荒漠草原猪毛蒿种群特征与土壤因子的关系
Relationship between Population Characteristics of Artemisia Scopariain and Soil Factors in Desert Steppe

宁夏荒漠草原主要分布在干旱半干旱气候区,约占全区草地总面积的55%,是宁夏生态环境的重要屏障。近年来,随着退耕还林还草、封育禁牧和生态移民等政策的实施,区域生态系统在排除外界人畜干扰后将进行自我恢复,植被覆盖度得到显著提高。但在荒漠草原恢复的前期阶段缺乏科学的管理,对草地生态系统的结构和功能缺乏认识,像猪毛蒿(Artemisiascopariain)这种非优质牧草占据宁夏盐池中部荒漠草原多达1/4的草场,使得荒漠草原的植被结构和质量较差。因此本研究采用摄影定位法,基于不同零模型(完全空间随机模型、泊松聚块模型和嵌套双聚块模型)的点格局分析方法,对荒漠草原灰钙土、风沙土和基岩风化残积土上的猪毛蒿种群分布格局有了初步了解。在此基础上,在宁夏中部荒漠草原区应用随机取样的方法,选取37个典型的猪毛蒿种群样地,通过野外调查和室内试验获得研究区猪毛蒿生长特征和土壤因子特征数据,利用单因素方差分析对不同土壤类型下猪毛蒿分布区土壤因子特征和猪毛蒿生长指标进行了初步统计分析,利用RDA分析了不同土壤类型下猪毛蒿生长特征与土壤因子的关系,综合分析荒漠草原地区猪毛蒿的生长分布规律和土壤影响因子,为合理治理猪毛蒿、改善草场植被结构和质量提供理论依据,主要研究结论如下:(1)在一定的尺度范围内,不同土壤类型下猪毛蒿种群在小尺度上均表现为聚集分布,随着尺度的增加先表现为随机分布后表现为均匀分布。为了进一步揭示聚集分布的特征,采用泊松聚块模型和嵌套双聚块模型分析得出,基岩风化残积土上的猪毛蒿种群分布格局符合泊松聚块模型,即在大聚快中不存在密集的小聚块。风沙土和灰钙土上的猪毛蒿种群分布格局符合嵌套双聚块模型,即在大聚快中存在较高密集的小聚块。(2)宁夏荒漠草原猪毛蒿种群数量特征在不同的土壤类型下具有较大的差异。总体而言,猪毛蒿的高度、盖度、密度、冠幅和生物量在不同土壤类型上均表现为风沙土>灰钙土>基岩风化残积土。猪毛蒿的高度与盖度、冠幅和生物量之间存在显著或极显著的正相关关系。猪毛蒿的密度与盖度之间存在极显著的正相关关系,与冠幅之间存在极显著的负相关关系。(3)不同土壤类型中的有机碳含量、活性有机碳含量、氮磷钾养分、速效养分、pH值、电导率值和水分含量存在较大的差异。土壤有机碳平均含量和电导率平均值在不同土壤类型中均表现为:基岩风化残积土>灰钙土>风沙土。三种土壤类型中有机碳含量均表现出垂直分布特征,且表层(0-5cm)有机碳含量显著高于深层,表现出富集作用。风沙土中的电导率值呈现出先降低后增加的趋势。土壤易氧化有机碳、全氮平均含量在不同土壤类型中均表现为:灰钙土>风沙土>基岩风化残积土。风沙土中的易氧化有机碳含量表现出垂直分布特征,即随着土壤深度的增加土壤易氧化有机碳含量降低。三种土壤类型中土壤全氮含量表现出垂直分布特征,即随着土壤深度的增加土壤全氮的含量降低。土壤水溶性有机碳、速效磷和碱解氮的平均含量在不同土壤类型下均表现为:风沙土>灰钙土>基岩风化残积土。三种土壤类型中的速效磷含量表现出明显的垂直分布特征,即随着土壤深度的增加速效磷含量不断降低。风沙土中碱解氮的含量表现出垂直分布特征,即随着土壤深度的增加土壤碱解氮含量不断降低。土壤全磷、水分平均含量在不同土壤类型中均表现为:灰钙土>基岩风化残积土>风沙土。不同土壤类型中的土壤全磷、pH值和水分含量在不同土层之间未表现出显著性差异。不同土壤类型的土壤pH值大小随着土壤深度的增加而增加。土壤因子之间的相关性在不同土壤类型中具有差异且较为复杂。(4)猪毛蒿种群特征与土壤因子之间的相关关系在不同土壤类型下表现不同。总体而言,土壤水分是促进猪毛蒿生长的重要关键因子,土壤硬度是抑制猪毛蒿生长的重要关键因子。其余土壤因子对猪毛蒿数量特征的影响在不同土壤类型中具有差异。

