscape diversity and the proportion of surrounding grasslands on the composition, species richness and abundance of different feeding groups of true bugs (carnivores, specialist and generalist herbivores) were examined using ordinations and mixed-effect models. We found distinct herbivorous assemblages corresponding to microtopography-driven differences in water regime and vegetation between steppe and marsh plots, but this pattern was less pronounced in carnivorous assemblages. A higher species richness of true bugs was found in the more diverse steppe vegetation than in the salt marsh vegetation, while the abundance pattern of true bugs was opposite. Landscape diversity had a positive effect on the species richness and abundance of generalist herbivores and carnivores. Our results suggested that generalist herbivores and carnivores appear to drive diversity patterns in the local landscape due to their high dispersal abilities and the broader range of resources they can utilize. Specialist herbivores strongly influence the local insect biomass in relation to the distribution and density of their host plants. The present study highlights the importance of both habitat and landscape diversity for local insect diversity in Pannonic salt grasslands and suggests that the main threats for arthropod diversity are those processes and activities that homogenize these areas.     

The role of plant–soil feedbacks and land-use legacies in restoration of a temperate steppe in northern China

Plant–soil feedbacks affect plant performance and plant community dynamics; however, little is known about their role in ecological restoration. Here, we studied plant–soil feedbacks in restoration of steppe vegetation after agricultural disturbance in northern China. First, we analyzed abiotic and biotic soil properties under mono-dominant plant patches in an old-field restoration site and in a ‘target’ steppe site. Second, we tested plant–soil feedbacks by growing plant species from these two sites on soils from con- and heterospecific origin. Soil properties generally did not differ between the old-field site and steppe site, but there were significant differences among mono-dominant plant patches within the sites. While soil species origin (i.e., the plant species beneath which the soil was collected) affected biomass of individual plant species in the feedback experiment, species-level plant–soil feedbacks were ‘neutral’. Soil site origin (old-field, steppe) significantly affected biomass of old-field and steppe species. For example, old-field species had higher biomass in old-field soils than in steppe soils, indicating a positive land-use legacy. However, soil site origin effects depended on the plant species beneath which the soils were collected. The predictive value of abiotic and biotic soil properties in explaining plant biomass differed between and within groups of old-field and steppe species. We conclude that the occurrence of positive land-use legacies for old-field species may retard successional replacement of old-field species by steppe species. However, high levels of idiosyncrasy in responses of old-field and steppe plant species to con- and heterospecific soils indicate interspecific variation in the extent to which soil legacies and plant–soil feedbacks control successional species replacements in Chinese steppe ecosystems.     

内蒙古草原植物的生态替代及其对全球变化下草原动态的指示（英）

在内蒙古草原区,从荒漠草原带到森林草原带,沿气候干燥度变化的方向调查了119个草原样地的植被与环境特征,依此定量分析了植被—环境关系。 根据表述环境因子取样质量的环境因子墒值及环境因子与出现频率最高的50个植物种间的平均相互信息,分析了所调查30个环境因子在决定植被组成中的作用优势度。结果表明,气候因子的影响是占绝对优势的,而地形和管理因子的作用是次一级的,或是地区性的。群落的物种组成与其第一优势种关联极好,因而依群落第—优势种识别的植物群落类型是组成和结构相对稳定的群落单位。基于植物种在降水和气温梯度上最适区域的计算及依此在植物降水-气温平面上的直接排序,揭示出广泛的草原植物在气候梯度上的生态替代。这种替代,尤其是包括针茅属(Stipa)植物在内的草原优势植物的替代,导致了针茅草原的生态替代。本研究也定量刻划了内蒙古主要草原植物群落的植被特征,及其在气候、土壤和人为影响梯度上的分布幅度和生态适宜区域。草原植物种和植物群落在气候和放牧梯度上的直接排序提供了气候和土地利用变化后草原植被动态的可能图景。     

1961-2010年内蒙古草原植被分布和生产力变化——基于MaxEnt模型和综合模型的模拟分析

定量评估气候变化对内蒙古草原植被分布及其净第一性生产力的影响有助于理解干旱区域生态系统结构和功能对气候变化的响应。基于最大熵模型（MaxEnt）评价了气候因子的重要性,进而模拟了1961-2010年内蒙古草原植被的地理分布,同时应用综合模型模拟了净第一性生产力变化。研究表明,湿润指数（MI）、年降水量（P）、最暖月平均温度（T_w）和最冷月平均温度（T_c）是决定草原植被分布的主导气候因子。1961-2010年内蒙古草甸草原、典型草原和荒漠草原分布面积分别减少了5%、1%和62%,草原面积整体减少了11%,预示着草原向着荒漠化的方向发展。降水是决定内蒙古草原净第一性生产力变化的最重要因素。     

基于能量属性的植物功能群划分方法探索——以内蒙古锡林河流域草原植物群落为例

植物功能群(plant functional groups, PFGs) 是具有确定的植物功能特征的一系列植物的组合,是生态学家为研究植被对气候变化和干扰的响应而引入的生态学概念.目前功能群研究中最核心的问题仍在于决定植物功能群划分的植物特征的选择上.以内蒙古锡林河流域草原植物群落为例,选取3个草原类型(羊草草原、大针茅草原和羊草草甸草原)及其退化梯度系列(未退化、轻度退化、中度退化、重度退化),在对植物热值进行分析测定的基础上,依据植物的能量属性-单位重量干物质在完全燃烧后所释放出来的热量值,采用人为分段的方法对草原植物进行了能量功能群的划分(高能值植物功能群、中能值植物功能群和低能值植物功能群).并探讨了这种能量功能群划分方法在草原植被动态研究中的客观性与可行性.     

The effects of pH and disturbance on the bryophyte flora in calcareous sandy grasslands

The unique flora and fauna of calcareous sandy grasslands is threatened by acidification, eutrofication and changed land use. Restoration experiments in such grasslands in southern Sweden, including deep and shallow soil perturbation, allowed us to examine the effects of pH and disturbance on the bryophyte flora. We also studied natural pH and disturbance gradients in order to compare the natural pH and disturbance variation with the responses of experimental manipulation. We found that increased pH due to soil perturbation resulted in increased species richness. However, in naturally disturbed areas, pH seemed to have a lower effect, and instead, the location of the site and possibly the site history had a larger influence on species richness. We also found that some of the species that were common at naturally high pH (mainly acrocarps) were favoured by experimental pH manipulation. Our results pointed out Syntrichia ruraliformis as a sensitive pH indicator, being almost exclusively restricted to pH values above 7. The species can also serve as an indicator of sand steppe vegetation.