Subjects: Biology >> Botany >> Applied botany submitted time 2022-03-30 Cooperative journals: 《广西植物》
Abstract： To explore the effects of land use and ecological restoration on soil enzyme activities and C:N:P ratios in the karst ecosystem, three land use types [disturbed land, pasture grassland, and orchard forest (Loquat)] and four restoration types (evergreen forest, deciduous forest, evergreen-deciduous mixed forest, and natural restoration forest), which are long-term positioning observation experimental plots of the Huanjiang Observation and Research Station for Karst Ecosystems, were selected. We measured the activities of four soil enzymes [β-1,4-glucosidase (βG), β-1,4-N-acetylglucosidase (NAG), leucine aminopeptidase (LAP), and alkaline phosphatase (ALP)], and analyzed the relationship between activities level and the C:N:P ratios and soil-associated physical and chemical factors. The results were as follows: (1) Enzyme activities were higher in the three land use types than in the restoration types. In addition, the activities of the four enzymes, enzymatic N:P, and enzymatic C:P of pasture grassland were higher than those in the other restoration types. The βG and ALP activities in the evergreen-deciduous mixed and deciduous forests were significantly higher than those in the natural restoration and evergreen forest, and NAG activity in the evergreen forest was significantly higher than that in the other three restoration types. The enzymatic N:P ratios of the evergreen-deciduous mixed forests were significantly lower than those in the other restoration types, as was the enzymatic C:P ratio of the deciduous forest. In addition, vector analysis of the enzyme activity measurement ratio showed that all land use and restoration types were limited by P. (2) The activities of the four enzymes were positively correlated with organic C, ammonia N (NH4+-N), and nitrate N (NO3--N), whereas negatively correlated with total P (TP). βG activity was positively correlated with available P (AP) and ALP activity was positively correlated with total N (TN). (3) Redundancy analysis showed that the levels of TP, NH4+-N, NO3--N, and AP explained 38.3%, 9.5%, 9.3%, and 8.0%, respectively, of the changes in soil enzyme activity and C:N:P ratios. Based on these results, the different land use and restoration types in karst areas were shown to generally exist under the limitation of soil P, which implies that the fixation and transformation of P should be the focus of soil quality improvement in the land use development and restoration process. Furthermore, soil enzyme activities, C:P ratios, and AP contents in pasture grassland, evergreen-deciduous mixed forest, and deciduous forest were higher than those in the other land use and restoration types. The result indicates that forage and deciduous plants are important for soil nutrient cycling and should be considered in the process of karst land use and restoration.
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