Ningxia desert grassland is mainly distributed in arid and semi-arid climate area,accounting for about 55%of the total grassland area,which is an important barrier to the ecological environment of Ningxia.In recent years,with the implementation of policies such as returning farmland to forestry and grassland,closing off grazing and ecological migration,the regional ecosystem will recover itself after eliminating the disturbance of human and livestock,and the vegetation coverage has been significantly improved.However,in the early stage of the restoration of deserts and grasslands,there is a lack of scientific management and a lack of understanding of the structure and function of grassland ecosystems,such as Artemisia scopariain which is a non high quality forage,occupies as many as 1/4 of grassland in the middle part of Ningxia’s Yanchi desert,making the vegetation structure and quality of desert steppe poor.Therefore,based on the method of point location in different zero models(complete spatial random model,Poisson cluster model and nested double-cluster model),this study has a preliminary understanding of the distribution pattern of the initial life history of A.scoparia populations in desert grassland,calcareous soil,aeolian sandy soil and weathering bedrock.On the basis of this method,37 typical plots of A.scoparia communities were selected by random sampling method in the central desert steppe of Ningxia.The growth characteristics and soil factors data of A.scoparia were obtained through field investigation and laboratory tests.Soil factors and distribution indices of A.scoparia were studied by one-way ANOVA.Statistical analysis,and analysis of the relationship between soil physical and chemical factors.The relationship between growth characteristics and soil factors of A.scoparia under different soil conditions was analyzed by RDA.The growth distribution law and soil influence factors of A.scoparia in desert steppe were comprehensively analyzed,providing theoretical basis for reasonable management of A.scoparia and improving vegetation structure and quality.The main results are as follows:(1)Within a certain scale,the population of A.scoparia on different soil types showed aggregated distribution on a small scale.In order to further reveal the characteristics of aggregation distribution,Poisson distribution model and nested double lump model were used to analyze the distribution pattern of A.scoparia population on the weathering bedrock soil.The distribution pattern of A.scoparia population on aeolian sandy soil and sierozem soil conforms to the nested double lump model,that is,there are relatively dense small aggregates in the fast growing process.(2)The population characteristics of A.scoparia n in Ningxia desert grassland are quite different under different soil types.In general the height coverage,density,crown and biomass of A.scoparia are all aeolian sandy soil>sierozem soil>weathering bedrock soil in different soil types.There is a significant or very significant positive correlation between height and coverage,crown and biomass of A.scoparia There was a significant positive correlation between density and coverage of A.scoparia and a significant negative correlation between crown density and coverage.(3)The contents of organic carbon,active organic carbon,nitrogen,phosphorus,potassium,available nutrients,pH value,conductivity and water content in different soil types were different.The average content of soil organic carbon and conductivity in different soil types are as follows:weathering bedrock>sierozem soil>aeolian sandy soil.The content of organic carbon in the three soil types showed vertical distribution characteristics,and the content of organic carbon in the surface layer(0-5cm)was significantly higher than that in the deep layer,showing enrichment.The electrical conductivity of aeolian sandy soil shows a trend of decreasing first and then increasing.The average content of soil easily oxidized organic carbon and total nitrogen in different soil types is sierozem soil>aeolian sandy soil>weathering bedrock.The content of soil total nitrogen in three soil types showed a vertical distribution,that is,with the increase of soil depth,the average content of soil total nitrogen decreased.The average contents of water-soluble organic carbon,available phosphorus and alkali-hydrolyzed nitrogen in soils of different soil types were as follows:aeolian sandy soil>sierozem soil>weathering bedrock.Average content of available phosphorus in three soil types showed obvious vertical distribution characteristics,that is,the content of available phosphorus decreased with the increase of soil depth.The content of alkali-hydrolyzed nitrogen in aeolian sandy soil shows a vertical distribution,that is,with the increase of soil depth,the content of soil alkali-hydrolyzed nitrogen decreases continuously.The average contents of total phosphorus and water in soils of different soil types are as follows:sierozem soil>weathering bedrock>aeolian sandy soil.There was no significant difference in total phosphorus,pH value and average moisture content among different soil types.The soil pH value of different soil types increased with the increase of soil depth.The correlation between soil factors is different and complex in different soil types.(4)The correlation between population characteristics and soil factors of A.scoparia is different under different soil types.In general,soil moisture is an important factor to promote Artemisia scopariain growth.Soil hardness is an important factor to inhibit the growth of A.scoparia.The effects of other soil factors on the quantitative characteristics of A.scoparia are different in different soil types.

种群分布格局; 零模型; 种群数量特征; 土壤因子;

population distribution pattern; zero model; quantitative characteristics of population; soil factors;

李学斌; 陈林;

S812

21656531K