The Effect of Re-Planting Trees on Soil Microbial Communities in a Wildfire-Induced Subalpine Grassland

Ed-Haun Chang,Guanglong Tian,Chih-Yu Chiu

doi:10.3390/f8100385

Abstract

Wildfire often causes tremendous changes in ecosystems, particularly in subalpine and alpine areas, which are vulnerable due to severe climate conditions such as cold temperature and strong wind. This study aimed to clarify the effect of tree re-planting on ecosystem services such as the soil microbial community after several decades. We compared the re-planted forest and grassland with the mature forest as a reference in terms of soil microbial biomass C and N (Cmic and Nmic), enzyme activities, phospholipid fatty acids (PLFA) composition, and denaturing gradient gel electrophoresis (DGGE). The Cmic and Nmic did not differ among the grassland, re-planted forest and mature forest soil; however, ratios of Cmic/Corg and Nmic/Ntot decreased from the grassland to re-planted forest and mature forest soil. The total PLFAs and those attributed to bacteria and Gram-positive and Gram-negative bacteria did not differ between the re-planted forest and grassland soil. Principle component analysis of the PLFA content separated the grassland from re-planted forest and mature forest soil. Similarly, DGGE analysis revealed changes in both bacterial and fungal community structures with changes in vegetation. Our results suggest that the microbial community structure changes with the re-planting of trees after a fire event in this subalpine area. Recovery of the soil microbial community to the original state in a fire-damaged site in a subalpine area may require decades, even under a re-planted forest.

Highlights

In forest ecosystems, fire alters the soil microbial community composition and activity in the form of direct heat-induced microbial mortality [1,2]
Soil total phosphorus did not show any significant difference among the three types of vegetation, it was higher in the mature forest soil than in the re-planted forest and grassland soil
In our study of a Pinus plantation in central Taiwan (2600–2800 m asl) after a fire event, the trend we found in soil soil organic matter (SOM), total N, microbial activities and microbial community structure may be related to the vegetation and recovery history

Summary

Introduction

In forest ecosystems, fire alters the soil microbial community composition and activity in the form of direct heat-induced microbial mortality [1,2]. Loss of forest by fire and grass invasion may alter nutrient cycling and quality of organic matter [3], which can indirectly affect the soil microbial community. Soil bacterial and fungal biomass is lower in fire-induced grassland areas than unaffected forest areas [4]. Post-fire tree replanting can accelerate the recovery of forest function in an ecosystem [5], thereby leading to greater recovery of the soil microbial community. 50 years ago, a wildfire led to a vegetation shift from forest to grassland at Tatajia, the saddle (2600 to 2800 m asl) of Yushan, one of the highest mountains (3950 m) in East Asia

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