Alpine Tundra Zone Research Articles

The Changbai Alpine Shrub Tundra Will Be Replaced by Herbaceous Tundra under Global Climate Change.

Significant replacement of shrub species by herbaceous species has been observed in the Changbai alpine tundra zone, China, since the 1990s. This study used plot surveys to analyze variations in the spatial distribution of dominant plants and to ascertain the changing mechanisms of dominant species in the alpine tundra zone. We found that the two previously dominant shrubs, Rhododendron chrysanthum and Vaccinium uliginosum, differed markedly in their distribution characteristics. The former had the highest abundance and the lowest coefficient of variation, skewness, and kurtosis, and the latter showed the opposite results, while the six herb species invaded had intermediate values. R. chrysanthum still had a relatively uniform distribution, while the herbaceous species and V. uliginosum had a patch distribution deviating from the normal distribution in the tundra zone. Micro-topography and slope grade had stronger effects on the spatial distribution of the eight plant species than elevation. Herbs tended to easily replace the shrubs on a semi-sunny slope aspect, steep slope, and depression. Overall, the dominance of dwarf shrubs declined, while the herbaceous species have encroached and expanded on the alpine tundra zone and have become co-dominant plant species. Our results suggest that various micro-topographic factors associated with variations in climatic and edaphic conditions determine the spatial distribution of plants in the alpine tundra zone. Future climate warming may cause decreased snow thickness, increased growing season length, and drought stress, which may further promote replacement of the shrubs by herbs, which shows retrogressive vegetation successions in the Changbai alpine tundra zone. Further studies need to focus on the physio-ecological mechanisms underlying the vegetation change and species replacement in the alpine tundra area under global climate change.

Diversity and Spatial-Temporal Distribution of Soil Macrofauna Communities Along Elevation in the Changbai Mountain, China.

The understanding of patterns of vertical variation and diversity of flora and fauna along elevational change has been well established over the past century. However, it is unclear whether there is an elevational distribution pattern for soil fauna. This study revealed the diversity and spatial-temporal distribution of soil macrofauna communities in different vegetation zones from forest to alpine tundra along elevation of the Changbai Mountain, China. The abundance, richness, and Shannon-Wiener diversity index of soil macrofauna communities were compared in four distinguished vegetation zones including the coniferous and broadleaved mixed forest zone, the coniferous forest zone, the subalpine dwarf birch (Betula ermanii) forest zone, and the alpine tundra zone. Soil macrofauna were extracted in May, July, and September of 2009. In each season, the abundance and richness of the soil macrofauna decreased with the ascending elevation. The Shannon-Wiener diversity indices of the soil macrofauna were higher in the vegetation zones of lower elevation than of higher elevation. Significant differences were observed in the abundance, richness, and Shannon-Wiener diversity index for the studied vegetation zones. Soil macrofauna congregated mainly to the litter layer in the low-elevation areas and in the 0-5 cm soil layer of the higher elevation areas. The results emphasized that the diversity of soil macrofauna communities decreased as the elevation increased and possess the distinct characteristics of zonation in the mountain ecosystem. The diversity and distribution of soil macrofauna communities were influenced by mean annual precipitation, altitude, annual radiation quantity, and mean annual temperature.

Effective seed distribution pattern of an upward shift species in alpine tundra of Changbai Mountains

The vegetation of alpine tundra in the Changbai Mountains has experienced great changes in recent decades. Narrowleaf small reed (Deyeuxia angustifolia), a perennial herb from the birch forest zone had crossed the tree line and invaded into the alpine tundra zone. To reveal the driven mechanism of D. angustifolia invasion, there is an urgent need to figure out the effective seed distribution pattern, which could tell us where the potential risk regions are and help us to interpret the invasion process. In this study, we focus on the locations of the seeds in the soil layer and mean to characterize the effective seed distribution pattern of D. angustifolia. The relationship between the environmental variables and the effective seed distribution pattern was also assessed by redundancy analysis. Results showed that seeds of D. angustifolia spread in the alpine tundra with a considerable number (mean value of 322 per m2). They were mainly distributed in the low elevation areas with no significant differences in different slope positions. Effective seed number (ESN) occurrences of D. angustifolia were different in various plant communities. Plant communities with lower canopy cover tended to have more seeds of D. angustifolia. Our research indicated reliable quantitative information on the extent to which habitats are susceptible to invasion.

