Role of Seasonality and Fire in Regulating the Enzymatic Activities in Soils Covered by Different Vegetation in a Mediterranean Area

Valeria Memoli,Lucia Santorufo,Gabriella Di Natale,Rossella Barile,Anna De Marco,Giulia Maisto,Marco Trifuoggi,Paola Musella,Giorgia Santini

doi:10.3390/app11188342

Abstract

As they quickly respond to environmental conditions, soil enzymes, involved in nutrient cycles, are considered good indicators of soil quality. The Mediterranean area is a peculiar environment for climatic conditions and for fire frequency. Therefore, the research aimed to evaluate the role of seasonality and fire on enzymatic activities (i.e., hydrolase, dehydrogenase, and β-glucosidase) in soils covered by herbs, black locust, pine, and holm oak. In addition, the main soil abiotic properties that drive the enzymatic activities were also investigated. In order to achieve the aims, surface soils were collected in unburnt and burnt areas and characterized for water and organic matter contents, pH, concentrations of C and N, and available fractions of Al, Ca, Cu, Fe, Mg, Mn, Na, and Pb. The results highlighted that the soil enzymatic activities were mainly affected by seasonality more than by fire; in unburnt soils, their main drivers were nutrient availabilities, whereas, in burnt soils they were pH, water and organic matter contents, C and N concentrations, and both nutrient and metal availabilities. Finally, holm oak, as compared with herbs, pine, and black locust, conferred higher stability to soils that were affected by seasonality and fire.

Highlights

Soil enzymes, playing a fundamental role in organic matter decomposition, are involved in nutrient cycling and are critical to soil functioning [1]
The hydrolase (HA) activity ranged from 187 to 2544 mmol fluorescein diacetate (FDA) g−1 d.w. h−1 in soils covered by pine (P), from 285 to 1842 mmol FDA g−1 d.w. h−1 in soils covered by holm oak (HO), from 109 to 1275 mmol FDA g−1 d.w. h−1 in soils covered by black locust (BL), and from 36.2 to 1377 mmol FDA g−1 d.w. h−1 in soils covered by herbs (H)
The dehydrogenase (DHA) activity ranged from 0.01 to 3.65 mmol TFF g−1 d.w. h−1 in soils covered by pine (P), from 0.46 to 9.06 mmol TFF g−1 d.w. h−1 in soils covered by holm oak (HO), from 0.69 to 6.47 mmol TFF g−1 d.w. h−1 in soils covered by black locust (BL), and from 0.01 to 10.6 mmol TFF g−1 d.w. h−1 in soils covered by herbs (H)

Summary

Introduction

Soil enzymes, playing a fundamental role in organic matter decomposition, are involved in nutrient cycling and are critical to soil functioning [1]. As they quickly respond to environmental conditions, they are considered good indicators of soil quality [2]. Seasonality, responsible for changing in temperature, humidity, and precipitation, directly and indirectly alters soil enzymatic activity [4,5]. It is well documented that temperature and precipitation are the main drivers of soil enzymatic activity [9,10]

Methods

Discussion

Conclusion