[Soil microbial properties under different vegetation types in Loess hilly region]

Area of Science:

• Soil Science
• Microbiology
• Ecology

Background:

• Agricultural practices, such as intensive cropping, can deplete soil microbial resources.
• Vegetation restoration projects aim to improve ecosystem health, including soil microbial communities.
• Understanding the impact of different vegetation types on soil microbes is crucial for effective land management.

Purpose of the Study:

• To investigate soil microbial biomass and diversity under various vegetation types in Dingxi, Gansu Province.
• To analyze the relationships between soil microbes and soil nutrients.
• To evaluate the effectiveness of different vegetation types for soil microbial restoration.

Main Methods:

• Soil samples were collected from the 0-20 cm layer under five vegetation types: artificial woodland, shrubland, cropland, abandoned farmland, and natural grassland.
• Fumigation-extraction (FE) method was used to determine soil microbial biomass carbon and nitrogen.
• Biolog Ecoplate and path analysis were employed to assess microbial diversity, community catabolic activity, and nutrient relationships.

Main Results:

• Vegetation restoration projects, like "grain for green," significantly improved soil microbial biomass and diversity compared to cropland.
• Microbial biomass carbon and nitrogen were highest in ridge grassland, abandoned farmland, and pine woodland.
• Caragana korshinskii and Medicago sativa lands showed the highest ratio of soil microbial biomass nitrogen to total nitrogen due to N-fixing rhizobia.
• Cropland exhibited the lowest microbial quantity and activity due to continuous biomass loss.
• Soil microbial biomass and activity recovered with time under restored vegetation, with 20-year-old Caragana korshinskii land showing microbial activity comparable to 50-year-old Pinus tabulaeformis woodland.

Conclusions:

• Vegetation restoration, particularly through planting trees, shrubs, and grasses or fallowing, effectively recovers soil microbial biomass and activity.
• Caragana korshinskii is a highly effective species for local vegetation restoration, promoting microbial activity and nutrient cycling.
• The "grain for green" project demonstrates a positive impact on soil microbial resources, highlighting its ecological benefits.