黄土丘陵区典型植物枯落物凋落动态及其持水性

枯落物具有重要的径流拦蓄功能,研究枯落物的凋落动态和其持水性对认识枯落物初级生产力及其水土保持功能具有重要意义。通过对黄土丘陵区6种典型植物样地SymbolA@为期一年的凋落物动态监测及其持水性的测定。结果表明:(1)6种植物全年凋落物量为70.65—455.57 g/m~2,落叶占凋落物总量的48.17%—91.09%;逐月凋落物量为1.86—160.21 g/m~2,包含了单峰型、双峰型及不规则型的年动态变化。(2)凋落物持水量与浸水时间呈极显著对数函数关系(P0.01),浸水5 min、24 h和48 h时的持水量分别是其最大持水量的48.41%、93.96%和97.70%;逐月凋落物最大持水量变化范围为1.19—3.95 g/g。(3)6种植物全年凋落物拦蓄量为1.33—13.33 t/hm~2,落叶占凋落物拦蓄总量的57.19%—86.12%。综合可知:落叶是凋落物最主要成分并提供最多的径流拦蓄;密度对凋落物持水性有显著影响(P0.01),比表面积和结构特征的差异导致凋落物持水性不同;植物是通过影响枯落物的凋落继而对该植物样地枯落物的水土保持功能产生影响。研究结果旨在为评价该地区不同植物恢复模式的枯落物水土保持功能和维持提供科学依据。

Litter production and its water holding capability in typical plants communities in the hilly region of the Loess Plateau

Litter plays an important role in runoff interception. It is of great significance to investigate the litter production dynamics and water holding capability to understand the primary productivity and its functions in soil and water conservation, several kinds of plants (Robinia psendoacacia, Pinus tabulaeformis, Hippophae rhamnoides, Sophora viciifolia, Artemisia sacrorum and Bothriochloa ischaemum) were selected to monitor the litter production and water holding capability by month for one year in the loess hilly region. The annual volume of litter production, composition and monthly dynamics of different vegetation types were compared including the water holding capacity of litter and impact factors. Results showed that:(1) The total amount of the litter production of six plant types ranged from70.65 to 455.57 g/m², defoliation accounted for 48.17% to 91.09% of the total litter. The amount of litter production per month was 1.86 to 160.21 g/m² which can be divided into unimodal, bimodal or irregular modes of the annual dynamic. (2) There was an extremely significant logarithmic relationship between the water holding capacity of litter and the soaking time (P < 0.01). The water absorption rate of litter reached the maximum in the initial stage of soaking. Maximum water holding capacity of litter organs after being soaked for 72 hours ranged from 1.20 to 4.35 g/g. When the litter organs were being immersed in water for 5 min, 24 h and 48 h, their water holding capacity reached 48.41%, 93.96% and 97.70%. The maximum water holding capacity of the litter by month ranged from 1.19 to 3.95 g/g. (3) The interception of litter fall of six plant species in the whole year ranged from 1.33 to 13.33 t/hm², Defoliation accounted for 57.19% to 86.12% of the interception of the litter in the whole year. In conclusion,we concluded that defoliation accounted for the largest proportion of litter and made the greatest contribution to the interception of litter. Density has a significant effect on the water holding capacity of litter(P < 0.01), the differences in specific surface area and void spaces result in different water holding capacity of litter fall. Vegetation affect the soil and water conservation of litter in the plant samples by affecting its litter production. This study will provide the theoretical basis for evaluating the soil and water conservation function of litter in different vegetation restoration models on the Loess Plateau.