摘要
通过测定柴达木盆地诺木洪地区5种荒漠植物木质部水分及其不同潜在水源的稳定性氢氧同位素值,利用多源线性混合模型(Iso Source)分析了不同水分来源对荒漠植物的贡献率。结果表明:当地大气降水线为y=7.019x-3.217(R2=0.970,P<0.001),很好地反映了该地区气温高、湿度低的气候特点。诺木洪地区5种优势植物整个生长季使用土壤水比例最大,其次为地下水。驼绒藜使用10—50 cm土壤层水分,白刺、柽柳利用50—70 cm土壤层水分比例最大,这两种植物存在对50—70 cm土壤层水分的竞争;麻黄和沙拐枣对各层土壤水分的利用比例较为平均,因此存在对各层土壤水的竞争现象。4种灌木白刺、麻黄、柽柳、沙拐枣在生长季对不同水源的利用存在转换,但生长季末期都对地下水利用比例逐渐增大。地下水是荒漠植被的重要水源,因此维持干旱半干旱地区地下水水位对荒漠植物的生长具有重要意义。植物根系贯穿于整个土壤剖面,但是根系分布与其吸水位置不完全对应,过去利用根系结构进行植物水分来源判断的方法存在一定的局限性。
Water is one of the essential substances to maintain the plant system.Water resource selection is an important selection process in the botany cycle.Despite precipitation is the ultimate water source for all plants,factors like evaporation,difference in altitude,geological aquifer features,differences in the soil water characteristics may all influence both values of stable hydrogen and oxygen isotope（ δD,δ18O）.Where the plant extracts water is supposed to be revealed by comparing the water δ18O、δD values from stem xylems with that from the available water sources.Qaidam Basin is located in the northeast of Tibetan Plateau with its typical desert ecosystem being significantly sensitive to global change.Nevertheless,there is no information found on how its plant system distributes their water exploration among the available water sources in that area.How the river water and precipitation influence the plant water sources is unknown.The objective of this study is to determine the proportions of different water sources drawn by selected dominant plant species,examine the consistence of this proportion for different plant species during the growth season,investigate the watercompetition conditions among the selected dominant species.Five local dominant plant species（ Ceratoides latens,Nitraria tangutorum,Ephedra sinica,Tamarix ramosissima,Calligonum mongolicum） were selected to test the stem water δ18O andδD using Picarro L-2130 i and Finnegan MAT-253.δ18O and δD was also tested for different available water resources including groundwater,river water,soil water（ profiled as 0—10 cm,10—30 cm,30—50 cm,50—70 cm,70—90 cm）and effective precipitation at same time,as sampled every 15 days during June to September in 2010 in Nuomuhong Area.Meanwhile Decagon＇ s Em50 ／ Em50 R was used to measure soil water content.The Multi-source mixed linear model（ Iso Source） was used to analyze the contribution of different water sources to these desert plants.The local meteoric water line（ LMWL） equation was y = 7.019x-3.217（ R2= 0.970,P 0.001）,which indicated the warm and dry climate features of the study area.The result of δ18O and δD analysis showed that the selected plant species mainly used soil water in the whole growth season.The groundwater was the second major water sources.Ceratoides latens mostly used soil water in10—50 cm.Nitraria tangutorum and Tamarix ramosissima absorbed most soil water from 50 to 70 cm.Soil water competition existed in 50—70 cm between these two species.Ephedra sinica and Calligonum mongolicum used soil water from each layer more evenly.So their water competition exists in the whole profile.Nitraria tangutorum,Ephedra sinica,Tamarix ramosissima and Calligonum mongolicum changed the absorbing proportion of different water sources during growth season.Groundwater utilization is increased gradually in the test season as the plant grows,which indicated that groundwater is an important water source to the desert vegetation.Thus maintaining the groundwater tables in arid and semiarid area is important for desert plant system.For water scarce region,desert shrub root phenotype or spatial structure is an important aspect for root functioning.Mostly plant root system distributed throughout the whole soil profile.It does not always coincide with the water abstracting profile.So the way of judging the plant water sources only based on plant root profile has its limitation.
出处
《生态学报》
CAS
CSCD
北大核心
2014年第21期6277-6286,共10页
Acta Ecologica Sinica
基金
国家自然科学基金项目(40971118)
河北师范大学硕士研究生科研基金项目(201202021)
河北省自然地理学省级重点学科资助项目
关键词
柴达木盆地
诺木洪
荒漠植物
水分来源
氢氧同位素
Qaidam Basin Nuomuhong area desert plants water sources stable hydrogen and oxygen isotope