长白山西坡小叶章侵入苔原带过程及影响研究

长白山西坡岳桦林带的草本植物(以小叶章为代表)侵入了苔原带,形成了独特的植物入侵现象。在光谱及影像分析的基础上,结合GPS(Global Positional System)定位技术,并依据小叶章与牛皮杜鹃的光谱差异及其反演的NDVI (Normalized Difference Vegetation Index)植被指数,揭示小叶章侵入苔原带的过程;通过对不同侵入时间、强度的斑块进行群落调查及土壤测试,探究小叶章侵入苔原带的生态后果。结果显示小叶章侵入苔原带始于20世纪80年代后期,由低海拔向高海拔推进,进入21世纪后逐渐形成了稳定的以小叶章为优势物种的植物群落结构。目前,低海拔处的小叶章斑块经过多年扩张已连接成片,而高海拔处的斑块正处于扩张的初期阶段。从生物多样性变化可以看出,小叶章侵入苔原带导致植物群落多样性升高和物种数量的增加,苔原带原有的灌木数量明显减少,草本植物逐渐增多。植被的改变影响了土壤的理化性质,C/N比下降,土壤腐殖质含量和全氮含量下降,但速效氮和土壤持水能力上升,土壤养分的高效利用又进一步推动了小叶章的侵入。小叶章侵入苔原带已经造成了严重的生态后果。;In China, the alpine tundra of Changbai Mountain is one of only three areas in China with this type of rare alpine tundra. The vegetation has undergone significant change in recent decades. Herbaceous species from the ‘<em>Betula ermanii</em> zone’, represented by <em>Deyeuxia angustifolia</em>, have invaded the alpine tundra zone on Changbai Mountain. This incursion represents a unique phenomenon in the mountainous areas of China. We examined the incursion process of <em>D. angustifolia</em> using GPS (Global positional system) techniques based on spectral and image analysis. In the study area, GPS equipment was used to identify individual <em>D. angustifolia</em> patches. Spectral analysis, particularly the red edge bands, was conducted by comparing the hyperspectral data between the invasive D.<em> andustifolia</em> and the native species, <em>Rhododendron chrysanthum</em>. The spectral diversity of the invasive and native species' enabled us to compare their NDVI (Normalized Difference Vegetation Index), which was used to analyze within patch changes in vegetation. Landsat TM images from 1983, 1999, 2002, 2006 and 2008 were used to calculate the NDVI index. The results showed that the incursion of <em>D. angustifolia</em> began in the 1980s. Currently, <em>D. angustifolia</em>has successfully invaded this alpine landscape with the gradual trend following an altitudinal gradient. The incursion range has extended from relatively low elevations to higher elevations. Moreover, the inference is that <em>D. angustifolia</em> patches at lower elevations are interconnected forming relatively large patches. At higher elevations in the tundra landscape, these <em>D. angustifolia</em> patches were smaller and more scattered.We also investigated the ecological consequences of the <em>D. angustifolia</em> invasion using plant community surveys and soil tests. The <em>D. angustifolia</em> patches were defined as patches at different times of invasion, which consisted of three different invasive levels (low, medium and high levels of invasion). In the newly formed plant community <em>D. angustifolia</em> was the dominant species. While this invasion altered the native plant community structure and enhanced biodiversity, it altered some soil properties including both physical and chemical properties. Compared with the native plant community, dominated by <em>R. chrysanthum</em>, the invasive patches showed higher Shannon-Wiener diversity and species richness. Changes in abundance and evenness of the community suggested that <em>D. angustifolia</em> would occupy the most dominate position in that community. The change of community structure resulted in the reduction of shrubs and increased the number of herbaceous species. The change of vegetation directly or indirectly led to changes in soil properties. The progression of invasion resulted in a decrease in the carbon/nitrogen ratio, soil humus and total nitrogen. However, the available nitrogen and soil water content increased. The changes in soil nutrients were closely related to changes in physical soil properties, especially for soil water content. The increases in soil water content altered nitrogen fixation processes, microbial decomposition and nitrification. We propose that the efficient use of soil nutrients may promote further <em>D. angustifolia</em> invasion. Moreover, we suggest that a time lag occurs between changes in the vegetation and soil properties.The invasion of <em>D. angustifolia</em> on the alpine tundra ecosystem has and continues to have severe impacts.

