草原内陆河流域梯级生态带蒸散发及影响因子研究

Evapotranspiration and Its Influencing Factors of Cascade Ecological Zones in Inland River Basin of Grassland

蒸散发是全球水-碳-能量耦合循环的纽带,是量化水文循环的关键过程。然而,由于蒸散发的时空变化复杂、影响因素众多且实地观测有限,导致针对不同景观群落蒸散发研究存在较多不确定性。本文基于FAO PenmanMonteith模型估算了2021年和2022年草原内陆河流域典型梯级生态带上4种代表性景观群落的蒸散发,探讨了生态带蒸散发动态变化及其主要影响因子。结果表明,生态带蒸散发变化年内呈季节性,干湿年间差异显著。随高程的降低,景观由荒漠沙丘、山坡草地逐渐向河谷湿地、河流漫滩转变,伴随着蒸散发由减到增的变化特征,具体为:河谷湿地苔草群落(HG)>河流漫滩芨芨草群落(HM)>山坡草地针茅群落(SD)>荒漠沙丘灌木群落(SQ)。HM、SD、SQ群落蒸散发的主要影响因子为降水,其次为辐射和气温;HG群落受地下水补给,主要影响因子为土壤水分,其次是辐射和气温。

Evapotranspiration is not only the link of water-carbon-energy coupling cycle,but also the key process of quantifying hydrological cycle.However,research of evapotranspiration in different land-scape communities remained uncertain due to complicated temporal and spatial variation,numerous influ-encing factors,and limited field observations.This study focused on four landscape communities on cas-cade ecological zones in an inland river basin of grassland.The dynamic changes and influencing factors of evapotranspiration in 2021 and 2022 were analyzed based on the FAO Penman-Monteith model.The results showed that annual variation of evapotranspiration had obvious seasonal characteristics,and signifi-cant differences observed between dry and wet years.With the decrease of elevation,the landscape commu-nities gradually changed from desert dune or hillside grassland to valley wetland or river floodplain,accom-panied with the increase of evapotranspiration.Specifically,the evapotranspiration of the Carex community in valley wetland(HG)was the largest,followed by the Achnatherum splendens community in river flood-plain(HM),then the Stipa community of hillside grassland(SD),and finally the shrub community in des-ert dune(SQ)was the smallest.The evapotranspiration on HM,SD and SQ communities were mainly influenced by precipitation,whereas radiation and air temperature were in the second.Because of the recharging from groundwater,evapotranspiration of HG was influenced primarily by soil moisture,sec-ondly by radiation and temperature.