加强林场中幼林抚育及低质林改造是恢复森林生态的有效途径 摘 要：森林生态系统只有保持结构和功能的完整性，并具有抵抗和恢复能力，才能长期为人类社会服务。本篇着重论述了加强森林抚育及低质林改造是恢复森林生态的有效途径及其可行性和必要性。
关键词：森林抚育； 低质林改造； 森林质量； 生态
一个森林生态系统只有保持了结构和功能的完整性，并具有抵抗和恢复能力，才能长期为人类社会提供服务。但是由于人类的干扰导致森林生态系统的原有结构被破坏，从而致使森林生态系统退化，引起水土流失、土壤退化、洪灾等等。由于植被遭到破坏，坡地表面的土壤受到暴雨冲击，土壤孔隙被堵，雨水下渗速度随之减少，形成大量径流顺坡而下，同时带走大量表土、养分，使这些地区变成“走水、走土、走肥”的三走之地，土壤有机质含量降低，N、P、K等元素缺乏。因此，应该从维护国家安全、维护人类自身安全的角度出发认识维护森林生态安全的重要性，建立与健全森林生态系统安全保障体系，为社会、经济、环境的可持续发展提供不可缺少的基础。
1 森林质量的下降是导致生态环境恶化的根源
大岗林场的森林是镇赉县西北的天然屏障。近年来，随着国民经济的持续增长和经济实力的进一步提高，工业化水平的提高和人口的高速发展，生态环境恶化，自然灾害频繁。仅从大岗林场来看，全场水土流失面积已由90年代的500 hm?扩大到目前的1300 hm?。农业抗灾能力十分脆弱，全场水旱成灾率较高。由于生态环境恶化，风、
沙、旱成灾面积逐年增加，环境污染加剧，严重影响了我场农业和国民经济的发展及人民生活水平的提高。我们从第五次森林资源清查来看，导致生态环境恶化的一个重要原因就是森林资源的破坏，严格地说是森林质量的降低，既森林的林分结构、森林公顷蓄积量的降低。建场初期，有林地面积为9000多公顷，蓄积38万m?，每公顷平均蓄积量为40 m?，森林覆盖率为36.9%。而目前全场有林地面积为11300 hm?，蓄积30万m?，每公顷平均蓄积量为26.5 m?，森林覆盖率为41.9%。从上述数据来看，多年来森林面积增加而公顷蓄积下降，说明了多年来环境恶化的根本原因是森林林分质量的降低。也进一步论证了专家的测算，即当森林蓄积达到每公顷80 m?以上时，森林涵养水源等生态效能才能发挥的充分，而低于80 m?以下，生态效能相对来说是较为低下的理论。
2 加快中幼龄林抚育、低质林改造建设的可行性
2.1 在中幼龄林抚育、低质林改造中确立的一系列规章和政策
我们从90年代开始在封山育林的基础上，开展了中幼令抚育和低质林改造工作，制定了《大岗林场森林抚育、改造技术规程》。近几年来，我场针对幼龄林面积大，等待抚育的林分多的特点，制定了诸多有利于幼龄林抚育的政策.如：“抚育的小材小料可以抵抚育的工资”，“不安排抚育的不允许进行主伐’。并制定了《人工林抚育技术细则》，把人工幼林抚育列入了计划，促进了中幼龄林抚育、低质林改造工作的开展，并在已开展的中幼龄林抚育、低质林改造活动中积累了一定的经验。
2.2 中幼龄林抚育、低质林改造建设中的经验
在几十年的森林经营中，积累了一定的经验。如1998年对皆伐后天然更新起来的中幼龄林进行生长抚育，3年进行了调查得出如下数据:抚育的林分平均胸径每年净生长为1 .08 cm，而未抚育的林分平均胸径每年净生长仅为0.3 cm，林分公顷蓄积则分别为130 m?和90 m?。
2.3 中幼铃林抚育、低质林改造建设效益显著
2.3.1
生态效益
森林抚育、低质林改造不但能改善林分结构，提高森林质量，而且有利于改善林分的卫生状况，增强抗御自然灾害的能力。据研究，在幼、中令林阶段，由于林木密度较大，降雪后承受雪的压力比密度低的林分大，每公顷林冠受到雪压的重量可达500多t，林木胸高断面上每平方厘米承受的压力达2.5 kg；林木稀疏后，每公顷林冠受到雪压的重量可降到300多t，林木胸高断面上每平方厘米承受的压力可降至0.5 kg。由于森林抚育、低质林改造改善了林分的卫生状况，病虫害可下降90%以上，增强了抗灾的能力。
