水保所知识产出(1956---)知识库

水分是限制黄土高原植被恢复与重建的关键因子，降水变化直接影响着其生态系
统的结构和功能。本文以黄土高原水蚀风蚀交错带典型灌木沙柳和柠条为对象，研究
了模拟降雨改变（对照：自然降雨；增水：增加降雨 50%左右；干旱处理：遮去降雨
50%左右)对沙柳和柠条的林地水分平衡、植物生长、叶水分-光合特征、蒸腾耗水特
征的影响，研究结果不仅有助于揭示两种灌木适应干旱沙生环境的生理生态机制，而
且对于该地区未来生态系统的稳定性评价和植被的合理布局与建造具有十分重要的
意义。论文得到如下主要结论：
（1）不同处理下两种灌木林地土壤水分消耗量、补给深度和蒸散量明显不同。
沙柳对照、增水和干旱处理 6~9 月土壤水分变化量分别为 37.79、47.81 和 6.17mm，
生长季末土壤水分的补充深度分别为 2.2m、1.8m 和 1.8m；柠条对照、增水和干旱处
理 6~9 月土壤水分变化量分别为-39.80、38.66 和-60.05mm，生长季末土壤水分的补
充深度分别为 1m、2.2m 和 0.5m；沙柳和柠条 6~9 月蒸散量均表现为增水>对照>干
旱处理，干旱处理的蒸散量占水分输入量的比例高，而增水处理相对较低。
（2）沙柳和柠条叶水势、光合特征和生长对模拟降雨改变的响应不同。沙柳不
同处理叶水势差异不大，而柠条存在显著差异。沙柳的净光合速率、蒸腾速率和水分
利用效率对降雨改变有显著的响应，沙柳光合参数的响应时间早，且沙柳净光合速率
对增水的响应程度大，而蒸腾速率和水分利用效率对干旱的响应程度大；柠条的净光
合速率和蒸腾速率对降雨改变响应明显，净光合速率和蒸腾速率对干旱的响应程度更
大。增水显著增加了沙柳灌丛 10～25mm 和柠条 0～10mm 径阶分枝的生长，干旱则
降低了沙柳 5～10mm 和柠条<20mm 径阶内分枝的生长。
（3）模拟降雨改变影响柠条的液流特征。柠条液流速率日变化在 7 月底大多呈
双峰曲线，在 10 月初呈单峰曲线，影响液流速率的主要气象因素为太阳总辐射和蒸
汽压亏缺。所有处理相对液流速率均随太阳辐射增大而增大，且可用 S 型函数描述。
对照和增水处理相对液流速率与蒸汽压亏缺和整合变量之间均呈 S 型函数关系，干旱处理相对液流速率先随蒸汽压亏缺和整合变量增大而增大，当 VPD >2.04 kPa 或
V T >60.38 kPa·(w·m -2 ) 0.5 时，液流速率出现明显下降，干旱处理达到峰值对应的 VPD
或 V T 滞后于增水和对照。测定时段内各处理单枝耗水量表现为：增水﹥对照﹥干旱，
但其差异并未达到显著水平。
关键词：沙柳； 柠条； 模拟降雨改变； 生理生态特性

Water is a key factor of limiting vegetation restoration and rehabilitation on the Loess
Plateau, and precipitation variation plays an important role in shaping ecosystem structure
and function of this region. In this paper, we selected Salix psammophila and Caragana
korshinskii growing in water/wind erosion crisscross region of northern Shaanxi as the
objects, and explored the effects of manipulated precipitation variation (control treatment:
normal precipitation; water addition treatment: water was added by 50% or so, drought
treatment: water was removed by 50% or so) on shrubland water balance, plant growth,
leaf water-photosynthesis and sap flow transpiration characteristics. The major objective
were to reveal the physio-ecological mechanisms of the two shrubs adapting to the dry
sandy environment, and provide better understanding for the distribution and management
of these two shrubs in the future and the evaluation of the sustainability of ecosystems. The
main results were as the follows:
(1) Soil moisture consumption, water supply depth and evapotranspiration were
different for different treatments in two shrubs. For S. psammophila, the variation of soil
water content during June to September was 37.79 mm for the control, 47.81 mm for the
water addition treatment and 6.17 mm for the drought treatment, the corresponding soil
water supply depth at the end of the growing season was 2.2m, 1.8m and 1.8m,
respectively. For C. korshinskii, the variation of soil water content during June to
September was -39.80 mm for the control, 38.66 mm for the water addition treatment and
-60.05 mm for the drought treatment, the corresponding soil water supply depth at the end  of the growing season was >1m, 2.2m and 0.5m, respectively. Evapotranspiration of
S.psammophila and C.korshinskii shrublands under three different treatments followed the
order: water-added treatment > control treatment > drought treatment. Evapotranspiration
accounted for a higher proportion of water input under drought treatment, but the
proportion was relatively lower for water addition treatment.
(2) S. psammophila and C. korshinskii had different responses to manipulated
precipitation variation in leaf water potential, photosynthesis and growth. Leaf water
potential for different treatments of S. psammophila was almost the same, but it showed
significant differences in C. korshinskii. Net photosynthetic rate, transpiration rate and
water use efficiency of S. psammophila showed significant responses to precipitation
variation, while net photosynthetic rate and transpiration rate of C.korshinskii responded
obviously to precipitation variation. These photosynthetic parameters responded earlier in
S. psammophila than in C. korshinskii. Net photosynthetic rate of S. psammophila
increased with water addition, while transpiration rate and water use efficiency were
greater under drought treatment. Net photosynthetic rate and transpiration rate of C.
korshinskii were greater under drought treatment. The growth of the branches within 10~25
mm diameter classes for S.psammophila and within 5~10 mm for C.korshinskii were
increased by water supply, while growth of branches within 5~10 mm diameter classes for
S.psammophila and branches less than 20 mm diameter class for C.korshinskii were
decreased by drought.
(3) Sap flow characteristics of C. korshinskii were affected by manipulated
precipitation variation. The daily change of sap flow rate was almost a bimodal curve at the
end of July, but it had become an unimodal curve in early October. The main factors that
affected the sap flow rate were solar radiation and vapor pressure deficit. The relative sap
rate increased with solar radiation and the trends could be described by S-type function.
The relative sap flow rate of the control and water addition treatment showed an S-type
relationship with vapor pressure deficit or integrated variant (V T ). The relative sap flow
rate of drought treatment increased with the increase of vapor pressure deficit or integrated
variable variant firstly, but then the relative sap flow rate decreased significantly when
VPD> 2.04 kPa or when V T > 60.38 kPa·(w·m -2 ) 0.5 . VPD or V T of drought treatment
corresponding to peak relative sap flow rate was larger than the control and water addition  treatment. Single branch water consumption under different treatments was: water addition
treatment > control > drought treatment, but the difference did not reach significant level.
Key words: Salix psammophila, Caragana korshinskii, manipulated precipitation
variation, physio-ecological traits.