The interaction between exotic invasive plants and soil animal communities is an important aspect of understanding plant invasibility and susceptibility of receptive communities. Consequently, studies on the effects of plant invasion on soil animal communities and their physicochemical properties are becoming increasingly important in determining the effects of plant invasion on ecosystems and the relationship of the invasion mechanism to the underground soil biota. In this paper, we report the soil animal community structure and the soil physicochemical properties of three sampling areas in Jinhua, Zhejiang Province of Eastern China where Solidago canadensis has invaded native plant communities. The objectives of the study are to evaluate how S. canadensis invasion affects the physicochemical characteristics of the plant rhizosphere and the soil animal parameters and to determine whether these parameters can serve as indicators for the invasion density of S. canadensis. Soil samples were collected at three depths over four seasons in different S. canadensis鄄 invaded areas. A total of 9900 individual soil animals, which belong to 14 orders, 11 classes, and 3 phyla, were collected. The most dominant taxa in three invaded areas were Collembola and Acarina. Statistical analysis was performed with the SPSS 18. 0 program package. The one-way ANOVA shows that pH, organic carbon, ammonium nitrogen, available K, and http: / / www. ecologica. cn available P are significantly different among the sampling areas (p < 0. 05) , whereas soil water content and soil temperature were not (p > 0. 05). The sequence of the diversity indices and the evenness indices were as follows: newly invaded areas< moderately invaded areas < heavily invaded areas. A positive association was found between diversity index and dominance index. The spatial distribution of soil animals in the different S. canadensis invaded areas had obvious surface segregation. Using the non-metric multidimensional scaling method, the soil animals communities were classified into three types. Grey relevant analysis indicated that the soil physicochemical properties had different effects on the key soil animal communities, Ammonium nitrogen produced the most significant effect on soil animals, followed by organic carbon, available P, and finally by soil water content. Therefore, S. canadensis L. invasion changes the soil physicochemical properties (especially the NH 4 鄄N) , and then changes the soil animal community used by S. canadensis to expand its invasive range rapidly.
In landward coastal zones of most mangrove swamps in China, there are many shrimp ponds with surface sediments rich in nutrients such as N and P. During pond cleaning periods, some of these surface sediments are usually directly discharged into mangrove swamps after being flushed by using high鄄pressure hydraulic giants. Gradually, these sediments from shrimp ponds will accumulate on the floor of mangrove swamps, resulting in the increase in sedimentation thickness. However, the effects of sedimentation of shrimp pond cleaning discharges on mangrove ecosystems are still unknown. Therefore, to study their responses and endurances in growth and physiological characteristics, four thickness treatments (0, 2, 4, 8 cm) were applied to simulate the sedimentation condition of shrimp pond discharges into the mangrove swamp, and Acanthus ilicifolius seedlings were cultivated under these treatments for 424 days. In terms of growth indexes, including stem diameter, stem height, leaf number, leaf area, total biomass and relative growth rate, growths of A. ilicifolius seedlings were promoted due to the sedimentation of shrimp pond cleaning discharges. The growth condition of A. ilicifolius seedlings under four treatments followed the order of 8 cm > 4 cm > 2 cm > 0 cm. Results also indicated that a small quantity of cleaning discharges (sedimentation thickness of only 2 cm) could obviously enhance the growth of A. ilicifolius seedlings, and this enhancement would not be stronger comparing with the increasing of
