黄顶菊入侵对不同地区土壤氮循环及微生物量的影响

外来入侵植物对入侵地土壤生态系统的影响日益受到生态学家的关注。本文选取天津静海、河北献县及河北衡水湖3个黄顶菊入侵样地,研究黄顶菊入侵对不同地区土壤养分、酶活性及土壤微生物量的影响。结果表明,与未入侵地土壤(CK)相比,黄顶菊入侵明显地改变了3个地区的土壤理化性质且存在地区差异,静海和献县入侵地全氮升高,衡水湖则下降;静海和衡水湖土壤硝态氮下降,而献县上升,土壤氨氧化潜势的变化趋势与硝态氮的变化趋势一致。土壤氮循环相关酶活性也表现出明显的地区特异性。同时,黄顶菊入侵静海、献县和衡水湖3个地区样地中的微生物量碳分别比CK提高27.05%,57.62%和40.31%;静海和献县入侵地的微生物量氮分别比CK高37.40%,106.48%,差异显著。黄顶菊入侵对土壤氮素养分、氮相关酶活性及微生物量影响的地区差异可能与入侵地被入侵前养分含量有关,表现出使土壤养分状况均一化趋势。对于黄顶菊防控策略的制定要根据各地区情况因地制宜。

Effects of Flaveria bidentis invasion on soil nitrogen cycling and soil microbial biomass in different regions

The effect of plant invasion on soil ecosystems has attracted increased attention from ecologists. To study the influences of Flaveria bidentis invasion on soil nutrients, enzyme activities and soil microbial biomass in different regions, soils were sampled at three sites: in Jinghai County in Tianjin and in Xian County and Hengshui City in Hebei Province. Results indicate that the invasion of F. bidentis changed the soils’ chemical and biological characteristics, but that these changes varied by regions. Total soil nitrogen increased in Jinghai and Xian but decreased in Hengshui, compared to the control. Soil nitrate was significantly lower in Jinghai and Hengshui while significantly higher in Xian than the control. Changes in the Potential Nitrification Rate followed the same pattern as that of nitrate. Nitrogen cycling-related enzyme activities also changed differently across the three regions. Soil microbial biomass carbon increased by 27.05%, 57.62% and 40.31% in Jinghai, Xian and Hengshui, respectively. Soil microbial biomass nitrogen increased by 37.40% in Jinghai and by 106.48% in Xian. These regional differences may be related to soil nutrient status before the invasion of F. bidentis. This study suggests that different management strategies should be taken in different invasion regions.