Fungal communities at the edge: Ecological lessons from high alpine fungi

Abstract One of the least studied ecosystems on Earth is the plant-free zone found between the alpine tundra zone and the zone of permanent ice and snow. This unique ecosystem-type occurs in all of the major mountain ranges on Earth and is especially widespread in the Andes and Himalayas. Here we describe recent molecular-phylogenetic studies of the fungi that inhabit these apparently barren soils. Sites that receive significant amounts of snowfall (in the Himalayas, Rocky and Andes ranges) are dominated by unique clades of zoosporic fungi (especially the Spizellomycetales), which likely use the saturated soil conditions during snow melt to complete their life cycles and then remain dormant for most of the year during periods of extreme cold and dryness. In more extreme sites that have very sporadic and shallow snow packs, such as the upper slopes of Llullaillaco Volcano (el. 6 741 m above sea level) on the Chilean-Argentinian border, fungal communities show very little diversity and are dominated by clades of yeasts related to the Antarctic endolithic yeasts in the Filobasidiales group. The other major group found on Llullaillaco form a clade most closely affiliated with the Dothideomycetes. Overall, our phylogenetic approach and spatially explicit sampling scheme allow us to formulate new hypotheses about the ecological functioning of fungi that inhabit critically endangered high elevation ecosystems.

Palaeolimnological and sedimentary responses to Holocene forest retreat in the Scandes Mountains, west-central Sweden

A suite of analyses was performed on sediments accumulated during the last 10 700 years in Lake Spaime, a small, hydrologically open water body in the modem alpine tundra zone of the Scandes Mountains, west-central Sweden. The study aimed to evaluate (1) the nature of climate changes that forced the late-Holocene lowering of altitudinal tree limit in the region, the timing of which is known from prior studies based on radiocarbon dating of subfossil wood, and (2) the impact of these vegetational changes on an aquatic ecosystem. Arboreal pollen and plant macrofossil data confirm the persistence of trees in the lake catchment at least from c. 9700 cal. BP until c. 3700 cal. BP. Although growing-season temperature is commonly believed to be the dominant factor driving boreal forest tree-limit variations in the region, a chironomid-based reconstruction of mean July air temperature suggests that local deforestation during the late Holocene was not accompanied by a significant cooling. The tree-limit retreat was more likely caused by increasing effective moisture and declining length of the growing season. The ecohydrological response of Lake Spaime to this combination of climate and vegetational changes included a decline in primary productivity, as indicated by an abrupt decrease in sediment organic matter content, while associated increases in organic 613C, 615N and C/N point to diminished fluxes and altered balance of catchment derived nutrients following deforestation. The decline in aquatic productivity is also marked by a distinct change in the mineral magnetic properties, from a high magnetic concentration assemblage dominated by fine-grained magnetite of biogenic origin to one dominated by background levels of coarse-grained detrital magnetite.

Holocene treeline dynamics in the mountains of northeastern British Columbia, Canada, inferred from fossil pollen and stomata

Changes in pollen and stomata assemblages in sediment cores recovered from tundra and foresttundra lakes in alpine regions of northeastern British Columbia reflect vegetation and inferred climatic change throughout the Holocene. Pollen and stomata records are presented from two lakes, BC2 located in the alpinetundra zone and Dead Spruce Lake at the present elevation of subalpine treeline. The pollen and stomata records from BC2 indicate that an ephemeral shrub and herb assemblage was rapidly replaced by an aspen (Populus)-spruce (Picea)-birch (Betula) woodland at ~ 10600 cal. yr BP. The occurrence of stomata suggests that treeline was at least 235 m higher than present from ~10 600 until ~7500 cal. yr BP and temperatures were at least 1.4°C warmer than at present. Analyses from Dead Spruce Lake indicate that the density of trees was also higher between ~9000 and 4800 cal. yr BP. High concentrations of macroscopic charcoal between ~9800 and 8000 cal. yr BP suggest that conditions were also drier at this time. Changes in the position of treeline during the early to mid-Holocene appear to track closely shifts in climate, while forest development at our forest-tundra site reflects a combination of both heightened summer insolation and increased fire activity. The fossil stomata record from BC2 suggests that a rapid cooling event at ~8200 cal. yr BP may have been the trigger that resulted in the downslope movement of treeline to its present elevation. Increased Picea percent ages, pollen-accumulation rates (PARs) and concentration of stomata between ~3600 and 2700 cal. yr BP provide evidence for a late-Holocene increase in forest-tundra density in response to warmer temperatures.

