| The succession of biodiversity is an important component of global ecosystem change. The influence of alien species invasion on biodiversity has become one of popular issues of global change field. Interaction between exotic invasive plant and soil animals community is an important aspect to understand plant invasibility and susceptibility of receptive communities, as a result, studies on effects of plant invasion on soil animals community and physico-chemical properties are becoming increasingly important to explore the effects of plant invasion on ecosystem and the underground soil biota related invasion mechanism.A perennial goldenrod weed Solidago canadensis L. is perennial rhizomatic plant native to North America; was intentionally introduced as an ornamental plant to Shanghai in 1935 in China, then it was rapidly spreading in China and now posed a serious threat to native ecosystem structure and function. S. canadensis seeds unintentionally spread from garden to natural environments by wind or other dispersal mechanisms, and became detrimental weeds in Eastern China, including Zhejiang Province. It will form a single dominant species in the invasion process gradually because of its strong reproductive and survival abilities. In particular, its surrounding neighboring plants are unable growth, and destroy the biodiversity and soil utility, therefore, pose significant threats to native ecosystems and regional economies. The former research about S. canadensis mainly focused on biological characteristics, spread model, perniciousness and quarantine, allelopathic effects, soil microecology, et al. Little was known about the effects of S. canadensis invasion on soil physico-chemical and soil animal community relatively. Therefore, the invasion mechanism of S. canadensis were not completely understood.In this paper, we reported soil animal community diversity, as well as soil physico-chemical properties for three sampling area in Jinhua, Zhejiang province of Eastern China where S. canadensis had invaded native plant communities. The objectives of the present study were to evaluate how S. canadensis invasion affects plant rhizosphere physico-chemical and soil animals'parameters and determine if these parameters can serve as indicators of S. canadensis invasion density. The main results are as follows:(1) Influence on composition and individual of soil animal in different S. canadensis invaded areasSoil samples were collected at three depths (0—5 cm,5—10 cm,10—15 cm) over four seasons in different S. canadensis invaded areas. A total of 9900 individual soil animals were collected belonging to 14 orders,11 classes and 3 phyla. The common dominant groups were Collembola and Acarina in three invaded areas. The individuals and the number of soil animal groups were obviously different among the sampling areas. The sequence of group number and individual was newly invaded areas (Ⅰ)>moderately invaded areas (Ⅱ)>heavily invaded areas (Ⅲ). Statistical analysis was performed with the SPSS 18.0 program package. The results showed the individual of Collembola were significantly different between the different S. canadensis invaded areas (p<0.05), but the individual of Acarina were not significantly different by one way analysis of variance (p>0.05).(2) The diversity change of soil animal in different S. canadensis invaded areasSeveral of diversity indices were used to analyze the soil animal community structure, and displayed different result. The sequence of the diversity index and evenness index was newly invaded areas (Ⅰ)<moderately invaded areas (Ⅱ)<heavily invaded areas (Ⅲ), while a positive association was found between diversity index and dominance index, newly invaded areas (Ⅰ)>moderately invaded areas (Ⅱ)>heavily invaded areas (Ⅲ).(3) The seasonal changes of soil animal in different S. canadensis invaded areasThe individual and the number of soil animal group did not vary widely in four seasons; the seasonal fluctuation of soil animal individual was represented as: spring<autumn<winter<summer in NIA (Ⅰ), summer<spring=winter<autumn in MIA (Ⅱ), autumn<spring<winter<summer in HIA (Ⅲ). The seasonal changes of diversity indices with different invaded were not the same at any season.(4) Spatial distribution of soil animal in different S. canadensis invaded areasThe spatial distribution of soil animal had obvious surface segregation in different S. canadensis invaded areas, also showed that the individual of soil animal in sampling areas were decreased with the increasing soil depth. The individual of soil animal were significantly different in spatial distribution by one way analysis of variance (F=95.10, p<0.01). S. canadensis impacted the composition of soil animal communities, the more intense the invasion, the less number of individual in 0—5 cm.(5) The hierarchical cluster dendrogram and 2-dimentional MDS ordinal configuration of the soil animal communities in Solidago Canadensis L. invaded areas.Jaccard coefficients had a high or moderate similarity among soil animal communities in sampling areas, which reached the range of 0.6667—1. Using hierarchical cluster of between-groups linkage method and the Non-matric Multidimentional Scaling method (MDS), those soil animals communities could classify into three types:newly invaded areas (Ⅰ), moderately invaded areas (Ⅱ), heavily invaded areas (Ⅲ).(6) The impact on soil animal communities by soil physico-chemical propertiesThe data showed that pH, Organic carbon, Ammonium nitrogen, Available K and Available P were significantly different between the sampling areas (p<0.05), soil water content and soil temperature were not significantly different by one way analysis of variance (p>0.05). pH, Ammonium nitrogen, Available K were lower when S. canadensis invaded aggravates. Grey Relevant Analysis revealed that soil physico-chemical properties had different effect on the key soil animal communities, Ammonium nitrogen produced the most effect on soil animals, the second effect factor was Organic carbon, Available P was the third, and soil water content had less significant effects on the soil animals. Modification of soil biota is an important part of S. canadensis invasion process, and the invasion-induced changes of soil animal community may lead to soil available nutrition abundance, through which S. canadensis gains it superiority in competition. |
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