节水型农田防护林侧根生物量增长偏极现象的研究

为了解林带根系适应干旱气候长期进化而形成的生态特性，探明干旱区农田防护林侧根生物量分配结构，采用空间代替时间的方法，按胸径径级和固定样方挖根，调查了乌兰布和沙漠磴口绿洲新疆杨田渠林路式农田防护林带侧根生物量。结果表明：随着胸径的增长，各径级侧根生物量均有增大的趋势，粗、大侧根生物量占侧根81.55%以上，是侧根生物量主体部分，剩余为中、小、细侧根生物量；粗侧根生物量分配比例随着胸径增长而增大，大、中、小、细侧根生物量分配比例则减小。通过调查建立了17个侧根生物量增长模型，经回归模型显著性检验均显著相关。绿洲农田防护林林带5个等级侧根生物量增长呈不均衡偏极现象，随着胸径的增长，趋于粗侧根生物量分配比例单侧偏极增长趋势，这是沙漠绿洲人工林适应干旱环境进化的结果。

Studies on Lateral Root Biomass and Growth Inequality Phenomenon in Oasis Water-saving Shelterbelt

In order to understand the ecological characteristics of the oasis shelterbelt root system formed in adapting drought climate; verify the lateral root biomass distribution structure of the farmland shelterbelt in arid region, this paper measured the lateral root biomass of different soil layers of Populus alba var. pyramidalis shelterbelt of farm-channel-forest-road type in Dengkou oasis of Ulan Buh Desert by the method of space instead of time. The results showed that with the increase of diameter at breast height (DBH), the lateral root biomass of each diameter grade had an increasing trend, the biomass of rough and large lateral roots accounted for over 81.55% of the lateral root biomass, being the main part of the lateral root biomass. The rest parts were the biomass of medium, small and thin lateral roots. The proportion of rough root biomass increased with the increase of DBH, while the biomass of roots of large, middle, small and fine roots decreased. Through survey, 17 lateral root biomass growth models were established. Their significance were all outstanding proofed by regression model test. The growth of lateral root biomass in 5 grades of shelterbelt in oasis farmland were unbalanced and biased. Along with the increased of DBH, the biomass growth of lateral roots tended to be polarity, and this was the result of evolution when the artificial forest adapted to the drought environment.