北京的板栗多集中分布在怀柔、昌平、密云等区县,属燕山板栗。因品质极佳,在国际市场享有声誉,是换汇率较高的出口物资。历史上多为实生繁殖,种间、单株之间差异大,加上管理粗放,产量低而不稳,空棚树的存在又严重影响产量的提高,即使嫁接优种,在有些板栗产区仍表现出空棚,有的甚至成片是空棚树。经调查,品种不同亦程度不同地存在空棚率,一般为7-15％,高在40％以上。单株之间差异更大,空棚率低的为2-4％,高的 Beijing’s chestnut and more concentrated in Huairou, Changping, Miyun and other counties, is a Yanshan chestnut. Because of its excellent quality, its reputation in the international market is a high exchange rate of export materials. In the history of many real-life breeding, interspecific, large differences between single plant, coupled with extensive management, low yield and instability, the existence of empty shelter trees and seriously affect the yield increase, even grafted superior species, in some chestnut areas Still show the empty shed, and some even into a piece of empty shed tree. After investigation, there are varying degrees of different varieties of empty shed there, generally 7-15%, higher than 40%. The difference between the individual strains is even greater, with a low shelf shedding of 2-4%, high