Root Distribution Characteristics Of Typical Plant Community In Ulan Buh Desert

The root system is the main organ for plants to absorb water and nutrients.In this experiment,in order to study the adaptation strategies of the root system of plants to the environment in Ulan Buh Desert,the Ammopiptanthus mongolicus community,Artemisia ordosica community,and Haloxylon ammodendron community were chosen as experimental materials.The characteristics of root distribution of plants were studied:(1)The root distribution of different life form in the A.mongolicus community;(2)The root distribution of A.ordosica in different habitats;(3)Root distribution of different plantation ages of H.ammodendron.The research is conducted by the full digging method.For every 10 cm soil layer,the roots are divided into three types: coarse root(diameter ? 5mm),middle root(5 mm > d ? 1 mm)and fine root(d < 1 mm).The root dry mass and length were measured.Main results obtained are as following:(1)There were four forms of root system based on their distribution depth for seven plants in A.mongolicus community.The shrub A.mongolicus has the deepest root which was mainly distributed in soil depths within 120 cm.Two sub-shrub A.xerophytica and A.ordosica have deeper root which were mainly distributed within 80 cm and 70 cm,respectively.The perennial herb Oxytropis neimonggolica has deep root which was mainly distributed within 50 cm.Two perennial herb Jurinea mongolica,Allium mongolicum and the annual Corispermum mongolicum have shallow root which were mainly distributed within 30 cm,20 cm and 10 cm,respectively.The root depth order was: A.mongolicus(160 cm)> A.xerophytica(130 cm)> A.ordosica(100 cm)> O.neimonggolica(80 cm)> J.mongolica(30 cm)> A.mongolicum(20 cm)and C.mongolicum(20 cm).(2)In the A.ordosica community,the average root dry mass of A.ordosica was mainly distributed at 0-100 cm.The coarse root,middle and fine root dry mass of each plant were mainly distributed at 0-120 cm,0-100 cm and 0-50 cm,respectively.The length of the coarse,medium and fine roots were mainly distributed at 0-60 cm,0-40 cm and 0-50 cm,respectively.In the A.mongolicus community,the average root dry mass of A.ordosica was mainly distributed at 0-50 cm.Among them,the average dry mass of corase,middle and fine root were mainly distributed at 0-50 cm,0-70 cm and 0-50 cm,respectively.The length of the coarse,medium and fine roots is mainly distributed at 0-30 cm.For the growth of A.ordosica as associated plant in the A.mongolicus community,although the root system is vertically distributed within 100 cm,which is less than 220 cm of the A.ordosica community,the proportion of underground biomass input is higher than that of A.ordosica community.(3)The root biomass of two ages of H.ammodendron decreased with the increase of soil depths.The root dry mass of the 5-year H.ammodendron were 1045.25 g,which mainly distributed at 0-50 cm.The dry mass of coarse,middle and fine roots were 912.27 g,117.92 g and 15.06 g,respectively,which were mainly distributed at 0-50 cm,0-80 cm and 0-90 cm.The length of the coarse,medium and fine roots is mainly distributed at 0-110 cm,0-110 cm and 0-60 cm.The root dry mass of 37-year H.ammodendron were 671.57 g,which mainly distributed at 0-100 cm.The dry mass of coarse,middle and fine roots were 603.28 g,83.91 g and 13.52 g,respectively,which were mainly distributed at 0-110 cm,0-90 cm and 0-150 cm.The length of the coarse,medium and fine roots is mainly distributed at 0-180 cm,0-160 cm and 0-130 cm.Although the total biomass and root length of 37-year H.ammodendron are lower than 5-year H.ammodendron,its investment to the root system is higher than 5-year H.ammodendron,especially the fine root length is 1/3 longer than the 5-year H.ammodendron.Therefore,plants of several typical communities in Ulan Buh Desert adapt to the environment through changes in root morphology.Among them,the utilization of soil water in different depths was achieved through the spatial difference of root distribution,and thus the coexistence of species was promoted and the plant diversity was improved in A.mongolicus community.The root plasticity of A.ordosica can adapt to the habitat heterogeneity in Ulan Buh Desert.The H.ammodendron will increase the growing of the root as the age increases,and increase the proportion of the fine roots,so that it can use deeper moisture for its growth.