京津风沙源浑善达克沙地治理区退耕还林地的植被变化

Research on the Vegetation Changing of Artifical Forests Converted from Farmland in Otindag Sandy Land Sub-regions of Beijing-Tianjin Sandstorm-control Area

本文选择京津风沙源区浑善达克沙地治理区大兴安岭南部亚区2004年退耕的榆树-小叶锦鸡儿林及山杏林和浑善达克沙地亚区2002年退耕的榆树-小叶锦鸡儿、小叶锦鸡儿退耕林及榆树疏林沙地设置监测样地,对植被盖度、生物量、物种多样性等进行了连续4年的监测调查,结果表明:在大兴安岭南部亚区,退耕后4～7年,榆树-小叶锦鸡儿林总盖度和总生物量均极显著高于对照的蒿类草地(p<0.01),且呈逐年上升趋势;山杏人工林总盖度在前期低于天然胡枝子灌丛,但后期优于对照;山杏人工林总生物量逐年增加,并在2010年和2011年显著大于胡枝子灌丛(p<0.05)。榆树-小叶锦鸡儿和山杏人工林及其对照样地的Shannon-Wiener指数均呈波状变化,差异不显著。在浑善达克沙地亚区,退耕后6～9年,榆树-小叶锦鸡儿林地的总盖度显著高于小叶锦鸡儿和榆树疏林沙地(p<0.05),但榆树疏林沙地在年际间的变化更稳定,榆树疏林沙地总生物量在2008—2010年间均高于榆树-小叶锦鸡儿和小叶锦鸡儿人工林,但人工林逐年增加的趋势更明显。小叶锦鸡儿人工林和榆树疏林沙地的Shannon-Wiener指数明显高于榆树-小叶锦鸡儿林地,并且都呈波状增加趋势,而榆树-小叶锦鸡儿林地的Shannon-Wiener指数表现出与降雨变化同样的趋势。

Two kinds of typical artifical forests, converted from farmland in 2004, of the Ulmus pumila-- Caragana microphylla and Prunus sibirica, located in southern Daxinganling sub-region, were selected for model, other two kinds of typical artificial forests, converted from farmland in 2002, of the Ulmus pumila--Caragana microphylla and Caragana microphylla, located at Otindag Sandy Land sub-region were also selected to investigate the effects of the converting engineering on the vegetation. Both the re- gions are part of Beijing-Tianjin sandstorm-control area. The vegetation coverage, biomass and species di- versity had been monitored for four consecutive years. The results indicated that： In southern Daxinganling sub-region, the total vegetation coverage and total biomass of the Ulmus pumila--Caragana microphyl- la, after converted from farmland for four to seven years, wer,e significantly higher than that of the Arte- misia grassland, and the former showed an increasing trend by year but the later a wave-like trend with no significant difference within the four years. The artificial Prunus armeniaca coverage was lower than the natural lespedeza Shrub in the topphase, but it was superior to the control in later. The total biomass of Ca- ragana microphylla artificial forests increased year by year and significantly greater than that of Lespedeza bicolor scrublands in 2010 and 2011. The total vegetation coverage of Caragana microphylla artificial for- ests was very significantly higher than that of Lespedeza bicoiior in 2008, and the vegetation coverage of Lespedeza bicolor shrubland reduced significantly in the year o：[ 2009 and 2010. The Shannon-Wiener index of the Ulmus pumila-Caragana microphylla, Prunus armeniaca and its counterpart plots showed a trend of wave-like change, and no obvious difference was found between them. In Otindag Sandy Land sub- region, after converted from farmland for six to nine years, the total vegetation coverage of the Ulmus pumila-Caragana microphylla was higher than that of the Caragana microphylla and open sandy land with sparse Ulmus pumila, and the Ulmus pumila-Caragana microphylla forest had a more stable annu- al change. The total biomass of the open sandy land with sparse Ulmus pumila was higher than that of the artificial forests of Caragana microphylla and Ulmus pumila- Caragana microphylla during 2008-- 2010. The biomass of the artificial forests had a more clearer increasing trend than that of natural forest. The Shannon-Wiener index of the Caragana microphylla and Ulmus pumila forests were significantly higher than that of the Ulmus pumila-Caragana microphylla. This index showed a close relation to rainfall.