河西走廊东部2019—2022年空气孢粉组合特征及影响因素

Characteristics and Influencing Factors of Airborne Pollen Assemblage in Eastern Hexi Corridor from 2019 to 2022

对空气孢粉散播和沉积过程的研究有助于理解现代植被组成及其与气候变化的关系,但迄今为止在干旱区开展的空气孢粉研究工作仍十分有限。利用自主设计的孢粉收集装置,在河西走廊东部祁连山北侧的古浪地区进行了连续3年(2019年7月至2022年6月)以月为时间尺度的观测研究,分析了草本植物、木本植物花期和非花期的孢粉百分比组成特征,探究了主要花粉的代表性;同时,讨论了孢粉浓度变化基本特征及其与典型气象要素(温度、降水、风速和风向)之间的关系。研究结果表明:①研究点空气孢粉组合主要以草本类型为主,高值出现在7~10月(93.7%),低值出现在4~6月(62.9%),相应的木本植物花粉高值出现在4~6月(37.1%),低值出现在7~10月(6.3%)。草本植物和木本植物孢粉浓度与各自花期有很好的对应关系:草本植物花期和高浓度出现在7~10月,木本植物则主要出现在4~6月,草本植物浓度对总浓度影响最大。②孢粉组合与当地植被有很好的对应关系,杨属(Populus)和柏科(Cupressaceae)花粉能较好地反映当地植被特征,禾本科(Poaceae)花粉具低代表性,蒿属(Artemisia)、苋科(Amaranthaceae)、桦木属(Betula)以及云杉属(Picea)花粉具有超代表性。③由于木本植物主要分布在东南方,其花期(4~6月)的风向会影响木本植物花粉含量,非花期(11月至次年3月)风速在1.48~1.75 m/s时最有利于花粉的传播,风速过小时风的携带能力差,风速过大,对孢粉的飘散和收集产生负面影响;降水与孢粉产量存在正相关关系,即花期时降水越多孢粉浓度越高。上述研究结果可以为解释河西走廊东部不同时间尺度的孢粉记录与气候环境变化的关系,以及河西走廊地区生态环境保护提供重要的孢粉生态学方面的参考依据。

Studies of aerospore dispersal and deposition processes can contribute to the understanding of modern vegetation composition and its relationship with climate change.However,studies on aerospore dispersal in arid regions are still very limited.Using a self-designed spore pollen collection device,a study was conducted in the Gulang area located in the northern side of the Qilian Mountains in the eastern part of the Hexi Corridor for three consecutive years(July 2019 to June 2022)on a monthly time scale.The aims were to analyze the characteristics of spore pollen percentage composition of herbaceous and woody plants during the flowering and non-flowering periods,and to explore the representativeness of major pollens.The basic characteristics of spore pollen concentration changes and their relationship with typical.At the same time,the basic characteristics of sporulation concentration and its relationship with typical meteorological elements(temperature,precipitation,wind speed and wind direction)were examined.Four main results were obtained.First,the air pollen assemblage at the study site was mainly herbaceous,with high values occurring from July to October(93.7%)and low values from April to June(62.9%).The corresponding high values of woody plant pollen occurred from April to June(37.1%)and low values from July to October(6.3%).The pollen concentrations of herbaceous and woody plants corresponded well with their respective flowering periods.The flowering period and high concentrations of herbaceous plants occurred from July to October,while woody plants mainly occurred from April to June.The herbaceous plant concentration had the greatest influence on the total concentration.Second,the spore pollen combinations corresponded well with the local vegetation,poplar(Populus),and cypress(Cupressaceae)pollen.The pollen of Populus and Cupressaceae can better reflect the characteristics of local vegetation,while the pollen of Poaceae has low representativeness and the pollen of Artemisia,Amaranthaceae,Betula and Picea has super representativeness.Third,since woody plants are mainly distributed in the southeast,the wind direction during the flowering period from April to June affects the pollen content of woody plants,and the wind speed during the non-flowering period(November to March)is in the interval of 1.48~1.75 m/s which is most favorable for pollen dispersal.Too little wind speed has poor wind carrying capacity,and too much wind speed negatively affects the dispersal and collection of spore pollen.A positive correlation between precipitation and pollen production was evident.In other words,the higher the precipitation at the time of flowering,the higher the pollen concentration.The above findings can provide an important reference basis for interpreting the use of pollen to study the relationship between spore pollen records and climate and environmental changes at different time scales in the Hexi Corridor,as well as for the ecological protection in the Hexi Corridor region in terms of spore pollen ecology.