毛竹笋用林覆盖对地温及出笋时间的影响分析

Impacts of Land Cover on Soil Temperature and Shooting Time of Moso Forest

毛竹笋用林经连续5 a覆盖后,对竹鞭的长度生长未见影响;但对1～2 a生的新鞭鞭径产生影响,使鞭径变小,与3～4 a生鞭径相比,下降29.7%;对竹鞭上的活芽分布产生影响,活芽基本分布在1～2 a生的竹鞭上,3 a生以上竹鞭上的活芽已很少。而在覆盖2 a的情况下,对竹鞭生长无影响。覆盖厚度在25 cm以上时,在气候最冷时平均地温基本保持在17℃左右,能达到理想的增温效果。覆盖时间和浇水量也影响土壤湿度的提高和持续性,覆盖时间过早(气温在10℃以上时),反而促使竹鞭继续生长,造成竹鞭上的芽孕笋推迟。在第一层覆盖物上浇水过多,造成稻草、竹叶等覆盖物加速发酵,温度虽然在短期内快速上升,但在较短时间后又迅速下降,起不到持续增温的效果。

The growth of rhizome length showed no difference after a successive covering of forest land for 5 years. Nevertheless, the diameter of 1 - 2 years old rhizomes became smaller in comparison with that of 3 -4 years old ones, reducing 29.7%. The distribution of active buds on the rhizomes were influenced so that they mainly restricted on 1 -2 years old rhizomes and rarely lasted on rhizomes of more that 3 years old. In the circumstance of land covering for only 2 years, there found no significant changes in the growth of rhizomes. The average ground temperature was kept at 17 % in the coldest winter by land covering of thicker than 25 cm, achieving the desired effects to increase temperature. The time to start land-cover and watering dosage also had significant influences. If the land were covered too early （temperature at 10 ℃ ）, the rhizomes would continue to grow and shoots would delay to sprout. If too much water was irrigated on the surface of the cover, covering materials such as straw and bamboo leaves would be accelerated to ferment and result in a fast increase of temperature in a short time but then it dropped rapidly, there would not obtain the effects of sustained warming.