论文部分内容阅读
众所周知,森林除了生产木材、果品等产品,具有直接经济效益外,还有水土保持,防风固沙,抗旱御涝,净化空气,美化环境等多种生态效益。若把后者也折合成经济效益,往往是前者的数倍,甚至十几倍。防护林的生态效益就更大了,无论是水土保持林、防风固沙林,对农田均有增产作用。防护林引起减产的事闻所未闻,然而这对防护林经营者来说却是事实。防护林何以引起减产呢? 例如,河北省西部的太行山区近几年营造的防风固沙、水土保持等生态工程林,其经营权大都承包给了农户。而这些林地大都又紧挨承包者的粮田,头几年胁地欺粮效应还不太明显,但五六年后,一般是随着其生态效益的逐渐增强,胁地欺粮效应也随之加大。以水土保持的主要树种刺槐为例,其根系发达、粗壮,韧性强,5年
As we all know, in addition to forest production of timber, fruit and other products, with direct economic benefits, but also soil and water conservation, wind and sand, drought and waterlogging, air purification, landscaping and other ecological benefits. If the latter is also converted into economic benefits, often the former several times, or even ten times. The ecological benefits of shelterbelts are even greater. Both the soil and water conservation forests and windbreaks and sand-fixing forests have the effect of increasing the yield of farmland. It is unheard of by the shelter forest to cut production, but it is a fact for shelter operators. For example, in the Taihang Mountains in the western part of Hebei Province, ecological engineering forests such as windbreak and sand fixation and soil and water conservation have been mostly contracted to farmers. However, most of these forests are closely adjacent to the contractors’ grain fields. The effect of land-based bullying in the first few years is not obvious. However, after five or six years, the ecological benefits are generally enhanced and the effects of land-warming and bulging grains are also affected Increase. Take the Robinia pseudoacacia, the main tree species for soil and water conservation, as an example, the root system is developed, sturdy and strong, with a toughness of 5 years