Plant community composition, soil nutrients, tussock morphometrics, C. rubra root colonisation, soil microbial PLFA and NLFA in 75 plots that vary in invasive Calluna vulgaris density, Tongariro National Park, New Zealand

We studied invasion by an ericoid mycorrhizal host plant (Calluna vulgaris L., heather) in alpine tussock grasslands in New Zealand. We investigate the effects of increasing C. vulgaris density on the plant and soil microbial community and on mycorrhization in the dominant native species (Chionochloa rubra Z., red tussock), an arbuscular mycorrhizal host. We show that variation in plant community composition among sites was driven by C. vulgaris density. Higher densities of C. vulgaris were associated with a reduced diameter of C. rubra plants and lower densities of neighbouring plant species, especially woody shrubs. Belowground, we show that higher densities of C. vulgaris were associated with lower rates of mycorrhization in native C. rubra and higher abundances of the fungal fatty acid methyl ester (FAME) biomarker but had little effect on the total microbial community biomass, suggesting that increased ericoid mycorrhizal fungal biomass increased the ratio of fungi relative to bacteria in high C. vulgaris density stands.

我们以新西兰高山草丛草原（alpine tussock grasslands）为研究对象，针对欧石楠类菌根（ericoid mycorrhizal）宿主植物帚石楠（Calluna vulgaris L.，俗称heather）的入侵现象展开研究。本研究考察了帚石楠种群密度升高对植物群落、土壤微生物群落，以及优势本土物种红穗茅（Chionochloa rubra Z.，俗称red tussock）——一种丛枝菌根（arbuscular mycorrhizal）宿主——的菌根定植（mycorrhization）水平的影响。研究结果表明，不同样地间植物群落组成的差异由帚石楠种群密度主导。更高的帚石楠种群密度与红穗茅植株径级减小、邻株植物（尤其木本灌木类群）种群密度降低显著相关。在地下生态维度，我们发现更高的帚石楠种群密度与本土红穗茅的菌根定植率降低存在关联，同时伴随真菌脂肪酸甲酯（FAME，fungal fatty acid methyl ester）生物标志物丰度升高，但对微生物群落总生物量几乎无影响；这表明在帚石楠高密度样地中，欧石楠类菌根真菌生物量的提升会提高真菌与细菌的生物量比值。