小美旱杨防护林对林带下土壤盐分均衡的影响

Salt balance with a Populus simonii ×(Populus pyramidalis + Salix matsudana) 'Poplaris' shelterbelt

通过测定小美旱杨Populus simonii×(Populus pyramidalis+Salix matsudana)‘Poparis’标准木耗水量、树体不同部位储盐质量浓度和标准木生物量,推算12年生小美旱杨全生长期耗水量中总盐分质量浓度以及小美旱杨采伐时可带离的盐分,分析小美旱杨水分代谢过程对林下土壤-潜水系统盐分均衡的影响。结果表明,小美旱杨耗水中所含盐分离子的92%左右进入林下土壤-潜水系统中,其余随采伐被带离,但小美旱杨农田防护林带蒸腾造成的林下积盐在灌区积盐中仅占很小的比例。小美旱杨对营养元素的选择性吸收和对有害离子的拒吸作用,对林下土壤的可溶盐离子组分比例有一定的影响,主要表现是使进入土壤-潜水系统的Ca2+组分比例减小。

To calculate a） the total salt in water consumed during the entire growth period of 12-year-old Populus simonii × （Populus pyramidalis ＋ Salix matsudana） ＇Poplaris＇ and b） the total extractable salt when harvested and to analyze this cuhivar＇s water metabolism influence on salt balance in the soil-groundwater system under the tree, water consumption and the salt ion concentration in different plant parts as well as biomass of sample tree were measured. Results indicated that of the salt in the water that ＇ Poplaris＇ absorbed about 92% had entered in the soil- groundwater system under the tree; the rest of the salt remained in the tree when harvested. Also, the composition ratio of Ca^2＋ to soluble salts in the s0il-ground water system decreased. However, salt accumulation in soils under ＇Poplaris＇ shelterbehs was only a small proportion of salt accumulated in irrigated areas. Thus, selective absorption of nutrients with P . simonii × （ P . pyramidalis ＋ S . matsudana ） ＇ Poplaris＇ and its resistance to harmful ions influenced the soluble salt ion component in the soil-groundwater system under this shelterbelt. [Ch, 9 tab. 15 ref. ]