2.3.2
经济效益
中幼龄林抚育投入少，见效快，在一个森林经营周期内(10年)抚育林分与未抚育林分，林分生长量年净增每公顷3 m?，10年净增蓄积量30 m?，新增木材产值9000元/公顷(按300元/公顷计算)，是森林抚育费用900元/公顷的10倍。如果将全场1万多公顷的森林全部抚育一遍，每年至少可净增蓄积量3万m?，新增木材产值900万。
2.3.3
社会效益
中幼龄林抚育工程不仅缓解了大中径级后备森林资源的不足，而且壮大了林业产业，增加了职工收人。森林抚
育和改造投入资金的70%可转化为劳务收人，以年抚育和改造1000hm?计算，年均投资90万元，相当于每年可吸纳近万个剩余劳动力，社会效益显著。
3 加快中幼龄林抚育、低质林改造建设的必要性
3.1 加快中幼龄林抚育、低质林改造建设是提高森林资源数量和质量的迫切需要
目前由于未能采取切实有效的抚育和改造等培育措施，致使部分中幼龄林因单位面积株数太多，密度过大，生长不良，严重影响了林分的质量;部分中幼龄林杂草丛生，霸王树、灌木等非目的树种占据主要生长空间。严重制约着目的树种的生长，影响林木的生长发育;部分中幼龄林因自然稀疏，枯死木急剧增多，枯立木比重显著提高，为森林病虫害的发生和蔓延提供了场所，为森林火灾、雪压、风倒等自然灾害创造了条件;部分中幼龄林因公顷株数太少、林分质量低，影响了林地生产力的发挥，影响了森林效益的发挥。而加强森林抚育和改造，可以改善林分生长条件，促进林木生长，据调查，抚育后的林分生长率可提高了6.8%，提高了林分的生产力和森林资源的质量。
3.2 加快中幼龄林抚育、低质林改造工程建设是充分发挥森林各种功能的需要
我们曾对不同的林分进行了调查研究，结果发现不同林分其生态效益发挥的差异较大。正是进行了森林结构和类型的调整，改善了林木生长发育的生态环境条件，促进了林分质量的提高，增加了森林的整体效能，使森林的多种效能得到了充分发挥。
3.3 加快中幼龄林抚育、低效林改造建设是况固造林绿化成果的
需要
多年来 ，国家集中人力、物力、财力，大抓造林绿化建设取得重大进展，但是存在一个非常重要的问题，就是保存率太低，影响了造林绿化成果。对我场的更新造林进行了普查，结果是保存率仅为65.2%，目前在加强更新造林的基础上，必须加速进行森林的抚育和改造，提高造林的成活率、保存率、成林率。
3.4 加快中幼龄林抚育、低质林改造工程建设是强化森林经营管理的需要
长期以来 ，我们对森林经营这一关键环节没有给予足够的重视。由于没有投资，加上管理工作滞后，致使抚育、改造工作欠账十分严重。为了扭转这种状况，必须加强森林经营工作，抓紧进行中幼令林抚育和改造工程的建设。
To strengthen forestry ZhongYouLin tending and low-quality forest reconstruction is an effective way of recovery of forest ecosystem Pick to: the forest ecological system is only to keep the integrity of the structure and function, and has the resistance and resilience, to serving human society in the long run.This paper focuses on the strengthen forest tending and low-quality forest reconstruction is an effective way to restore forest ecological and its feasibility and neceity.
