Morphogenesis of the Procumbent Life Form in Siberian Stone Pine at the Timberline in the Western Sayan Mountains

The morphology and development are described for Siberian stone pine (Pinus sibiricaDu Tour) growing at the timberline in the Western Sayan Mountains. Throughout ontogeny, these plants have a short stem trailing in an approximately horizontal direction. Maximal longevity and viability are characteristic of basal branches, which are able to root and produce vegetative generations. This allows these plants to be classified with the procumbent tree life form, in which the clones of most adaptive genotypes not only survive under extreme environmental conditions, but can also reproduce vegetatively.     

Spatiotemporal dynamics of forest-tundra communities in the polar urals

The spatiotemporal dynamics of forest-tundra communities in the 20th century have been studied in the timberline ecotone of the Polar Urals. Maps reflecting the distribution of different types of forest-tundra communities have been made, and data on the morphological and age structure of tree stands have been obtained for three time sections (the mid-1910s, 1960s, and 2000s). They show that open and closed forests have markedly expanded due to natural afforestation of the tundra and increase in the density and productivity of existing forest stands. The unidirectional pattern of plant community transition (from the tundra to closed forests) and meteorological data provide evidence that this transition has been conditioned by climate warming and increasing humidity recorded during the past 90 years.Translated from Ekologiya, No. 2, 2005, pp. 83–90.Original Russian Text Copyright © 2005 by Shiyatov, Terentev, Fomin.     

Reproduction of the Siberian spruce in the timberline ecotone of the Iremel’ Massif

Quantitative and qualitative characteristics of cones and seeds and the emergence and survival of seedlings in the Siberian spruce (Picea obovata Ledeb.) were studied in different parts of the timberline ecotone on the Iremel’ Massif, the Southern Urals, from 2003 to 2006. In the productive year 2003, a decrease in the number of cones (from 110000 to 3000 per hectare), the yield of seeds (from 13 × 10⁶ to 0.09 × 10⁶ per hectare), and their laboratory germination rate (from 34 to 14%) with an increase in elevation above sea level was recorded. In 2004, significant differences in the number of seedlings per hectare were revealed between the lower, middle, and upper parts of the ecotone (85 200, 19 800, and 0–400 ind., respectively). It has been shown that the greater part of seedlings (76–96%) perish during the first cold period. New generations of spruce trees are formed only after productive years. Seed production and seedling mortality in spruce apparently depend not only on air temperature and soil moistening but also on snow depth and soil temperature, which change more abruptly along the altitudinal gradient.     

基于RS和GIS的贺兰山高山林线初步研究

论文基于RS和GIS方法,运用Landsat 8-OLI影像和DEM数据获取贺兰山高山林线分布信息,并对林线植被NDVI特征和林线分布特征进行研究。结果表明：1）生长季初期山地针叶林和高山灌丛草甸NDVI值差异明显,两种植被NDVI栅格像元的分布及其数量在山地垂直空间的变化指示出贺兰山2 900~3 200 m海拔范围出现高山林线现象。2）贺兰山高山林线主要分布在中部顶峰周边区域,林线上边界平均高度3 106 m,下边界平均高度3 022 m。主山脊两侧区域的东坡和北坡林线的平均高度较高,西坡和南坡低。3）山地针叶林与高山灌丛草甸NDVI栅格数据可以作为影像分类数据的补充,对影像分类方式确定的高山林线分布区域进行修正,能够提高林线提取的准确性。     

Ecological Variation in the Morphological Structure of the Crown in Siberian Stone Pine at the Timberline

The structure of the crown and branching; the growth, development, and ontogeny of branches; and organogenesis and growth of female shoots in the model Siberian stone pine trees were studied in four types of habitats at the timberline in the central Altai Mountains (1700–2170 m a.s.l.). The results provided evidence that the ecological forms of trees appear due to changes in the pattern of branching as well as to the decreased rate of vegetative (primarily apical) growth. The diameter of the shoot pith is one of the most variable characters reflecting the deterioration of environmental conditions at higher elevations.     

林线树种太白红杉碳储量估算

林线对气候变化十分敏感,有关环境如何影响林线植被碳储量分布的研究鲜见报道.采用野外调查、遥感影像解译和生物量模型计算相结合的方法,对秦岭主峰太白山林线树种——太白红杉(Larix chinensis)碳储量、碳密度及其分布进行了估算.结果表明:太白红杉林总碳储量为5.290×105 t,其中南坡碳储量为1.765×105 t,北坡碳储量为3.525×105 t,南北坡碳储量分布不均与太白红杉分布面积和海拔有很大的关系;太白红杉林碳密度为0～17.40 kg/m2,平均值为(7.65±4.15)kg/m2,与年均温度呈正相关,与海拔和年降水量呈负相关,温度是影响太白红杉林碳密度的关键因素.     

Changes in the upper limits of tree species distribution in the Western Caucasus (Belaya River basin) related to recent climate warming

To estimate the response of tree vegetation to recent climate warming in the Western Caucasus, the population state of several tree species at the upper limit of their distribution has been estimated in three mountain massifs in the Belaya River basin. For this purpose, the average and maximum stem diameters, vitality, and age of trees have been determined in the transitional zone between middle-mountain and high-mountain beech-fir forests (1400–1700 m a.s.l.) and in crooked birch forests growing at the upper timberline (1810–2025 m). The upper limits of Acer platanoides, A. pseudoplatanus, Ulmus glabra, and Betula litwinowii have shown a tendency to rise. The upper limit of Abies nordmanniana has remained unchanged over the past few decades, which may be explained by a decrease in moisture supply during the warm season.     

Stability of alpine timberline ecotone on Taibai Mountain,China

--Landscape boundaries are always indicated by thevegetation boundaries. As an ecotone between closed forest andtreeline, alpine timberline may respond to global climate changessensitively. The stability of timberline and treeline depend notonly on climate change, but also on the interaction of both sidesof the ecosystems. Three natural boundaries existing in thetimberline transitional zone are recognized (1) timberline (upperlimit of closed forest zone); (2) treeline (upper limit of treeislands zone); (3) tree-species line (upper limit of individualtree growth). Paleobotanical and sedimentary evidences suggest thatthere were several times of climate fluctuation during the Holoceneperiod in this area. The timberline of Taibai Mountain must havemoved for four times on the millennium scale. Being a stochasticoscillation boundary, treeline appears in a semi-stable conditionon the century scale. The tree-species line is even more unstable,which appears in an unstable status on the decades scale. Thecomparison of the stability within several landscape boundaries,shed light on the sensibility of these communities to variousperturbation and environmental heterogeneity, i.e., herb community is the most sensitive one, which is followed by shrubs, and forestis the most stable one. Trees and shrubs can adapt to rocky andpoor soils. On the contrary, alpine herbs are able to adapt towetter and cooler soils. Finally, under a scenario of a temperatureof 1.5-4.5℃ increase, the present timberline will be relativelystable but treeline and tree-species line will move upward.