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Université du Xinjiang (2017)

Litter Decomposition Characteristics of Main Species in Tarim Desert Highway Shelterbelt

张雪梅;

Titre : Litter Decomposition Characteristics of Main Species in Tarim Desert Highway Shelterbelt

Auteur : 张雪梅;

Grade : Doctoral Dissertation 2017

Université : Université du Xinjiang

Résumé partiel
The Tarim Desert Highway,which was the important transport highway across the Taklimakan Desert from north to south,it was the world’s longest highway that through mobile desert.It is extreme arid climate,scarcity of surface water resource,highly salinity groundwater,intensive wind erosion activity and shifting dunes along the Tarim Desert Highway.To build biological sand control system along the highway on both sides of the Tarim Desert Highway,which was drip irrigation with local salinity groundwater,and have the high stress resistance genus of Calligonu,m L.,Haloxylon Bunge and Tamarix Linn,as the main forestation.Because of the special geographic environment of the Tarim Desert Highway Shelterbelt,the nutrients release by litter decomposition was the main source of plant nutrients and soil fertility.This study has selected the main litter components of Calligonum arborescens,Haloxylon ammodendron and Tamarix ramosissima in the Tarim Desert Highway Shelterbelt as object.From 2012 to 2014,through wild fixed point observation,in-situ decomposition experiment,control experiment,and laboratory analysis of litter,we have studied the dynamics of litterfall biomass and components changed with the planting year of shelterbelt.The litter mass remaining,litter decomposition rate,dynamic variation of elements(C,N,P,K,Ca,Mg,lignin,and cellulose)and element ratios on different litter types,planting year of shelterbelt,different stand ages and regulation treatments.To reveal the litterfall biomass dynamics,to discuss the effects of reguhtory treatments on litter decomposition ;to preliminary understanding the decomposition and nutrients release and controlling factors to the main litter type for three species in the Tarim Desert Highway Shelterbelt.The main results as following:In the Tarim Desert Highway Shelterbe lt,the annual litterfall biomass of shelterbelt planting years for 1995a,1998a,2001a,2004a and 2006a were 7.93 t·hm-2 ;6.19 t·hm-2,10.54 t·hm-2,9.10 t·hm-2 and 8.31 t·hm-2 respectively.The total biomass of litterfall and components among species were decreased in the order of H.ammodendron,T.ramosissirma and C.arborescens with different planting years,and the highest litterfall biomass in autumn.The largest litterfall biomass components were assimilative branches of H.ammodendron,branches of T.ramosissima,and assimilative branches of C.arborescens,accounting for 70.58%~88.93%of the total amount.There was similar seasonal dynamic in different planting year’s shelterbelt.Monthly changes in litterfall pattern showed three peaks in the total biomass and biomass for the assimilative branches of C.arborescens and H.ammodendron,and the branches of T.ramosissima,reaching the peaks in March to May,July,and September to November,and the highest amount in November.While no obvious litterfall pattern was found for leaves,seeds and others,they reaching the peaks in different times,branches of H.ammodendron and leaves of T.ramosissima in May to July,seeds of H.ammodendron in September to October,seeds of C.arborescens in June and July,flowers of C.arborescens and T.ramosissima only present from May to August.The genetic and ecological physiological processes and climatic conditions for the species in Tarim Desert Highway Shelterbelt have effect on the dynamics of litterfall biomass and components.The study on litter decomposition in shelterbelt of different planting years showed that litter decomposition rate were decrease as the order of branches of T.ramosissima(0.24~0.32g·g-1·a-1),assimilative branches of C.arborescens(0.17~0.23g·g-1·a-1),and branches of H.ammodendron(0.13~0.18g·g-1·a-1).The lowest decomposition rate was appeared at 1995a planting shelterbelt for three litters,the largest decomposition rate was appeared at 2004a planting shelterbelt for branches of T.ramosissima and assimilative branches of C.arborescens.at 2001a planting shelterbelt for branches of H.ammodendron.Shelterbelt planting years mainly through the micro environmental conditions have significant directly or indirectly effects on litter decomposition rates.The initial litter C,P,K and Mg content were the main controlling factors of early decomposition,initial lignin,cellulose and C/N,N/P ratio were the main limiting factors to later decomposition.During the litter decomposition for 720 days,C element for three litters showed net release pattern,N and P element showed enrichment-release pattern,K element present release-enrichment pattern.Ca and Mg element for assimilative branches of C.arborescens and branches of H.ammodendron were showed accumulation pattern,and for the branches of T.ramosissima was showed release-enrichment pattern

Mots clés : Tarim Desert Highway Shelterbelt; Woody halophyte; Decomposition rate; Nutrients; Regulation treatment;

Présentation (CNKI)

Page publiée le 17 janvier 2018