以典型沙质草地为研究区域,通过养分和水分添加控制试验,研究了群落尺度上生产力的变化及其对不同养分和水分处理响应的差异。从不同功能群植物地上生物量对养分和水分响应分异的角度揭示群落尺度初级生产力的变化机理。结果显示:(1)单纯的氮素、磷素、水分添加对群落生产力的影响不明显,只有养分和水分交互作用才能显著增加群落生产力。氮素添加×冬季增雪、氮素添加×夏季增雨、磷素添加×夏季增雨处理使得群落生产力比对照分别提高了85.1%、107.9%、57.2%。(2)氮素添加×冬季增雪处理后群落生产力比磷素×冬季增雪处理高出86.7%,表明虽然水分添加提高了植物对氮素与磷素的利用效率,但水分添加后植物对氮素的利用效率更高。(3)不同功能群植物地上生物量对养分和水分添加的响应程度不一致。总体而言,养分和水分添加对禾本科植物生物量的影响最明显,对杂类草植物生物量的影响不明显。单纯磷素添加明显降低了群落中禾本科植物的生物量,比对照低61.9%;冬季增雪、夏季增雨增加了群落中豆科植物的生物量,与对照相比分别增加了193.3%、220.5%;氮素添加×冬季增雪、氮素×夏季增雨显著增加了禾本科植物的生物量,分别比对照增加了80.4%、91.6%。
Responses of plant community structure and biomass to nutrient addition and increased precipitation were examined in the Horqin Sandy Grassland. We studied the variations of responses to nutrient and water addition of different functional group species biomasses, and discussed how effect of the variations on community productivity. The main conclusions are as follows: (1) Community productivities were not affected by nitrogen, phosphorus and water addition. But the community productivity were significant affected by the interaction of nitrogen and water addition. For example, community productivity were increased 85.1%, 107.9% and 57.2% in nitrogen addition×increase snow in winter, nitrogen addition×increase precipitation in summer and phosphorus addition×increase precipitation in summer treatments. (2) We also found that community productivities were higher in nitrogen addition×increase precipitation in summer than phosphorus addition×increase precipitation in summer, this result may suggested that the plant were more favor nitrogen at high water levels although water increased would enhanced the plant to nitrogen and phosphors use efficiency. (3) The sensitivity of the three plant functional groups was quite different. Grasses were most, forbs were less sensitive to simulated rainfall and available nitrogen in the improved disturbing condition. The biomasses of three functional groups plants were increased as available nitrogen increased. Biomasses of grasses were decreased in phosphorus addition treatments which were 61.9% lower than control treatments. Water addition only affected the biomass of legumes, for example, snow and precipitation decreased 193.3% and 220.5%, respectively, of legumes biomasses. The grasses biomasses were significantly increased in the interaction of nitrogen and water treatment, for example, the biomasses of grasses increase 80.4% in nitrogen×snow treatments and 91.6% in snow×precipitation treatments.
[1] 安渊,李博,杨持,等.内蒙古大针茅草原草地生产力及其可持续利用研究 I.放牧系统植物地上现存量动态研究[J].草业学报,2001,10(2):22-27.
[2] 黄富祥,高琼,傅德山,等.内蒙古鄂尔多斯高原典型草原百里香-本氏针茅草地地上生物量对气候响应动态回归分析[J].生态学报,2001,21(8):1339-1346.
[3] 王启基,王文颖,邓自发.青海海北地区高山嵩草草甸植物群落生物量动态及能量分配[J].植物生态学报,1998,22(3):222-230.
[4] Dueck T A.Effect of ammonial and sulphur dioxide on the survival and growth of Calluna vugaris (L.) Hull seedlings[J].Functional Ecology,1990,4(1):109-116.
[5] Song L,Bao X,Liu X,et al.Impact of nitrogen addition on plant community in a semi-arid temperate steppe in China[J].Journal of Arid Land,2012,4(1):3-10.
