内蒙古砒砂岩区沙棘细根生长特征对平茬的响应

针对目前内蒙古砒砂岩区生态功能退化、水土流失严重等问题，以该区已进入衰退期的沙棘(Hippophae rhamnoides)人工林为研究对象，对平茬（留茬10 cm）与未平茬（CK）条件下沙棘细根根长密度、生长速率、死亡速率和生死之比等指标进行分析。结果表明：①平茬组沙棘细根量在垂直空间上比CK组有所增加。CK组沙棘细根主要集中在浅土层；而平茬组细根在深土层的分布量明显增加，且46—100 cm土层的分布量是CK组的2倍以上。整体上，平茬后沙棘细根各项生长指标均优于对照组。②沙棘细根根长密度和生长速率在4—10月份均呈“单峰型”变化，在7—8月份增长达峰值；细根死亡速率表现为持续增长趋势，生死之比则与死亡速率规律相反。总之，平茬有利于改善沙棘植株生长状况，间接反映出平茬措施对沙棘更新复壮是有利的。研究结果可为地区沙棘人工林更新复壮及地区生态恢复提供科学依据。

Response of the Root Characteristics of Hippophae rhamnoides to Stumping in Sandstone Area of Inner Mongolia

Aiming at the degradation of ecological function and serious soil erosion in the sandstone area of Inner Mongolia, this paper took Hippophae rhamnoides plantation as the research object, and analyzed the indexes such as root length density(RLD), growth rate(RLDgr), death rate(RLDdr) and the ratio of growth to death (Rgd)of the fine root of Hippophae rhamnoides under the conditions of the stumping group (10 cm) and non-stumping group (CK). The results showed that: ① The fine root amount of the stumping group increased in vertical space compared with CK. The fine roots of Hippophae rhamnoides in the CK were concentrated in the shallow soil layer, but the distribution of the fine roots of the stumping group in the deep soil layer increased significantly, and the distribution of the soil layer between 46 and 100 cm was more than twice that of the CK. On the whole, the growth index of the fine root of Hippophae rhamnoides after the stumping was better than the CK. ② From April to October, the RLD and RLDgr of the fine roots of Hippophae rhamnoides were a single-peak dynamic change, and reached the peak in July to August. The RLDdr of fine roots showed a trend of continuous increase, while the Rgd was contrary to the law of RLDdr. In a word, flat stubble was beneficial to improve the growth of Hippophae rhamnoides, which indirectly reflected that flat stubble was beneficial to renew and rejuvenate Hippophae rhamnoides. The results could provide scientific basis for the regeneration and rejuvenation of Hippophae rhamnoides plantations and regional ecological restoration.