BayCEER Workshop 2019

Impact of deadwood on chemical and microbial soil parameters: A multifactorial experiment with logs of 13 tree species in 30 forests

Deadwood is a specific litter type that may alter the chemical and microbial properties of forest soils. However, it is unclear how downed deadwood (logs) of different tree species affect nutrients, microbial activity, and biomass of different forest soils in frequently occurring forest types. We investigated the impact of logs on underlying soils after eight years of decomposition in a multifactorial experiment consisting of 13 deadwood tree species replicated at 30 forest sites across three German regions (ALB, HAI, SCH). Soils beneath logs were compared to soils in 8 m distance (control) without recognizable influence of deadwood. Carbon, nitrogen, phosphorous, and calcium concentrations significantly increased in underlying soils by 9 – 55 %, whereas soil potassium, magnesium, iron, manganese, and aluminum were not or slightly negatively affected by logs. Soils beneath logs exhibited 54, 70, and 84 % higher carbon mineralization, microbial biomass and ergosterol contents, respectively. Despite major differences in decay rates, logs of 13 tree species did not differ in their effect on soil properties. Impact of logs on microbial and chemical soil parameters increased with decreasing concentration of soil nutrients and soil pH. Consequently, logs improved the soil status at SCH and to some extent at HAI, whereas calcareous and nutrients-rich soils at ALB were hardly affected by logs. The strongest impact of logs on soils occurred in pine forests with soils of low nutrient contents and pH. Our results suggest that logs of all tree species primarily improve the microbial and chemical conditions of acidic and nutrient-poor soils.