al 地理 生態系統

1. sun-facing slope with greater intensity of insolation which lead to a higher temperature and better primary productivity
2. In summer with temperature above 0C which lead to snowmelt and with liquid water for primary production
3. flatland and very swanmpy wet tundra of grass-like sedges prolierates
4. Slight sloping ground offeres better drainage, thickets of dwarf, woody shrubs can be found.
5. Higher exposed slopes, only mosses and lichens manage to survive on rock layer

I suggest u read follow:

http://hk.wrs.yahoo.com/_ylt=A8tU33DaswhHOhwBwrCzygt.;_ylu=X3oDMTE3ODhvYWxkBGNvbG8DdwRsA1dTMQRwb3MDMwRzZWMDc3IEdnRpZANoa2MwMDNfMQ--/SIG=12b9qste8/EXP=1191839066/**http%3A//picea.sel.uaf.edu/manuscripts/McGuireJVS2002.pdf

this is a good article for Environmental variation, vegetation distribution, carbon dynamicsand water/energy exchange at high latitude

Abstract. The responses of high latitude ecosystems to global
change involve complex interactions among environmental
variables, vegetation distribution, carbon dynamics, and water
and energy exchange. These responses may have important
consequences for the earth system. In this study, we evaluated
how vegetation distribution, carbon stocks and turnover, and
water and energy exchange are related to environmental
variation spanned by the network of the IGBP high latitude
transects. While the most notable feature of the high latitude
transects is that they generally span temperature gradients
from southern to northern latitudes, there are substantial
differences in temperature among the transects. Also, along
each transect temperature co-varies with precipitation and
photosynthetically active radiation, which are also variable
among the transects. Both climate and disturbance interact to
influence latitudinal patterns of vegetation and soil carbon
storage among the transects, and vegetation distribution appears
to interact with climate to determine exchanges of heat and
moisture in high latitudes. Despite limitations imposed by the
data we assembled, the analyses in this study have taken an
important step toward clarifying the complexity of interactions
among environmental variables, vegetation distribution, carbon
stocks and turnover, and water and energy exchange in high
latitude regions. This study reveals the need to conduct
coordinated global change studies in high latitudes to further
elucidate how interactions among climate, disturbance, and
vegetation distribution influence carbon dynamics and water
and energy exchange in high latitudes.