摘要:农田防护林能够防风固沙，但同时也会和农作物竞争水分，引起防护林体系水资源利用紧张。运用氧同位素焦点法与SIAR模型，量化分析新疆莫索湾地区不同生长季棉花与杨树防护林的主要水分来源区域，探究杨树对棉花水分利用的影响。结果表明：棉花在膜下滴灌方式下主要吸收表层土壤水，蕾期主要利用0-20 cm的土壤水，花铃期主要利用20-40 cm土壤水；而杨树在漫灌前主要利用深层40 cm以下土壤水，在灌溉后水分来源虽有向上迁移倾向，但仍大约有60%的水分源于土壤40 cm以下。δD同位素示踪发现杨树根系垂向可生长到土层200-400 cm范围，水平延伸至棉田内5-8 m，在5 m内棉花必定面临着杨树的水分与养分竞争。通过两种同位素方法分析出杨树和农作物的主要水分来源与潜在竞争区域，对防护林采取合理的管理措施及绿洲环境生态平衡提供指导。



Abstract:Shelterbelt construction is considered an ecological solution to prevent sand erosion in the Xinjiang oasis. Shelterbelts, constructed from poplar (Populus), compete with crops for water, and thereby cause economic loss for farmers. We used direct inference of a stable oxygen isotope (δ¹⁸O) and the SIAR model to analyse the most common water uptake depth water uptake depth of cotton (Gossypium) at different growth stages under mulched drip irrigation, and poplar's water utilization strategy before and after irrigation. Results showed cotton primarily relies on soil water from a depth of 0-40 cm, taking up water from the 0-20 cm layer in bud stage, and from the 20-40 cm layer in boll stage. However, poplar mainly utilized soil water from below 40 cm, and the depth of soil water used by poplar gradually decreased after irrigation. We identified poplar roots in soil at 200-400 cm deep, extending 5-8 m into the cotton field. This reflected that poplar must compete for water and nutrition within this 5 m, especially the inner 3 m. This research increases our understanding of potential areas of water competition between poplar and crops and suggests reasonable management for shelter forest to maintain oasis ecological balance.





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