内蒙古の放牧強度の異なる典型草原における地上部生産量と土壌および植物中成分との関係 Relationship between Aboveground Productivity and Chemical Components of Soil and Plant in Typical Steppe with Different Productivities and Grazing Intensity in Inner Mongolia

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内蒙古典型草原の地上部生産量(AGP)の地域差に関与する土壌成分を明らかにするために,生産量および放牧条件が異なる3地区の典型草原から,土壌および植物を採取した.克什克騰旗(採取地1:S1),錫林浩特市(S2),四王子旗(S3)に採取地を設定した.3段階の放牧条件区(高放牧圧:HG,低放牧圧:LG,禁牧:NG)を各採取地に設けた.5月上旬にHGおよびLGに,それぞれ,家畜からの防護柵(2 m × 2 m)を3個設置した.土壌および植物のサンプリングを行い,総窒素(TN),総リン(TP),硝酸態窒素およびリン酸の分析を行った. S2のHGにおいてのみ,AGP,植生および被度に対する放牧の有意な効果が認められた.この結果は,最も高い放牧強度を有するS2のH2における植生退化によるものかも知れない.一方,AGPと0-5 cmの深さの土壌中のTNとTPとの間に有意な正の相関関係が示された(それぞれ,r=0.820および0.543, <i>P</i><0.05).土壌および植物中TPは1960年代の記録と比べて明らかに低かった.従って,土壌TPがAGPを制限する要因の一つかもしれない.しかし,土壌のリン酸および硝酸態窒素のレベルはいずれもAGPとの間に有意な相関関係が示されなかった.

To identify soil factors affecting regional difference in aboveground productivity (AGP), soil and plant samples were collected from three typical steppe grasslands of Inner Mongolia exhibiting different productivity levels, and subjected to different grazing conditions. The sampling sites were located in grasslands used for grazing at Keshiketeng Banner (site 1; S1), Xilinhot city (S2), and Siziwang Banner (S3). Three grazing conditions (high grazing intensity: HG; low grazing intensity: LG; no grazing: NG) were categorized in each site. In early May, three fences (2 m × 2 m) for protecting land from grazing were built each in the HG and LG sites. Soil and plant samples were collected from three quadrate areas (1 × 1 m each) in each of the three sampling sites. Concentrations of total nitrogen (TN), total phosphorus (TP), nitrate nitrogen (NO<sub>3</sub><sup>-</sup>-N), and P<sub>2</sub>O<sub>5</sub> in the soil and plant samples were measured.Significant effects of grazing on AGP, plant species diversity, and plant coverage rates were observed only when S2 was subjected to HG. This may have contributed to degradation of vegetation in HG of S2 with a highest grazing intensity. On the one hand, the correlations between AGP and TN or TP in the 0-5 cm depth soil were significant (r=0.820 and 0.543, respectively, <i>P</i><0.05). Notably, TP levels in soil and plant were lower than those in the 1960s. Thus, soil TP may be a factor limiting AGP. However, soil NO<sub>3</sub><sup>-</sup>-N and P<sub>2</sub>O<sub>5</sub> levels did not correlate with AGP, and thus may not contribute to productivity differences among sampling sites.

収録刊行物

  • 沙漠研究

    沙漠研究 25(2), 25-30, 2015

    日本沙漠学会

各種コード

  • NII論文ID(NAID)
    130005107948
  • NII書誌ID(NCID)
    AA11338296
  • 本文言語コード
    JPN
  • ISSN
    0917-6985
  • NDL 記事登録ID
    026942449
  • NDL 請求記号
    Z15-770
  • データ提供元
    NDL  J-STAGE 
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