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| Soil polarizations of forest plantation in semi-humid gullied area of southern Loess Plateau |
| Liu Zengwen,Duan Erjun,Fu Gang,Cui Fangfang |
| College of Resources and Environment,Northwest A & F University,712100,Yangling,Shaanxi,China |
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Abstract Soil property polarization means non-equilibrium or polarizing tendency of development.In order to recognizing the trends of soil polarization of planted pure forests in semi-humid gullied area of southern Loess Plateau,soil properties of planted forests of Pinus tabulaeformis,Platycladus orientalis and Robinia pseudoacia were determined with sampling methods of multi-plots and multi-sites.It can be conclusioned that: 1) Forest soil of Pinus tabulaeformis was light worsened in physical properties(polarization value Pr is -9.26%,the same as following),partially acidified,moderate leaned in nutrients(Pr is-11.54%),moderate worsened in some enzyme activities(Pr is-12.88%) and its total number of microorganisms increased.2) Forest soil of Platycladus orientalis showed tendency of being worsened in physical properties,conserved stable in pH value,light leaned in nutrients(Pr is-8.24%),no obviouse indication of polarized in some enzyme activities and its total number of microorganisms conserved stable.3) Forest soil of Robinia pseudoacia was moderate worsened in physical properties(Pr is-12.74%),conserved stable in pH value,moderate leaned in nutrients(Pr is-12.77%),light worsened in some enzyme activities(Pr is-8.89%) and its total number of microorganisms conserved stable.4) The absolute comprehensive polarizations of soil among different properties took quantitative composition of microorganisms as the most sensitive and pH as the most slowly.These conclusions mean that long-term grown or continuous planted pure forests will risk soil polarization and degradation.
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Received: 04 May 2008
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