覆膜方式对4种林木直播造林出苗率的影响

为了较好地解决山东省瘠薄山地春季直播造林中干旱和动物危害等问题，提高出苗率和保存率，以刺槐、紫穗槐、国槐和皂荚4种林木种子为试验材料，提出了一种新的覆膜方式（覆膜2），并通过与常规覆膜（覆膜1）和露地（对照）造林的对比分析得出：1）覆膜1提高了土壤日平均温度，有效地增加了土壤各层温度，为种子的萌发提供了适宜的温度，覆膜2表层温度低于土壤表层温度，适于晚春播种；2）覆膜2能有效利用有限降水，保水蓄水能力高于覆膜1，较好地解决了瘠薄山地造林的干旱问题；3）4种林木种子出苗率和苗高覆膜处理均显著性高于对照，覆膜1对小粒种子较好，覆膜2对大粒种子效果最好；4）对于瘠薄山地的直播造林，应多选取一些大粒种子，对于小粒种子，应加大单穴的播种粒数。

Effects of mulching on emergence rate of direct seeding of four tree species

In order to solve the problems of drought and animal damages and so on with direct seeding in spring in Shandong barren mountain area,taking four species tree seeds as the test material,a new film mulching(film mulching 2) was studied.The results showed that compared with the conventional film mulching(film mulching 1) and open field(control area),film mulching 1 increases day average temperature of surface and soil temperature of vertical profile,which supplies suitable temperature to the generation of seeds,and that the surface temperature of film mulching 2 is higher than that of the soil,which is suitable to sow in later spring.Film mulching 2 can effectively improve water content in the soil of 020 cm depth and use limited precipitation resource and the water preservation and storage capacity are higher than these of the conventional film mulching,which efficiently settles the problems of drought and supplied a perfect water environment to seedling growth.The enmergence rate and seedling height of four tree species with film mulching methods are significantly higher than those with open field treatment.And for litter seeds,including Robinia pseudoacacia L.and Amorpha fruticosa L.,the enmergence rate and seedling height with film mulching 1 are higher,while those are greater with film mulching 2 for big seeds,including Sophora japonica L.and Gleditsia sinensis Lam..Those big seeds should be choosen in direct seeding in barren field.For direct seeding with little seeds,more grains in each hole are needed to keep high enmergence rate.