The Study On Root-system Structure Of Shelter-belt

The spatial structure of root-system of shelter-belts composed of different species and matching patterns was investigated, the impact of root-trench on the tree-root distribution was discussed, with the aim to evaluate their effects on the root competition to crops.The field research methods of soil coring and digging were used, to measure the distribution of roots and to collect root samples. In the laboratory, The sampled cores and roots were washed, scanned, dried and weighted. Win-RHIZO system was used to analyze the different morphological characters of root samples. Then, the indexes of roots per unit soil volume were calculated as root biomass (g/m3), root length (m/m3), root surface area (m2/m3), root volume (cm3/m3) and root tips (tips/m3).The root distribution characters of the shelter-belts with different tree species, matching patterns, and with/without root-trench were analyzed and compared. It was found: 1) the extent of root competition between forest belts and crops for the Poplar forest-belt, which has been root-trenched several years ago, was stronger than those belts without root-trench; 2) The root competition to crops of the tightly structured forest-belt is stronger than those with sparse structure. 3) The extent of root competition of the inter-cropping poplar forest-belt is approximately equal to that of the two-row-belt of poplar without root-cut trench;4) The willow forest-belt has less root competition to crops than the poplar forest-belt without root-trench;5) Although root-trench can alleviate the root competition between forest-belts and crops for a shorter time period, the root-trench measure is not an effective method to reduce the root competition for a long time period, because it will lead to a much stronger root competition later. It seems to be very necessary to further look for long-time effective ways, such as in the aspects of shelter-belt design and tree species selection, to alleviate the root competition.