杉木种植和磷添加对土壤微生物生物量及胞外酶活性的影响

Effects of Chinese fir planting and phosphorus addition on soil microbial biomass and extracellular enzyme activities

植物可以通过凋落物和根系分泌物改变土壤微生物生物量及碳氮磷转化胞外酶活性,进而影响土壤碳氮磷循环过程。然而,针对土壤磷有效性如何影响植物与土壤微生物之间的关系依然不清楚。本研究在不同磷添加水平下(0、1.95、3.9、7.8、15.6 g P·m-2·a^(-1)),分析杉木种植对土壤微生物生物量和碳氮磷转化胞外酶活性的影响。结果表明:杉木种植显著改变了土壤微生物生物量与碳氮磷转化胞外酶活性,而且影响程度受磷添加水平的调控。在不添加磷处理下,种植杉木显著降低了土壤养分有效性,并引起土壤酸化,导致磷限制加剧,抑制土壤微生物生物量。磷添加逐渐减缓磷限制,随着磷添加水平的升高(1.95、3.9、7.8、15.6 g P·m^(-2)·a^(-1))土壤酸性磷酸酶活性比对照分别降低30.0%、30.5%、35.3%和47.1%。在3个磷添加水平处理下(1.95、3.9、7.8 g P·m^(-2)·a^(-1)),杉木对土壤微生物生长的抑制作用得到缓解。在高水平磷添加处理下(15.6 g P·m^(-2)·a^(-1)),由于磷添加引起的氮养分限制,杉木种植对土壤微生物再次呈抑制作用。杉木种植和土壤磷有效性共同调控土壤微生物生物量与胞外酶活性,改变磷限制。

Plants can alter soil microbial biomass and extracellular enzyme activities related with carbon(C),nitrogen(N),and phosphorus(P),through litter and root exudates,with consequences on soil carbon,nitrogen and phosphorus(P)cycling.However,it is not well known how the changes in soil phosphorus availability affect the relationships between plants and soil microorganisms.In this study,a factorial experiment was conducted to investigate the effects of Chinese fir(Cunninghamia lanceolata)planting and different levels of P addition(0,1.95,3.9,7.8 and 15.6 g P·m^(-2)·a^(-1))on soil microbial biomass and extracellular enzyme activities.The results showed that planting Chinese fir planting significantly altered soil microbial biomass and C-and N-and P-related extracellular enzyme activities,but the effects were dependent on P addition levels.Without P addition,Chinese fir planting significantly reduced soil nutrient availability and pH,which led to the aggravation of P limitation and lower soil microbial biomass.P addition relieved P limitation,and reduced soil acid phosphatase(ACP)activities by 30.0%,30.5%,35.3%and 47.1%with the increasing P addition level(1.95,3.9,7.8 and 15.6 g P·m^(-2)·a^(-1)).Under three P addition levels(1.95,3.9 and 7.8 g P·m^(-2)·a^(-1)),the negative effects of Chinese fir planting on soil microbial growth were alleviated.Under the high P addition level(15.6 g P·m^(-2)·a^(-1)),the negative effects of Chinese fir planting on soil microbial growth occurred again due to soil N limitation.Taken together,Chinese fir planting and soil P availability generally affected soil microbial biomass and extracellular enzyme activities,and changed P limitation.