[6] 李晓刚,朱志红,周晓松,等.刈割、施肥和浇水对高寒草甸物种多样性、功能多样性与初级生产力关系的影响[J].植物生态学报,2011,35(11):1136-1147.
[7] Harpole W S,Potts D L,Suding K N.Ecosystem responses to water and nitrogen amendment in a California grassland[J].Global Change Biology,2007,13(11):2341-2348.
[8] 常学礼,赵爱芬,李胜功.科尔沁沙地固定沙丘植被物种多样性对降水变化的响应[J].植物生态学报,2000,24(2):147-151.
[9] Wipf S.Phenology,growth,and fecundity of eight subarctic tundra species in response to snowmelt manipulations[J].Plant Ecology,2010,207:53-66.
[10] 袁文平,周广胜.中国东北样带三种针茅草原群落初级生产力对降水季节分配的响应[J].应用生态学报,2005,16(4):605-609.
[11] Lajtha K,Schlesinger W H.The biogeochemistry of phosphorus cycling and phosphorus availability along a desert soil chronosequence[J].Ecology,1988,69(1):24-39.
[12] 陈静,李玉霖,崔夺,等.氮素及水分添加对科尔沁沙地4种优势植物地上生物量分配的影响[J].中国沙漠,2014,34(3):696-703.
[13] 沈振西,周兴民,陈佐忠,等.高寒矮嵩草草甸植物类群对模拟降水和施氮的响应[J].植物生态学报,2002,26(3):288-294.
[14] Hooper D U,Johnson L.Nitrogen limitation in dryland ecosystems:responses to geographical and temporal variation in precipitation[J].Biogeochemistry,1999,46(1):247-293.
[15] 赵哈林,曲浩,周瑞莲,等.沙埋对小麦(Triticum aestivum)生长的影响及其生理响应[J].中国沙漠,2014,34(3):689-695.
[16] Mao W,Ginger A,Li Y L,et al.Life history strategy influences biomass allocation in response to limiting nutrients and water in an arid system[J].Polish Journal of Ecology,2012,60(3):381-389.
[17] Yang H,Li Y,Wu M,et al.Plant community responses to nitrogen addition and increased precipitation:the importance of water availability and species traits[J].Global Change Biology,2011,17(9):2936-2944.
[18] Paul D B,Mark W W.Snowpack controls on nitrogen cyclying and export in seasonally snow-covered catchments[J].Hydrological Processes,1999,13(14):2177-2190.
[19] Kassen R,Buckling A,Bell G,et al.Diversity peaks at intermediate productivity in a laboratory microcosm[J].Nature,2000,406(6795):508-512.
[20] Tilman D.Resource Competition and Community Structure[M].Princeton,USA:Princeton University Press,1982.
[21] Huston M.A general hypothesis of species diversity[J].The American Naturalist,1979,113(1):81-101.
[22] Abramsky Z,Rosenzweig M.Tilman's predicted productivity-diversity relationship shown by desert rodents[J].Nature,1984,309(5964):150-151.
[23] 牛克昌,赵志刚,罗燕江,等.施肥对高寒草甸植物群落组分种繁殖分配的影响[J].植物生态学报,2006,30(5):817-826.
[24] Bai Y,Wu J,Clark C M,et al.Tradeoffs and thresholds in the effects of nitrogen addition on biodiversity and ecosystem functioning:evidence from inner Mongolia Grasslands[J].Global Change Biology,2010,16(1):358-372.
[25] Roland B,Michael H,Jand G M R.The effects of air-borne nitrogen pollutants on species diversity in natural and semi-natural European vegetation[J].Jounal of Ecology,1998,86(5):717-738.
[26] Yang H,Li Y,Wu M,et al.Plant community responses to nitrogen addition and increased precipitation:the importance of water availability and species traits[J].Global Change Biology,2011,17(9):2936-2944.
[27] Schwinning S,Ehleringer J R.Water use trade-offs and optimal adaptations to pulse-driven arid ecosystems[J].Journal of Ecology,2001,89(3):464-480.