Space And Temporal Distribution Of Fine Root And Its Influencing Factors Research In Plantation Of Coastal Salt Land

At present, the coastal new city with fast development in the domestic, and large number of in them were built on reclaimed the near coastal saline-alkali land with the high concentration of salinity. There are very few plants can grow normally salinity land; Therefore, the research on the adaptability of saline-alkali land plants for greening tree species selection of coastal new city is of great importance. Fine roots are the main organ of plants absorb moisture and nutrient and the most vulnerable to high soil salt damage, which the change of its form and characteristics, biomass can reflect the plant’s ability to adapt to soil salinity differences.Saline-alkali land as the studied object in shanghai lingang new reclaimed area, on the basis of field investigation in this paper, selected 12 plantation samples; Using soil drilling method, mining method and endogenous monthly and vertical depth acquisition fine root samples in plantations, Simultaneous determination the ecological factors of soil electrical conductivity, moisture, temperature, etc. And sampling for determining the content of soil organic matter in indoor; Adopt two-way ANOVA analysis of variance, the least significant difference method, Least squares method, etc. The space-time distribution and influencing factors for biomass and morphologys of fine root (diameter<2mm) were systematic analysised in the plantations. And explore the adaptability of fine root in different tree species on soil salt, the main results were as follows:1. Different artificial forest fine root biomass (FRB) in 0-60cm (0-10 cm、10-20 cm、 20-30 cm、30-40 cm、40-60cm) depth distribution exist significant differences. Fine root distribution affected by soil salinity and mainly distributed in the 0-10 cm soil layer depth, FRB of 40-60cm soil layer lowest, and the concentrated distribution of fine root on the surface, and FRB decreasing exponentially with the increase of soil depth (P<0.05). FRB of living of Cinnamonum japonicum is largest for 540.56 g/m2, and Robinia psendoacacia minimum on the FRB in 148.17 g/m2. FRB of die root, root length density and specific root length change trend consistent with live fine roots distribution. There were also significant differences between FRB in different configuration mode (P<0.05). The FRB of tree+shrubs plant configuration model was 170.74 g/m2, tree plant configuration model for 148.49 g/m2 and shrubs plant configuration model for 116.88 g/m2, and the distribution of live fine roots are mainly in the 0-20 cm soil layer, and the proportion of the total FRB tree+shrubs plant configuration model was 78.29%, the tree model 78.04% and shrubs model 73.11%. In addition to the tree+shrubs model FRB are higher in 30 to 40 cm soil layer than 20-30 cm soil layer. The prompted a niche differentiation of fine roots might be affected by soil salinity.2. Different plantations seasonal dynamics of FRB were different in different months each years (P<0.05). FRB appeared bimodal type or unimodal type change between different species. Due to the effect of salt mainly the peak of FRB concentrated in July and September. The living fine root twin peaks appear time is also different in same species (P<0.05). The changing trends of dead and live fine root were corresponding. Every time when the peak of live fine roots appeared, the next peak of dead fine roots will appear. There are significant differences fine root biomass in different configuration mode (P<0.05). The FRB peak of tree configuration and brush configuration occurred in April and September. Whereas the peak of FRB in tree+shrubs model in July and September, and FRB were lowest in August.3. The production, decomposition and turnover of fine roots were studied, fine root production affected by the salt the average fine roots production in between 38.13～ 60.62 g·m-2·a-1. And found years growth of Robinia pseudoacacia is higher for 60.62 g·m-2·a-1 in four kinds. Broussonetia papyrifera lower for 38.13 g·m-2·a-1. Fine roots decomposition mechanism exist certain differences in different plant. Robinia pseudoacacia the fastest decomposition, decomposition rate was 0.036 kg·kg-1·month-1 turns to 0.91 times·a-1. Broussonetia papyrifera the slowest for 0.018 kg·kg-1·month-1 turns to 0.79 times·a-1.4. The regression analysis between fine root in different plants and configuration mode and environmental factors. Soil moisture, temperature and organic matter for FRB were positively relationship (P<0.05). The main limiting factors is the soil electrical conductivity in limit fine root biomass. And adaptation analysis of different plant fine roots morphological structure in soil salt, we found that fine root long show significant differences in different species (P<0.05), and fine root the longer plant growth the faster. Fine roots with strong plasticity, under salt stress by changing the root morphology, reduced growth at the expense of fine root, and increase the resistance of fine root to salt stress, which is one of the types of adapted to salt stress adaptive strategy. According to the result of salt-tolerant membership functions of plant, and thos plants divided into three categories, the first category of Elaeocarpus sylvestris, the second type of Metasequoia glyptostroboides and Taxodium distichum, and the rest belongs to the third class.The salt resistance in the top ten is Taxodium distichum > Metasequoia glyptostroboides > Aesculus chinensis> Robinia pseudoacacia> Ginkgo biloba> Bischofia polycarpa>Nerium oleander>Salix matsudana>Magnolia denudate.In conclusion, soil salt has obvious inhibitory effect to fine roots of plants in the coastal reclamation soil. The tree+shrubs plant configuration model for soil salinity control is better in three different kinds of plant configuration mode. The improvement effect of vegetation on salt land is a kind of positive feedback mechanism. At the same time, to solve the problem of ecological restoration in coastal reclamation soil. First of all, we should consider to construction of plant communitys by choosing the dominant species in local salt-tolerant plant (This article trees recommended:Elaeocarpus sylvestris, Taxodium distichum, Metasequoia glyptostroboides, Aesculus chinensis, Ginkgo biloba, Bischofia polycarpa, Nerium oleander, Salix matsudana, Robinia pseudoacacia, Ligustrum compactum, Sapium sebiferum Magnolia denudate, and so on; Brush recommended species:Nerium oleander, Broussonetia papyriera, Eurya emarginata; Trees-shrubs plants configure reasonable configuration type mainly recommended in salt land). Second, Plant of trees and shrubs from the perspective of soil saline mature plants-root-saline in different temporal and spatial scales; So as to achieve good ecological recovery purposes.