Key words: forest tending; Low-quality forest transformation; The forest quality; The ecological
A forest ecosystem is only to keep the integrity of the structure and function, and has the resistance and resilience, can provide service for
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human society in the long run.But caused due to human disturbance of forest ecosystem destroy structures, thus causing degraded forest ecosystems, cause soil erosion, soil degradation, floods and so on.Due to vegetation destroyed, soil impacted by heavy rain on the surface of the slope, soil pore blocked, le rain infiltration rate, down a lot of runoff formation, at the same time take away a large number of top soil, nutrients, make the region into a \"slice, go, go fat\" SanZou land, soil organic matter content is reduced, lack of N, P, K and other elements., therefore, should from safeguarding state security, maintain human security Angle to know the importance of maintaining forest ecological safety, establish and improve the forest ecological system security guarantee system, for the sustainable development of society, economy and environment indispensable foundation.
1 a drop in the quality of forest is the root of leads to the deterioration of the ecological environment
DaGang forest farm in the forest is a natural barrier town county northwest of adlai was in charge.In recent years, with the steady growth of national economy and economic strength to further improve, the improvement of industrialization and the rapid development of population, the deterioration of ecological environment and frequent natural disasters.Only from the point of DaGang forest farm, to the area of soil and water lo has been in the 90 s from 90 hm? Expanded to the current 1300 hm? .
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Vulnerable agricultural disaster, severe hazard rate is higher.Due to the deterioration of ecological environment, wind, sand and drought inundated area increased year by year, the environmental pollution, serious influence the development of my field of agriculture and national economy and the improvement of people\'s living standards.We from the fifth forest resource inventory, leads to the deterioration of the ecological environment is an important reason why the destruction of the forest resources, lower quality strictly, a forest, forest stock volume of forest structure, forest ha already reduced.Early construction field, the forestland area of more than 9000 hectares, 380000 m? , the average volume per hectare of 40 m? , the forest coverage rate of 36.9%.And the whole forestland of 11300 hm? , 300000 m? , the average volume per hectare is 26.5 m? , the forest coverage rate of 41.9%.From the above data, forest area increases with the ha decline for years, shows that over the years, the root cause of environmental degradation is the forest stand quality decreased.Further demonstrated the calculations, the experts when forest accumulation reached 80 m per hectare? Above water conservation forest ecological efficiency, such as to play fully, and le than 80 m? , under the theory of ecological efficiency is relatively low. 2 to speed up the construction feasibility of transforming sapling forest, low-quality forest
2.1 in the young forest tending, low-quality forest reform established a
series of regulations and policies in the us since the 90 s on the basis of afforestation, carried out in young to cradle and low-quality forest reconstruction work, formulated the \"technical specification\" DaGang forest farm forest tending, reconstruction.In recent years, I field in young forest area is large, waiting for tending stand more characteristic, established many of sapling forest policy.Such as: \"the cradle of the little wood material can be arrived in raising wages\", \"don\'t arrange tending does not allow for final felling.\'and set the rules of plantation tending technology, include artificial young forest tending on the plan, promoted in the young forest tending, low-quality forest reconstruction work, and has been carried out in the young forest tending, forest of low-quality renovation accumulated certain experience in the activities.
2.2 sapling forest, low-quality forest reform in the construction experiences in decades of forest management, accumulated certain experience.Such as 1998 years for natural regeneration after clear cutting up the are grown, young forest tending, three years has carried on the survey data as follows: raise the stand average diameter at breast height net growth each year to 1.8 cm, tending stand average diameter at breast height of annual net growth of only 0.3 cm, stand ha accumulation is 130 m respectively? And 90 m? .
