Abstract

Agricultural peatlands are essential for a myriad of ecosystem functions and play an important role in the global carbon (C) cycle through C sequestration. Management of these agricultural peatlands takes place at different spatial scales, ranging from local to landscape management, and drivers of soil microbial community structure and function may be scale-dependent. Effective management for an optimal biogeochemical functioning thus requires knowledge of the drivers on soil microbial community structure and functioning, as well as the spatial scales upon which they are influenced. During two field campaigns, we examined the importance of different drivers (i.e., soil characteristics, nutrient management, vegetation composition) at two spatial scales (local vs. landscape) for, respectively, the soil microbial community structure (determined by PLFA) and soil microbial community functional capacity (as assessed by CLPP) in agricultural peatlands. First, we show by an analysis of PLFA profiles that the total microbial biomass changes with soil moisture and relative C:P nutrient availability. Secondly, we showed that soil communities are controlled by a distinct set of drivers at the local, as opposed to landscape, scale. Community structure was found to be markedly different between areas, in contrast to community function which showed high variability within areas. We further found that microbial structure appears to be controlled more at a landscape scale by nutrient-related variables, whereas microbial functional capacity is driven locally through plant community feedbacks. Optimal management strategies within such peatlands should therefore consider the scale-dependent action of soil microbial community drivers, for example by first optimizing microbial structure at the landscape scale by targeted areal management, and then optimizing soil microbial function by local vegetation management.

Highlights

  • Peatlands play an important role in Earth’s biogeochemical cycles by storing about an estimated third of all terrestrial carbon (C) (Turetsky et al, 2002; Turunen et al, 2002)

  • The range of soil properties was even greater for the samples examined by community level physiological profiling (CLPP), though average soil chemical properties were within the same general range (Table 3)

  • The underlying variables were found to be largely different as well. This implies that the spatial scale of soil microbial studies is important when talking about driving forces of soil microbial community structure and functioning, enforcing the idea that the scale of soil management and the scale of study of soil microbial structure and functioning need to be well aligned

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Summary

INTRODUCTION

Peatlands play an important role in Earth’s biogeochemical cycles by storing about an estimated third of all terrestrial carbon (C) (Turetsky et al, 2002; Turunen et al, 2002). Soil microbes are often considered to have high functional redundancy (Strickland et al, 2009); and drivers of soil microbial community structure may have minimal effect on soil microbial functioning This perspective would imply that management practices designed to control only the drivers of community function would be sufficient to achieve the desired ecosystem functions. We combine data from two sampling campaigns across agricultural peatlands in The Netherlands (Figures 1a,b), one that examined drivers of soil microbial community structure, as determined by phospholipid fatty acid (PLFA) analysis, and one that examined drivers of soil microbial community functional capacity, as estimated by community level physiological profiling (CLPP). Comparison of samples within and between different polder areas made it possible to analyze drivers at two different spatial scales: local scale (sites within a sampled area) and landscape scale (differences between sampled polder areas)

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