The belt of oasis border is usually called as ecotone of desert and oasis,which is mainly composed of shrub dunes.These shrub dunes can be divided into stable dune,semi-stable dune,semi-shift dune and shift dune by coverage of vegetation.A lot of studies have indicated that these shrub dunes are nature roughness unit and they have significant roles on airflow near land surface.They can change airflow structure and interchange of air torrent at boundary layer near land surface.They can also increase resistance of land surface to moving airflow by enhancing aerodynamic roughness length.When airflow blow passed shrub dunes,wind speed will be decreased remarkably because the dunes resist wind.So,shrub dunes in ecotone are very important defending barrier to nature oasis.This research selected a sample line(965m) mainly composed of stable dune,semi-stable dune and semi-shift dune in ecotone of Minqing oasis and one of stable shrub dune as study object.Field observation results indicate that mean wind speed at layers near land surface decrease 4.4% through the sample stable shrub dune and decrease 57% through the sample line.The mean wind velocity is reduced continuously along the sample line.At the edge of cropland inner of oasis,the wind velocity is only 21% referring to reference observation point. But shrub dunes in ecotone of oasis are one kind of the most vulnerable and unstable ecosystem and they are easily vulnerable to become degeneration ecosystem so as to threaten the sustainable development of oasis.The evolutions of shrub dunes are mainly influenced by human activities and climate changes.If they degenerate to be shift dunes,they will change from shelter barrier to be dust bowl.So,attention should be paid not only to the inner but also to the outer of oasis about its protection.Shrub and grass belts should be built in the surroundings while windbreak grid built in the inner and base windbreak built at the edge of oasis.Water is the most important factor to the stableness of the ecotone.It is significant for the sustainable development of oasis to supply sufficient ecological water utilized to realize the stableness of the belts of oasis border,at the same time,all kinds of human destruction activities should be forbidden.
WANG Sheng-Tang, ZOU Xue-Yong, CHANG Chun-Lai, CHENG Hong
. Wind-protecting Effect of Shrub Dunes in Ecotone of Minqin Oasis[J]. SCIENTIA GEOGRAPHICA SINICA, 2007
, 27(1)
: 104
-108
.
DOI: 10.13249/j.cnki.sgs.2007.01.104
[1] 韩德林.关于绿洲若干问题的认识[J].干旱区资源与环境,1995,9(3):15~31.
[2] 黄培佑.绿洲与沙漠化过程的初步研究[J].新疆环境保护,1990,12(2):13~16.
[3] 贾宝全,闫顺.绿洲一荒漠生态系统交错带环境演变过程初步研究[J].干旱区资源与环境,1995,9(3):58~64.
[4] 楚新正,张素红.景观边缘带性质、功能及动态变化的初步研究[J].新疆师范大学学报(自然科学版)2002,21(3):50~54.
[5] 程国栋,肖笃宁,王根绪.论干旱区景观生态特征与景观生态建设[J].地球科学进展,1999,14(1):11~14.
[6] 王兵,崔向慧.民勤绿洲一荒漠过渡区水量平衡规律研究[J].生态学报,2004,24(2):235~239.
[7] 赵成义,王玉朝,李国振.荒漠一绿洲边缘区研究[J].水土保持学报,2001,15(3).93~95.
[8] 陈鹏,初雨,顾峰雪,等.绿洲一荒漠过渡带景观的植被与土壤特征要素的空间异质性分析[J].应用生态学报,2003,14(6):904~908.
[9] 李向义,张希明,何兴元,等.沙漠一绿洲过渡带四种多年生植物水分关系特征[J].生态学报,2004,24(6):1164~1171.
[10] 曹宇,欧阳华,肖笃宁,等.额济纳天然绿洲景观变化及其生态环境效应[J].地理研究,2005,24(1):130~139.
[11] 颉耀文,陈发虎,王乃昂.近2000年来甘肃民勤盆地绿洲的空间变化[J].地理学报,2004,59(5):662~670.
[12] 孙雪涛.民勤绿洲水资源利用的历史现状和未来[J].中国工程科学,2004,6(1):1~9.
[13] 徐宪立,张科利,庞玲,等.青藏公路路堤边坡产流产沙规律及影响因素分析[J].地理科学,2006,26(2):211~216.
[14] 王升堂,赵延治,邹学勇,等.北京郊区不同土地利用类型起沙起尘的特征研究[J].地理科学,2005,25(5):601 605.
[15] 哈斯,董光荣,王贵勇.腾格里沙漠东南缘沙丘表面气流与坡面形态的关系[J].中国沙漠,1999,19(1):1~4.
[16] 哈斯,王贵勇.沙丘背风侧气流的变化特征及其意义[J].地理科学,2000,20(6):573~576.
[17] Zhibao Dong,Shangyu Gao,Donald W.Fryrear.Drag coefficients,roughness length and zero-plane displacement height as disturbed by artificial standing vegetation[J].Journal of Arid Environments,2001,49(3):485-505.
[18] 张春来,邹学勇,董光荣,等植被对土壤风蚀影响的风洞实验研究[J].水土保持学报,2003,17(3):31~33.