Effects Of Pastures Leaf Litters Controlling Soil Polarization Of Pure Broadleaved Forests In The Loess Plateau

Nutrient selective utilization and litter special effects are considered to be fundamental reasons leading to soil polarization in the pure forests. Based on previous studies on soil polarization of mono-species broad-leaved forests in the Loess Plateau, an incubation-for-decomposition experiment was conducted of mixtures of soil samples collected from humus layers of Populus simonii, Quercus liaotungensis, Betula platyphylla and Robinia pseudoacia forests in the semi-humid loess hilly region of Shaanxi and the humus layers of R. pseudoacacia pure forest in the Loess Gullied Area with litters of seven species of forage grass to explore effects of forage litters remedying pure broad-leaved forest soils and hence to accumulate scientific data for selection of suitable soil-remedying species of forage grass. Results show that:(1) For the pure P. simonii forersts in the semi-humid Loess Hilly Area of Northern Shaanxi, the litters of Leapedeza bicolor and Onobrychis viciaefolia displayed significant effects mitigating the negative polarization of organic matter, the order of the improved effects are L. bicolor>O. viciaefolia. The litters of Medicago sativa, Coronilla varia, Melilotus officinalis, Vicia villosa, L. bicolor and Astragalus adsurgens displayed significant effects mitigating the negative polarization of alkeline-N, the order of the improved effects are M. officinalis>M. sativa>V. villosa>A. adsurgens>L. bicolor>C. varia. The litters of M. sativa, C. varia, M. officinalis, V. villosa, O. viciaefolia and A. adsurgens displayed significant effects mitigating the negative polarization of available P, the order of the improved effects are M. sativa>V. villosa>O. viciaefolia>M. officinalis>A. adsurgens>C. varia. All the litters displayed significant effects mitigating the negative polarization of readily CEC. The litters of L. bicolor, A. adsurgens, C. varia and V. villosa displayed significant effects mitigating the negative polarization of urease activity, the order of the improved effects are A. adsurgens>L. bicolor>V. villosa>C. varia. All the litters displayed significant effects mitigating the negative polarization of sucrase activity, and all the litters displayed significant effects mitigating the negative polarization of protease activity. The litters of C. varia, M. officinalis, O. viciaefolia, M. sativa and L. bicolor displayed significant effects mitigating the negative polarization of microbes quantity, the order of the improved effects are C. varia>M. officinalis>O. viciaefolia>M. sativa>L. bicolor. Integrated PCA(principal component analysis) shows that litter of V. villosa had the most obvious comprehensive effect mitigating the negative polarization of soil form pure P. simonii forest, flowed by A. adsurgens and L. bicolor. But M. officinalis exacerbated soil properties obviously, followed by M. sativa and O. viciaefolia.(2) For the pure B. platyphylla forersts in the semi-humid Loess Hilly Area of Northern Shaanxi, all the litters displayed significant effects mitigating the negative polarization of available P and available K, the order of the improved effects are C. varia>V. villosa>M. officinalis>M. sativa>A. adsurgens>O. viciaefolia>L. bicolor. The litters of A. adsurgens, V. villosa, C. varia, M. officinalis, M. sativa and O. viciaefolia had similar effects on the activity of sucrase activity, the order of the improved effects are M. sativa>C. varia>O. viciaefolia>M. officinalis>V. villosa>A. adsurgens. The litters of O. viciaefolia displayed significant effects mitigating the negative polarization of phosphatase activity. Integrated PCA(principal component analysis) shows that litter of L. bicolor had the most obvious comprehensive effect mitigating the negative polarization of soil form pure B. platyphylla forest, flowed by O. viciaefolia, A. adsurgens and M. officinalis. But M. sativa exacerbated soil properties obviously, followed by C. varia and V. villosa.