Climate change in the Colorado Rocky Mountains: free air versus surface temperature trends

AbstractA high elevation data set of surface temperatures from the Front Range of the Rocky Mountains in Colorado, USA, is analysed for evidence of long‐term change (1952–98). Sites range from the high plains of Colorado (1509 m) to the alpine tundra (3749 m). Systematic changes in surface‐based lapse rates are uncovered, with absolute cooling at the highest elevations, but little temperature change on the high plains. There is lapse‐rate steepening at the higher elevations (&gt;3000 m). A synoptic analysis using gridded pressure data shows lapse rate changes to be largely independent of synoptic type. Radiosonde ascents from Denver (1956–98) and Grand Junction (1946–98) are used to derive air equivalent temperatures (AETs) at the same elevations as the surface records. AETs show a contrasting temporal trend, with absolute warming at all levels. Furthermore, free‐air lapse rates are weakening at higher elevations, the warming becoming stronger with height. A comparison of the two data sets through derivation of free‐air–surface temperature differences shows that the alpine tundra zone of the high Rockies is becoming a progressively stronger heat sink. Possible explanations include increased snow cover, enhanced air movement over the surface and decreased solar radiation input. The heat sink enhancement has led to rapid cooling in the alpine tundra that could not be predicted from the free‐air record, casting doubt upon the strong dependence on free‐air temperature changes in climate modelling when investigating the potential effects of global warming in mountainous regions. In addition, these local surface trends are of the opposite sign to global and other regional trends identified in many recent observational and modelling studies. Copyright © 2002 Royal Meteorological Society.

Study on complexity of plant communities at different altitudes on the Northern Slope of Changbai Mountain

By the method of gradient pattern analysis, twenty plots were set at altitudes of 700–2600 m with an interval of 100 m on the northern slope of the Changbai Mountain. The dissimilarity of respective sub-plots in the same community was measured and the complexity of plant communities at different altitudes was analyzed. The result from binary data of tree species in canopy tree indicated that the sub-plots in the communities, except subalpineBetula ermanii forest, showed comparatively high dissimilarity in species composition. Especially, the dissimilarity index (0.7) of broadleaved/Korean pine forest at low altitudes was obviously higher than other communities. The differences are not obvious between communities referring to dark coniferous forest. Comparatively, the dissimilarity in sub-plots of the communities at altitude of 1400 m was slightly higher than that of other communities, which reflected the complexity of tree species compositions of transitory-type communities. For subalpineBetula ermanii forest, tree species composition was simple and showed a high similarity between sub-plots. The results derived from binary data of shrub showed that the dissimilarity index of shrub species in broadleaved/Korean pine forest at low altitudes was higher than that in other communities, but the divergence tendency wasn’t so obvious as that of arbor species. The dissimilarity derived from binary data of herb and all plant species at different altitudes showed greatly close tendency, and the differences in herb and all plant species between sub-plots were the greatest for the communities of broad-leaved-Korean pine forest and alpine tundra zone.

Comparison of pollen and conifer stomates as indicators of alpine treeline in northwestern Canadian lake sediments

We compare fossil pollen and stomate assemblages in 29 lake sediment surface samples from mountainous regions in northwestern Canada to characterize the relationship between modern vegetation, and pollen and stomate deposition. Modern pollen spectra were dominated by arboreal taxa originating from lower elevation sites. Pinus pollen frequently reached 30% of the pollen sum, regardless of elevation. Alpine-tundra vegetation has lower pollen abundance, even in the alpine-tundra zone, where it dominates the sparse vegetation cover. Fossil stomates were observed in all but one site where trees currently exist in the vicinity of the lake, while no stomates were found in the sediments from alpine-tundra sites. The highest concentration of stomates occurred in lake sediments from closed-canopy forested areas. Our data suggest that different boreal forest types may be differentiated based on pollen assemblages and that the presence of stomates clearly distinguishes vegetation zones dominated by arboreal vegetation from alpine-tundra zones where trees are not present.Key words: pollen, conifer stomates, treeline, Pacific Northwest.

