Long-term impacts of land-use change on dynamics of tropical soil carbon and nitrogen pools
Long-term impacts of land-use change on dynamics of tropical soil carbon and nitrogen pools
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发表时间：
2004
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通讯作者：
YANGJing-cheng;HUANGJian-hui;PanQing-min;TANGJian-wei;HANXing-guo
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作者：
YANGJing-cheng;HUANGJian-hui;PanQing-min;TANGJian-wei;HANXing-guo
热带地区土地利用变化，特别是原生森林植被向农田和人工林的转变，可以改变土壤碳氮库和植物吸收氮的有效性。在西双版纳地区，毁林、轮作、建立橡胶林是一种常见的土地利用变化。然而，这种土地利用变化对该地区土壤碳氮动态的影响尚不清楚。本研究旨在探讨土地利用变化对土壤碳氮库的影响。土壤样品采集于5个相邻样地，分别属于3种土地利用类型，包括次生林—青香蕉次生林和雄竹次生林、轮作栽培和橡胶树。Arg.)种植园（一块是3年的，另一块是7年的）。测定了0-3、3-20、20-40和40-60 cm土层的土壤容重（BP）、pH值、含水量和土壤有机碳（SOC）、土壤全氮（TSN）、无机氮（NO-3 -N和NH~ -N）浓度，并计算了0-20、20-40、40-60和0-60 cm土层的C库和N库。与邻近次生林相比，橡胶林的移栽和建立导致0-20和0-60 cm土层的有机碳和TSN浓度和储量显著下降，0-3、3-20和20-40 cm土层的pH和容重增加。在轮作和人工林中，只有0 ~ 20 cm表层土壤含水量下降。矿物氮的动态则复杂得多，在不同的深度和生态系统中有不同的变化趋势。与次生林相比，轮作和橡胶林（3年生和7年生）0 ~ 20 cm表层土壤有机碳储量分别减少了34.0%、33%和23%；土壤有机碳和TSN储量分别减少32.2%、20.4%和20.4%，而0 ~ 60 cm土壤有机碳和TSN储量均减少
Land-use changes, especially the conversion of native forest vegetation to cropland and plantations intropical region, can alter soil C and N pools and N availability for plant uptake. Deforestation, followed by shiftingcultivation and establishment of rubber tree plantation, is a common land-use change in Xishuangbanna, southwestChina. However the influence of this kind of land-use change on soil C and N dynamics in this region remains poorlyunderstood. This study was conducted to assess the effects of land-use change on soil C and N pools. Soil sampleswere collected on five adjacent plots, which belong to three land-use types including secondary forest-an acuminatebanana( Musa itinerans) secondary forest and a male bamboo( Dendrocalamus membranaceae) secondary forest,shifting cultivation, and rubber tree ( Hevea brasiliensis (H. B. K. ) Muell. Arg. ) plantation (one plot is 3-year-old,and another is 7-year-old). We measured soil bulk density (BP), pH value, moisture content and concentrations ofsoil organic carbon(SOC), total soil nitrogen(TSN), and inorganic N(NO-3 -N and NH~ -N) at 0-3, 3-20, 20-40and 40-60 cm depths, and calculated C and N pools in 0-20, 20-40, 40-60, and 0-60 cm soil layers.Compared with the adjacent secondary forests, shifting cultivation and establishment of rubber tree plantationsresulted in significant decline in concentrations and stocks of SOC and TSN in 0-20 and 0-60 cm soil layers, andincrease in pH and bulk density at 0-3, 3-20, and 20-40 cm depths. Soil moisture content decreased only in 0-20 cm surface soils in shifting cultivation and plantations. The dynamics of mineral N was much more complex,which had different trends among depths and ecosystems. Compared with the secondary forests, SOC stocks in 0-20 cm surface soils in shifting cultivation and rubber tree plantations(3-year-old plantation and 7-year-old plantation)decreased by 34.0%, 33%, and 23%; and TSN stocks decreased by 32.2%, 20.4%, and 20.4%, respectively,whereas the decreases of SOC and TSN stocks in 0-60 cm soil la