[Stoichiometric characteristics of plant and soil C, N and P in different forest types in depressions between karst hills, southwest China].

The stoichiometric properties of plant carbon (C), nitrogen (N) and phosphorus (P) and their relationships with soil were studied in six dominant plant communities in three forest types, i.e., plantation forest, secondary forest and primary forest in depressions between karst hills, southwest China.

[Stability and organic carbon characteristics of soil aggregates under different ecosystems in karst canyon region].

Soil aggregates and their organic carbon distributions were studied under six ecosystems, i. e., farmland (short for ST), dry land (HD), grassland (CD), shrubbery (GC), plantation (RGL) and secondary forest (CSL), in a karst canyon region of China by a combination of field investigation and laboratory analysis.

[Characteristics of spatial variation of soil nutrients in sloping field in a gorge karst region, southwest China].

Based on a grid (20 m x 20 m) sampling, spatial heterogeneity and pattern of soil nutrients in sloping field in the gorge karst region, southwestern China, were explored by using classical statistics and geostatistics methods. The results showed that soil nutrient contents in slope field in the canyon karst region were more abundant, where pH value had a weak variation and the soil organic matter (SOM) had a moderate degree of variation. All the soil nutrients had moderate or strong variation with an order of available phosphorus (AP) > total potassium (TK) > SOM > alkaline nitrogen (AN) > total nitrogen (TN) > total phosphorus (TP) > available potassium (AK).

[Characteristics of soil microbial populations in depressions between karst hills under different land use patterns].

Based on the investigation and analysis of six soil microbial indices, eight soil conventional nutrient indices, six soil mineral nutrient indices, and 15 vegetation indices in the farmland, grassland, scrub, forest plantation, secondary forest, and primary forest in the depressions between karst hills, this paper analyzed the main soil microbial populations, soil microbial biomass carbon (MBC), nitrogen (MBN), and phosphorus (MBP) and their fractal characteristics, and the relationships of the soil microbes with vegetation, soil nutrients, and soil mineral components under different land use patterns. The soil microbial populations differed in their quantity and composition under different land use patterns. Primary forest and farmland had the highest quantity of soil microbial populations, while forest plantation had the lowest one.