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Peng G., Wu C., Xu X., Yang D.

Polish Journal of Ecology

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2012

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Vol. 60, nr 2

311-321

EN

In woody perennials, leaf structure and biochemistry vary with tree age under changing environments. However, the related eco-physiological mechanisms have not been elucidated yet. In this study, we investigated agerelated responses of juvenile and mature subalpine fir trees (Abies faxoniana Rehder & E.H. Wilson.) growing at altitudes between 2,500 and 3,500 m in the Wanglang Natural Reserve in southwest China, to study the adaptive strategies of different age trees to suit changing environments. We found that there were distinct age- and altituderelated changes in the structural and biochemical characteristics of leaves. At all altitudes, mature trees exhibited higher area- and mass-based leaf nitrogen content (N[area], N[mass]), leaf mass per area (LMA) and stable isotope carbon composition ([delta^13]C), and a lower chlorophyll (Chl) content than those juvenile trees, except for N[mass] at 3,000 m as well as LMA at 2,750 m, where the values of N[mass] and LMA in mature trees were slightly lower than those in juvenile trees. Furthermore, leaf characteristics showed significant differences in the change rates with altitude between different age groups. Our results indicated that assimilative organs in mature trees do not suffering from nutrient deficiency and that juvenile and mature trees possess different adaptive growth strategies under changing environments, as indicated by higher leaf N content in mature trees and the opposite patterns of LMA and Chl content between two age groups. We also concluded that juvenile could be more sensitive to global warming due to a greater altitudinal influence on the leaf traits in juvenile trees than those in mature trees.

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Altitudinal patterns of vascular plant richness in high mountains: applying of Generative Additive Model

Tu W., Gao X., Wu N., Liu S.

Polish Journal of Ecology

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2010

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Vol. 58, nr 2

231-240

EN

To explore and describe the species richness patterns along altitudinal, high mountain gradients, two transects . northern exposure (YG) and southern exposure (TD) at Mt. Jiuding (1200.4200 m) in Western China (31[degrees]13'- 31[degrees]46'N, 103[degrees]29'-104[degrees]05'E) were selected. They differ from south to north in climate conditions and vegetation zonation, and each transect was sampled according to a uniform method. Every 200 m along the altitudinal gradient we set a sampling belt of 3000 m x 5 m to record the tree species, and 30 plots of 5 m x 5 m within every vegetation belt were used to investigate shrub and herb species. We compared the composition of plant species and calculated the coefficient of similarity between the two transects. A Generalized Additive Model (GAM) was used to describe the richness patterns. For the whole Mt. Jiuding, the richness at all three levels (species, genus and family) showed a monotonically decreasing pattern. As for the different growth forms, richness of the trees, shrubs and pteridophytes showed hump-shaped patterns; and herbs showed a slow decreasing pattern along the altitudinal gradients. In TD transect, the richness of species, genus and family also showed monotonically decreasing patterns; tree richness decreased with the increase of altitude; the shrub richness showed a humpshaped pattern; but pteridophytes and other herbs showed wave-like patterns. In YG transect, altitudinal gradient of richness at different taxonomic levels all showed hump-shaped patterns; and the species richness patterns for different growth forms peaked at middle attitude except for the graminoids and other herbs. The evolutionary history of the vegetation in Mt. Jiuding was quite consistent, and different richness patterns along altitudinal gradients might be resulted from different contemporary ecological conditions. Human disturbance and different range of altitudinal gradients were also important factors for different richness patterns between the two transects. In our study, species in different growth forms showed different altitudinal patterns, but those species with similar requirements to environmental conditions showed similar richness patterns along altitudinal gradients.

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Extreme radial growth reaction of Norway spruce along an altitudinal gradient in the Šumava Mountains

Čejkova A., Kolář T.

Geochronometria

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2009

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Vol. 33

41-47

EN

Extreme radial growth reactions were analyzed over a 79-year period (1922-2000) to compare response of Norway spruce (Picea abies [L.] Karst.) along an altitudinal gradient (376-1221 m a.s.l.) in the Šumava Mountains, the Czech Republic. Extreme growth events were defined as pointer years, when an average percentage of the site pointer years reached at least 50% strength observed at the relevant altitudinal zone (low < ca. 700 m; middle ca. 700-950 m, high > ca. 950 m). The comparison of the pointer years showed a specific pattern for altitudinal zones (Low: negative pointer years 2000, 1992, 1984, 1976, 1971 and positive 1997, 1975, 1960, 1949, 1932, 1926; middle: negative 2000, 1992, 1976 and positive 1997, 1989, 1978; high: negative 1996, 1980, 1974, 1965 and positive 1989, 1963, 1927). Negative pointer years were usually induced by summer drought at low elevations and by wet-cold summer at high altitudinal zone. These two main limiting factors were probably combined at the middle altitudinal zone. Detailed understanding of the extreme tree ring pattern along the altitudinal and geographical scale may be used as one of the additional indicators of dendrochronological dating and provenance identification of spruce sample among altitudinal zones in the Šumava Mountains.