罗如熠,张世熔,徐小逊,李婷.黑河下游湿地土壤有机氮组分剖面的分布特征. 生态学报,2015,35(4) :956鄄 964.Luo R Y, Zhang S R, Xu X X, Li T.Profile distribution characteristics of soil organic nitrogen fractions in the lower reaches of the Heihe River wetland. Acta Ecologica Sinica,2015,35(4) :956鄄 964. 黑河下游湿地土壤有机氮组分剖面的分布特征 罗如熠,张世熔 * ,徐小逊,李摇 婷 1 四川省土壤环境保护重点实验室,成都摇 611130 2 四川农业大学资源环境学院,成都摇 611130 摘要:结合野外调查,用 Bremner 法研究了黑河下游湿地不同土壤类型的有机氮组分,结果表明:在 0-50 cm 土层,5 种土壤有 机氮均以酸解性氮为主,占全氮的 71.04%-81.79%。 泥炭土、沼泽土、草甸土、亚高山草甸土所含的酸解氮、非酸解氮和酸解氮 组分氨态氮、氨基酸态氮、氨基糖态氮含量的剖面分布总体上均随土层深度的增加而呈降低趋势,而风沙土却相反,上述有机氮 组分呈升高趋势。 5 种土壤酸解氮及其组分氨态氮、氨基酸态氮、氨基糖态氮占全氮比例的剖面分布总体上均随土层深度的增 加而呈降低趋势,而非酸解氮却呈升高趋势。 5 种土壤酸解未知态氮含量及占全氮比例均在剖面分布上无明显特征。 在 0-30 cm各相同土层内,5 种土壤酸解氮各组分含量及占全氮比例的大小顺序均为氨基酸态氮>氨态氮>未知态氮>氨基糖态氮;而 在 30-50 cm 土层,5 种土壤酸解氮各组分含量及占全氮比例的大小顺序均无明显特征。 此外,黑河下游湿地土壤干化、沙化过 程中,表层 0-10 cm 土壤有机氮组分含量变化明显,其中土壤氨态氮对生态环境变化最为敏感。Abstract: Nitrogen ( N) is one of the most important element in plant growth and an important part of the global ecosystem substances circulation. Organic N is both the main form of soil N and pool of mineral N. Soil organic N plays an important role in soil fertility, N cycling and environmental protection. Usually, the concentration and distribution of soil organic N mainly affected by soil types, soil level, rhizospheric environment, fertility and farming conditions, etc, and the chemical forms and status of soil organic N is the important factor affecting the availability of soil N. Currently, researchers have focused more on effect of different land use systems on changes of soil organic N fractions, dissolved organic N, particulate organic N and microbial biomass N, as well as effect of different fertilization and irrigation approaches on concentrations and composition of organic N fractions by using the Bremner忆s method to separate soil organic N fractions. Combined with filed investigation, five types of soil samples in the lower reaches of Heihe river wetland were collected, and the organic N fractions were studied using the Bremner忆s method, the results showed that acidolysable N was the dominant fraction of organic N in all the soil samples (0-50 cm soil layer) , and the proportion of acidolysable N to total N was from 71.04% to 81.79%. The concentrations of acidolysable N, non鄄acidolysable N and acidolysable N fractions ( ammonia N, amino acid N, amino sugar N) of Peat soil, Boggy soil, Meadow soil, Subalpine meadow soil decreased, but increased in the Aeolian sandy soil generally with soil depth in the profile. Furthermore, the proportions of acidolysable N and acidolysable N fractions ( ammonia N, amino acid N, amino sugar N) to total N of all the soil samples generally decreased with soil depth2.2.1摇 氨态氮 氨态氮的来源比较复杂,其部分是无机态氮,包括土壤中吸附性铵和固定态铵;部分也可能是来自酸解过 程中某些氨基酸和氨基糖脱氨产生的;还有部分则来自酰胺类化合物,其他来源的相关研究很少 [22] 。 由图 3 可见,5 种土壤氨态氮含量的变化范围为 0郾 11-2.42 g / kg。 在 0-5 cm 土层氨态氮含量差异除泥炭土与沼泽 土、草甸土与亚高山草甸土外,其余土壤类型之间均达显著水平( P<0郾 05) ;在 5-10 cm 土层氨态氮含量差异 除泥炭土与沼泽土外,其余土壤类型之间均达显著水平( P<0郾 05) ;在 10-20 cm 土层氨态氮含量差异除泥炭 土与沼泽土、草甸土与亚高山草甸土、亚高山草甸土与风沙土外,其余土壤类型之间均达显著水平( P<0郾 05) ; 在 20-30 cm 土层氨态氮含量差异除泥炭土与沼泽土,草甸土、亚高山草甸...
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