Study On The Protective Effects Of Four Farmland Shelterbelts In Salty Places Of Coastal Area

For grasping the variability of farmland shelterbelt age on the microclimate, and understanding the influences of shelterbelt on soil salinity, the paper selected four different age farmland shelterbelts(The tree species were I-107 of Populus) as the study object which planted in LongChi Town, ChangYi city of Shandong, and the common farm without the shelterbelts as the control check. Then the effects of dynamic, temperature, hydrological, salt content of soil and yield increase of crops were analyzed. Aims to certain the protective effects of farmland shelterbelt, then analysis the differences of benefits between different age farmland shelterbelt, get the optimal age of farmland shelterbelt finally. These results in terms to provide data support for the construction of farmland shelterbelt in the similar site conditions, and provide theory basis for regeneration of farmland shelterbelts. The results suggest as the following:(1) Wind speed, air temperature and soil temperature can be reduced under the work of four farmland shelterbelts, and the farmland shelterbelt also play a decreasing role in the water evaporation and soil salt content. In addition, the farmland shelterbelts have the abilities of increasing the air relative humidity and soil relative humidity, and also play a part in the wheat yield on a great degree.(2) The order of four kinds of farmland shelterbelts in protection effects showed that 10 years old>8 years old>6 years old>4 years old. This result showed that the protective effects of farmland shelterbelt are increasing with the age. On the whole, the farmland shelterbelts with 10 years old had a better protection effects, and it can provide an appropriate environment for local crop yield.(3) The correlations of 4 kinds of farmland shelterbelts were analyzed among seven microclimate factors. The results showed that: there have certain relationships among the seven microclimate factors, and it including the wind speed, air temperature, soil temperature, water evaporation, soil salt content, soil relative humidity and air relative humidity in different farmland shelterbelts.(4) The results of the principal component analysis showed that the air temperature is the main factor in four different farmland shelterbelts among the seven microclimate factors, and the factor load value is 0.145.To sum up, in the Longchi town of Changyi city in Shandong province or in the similar site conditions region, we should pay attention to the influences of different ages on the micro-environment, and also should pay attention to the adjustment of stereoscopic structure and vertical structure, aims to get the most suitable microclimate in the farmland shelterbelts, and promote the crop yield highly and steady.