2006年特大干旱中森林植被对农作物的防护作用

2006年四川发生了百年一遇的特大干旱。按照自然地理条件相近、森林覆盖率有较大差异的原则;同时,在同一行政区内按森林覆盖率的高低分成对照组。在县层面上,共3对对比县,在乡层面上共7对对比乡。对比县中,森林覆盖率高的一组森森覆盖率为34.20%～52.29%,平均为43.16%,森林覆盖率低的一组为16.60%～27.28%,平均为20.84%;对比乡镇中,森林覆盖率高的一组森林覆盖率为28.50%～56.23%,平均为41.29%,森林覆盖率低的一组为10.70%～19.12%,平均为14.61%。在干旱后期,调查了四川盆地丘陵区9个县14个乡镇主要农作物(水稻、玉米和红薯)的受灾率、成灾率和绝收率。调研结果表明,森林对农业的旱情具有一定的缓解作用。在县层次上,与森林覆盖率低的相比,森林覆盖率高的主要农作物(水稻、玉米和红薯)的平均受灾率、成灾率、绝收率分别降低16.6%、16.2%、4.0%;在乡镇层次上,与森林覆盖率低的相比,森林覆盖率高的主要农作物(水稻、玉米和红薯)的平均受灾率、成灾率、绝收率分别降低20.3%、19.7%、12.7%;与无农田防护林网相比,有农田防护林网的水稻平均受灾率、成灾率分别降低5.8%、22.8%,没有绝收现象,而无防护林的水稻平均绝收率为6.5%。

The Protective Effect of Forest Ecosystems on Crops in the Hilly Area in the Sichuan Basin in the Unusual Drought in 2006

A centennial drought event happened to Sichuan province in 2006;In this paper,by the princi- ple of similarity in the physical geography and biggish dissimilarity in the forest coverage,and according to high or low forest coverage,the investigated areas in the same district are to be grouped under two heads, one has a higher coverage,the other a lower coverage;So there are 3 groups in investigated counties,and 7 groups in investigated towns;In the contrast counties,the mean forest coverage of counties with higher coverage was 43;16%,from 34;20% to 52;29%,and that of counties with lower coverage was 20;84%, from 16;60% to 27.28%;And the mean forest coverage of towns with higher coverage was 41.29% ,from 28;50% to 56;23%,and that of towns with lower coverage was 14;61% ,from 10;70% to 19;72% in the contrast towns;Drought-covered percentage(which was defined as the ratio of area covered by drought to total seeding area),drought-affected percentage(which was defined as the ratio of area affected by drought to total seeding area)and drought-sterile percentage(which was defined as the ratio of sterile ar- ea by drought to total seeding area)of crop(e;g;rice,maize and sweat potato)were investigated in 14 towns of 9 counties in hilly areas in the Sichuan Basin at the end of arid season;The results indicated that drought-covered percentage,drought-affected percentage,and drought-sterile percentage of crops of coun- ties with higher coverage decreased by 16;6%,16;2% and 4;0%,respectively,as compared with coun- ties with lower coverage;And drought-covered percentage,drought-affected percentage,and drought-sterile percentage of crops in towns with higher coverage decreased by 20;3%,19.7% and 12;7%,respective- ly,as compared with towns with lower coverage;The results also demonstrated that drought-covered per- centage and drought-affected percentage of rice protected by farmland shelter forest decreased by 5.8% and 22;8%,respectively,as compared with rice unprotected by farmland shelter forest.