Dynamics of the vegetation eco-boundary under climate warming in Northeast China

Based on data from 210 meteorological stations in Northeast China and survey on zonal climax vegetation, the Kira's warmth index (Wl), coldness index (Cl), and Xu Wenduo's humidity index (Hl) were adopted to simulate and predict the dynamics of the vegetation eco-boundary under climate warming in Northeast China. The future vegetation eco-boundary alteration types of zonal climax vegetation could be divided into three types, such as extended vegetation eco-boundary species (Wl value range for 45–95°C · month) which would move northwards under climate warming, retreated vegetation eco-boundary species (Wl value range for 25–65°C · month) which would retreat from the present localities, and extinct population species (Wl value range for 5–35°C · month) which would be extinguished because the ecosystems they depend on disappeared. In Northeast China, there were differences for 15° latitudinal and 2600 m altitudinal. Based on our research results, the edificators would move northwards about 400–700 km, steppe vegetation would move eastwords 900 km, and the populations would move upwards about 260–360 m in mountains if the global temperature increases 2°C in the future. However, the moving distance would become shorter and shorter as the latitude and altitude increased. Therefore, the populations in alpine tundra zone at Daxing'an Mountains and Changbai Mountain might disappear. The results were expected to supply reference to local government when they set down strategies to respond to climate change in the future.

Stratifying Alpine Tundra for Geomorphic Studies Using Digitized Aerial Imagery

In the alpine tundra zone of Niwot Ridge, Colorado Front Range, U.S.A., order of magnitude differences in surficial geomorphic process rates were found when the data were stratified by plant community. A two-stage classification technique to stratify vegetation units in the alpine zone for use in geomorphic studies is presented. In the first stage, spectral reflectance measurements from a digitized color infrared aerial photograph were used to classify general vegetation and cover classes on Niwot Ridge. This classification was able to distinguish between dry and moist meadow communities, scree slopes, and snowbed communities. A digital terrain model of Niwot Ridge was subsequently constructed to study the topographic influences on the distribution of alpine vegetation. The joint frequency distribution of alpine vegetation and elevation, slope, and aspect was estimated from previously mapped vegetation patterns, and the digital terrain model developed in the present study. In the second-stage classification, vegetation and other cover classes we reclassified based on the topographic distribution of vegetation and other cover classes such as fellfields. Surficial soil loss estimated from the present classification indicated that order of magnitude comparisons can be made between these estimates and those previously published.

Gopher Disturbance: Its Variability by Braun-Blanquet Vegetation Units in the Niwot Ridge Alpine Tundra Zone, Colorado Front Range, U.S.A.

Gopher Disturbance: Its Variability by Braun-Blanquet Vegetation Units in the Niwot Ridge Alpine Tundra Zone, Colorado Front Range, U.S.A.

Gopher Disturbance: Its Variability by Braun-Blanquet Vegetation Units in the Niwot Ridge Alpine Tundra Zone, Colorado Front Range, U.S.A.

Gopher Disturbance: Its Variability by Braun-Blanquet Vegetation Units in the Niwot Ridge Alpine Tundra Zone, Colorado Front Range, U.S.A.

Modern pollen rain of Washington

Modern pollen rain was studied at 98 sites distributed in a belt transect some 250 km wide running a distance of 425 km between La Push on the Pacific coast and Grand Coulee on the Columbia Plateau. Sites are located in a variety of plant communities from the Picea sitchensis Zone near sea level to the Alpine Tundra Zone at 2285 m in the Cascades. The purposes of the study are (1) to establish the nature of the pollen rain and its relation to vegetation sources and (2) to develop further the pool of potential analogs of fossil pollen spectra for use in the reconstruction of Quaternary environments.Relative frequencies are shown for the pollen of Pinus, Picea, Abies, Tsuga, Pseudotsuga, Cupressaceae, Alnus, Gramineae, Cyperaceae, Chenopodiaceae, Artemisia, and Compositae. Results indicate the pollen rain to be related to source vegetation at the collection sites except for certain instances of infiltration by extraneous types, of which Pinus is most conspicuous. Alnus is the dominant pollen in the Puget Lowland and the western Coast and Cascade Ranges; Tsuga heterophylla is most prominent in the Coast Range; and Pinus ranks foremost in the eastern Cascades and on the Columbia Plateau. On the Columbia Plateau, the Gramineae, Artemisia, Compositae, and Chenopodiaceae are also distinctive. Subalpine forest types and nonarboreals are generally characteristic of the Timberline and Alpine Tundra Zones.