贺兰山天然油松林凋落物储量与分解过程的研究

油松是贺兰山天然林区的重要建群种,生长已有近百年历史,已经形成了深厚的凋落物层,对促进森林土壤养分积累与森林的自然更新起着重要的作用。通过标准样地的凋落物调查,结果表明：不同龄级的油松凋落物厚度与储量不同,72龄级的储量最高,为46.09 t/hm2,其次是63龄级,为45.32 t/hm2,45龄级的储量较低,为22.41 t/hm2;不同立地条件下凋落物的储量不同,坡下部储量最大,为29.64 t/hm2,其次是坡中部和坡上部,分别为21.38 t/hm2和16.31 t/hm2。表明在贺兰山的生态条件下,油松林凋落物的储量受生长年限和立地条件的影响,分解过程也出现了较为明显的异质性,其趋势是大龄级的分解速率远高于中龄级,坡下部大于坡中部和坡上部,成为目前林区土壤有机质积累的重要来源。

Reserves and Decomposition Process of Litter in Natural Pinus tabulaeformis Forest in the Helan Mountain

As an important constructive arbor species in Helan Mountain Natural Forest Region,growing nearly a century,Pinus tabulaeformis has formed a deep litter layer,which plays an important role in promoting soil nutrient accumulation and natural regeneration.The results of the litter survey on standard plots show that： reserves and thickness of Pinus tabulaeformis litter change among age classes,the reserves of up to 72 age class,as 46.09t/hm2,followed by 63 age classes for 45.32 t/hm2,the lower reserves of 45 age class for 22.41 t/hm2.And litter reserves vary under different site conditions： the lower slopes up to 29.64 t/hm2,followed by the central and the upper slope,respectively,21.38 t/hm2 and 16.31 t/hm2.It shows that Pinus tabulaeformis litter reserves in the Helan Mountain are influenced by the growing years and site conditions.Also,there is an apparent heterogeneity in decomposition process.The tendency shows that decomposition rate of litter at older age class is much higher than the younger age class;the lower slope is greater than the central and the upper slope.The litter is an important part of soil organic matter accumulation in current forest region,which provides important scientific basis for the research of global climate change and biodiversity.