Landscape boundaries are always indicated by the vegetation boundaries. As an ecotone between closed forest and treeline, alpine timberline may respond to global climate changes sensitively. The stability of timberlin...Landscape boundaries are always indicated by the vegetation boundaries. As an ecotone between closed forest and treeline, alpine timberline may respond to global climate changes sensitively. The stability of timberline and treeline depend not only on climate change, but also on the interaction of both sides of the ecosystems. Three natural boundaries existing in the timberline transitional zone are recognized: (1) timberline (upper limit of closed forest zone); (2) treeline (upper limit of tree islands zone); (3) tree species line (upper limit of individual tree growth). Paleobotanical and sedimentary evidences suggest that there were several times of climate fluctuation during the Holocene period in this area. The timberline of Taibai Mountain must have moved for four times on the millennium scale. Being a stochastic oscillation boundary, treeline appears in a semi stable condition on the century scale. The tree species line is even more unstable, which appears in an unstable status on the decades scale. The comparison of the stability within several landscape boundaries, shed light on the sensibility of these communities to various perturbation and environmental heterogeneity, i.e., herb community is the most sensitive one, which is followed by shrubs, and forest is the most stable one. Trees and shrubs can adapt to rocky and poor soils. On the contrary, alpine herbs are able to adapt to wetter and cooler soils. Finally, under a scenario of a temperature of 1.5 4.5℃ increase, the present timberline will be relatively stable but treeline and tree species line will move upward.展开更多
文摘Landscape boundaries are always indicated by the vegetation boundaries. As an ecotone between closed forest and treeline, alpine timberline may respond to global climate changes sensitively. The stability of timberline and treeline depend not only on climate change, but also on the interaction of both sides of the ecosystems. Three natural boundaries existing in the timberline transitional zone are recognized: (1) timberline (upper limit of closed forest zone); (2) treeline (upper limit of tree islands zone); (3) tree species line (upper limit of individual tree growth). Paleobotanical and sedimentary evidences suggest that there were several times of climate fluctuation during the Holocene period in this area. The timberline of Taibai Mountain must have moved for four times on the millennium scale. Being a stochastic oscillation boundary, treeline appears in a semi stable condition on the century scale. The tree species line is even more unstable, which appears in an unstable status on the decades scale. The comparison of the stability within several landscape boundaries, shed light on the sensibility of these communities to various perturbation and environmental heterogeneity, i.e., herb community is the most sensitive one, which is followed by shrubs, and forest is the most stable one. Trees and shrubs can adapt to rocky and poor soils. On the contrary, alpine herbs are able to adapt to wetter and cooler soils. Finally, under a scenario of a temperature of 1.5 4.5℃ increase, the present timberline will be relatively stable but treeline and tree species line will move upward.
