桂西北光皮桦人工林水源涵养功能

为了研究广西西北部不同林龄光皮桦人工林的水源涵养功能,选择具有代表性的11,16年生光皮桦人工林、16年生杉木林,从林冠层、枯枝落叶层和土壤层3个层次及综合性的水源涵养能力进行了定量分析。结果表明:(1)11,16年生光皮桦人工林林冠层、灌木层、草本层持水量范围分别为12.54～21.06,2.15～3.05,1.27～1.52 t/hm~2,凋落物总储量为4.54～7.42 t/hm~2,最大持水量为12.55～16.00 t/hm~2,16年生均显著大于11年生(P0.05),凋落物吸水速率与浸水时间存在良好的线性关系(R~20.86,P0.05)。(2)土壤的孔隙状况表现为16年生光皮桦林11年生光皮桦林,均大于对照的16年生杉木林,0—20 cm显著大于20—40,40—80 cm土层。(3)11年生光皮桦土壤最大持水量、毛管持水量、非毛管持水量的变化范围分别为28.97%～60.55%,25.35%～47.21%,3.71%～13.34%,16年生的为29.06%～63.45%,25.63%～48.70%,3.34%～14.75%,均随着土层的加深而减少;11,16年生光皮桦林0—80 cm土壤层自然含水量范围分别为27.46～30.16,28.12～30.22 g/cm~3;总蓄水量分别为3 813.4,3 732.2 t/hm~2,均大于16年生杉木林(3 659.2 t/hm~2)。总体上,林龄较大的光皮桦人工林表现出较强的水源涵养功能,且优于同林龄的杉木人工林。研究结果可为该地区光皮桦人工林的经营管理提供科学依据。

Water Conservation Function of Betula luminifera Plantation in Northwest Guangxi

To evaluate the water conservation function of Betula luminifera plantations with different ages in Northwestern Guangxi, the representative 11 and 16-year-old B. luminifera plantations and 16-year-old Cunninghamia lanceolata were selected as main research object, and the water conservation capacities in three layers including the forest canopy, litter layer and the soil layer, as well as the comprehensive water conservation capacity were analyzed quantitatively. The results showed that:(1) The water holding capacity of the canopy, shrub layer and herb layer of the 11 and 16 year-old B. Luminifera plantations ranged from 12.54 to 21.06 t/hm², 2.15 to 3.05 t/hm² and 1.27 to 1.52 t/hm². The total litter reserve was 4.54~7.42 t/hm², and the maximum water holding capacity was 12.55~16.00 t/hm², which of 16-year-old plantation was significantly higher than that of 11-year-old plantation (P<0.05). There was a good linear relationship between the water absorption rate and water soaking time (R²>0.86, P<0.05). (2) The pore condition of soil followed the order of 16-year-old B. Luminifera forest > 11-year-old B. Luminifera forest > 16-years-old C. lanceolata forest, and the pore condition of soil was significantly higher in 0-20 cm soil layer than that in 20-40 cm and 40-80 cm soil layer. (3) The variation range of maximum water holding capacity, capillary water holding capacity and non-capillary water holding capacity of the 11-year-old B. Luminifera soil was 28.97%~60.55%, 25.35%~47.21% and 3.71%~13.34%, and the range was 26.06%~63.45%, 25.63%~48.70% and 3.34%~14.75% in 16-years-old B. Luminifera plantation, respectively, and all the values decreased with the increasing of the soil layer. The natural water content ranges of 0-80 cm soil layer in 11 and 16 year-old forest were 27.46~30.16 g/cm³ and 28.12~30.22 g/cm³, respectively, and total water storage capacities were 3 813.4 t/hm² and 3 732.2 t/hm², respectively, and all the values were greater than those in 16-year-old C. lanceolata forest (3 659.2 t/hm²). On the whole, the older B. luminifera plantation had stronger water conservation function, and it was superior to the same age C. lanceolata plantation. The results could provide scientific basis for the management of B. luminifera plantation in this area.