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In order to investigate the effects of vegetation restoration on soil aggregates and organic carbon in severe burning sites in Greater Khingan Mountains, this paper used larch plantations of different stand ages (11, 21 and 32 years) planted on heavy fire sites as the research object, and conducted a study on the stability of soil aggregates and organic carbon characteristics of soil aggregates by measuring the percentage content of each particle size and the organic carbon content of soil aggregates. The results showed that: 1)After vegetation restoration of burned areas, the mechanical stability and water stability of soil aggregates in larch plantations of different stand ages were dominated by the content of >0. 25 mm particle size, accounting for 85. 57%-89. 42% and 62. 86%-83. 19%, respectively. With the increase of stand age, the content of soil mechanical stability aggregates >2 mm particle size in 0-10 cm layer of larch plantation decreased significantly and the content of 0. 25-2 mm particle size increased significantly, while the water stability aggregates showed a trend that the content of >2 mm particle size decreased significantly and the content of 0. 5-2 mm particle size increased significantly (P < 0. 05). 2)32 years of larch plantation soil mechanical stability aggregates mean weight diameter (MWD) and geometric mean diameter (GMD) of the upper soil water-stable aggregates were significantly smaller than 11 years, and the MWD of the upper soil water-stable aggregates was consistent with the characteristics of the mechanically stable aggregates. Water-stable macroaggregate content (WSA 0. 25 ) gradually increased with the increase of restoration years, and the percentage of aggregate destruction (PAD) of the 32 years old larch plantation decreased significantly. 3)With the increase of forest age, the organic carbon content of soil aggregates in larch plantation forest increased, and the increase was more in the upper layer. The organic carbon contribution of large aggregates (>0. 25 mm fraction) dominated. The results could provide scientific basis for vegetation restoration of burned areas in Greater Khingan Mountains. [ABSTRACT FROM AUTHOR]

To explore the differences and change rules of soil nutrients and enzyme activities in Larix gmelinii forest in the cold temperate zone, so as to provide scientific basis and data basis for in-depth understanding of forest ecosystem functions and future development trends in the cold temperate forest ecotone in China. In this paper, four different types of larch forest (Betula platyphylla -Larix gmelinii, Rhododendron dauricum-Larix gmelinii, Larix gmelinii, and Larix gmelinii plantation) in Heilongjiang Zhongyangzhan Black-Billed Capercaillie Nature Reserve were selected as the research objects. Sampling was carried out by season, and the soil. chemical properties and enzyme activities ( catalase, acid phosphatase, urease, sucrase and cellulase) were determined in different seasons, and the dynamic changes with seasons were also explored. Results showed that: (1) Soil chemical properties and enzyme activities were significantly different in different forest types and seasons, and the changing trends were also different to some extent. (2)Soil acid phosphatase was significantly affected by the contents of soil total P, total N and available K. Soil catalase was significantly positively correlated with the contents of total N, available N, available K and available P. Soil sucrase was mainly affected by the contents of available P and available N. Soil urease and cellulase were most affected by soil organic carbon content. (3)The principal component analysis showed that there were significant differences in soil enzyme activities and soil chemical properties among the four forest types, and first principal component 1 could explain more than 50% of the variance variables. The soil chemical properties and enzyme activities in different Larix gmelinii were significantly different with the seasons, which were related to the accumulation of litter and the difference of vegetation types. Soil enzyme activities were correlated with soil chemical properties to varying degrees. [ABSTRACT FROM AUTHOR]

This paper studies and discusses the changes of soil chemical indexes in different recovery years of XingJ an larch forest in Daxinganling, Inner Mongolia, in order to evaluate the self recovery of natural forest and provide basis for the management of Daxin- ganling forest in Inner Mongolia. The pH, C content, whole nitrogen, whole phosphorus and whole potassium content of the soil used in the experiment were calculated according to the Forest Soil Experiment Tutorial and the Soil Agroization Analysis. The effects of logging interference on the chemical properties of soil were studied using a single - factor variance ( ANOVA) analysis ( SPPS 13. 0 software). Results showed that ： ® comparing the differences in soil pH, soil C and other nutrients in Xing * an larch natural forest and two differ¬ent interference plots of clear cut and gradual cut, it is found that clear cut and gradual cut have significant differences in soil chemical properties (P<0.05). Clear cut has an extreme significant positive correlation with soil total nitrogen (P<0.01) , and a significant positive correlation with soil carbon content and pH ( P < 0. 05 ). (2) Comparing the significance of different cutting methods on soil physical and chemical properties in different years, there is a certain gap between the logging sites in 1987 and 2014, while the differ¬ences between the logging sites in 2009, 1987 and 2014 are not significant. Conclusion ： deforestation interference can reduce the pH of soil, objectively increase soil nutrients, and may be conducive to the natural renewal of forests. Logging interference significantly af¬fects the balance of soil carbon and other nutrients [ABSTRACT FROM AUTHOR]