Informatics Publishing Limited

Xiao-Xi Zhang ¹, Bo-Chao Zhu ², Zeng-Wen Liu ³, Yuan-Hao Bing ⁴, Xiao-Bo Liu ⁴, Xiao Liang ¹

Affiliations
1 Institute of Soil and Water Conservation, Northwest A&F University, Yangling-712100, CN
2 College of Natural Resources and Environment, Northwest A&F University, Yangling-712100, CN
3 Key Laboratory of Plant Nutrition and the Agri-Environment, Northwest China, Ministry of Agriculture, Yangling-712100, CN
4 College of Forestry, Northwest A& F University, Yangling-712100, CN

Abstract

Allelopathic effect of humus soil of mono-species-community on the understory plants was a critical problem in the mixed reformation of planted pure forests. In order to investigate the practical allelopathic effect of humus soil of Platycladus orientalis forest on understory plants in the Loess Plateau of China and provide a scientific basis for its future management, humus soils of P. orientalis forests in the hilly (north) and gullied (south) areas of the Loess Plateau were sampled separately for pot experiment of 10 common species of shrubs and grasses, and seed germination, seedling growth and physiological indexes were measured during the whole test. According to the comprehensive analysis, humus soil of P. orientalis forest in the hilly area showed obvious allelopathic inhibition on Medicago sativa, Melilotus officinalis, Vicia villosa and Astragalus adsurgens; while in the gully area, it showed obvious allelopathic inhibition on M. officinalis, V. villosa and Coronilla varia. Species which are inhibited by allelopathic effects should be avoided choosing, to form mixed vegetation with P. orientalis.

Keywords

Allelopathy, Humus Soil, Platycladus orientalis, Understory Plants.

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Cai-Hong Mi ¹, Zeng-Wen Liu ¹, Bo-Chao Zhu ¹

Affiliations
1 College of Natural Resources and Environment, Northwest A&F University, Yangling-712100, CN

Abstract

Soil polarization is a new concept which describes the deviation of soil properties of planted pure forest from its original equilibrium status towards an extreme condition due to long-term growth or continuous planting of single tree species. It is thought to be one obstacle of forest. In order to investigate the effect of litter decomposition on soil polarization of planted forests in the gully region of Loess Plateau, China, humus soil and litter were sampled in two typical broadleaved forests, and 4 treatments as "soil + leaf litter", "soil + ischolar_mains", "soil + leaf litter + ischolar_mains", and CK were set for laboratory incubation experiment in this research. The results showed that polarizations of different properties were variable, in both direction and degree, after the incubation with litters. Based on analyzing the polarization ratios by PCA (principal component analysis) method, the results of comprehensive soil properties were showed as follows: in the Robinia pseudoacia forest soil, both of leaf litter and ischolar_mains resulted in negative polarization, and leaf litter showed greater effect than ischolar_mains; in the Betula platyphylla forest soil both of leaf litter and ischolar_mains resulted in negative polarization, and also leaf litter showed greater effect than ischolar_mains. When leaf litter and ischolar_mains mixed-together with the soil, the interaction sequence is R. pseudoacia (0.497) > B. platyphylla (-0.466). The result indicated that leaf litter and ischolar_mains when mix-incubated with forest soil showed promoting effect on soil properties in the R. pseudoacia forest soil, and showed inhibitory effect on soil properties in B. platyphylla forest soil. In general, litter decomposition in R. pseudoacia forest soil was more beneficial for soil properties than B. platyphylla.

Keywords

Litter Decomposition, Soil Polarization, Broadleaved Forests, Loess Plateau, Robinia pseudoacia, Betula platyphylla.

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