收稿日期: 2003-05-06
网络出版日期: 2004-03-19
Nitrogen Dynamics of Reforested Soils FollowingAgricultural Abandonment over Decades
Received date: 2003-05-06
Online published: 2004-03-19
Supported by
Supported by Yunnan Education Foundation for studying abroad, and Grants from USDA National Research Initiative and USNSF to Duke University
对 1962年以来采集的表层土壤和深层土壤样品进行培养实验,以研究退耕还林 40年来土壤氮的动态变化以及植被恢复对土壤氮库矿质化的影响.供试土样在专门设计的矿质化培养系统中,以温度 30℃、通气并保持土壤湿度的条件下培养 30d,以 2mol LKCl溶液浸提培养土并测定其氮含量.结果表明,土壤矿质氮及全氮含量均在造林的头 2 0年迅速下降,在 2 0年的林木生长过程中,生物吸收积累了土壤中约 80 %-90 %的有效氮,表明耕地中施入的氮对树木早期生长有着重要作用;树龄达 40年时,土壤原有矿质氮的 5 0 %-80 %已返还土壤.这一结果表明,森林地被已成为土壤营养的重要来源,并且森林生态系统提供的这种有机质可成为可持续利用的土壤氮资源.
田昆 , RICHTERD. D , HEINEP. R , HOFMOCKELM , 杨永兴 . 退耕还林 40年来森林土壤氮库营养的动态变化研究(英文)[J]. 中国科学院大学学报, 2004 , 21(2) : 241 -247 . DOI: 10.7523/j.issn.2095-6134.2004.2.014
Soil samples archived over four decades were used in an incubation experiment to measure theeffects of reforestation on nitrogen dynamics in old agricultural fields. Samples collected from depths 0cm to 715cm and 35cm to 60cm at intervals ranging between five and nine years since 1962 were incubatedaerobically at 30℃ for 30 days using a system specially designed to maintain constant soil moisture. Mineral N was measured in 2 molPL KCl extracts. The ratio of mineralized N to total N rapidly decreased inthe first two decades of forest development. Within 20 years of planting, 80 % to 90 %of plant available N had accumulated in the biomass indicating that agricultural inputs of N were important to early tree development. Significantly, by age 40, 50 % to 80 % of the original pool of mineral N had returned to thesoil profile. The accretion of mineralizable N suggests that forest floor is serving as an increasingly impor2tant source for this nutrient. Further, it indicates that forest managers have the opportunity to manipulatea large pool of forest organic matter to sustain soil N supply.
[1] Nadelhoffer KJ, Aber J D,Mellilo J M.Leaf2litter production and soil orgnic matter dynamics along a nitrogen mineralization gradient in southernWisconsin (U.S.A.).Canadian Journal of Forest Research, 1983, 13 :12-21
[2] Pastor J, Aber J D, McClaugherty C A, Mellilo J M.Aboveground production and N and P cycling along a nitrogen mineralization gradient onBlackhawk Island, Wisconsin.Ecology, 1984, 65 :225-268
[3] Reich P R, Grigal D F, Aber J D,Gower S T.Nitrogen mineralization and productivity in 50 hardwood and conifer stands on diverse soil.Ecolo2gy, 1997, 78 :335-347
[4] Campbell C A, Jame YW, Akinrem O O, Cabrera ML.Adapting the potentially mineralizable N concept for the prediction of fertilizer N require2ments.Fertilizer Research, 1995, 42 : 61-75
[5] Stanford G,Smith S J.Nitrogen mineralization potentials of soils.Soil Science Society of America Proceeding, 1972, 36 : 465-472
[6] Bonde T A,Roswall T.Seasonal variation of potentially mineralizable nitrogen in four cropping systems.Soil Science Society of America Journal,1987, 51 : 1508-1514
[7] Maimone R A, Moriris L A,Fox T R.Soil nitrogen mineralization potential in a fertilized loblolly pine plantation.Soil Science Society of AmericaJournal, 1991, 55 : 522-527
[8] Motavalli P P, Frey S D,Scott N A.Effects of filter type and extraction efficiency on nitrogen mineralization measurements using the aerobic leach2ing soil incubation method.Biology and Fertility of Soils, 1995, 20 : 197-204
[9] Richter D D, Markewitz D, Wells C G, Allen HL, Dunscomb J, Harrison K, Heine P R, Stuanes A Urrego B, Bonani G.Carbon cycling in anold2field pine forest : implications for the missing carbon sinc and for the concept of soil.In : WMcFee.(ed.) English North American Forest SoilConference.Gainesville :University of Florida, 1994.233-251
[10] Leigh R A,Johnston A E.(eds.) Long2term experiment in agricultural and ecological sciences.CAB International, Oxon, UK, 1994
[11] Richter D D, Markewitz D, Wells C G, Allen H L, April P, Heine P R, Urrego B.Soil chemical change during three decades in an old2fieldloblolly pine (pinus taeda) ecosystem.Ecology, 1994, 75 :1463-1473
[12] Richter D D, Babbar L I.Soil diversity in the tropics.Advances in Ecological Research, 1991, 21 :316-389
[13] Brady N C, Weil P R.The nature and properties of soils.12th ed.Prentice Hall, Inc.1999.184
[14] Keeney D R, Nelson D W.Nitrogen2inorganic forms, in methods of soil analysis, part 2.Chemical and Microbiological Properties (2 nd edition).1982.643-693
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