| Plant can be regarded as aggregation of modules. Studies on plant modules are helpful of discovering interaction of different modules , spatial distribution of biomass and different growth pattern formed in long-term evolution process .Furthermore , growth law of different module would be discussed . This thesis studies on different indexes of branching module, biomass of one-year-old branch and water-retaining capability of different modules. The results are summarized as follows:1. Branch angle is one of important indexes for evaluating the expansion ability of individual of different plants , which affect utilization of light ,temperature ,CO2 and allocation of biomass from different modules .Desert plants are divided into three types according to different branch angle : (1) small-branch angle type: branch angle of this type ranges from 35o to 50o ,including Sabina vulgaris , Melilotus suaveolens and 4 species of Calligonum ;(2) medium-branch angle type : branch angle ranges from 50o to 70o ,mainly including 8 species , such as Caryopteris mongolica, Hedysarum scoparium;(3)large-branch angle type: branch angle range from 50o to 70o ,consisting Pinus sylvestris var. mongolica and other 34 species.2. Length of branch is one of the indexes that indicate stretching capability of different branch. Desert plants are divided into three types by length of branch :(1) short-branch length type: including 6 species , such as Sabina vulgaris, Helianthemum soongoricum ,the third level of branch length is below 50cm ; (2) medium-branch length type: consisting of Pinus tabulaeformis and other 30 desert plants, scope of the third level branch ranges from 50cm to 150cm; (3) long-branch length type: including 11 species, such as Kochia prostrata, Atraphaxis replicate.3. Ratio of branch diameter (RBD) is the index indicating carrying capacity of different branch level .According to range of RBD 4:3 , desert plants can be divided into three types: (1) small-RBD type : RBD4:3 is below 3.5,including Sabina vulgaris,Calligonum captu-medusa and other 6 species; (2) medium-RBD type: RBD4:3 is between 3.5 and 5.0 ,mainly consisting 26 species ,such as Helianthemum soongoricum, Tamarix elongata; (3)large-RBD4:3 type: RBD4:3 is more than 5.0 , consisting Elaeagnus angustifolia and other 14 species .4．Overall bifurcation ratio(OBR) indicates the whole bifurcation capacity of desert plants and integrates information of branch quantity in different branching level. Desert plants can be divided into three type by the range of OBR : (1) small-OBR type : OBR is less than 5 and mainly includes Fraxinus americana and other 6 species ; (2) medium-OBR type : OBR range from 5 to 20 , mostly consisting 32 species, such as Calligonum rubicundum , which indicates most of desert plants belong to this type ; (3) large-OBR type: OBR is more than 20 , consisting Caragana intermedia and other 8 species .5.Stepwise bifurcation ratio(SBR) indicates bifurcation capability of different branching level . Desert plants can be divided into three types according to range of SBR3:4 : (1) small-SBR3:4 type: SBR3:4 is less than 5 , including Periploca sepium ; (2) medium-SBR3:4 type: scope of SBR3:4 is from 3.4 to 20, mainly including Calligonum klememtzii and other 37 species; (3) large-SBR3:4 type: SBR3:4 is more than 20 , consisting 10 species ,such as Atraphaxis replicata Lam. 6. Crown dimension (CD)indicates branching pattern of different plants by integrating branch length and ratio of branches . According to the range of CD , desert plants can be divided into three types : (1) small-CD type : the value of CD is less than 1.4000 , consisting Apocynum venetum and other 4 species ; (2) medium-CD type : CD range from 1.4000 to 1.8000, including 35 species , such as Atraphaxis frutescen , Periploca sepium;(3) large-CD type : the value of CD is more than 1.8000 , including Prunus mongolica and other 7 species.7. Desert plants can be divided into three types by bifurcation dimension (D): (1) small-D type : the value of D is less than 1...
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