(3) For the pure Q. liaotungensis forersts in the semi-humid Loess Hilly Area of Northern Shaanxi, all the litters displayed significant effects mitigating the negative polarization of available P, the order of the improved effects are M. sativa>V. villosa>M. officinalis>C. varia>A. adsurgens>L. bicolor>O. viciaefolia. All the litters displayed significant effects mitigating the negative polarization of available K, the order of the improved effects are C. varia>V. villosa>M. officinalis>M. sativa>A. adsurgens>O. viciaefolia>L. bicolor. All the litters had similar effects on the activity of sucrase activity, the order of the improved effects are M. sativa>M. officinalis>C. varia>V. villosa>A. adsurgens>L. bicolor>O. viciaefolia. The litters of A. adsurgens, L. bicolor, V. villosa, C. varia and M. officinalis displayed significant effects mitigating the negative polarization of protease activity, the order of the improved effects are M. officinalis> A. adsurgens> V. villosa> L. bicolor> C. varia. Integrated PCA(principal component analysis) shows that litter of M. sativa had the most obvious comprehensive effect mitigating the negative polarization of soil form pure Q. liaotungensis forest, flowed by C. varia, V. villosa and M. officinalis. But L. bicolor exacerbated soil properties obviously, followed by O. viciaefolia and A. adsurgens.(4) For the pure R. pseudoacia forersts in the semi-humid Loess Hilly Area of Northern Shaanxi, the litters of A. adsurgens, V. villosa, C. varia and L. bicolor displayed significant effects mitigating the negative polarization of organic matter, the order of the improved effects are A. adsurgens>V. villosa>C. varia>L. bicolor. The litters of M. sativa had similar effects on the available P. The litters of A. adsurgens, L. bicolor, V. villosa, C. varia and O. viciaefolia had similar effects on the catalase activity, the order of the improved effects are A. adsurgens>L. bicolor>V. villosa>C. varia>O. viciaefolia. The litters of A. adsurgens, V. villosa and L. bicolor had similar effects on the protease, the order of the improved effects are L. bicolor>A. adsurgens>V. villosa. The litters of C. varia, V. villosa, M. officinalis, M. sativa, A. adsurgens and O. viciaefolia had similar effects on the microbes quantity. Integrated PCA(principal component analysis) shows that litter of M. sativa had the most obvious comprehensive effect mitigating the negative polarization of soil form pure R. pseudoacia forest, flowed by M. officinalis. But L. bicolor exacerbated soil properties obviously, followed by V. villosa, O. viciifolia and A. adsurgens.(5) For the pure R. pseudoacia forerst in the Loess Gullied Area, all of the litters displayed significant effects mitigating the negative polarization of readily alkeline-N. The litters of A. adsurgens, L. bicolor, C. varia, M. officinalis, M. sativa and O. viciaefolia displayed significant effects mitigating the negative polarization of available K, the order of the improved effects are A. adsurgens>L. bicolor>C. varia>M. officinalis>M. sativa> O. viciaefolia. The litters of V. villosa, C. varia and M. officinalis had similar effects on the sucrase activity, the order of the improved effects are V. villosa>C. varia>M. officinalis. The litters of A. adsurgens, M. officinalis, M. sativa and O. viciaefolia had similar effects on the catalase activity, the order of the improved effects are A. adsurgens>M. officinalis>M. sativa>O. viciaefolia. Integrated PCA(principal component analysis) shows that litter of M. officinalis and A. adsurgens had the most obvious comprehensive effect mitigating the negative polarization of soil form pure R. pseudoacia forest, flowed by V. villosa. But C. varia exacerbated soil properties obviously, followed by O. viciifolia.(6) Based on the point of view of the comprehensive restoration on the polarization of soil from pure forests: On the pure forests of the semi-humid loess hilly area in Northen Shaanxi, A. adsurgens, V. villosa and L. bicolor are suitable forage species to be planted with P. simonii. L. bicolor, O. viciaefolia, A. adsurgens and M. officinalis are suitble forage species to be planted with B. platyphylla; M. sativa, C. varia, V. villosa and M. officinalis are suitable forage species to be planted with Q. liaotungensis. M. sativa and M. officinalis are suitable forage species to be planted with R. pseudoacia. The pure forests of the Loess Gullied Area, M. officinalis, A. adsurgens and V. villosa are suitble forage species to be planted with R. pseudoacia.