毛乌素沙地克隆植物沙鞭生长对AM真菌生态分布的影响

从毛乌素沙地沙鞭群落间隔空地沙鞭根状茎延伸方向设置样地,2007年5月、7月和10月在0-10、10-20、20-30、30-40和40-50 cm共5个土层分别采集土壤样品,研究了AM真菌时空分布及沙鞭侵入间隔空地前后对AM真菌分布的影响。结果表明,沙鞭能与AM真菌形成良好共生关系,菌根结构为中间型(I-型),AM真菌定殖率和孢子密度有明显的时空分布规律,并与土壤因子密切相关。随采样时间后延AM真菌定殖率先增后降,最大值出现在7月份;孢子密度先降后增,最大值出现在10月份。土壤采样深度对AM真菌定殖和孢子密度有显著影响,AM真菌最高定殖率和最大孢子密度均出现在0-20 cm浅土层。孢子密度仅与泡囊定殖率显著正相关。土壤速效N与菌丝和总定殖率极显著负相关;土壤温度与泡囊、丛枝、菌丝和总定殖率显著和极显著正相关,与孢子密度显著负相关;土壤湿度与丛枝、菌丝和总定殖率显著正相关,与孢子密度显著负相关。克隆植物沙鞭的生长对土壤AM真菌活动和分布有很大影响,沙鞭入侵前后样地中AM真菌孢子密度和定殖率变化显著。

Effects of the growth of clonal plant Psammochloa villosa Trin. bor on ecological distribution of arbuscular mycorrhizal fungi in Mu Us Sandland

The sampling plots represented the typical Psammochloa villosa community and were chosen based on the presence of P. villosa to investigate the effects of its clonal growth on the distribution of arbuscular mycorrhizal fungi in Mu Us sandland. The plots were established in May and sampled in May, July and October 2007. Soil samples were collected in 4 replicates and divided a depth of 50 cm into 5 sections, i.e. 0-10, 10-20, 20-30, 30-40 and 40-50 cm. The results showed that a functional symbiont is formed between AM fungi and P. villosa, with an intermediate mycorrhizal type. AM fungal colonization significantly (P<0.05) increased initially and later decreased with sampling time, peaking in July. Spore density showed an inverted pattern of development and maximum numbers were recorded in October. The soil sampling depth had a significant (P<0.05) effect on spore density and colonization of AM fungi with the highest percent colonization and spore density in the two topmost sections i.e., 0-20cm. Spore density was significantly (P<0.05) and positively correlated with vesicular colonization. Soil available N content was significantly (P<0.01) and negatively correlated with hyphal and total root colonization. Soil temperature was significantly (P<0.05) and positively correlated with vesicular, arbuscular, hyphal and total colonization, but had a significantly (P<0.05) negative effect on spore density. Soil moisture was significantly (P<0.05) and positively correlated with arbuscular, hyphal and total colonization but significantly (P<0.05) and negatively correlated with spore density. The results suggest that the clonal growth of P. villosa has an influence on the colonization activity and spore density of AM fungi.