黄土高原山地坡度对退耕农田生态系统自然植被演替初期的影响

Effects of hillside slopes on plant community succession of re-natural farmland in the Loess Plateau

黄土高原丘陵沟壑区是我国西部干旱半干旱生境下的典型生态脆弱地区,是国家实施退耕还林还草、再造秀美山川工程的重点区域,其中山地坡度作为一个重要的生态因子,探讨其对黄土高原生态恢复的影响具有重要意义。以封育5年的退耕农田为目标,探讨山地坡度对黄土高原受损生态系统恢复和保育的影响,结果表明:1)山地坡度的增加显著降低了阳坡植物群落的物种多样性(P<0.01);而对阴坡植物群落物种多样性没有显著影响(P>0.05)。2)山地坡度对阴坡群落的均匀度指数影响显著(P<0.05);而对阳坡群落的丰富度影响较大,呈现先增加后降低的趋势。3)坡度对阳坡植物群落的生物量影响显著(P<0.05)。分析表明,山地坡度对黄土高原丘陵沟壑区退耕农田植物群落演替初期的自然恢复具有显著影响:在坡度<30°的条件下,植被群落自然恢复效果较好;而对>30°的退耕山地,则需要人工辅助措施的促进,是开展退耕封育的重点区域。

This paper focused on the relationship between hillside slopes and primary stage of plant community succession in the re-natural farmland ecosystem in Loess Plateau. The results showed that the quantities of plant species decreased remarkably along with the hillside slopes exposed to the sunny sides （P〈0.01） ; but this results didn＇t exist in the shady sides. At the same time, the plant diversity indexes were influenced remarkable with the slopes in both sides of the hill （P〈0.05）. The evenness index of the shady side plant communities influenced remarkable with the slopes （P〈0.05）. At last, the total biomasses in each treatments changed remarkable in sunny side plant communities （P〈0.05） . In a word, the hillside slope was an important factor in the reclaimed agricultural ecosystem.