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Anthropogenic nitrogen (N) deposition significantly affects forest soil microbial biomass and extracellular enzymatic activities (EEA). However, the influence of mixed N fertilizations on soil microbial biomass and EEA remains unclear. In this work, NH 4 NO 3 was chosen as inorganic N, while urea and glycine were chosen as organic N. They were used to fertilize subtropical forest soil monthly for 1 year with different ratios (inorganic N : organic N=10 : 0, 7 : 3, 3 : 7 and 1 : 9 respectively.) and N inputs were equivalent to 7.2 g N m −2 y −1 .

Herbivores can influence plant species richness and plant aboveground biomass. However, only a few studies have examined their impact on the relationship between plant aboveground biomass and plant species richness, focusing on large herbivores. This study examined the influence of a small burrowing herbivore, the plateau pika (Ochotona curzoniae) with averaging 150 g, on the plant aboveground biomass, plant species richness, and their relationship in the alpine meadows on the Qinghai–Tibet Plateau. The study used a random stratified paired sampling design to collect data on plant species richness and plant aboveground biomass across five sites. Each site contained 10 pairs of plots. Each pair consisted of an undisturbed plot and a disturbed plot. Plant species richness was higher in the disturbed plots; whereas, plant aboveground biomass did not differ in relation to plateau pika disturbance. In the undisturbed plots, the plant species richness increased positively with plant aboveground biomass. In the disturbed plots, the plant species richness peaked at intermediate plant aboveground biomass levels. The findings suggest that small herbivores could alter the relationship between plant aboveground biomass and plant species richness by inducing an increase in plant species diversity, and they should be considered for assessing the management and conservation measures of alpine meadow.