Post-wildfire soil and plant foliar nutrient ratios and soil fungi : bacterial ratios in alpine meadows on the southeastern Qinghai-Tibet Plateau

摘要

Wildfire is increasingly considered as a common ecological phenomenon in grassland. However, little is known about its effects on soil and plant nutrient ratios, especially in alpine ecosystems where wildfires are common. In the present study, nutrient ratios of the post-wildfire surface soil (0-5cm) and nine dominant plant species leaves, in addition to soil fungi:bacterial ratios (F:B ratios), were investigated in the alpine meadows on the south-eastern Qinghai-Tibet Plateau, approximately 20 months after a high-severity wildfire. The results indicated that the burned sites had lower soil nitrogen:phosphorus (N:P) and nitrogen:potassium (N:K) ratios compared with unburned sites. Moreover, foliar N concentrations were lower on burned than unburned sites, but foliar N:P ratios were not different. Compared with the unburned sites, greater foliar K concentrations and lower N:K ratios were observed in burned sites. The idiosyncratic responses of foliar nutrient ratios to wildfire varied greatly, especially N and related nutrient ratios with plant species. Soil F:B ratios were positively correlated with soil C:N and C:P ratios, whereas they were negatively correlated with soil N:P and N:K ratios. The results of the present study suggest that there is reduced supply capacity of soil N for plants relative to soil P and K in the post-fire alpine meadow, which could have potential ecological implications in this region.