Affiliations: Laboratory of Quantitative Vegetation Ecology,
Institute of Botany, the Chinese Academy of Sciences, Beijing,100093, China.
E-mail: cwxiao@public2.east.net.cn
Abstract: Response pattern was investigated for seedlings of Salixpsammophila,
a dominant shrub in Maowusu sandland, to the simulated precipitation change by
artificially controlling water supply at four levels. The growth characters, in
term of plant height, stemdiameter, total branch number, total leaf number and
area, total bifurcation ratio, total branch length and branch number, length,
leaf number, leaf area of each branch order, and leaf, branch, root mass
significantly increased when water supply increased. Thatwater supply had
significant effect on biomass allocation showed different investment pattern of
biomass resource of the seedlings grwn different water supply treatments.
Stomatal density of abaxial leaf surface decreased, and stomatal apparatus
length and width of adaxial and abaxial leaf surface increased with the
increase in water supply, while Stomatal density of adaxial leaf surface was
not affected by water supply. Water supply obviously affected the diurnal
changes of photosynthetic rate, and the photo synthetic rate of the seedlings
showed strongly midday depression growing under the 157.5 mm water supply, but
not growing under higher water supply. Additionally the Assimilation-light
response curves and fluorescence efficiency more showed that water supply
improve photosynthesis capacity. Finally, S.psammophila seedlings stood out by
their slow growth and relatively high investments in root growth in order to
reduce tissue losing rate and consumption of water resource for keeping water
balance under water stress. The seedlings that grown under high water supply
did by their fast growth and relatively high investments in branch and leaf
growth in order to improve the power of capturing light energy for higher
photosynthesis.