2.3 in the young forest tending, low-quality forest bell renovation construction benefit is remarkable
2.3.1 ecological benefit forest tending, low-quality forest transformation can not only improve the stand structure, improve the quality of forest, and to improve forest health condition, enhance the ability of resistance to natural disasters.According to research, makes forest stage, in the young, because of its high density of trees, snow snow preure after bigger than low stand density, canopy per hectare is the weight of the snow preure can reach more than 500 t, every square centimeter on trees chest high section preure up to 2.5 kg; Sparse trees, each hectare canopy under the weight of the snow preure to be more than 300 t, trees chest high profile per square centimetre of under preure can drop to 0.5 kg.Because the forest tending, low-quality forest reform improved the health of forest stand, plant diseases and insect pests can be decreased by more than 90%, enhances the ability of the disaster.
2.3.2 economic benefits in the young forest tending le investment, quick effect, in a forest management cycle (10 years) bare stand and tending forest, forest stand growth in net 3 m per hectare? Net increase of volume of 30 m, 10 years? Output value of 9000 yuan/ha, new wood (pre) of computation of 300 yuan/ha, forest tending cost is 10 times as much as 900 yuan/ha.If all will be full of more than 10000 hectares of forest tending, annual net increase of volume of at least 30000 m? Output value of 9 million, the new wood.
2.3.3 social benefits in the sapling forest engineering not only relieves the
large and medium size level backup the shortage of forest resources, and expand the forestry industry, increased the worker income.Forest tending and 70% of the money can be converted into labor income, tending and upgrading 1000 hm? Computation, an annual investment of 900000 yuan, equivalent to a year to absorb nearly all surplus labor, social benefit is remarkable.
3 to speed up the construction of young forest tending, low-quality forest transformation in neceity
3.1 to speed up the construction of sapling forest, low-quality forest reform is to improve the urgent needs of the quantity and quality of forest resources at present due to the failure to take effective parenting and reforming the cultivating measures, such as the part in the young forest because of the number per unit area is too much, too much density, grow bad, seriously affect the quality of the forest; Overlord weeds in part sapling forest, trees, shrubs and nontarget species occupied the main growth space.Severely restricts the objective tree growth, affect forest growth and development; Part due to the natural thinning of sapling forest, unthinned stands sharp increase, considerably increase the proportion of dry wood, for the occurrence and spread of forest diseases and insect pests, such as forest fire, snow preure, and wind down created the condition for natural disasters; Part number is too little for ha of sapling forest, the forest stand quality low, influence the exertion of forest land
productivity, forest benefit is greatly influenced.And strengthening forest tending and transformation, can improve the stand growth conditions, promote the growth of forest trees, and according to the survey, after raising the forest stand growth rate can be increased by 6.8%, improve the quality of the forest productivity and forest resources.
3.2 accelerate the reform of sapling forest, low-quality forest in engineering construction is the need of forest functions into full play we have conducted a study of different forest stand, found that different forest it play the differences of ecological benefits.Adjustment of forest structure and type, improved forest tree growth and development of the ecological environment, promoting the improvement of the forest stand quality, increase the overall efficiency of the forest, the forest of a variety of performance got into full play.
3.3 accelerate the reform of sapling forest, the low efficiency in construction is KuangGu afforestation achievement needs over the years, countries concentrate manpower and material resources, financial resources, high holding afforestation construction made great progre, but there is a very important problem, BaoCunLv is too low, affected the afforestation achievement.For my field survey, the reforestation of the results is BaoCunLv is only 65.2%, currently on the basis of strengthening reforestation, must accelerate forest tending and renovation, increase the rate of afforestation survival rate, and forest.
3.4 accelerate the reform of sapling forest, low-quality forest in engineering construction is the need of strengthening forest management for a long time, we are a key link on forest management did not give enough attention.Because there is no investment, and management lag, cause tending, reconstruction work very serious debt.In order to reverse this situation, must strengthen forest management work, with the young forest tending and project construction.
