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1 商洛地区人工油松林现状目前全区有以油松为主的用材林53万ha,中幼龄林约占85%。其中人工油松中幼龄林18.6万 ha,占全区中幼龄林面积的41.29%。大面积油松林的形成,大体有4个部分:一是国营林场营造起来的油松林。本区六县一市先后办起了以造林为主的林场9个,共造油松林4.83万 ha,保存3.31万ha,已郁闭成林进入间伐抚育阶段的2.44万ha。二是集体和个人造的油松林。全区约 相似文献
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广东省现有林地面积800万ha,森林覆盖率48.4％,仅松纯林就有125.7万ha。松树是不依赖石化资源的可栽培植物资源。从松树取得的松香,松节油是价廉易得的可再生植物资源,它广泛使用于造纸、橡胶、涂料、油墨、胶粘剂等各 相似文献
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商洛地区有国营林场19个,据二类调查资料,经营总面积为20.2万 ha,有林地面积4.9万 ha;总蓄积404.8万 m~3,占全地区森林总蓄积1550.6万 m~3的26.1%。二类调查数据与四五清查数据相比,有林地面积增加约7912ha,蓄积增加约40.2万 m~3。从调查结果发现该区国有林经营方面存在的问题是:①成过熟林比例大,没有合理 相似文献
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本研究是在路易斯安那州北部3个正常采伐后的火炬松成熟林中;设样测定林分下层硬阔叶树和火炬松剩余物生物量干重、养分含量。估计采伐后林分中约有52t/ha 的下层硬阔、22t/ha 的松采伐剩余物存在。这些生物量中氮、磷、钾、钙和镁的含量分别为208kg/ha、16kg/ha、114kg/ha、215kg/ha 和40kg/ha,这些养分随着薪炭材的收获而发生了潜在转移,但并没有明显地减少土壤中相应的养分含量。 相似文献
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1森林病虫害防治现状及所面临的形势1．1森林病虫害发生面积居高不下，扩散蔓延迅猛我省是森林病虫害发生的重点区域，其病虫种类多，种群数量大。全省现有森林病虫种类约1500多种，其中对森林造成严重危害的有近50种。“八五”期间我省平均每年发生森林病虫害2667万ha，占有林地面积的6％。随着造林绿化步伐加快，人工纯林的面积迅速增加，我省森林病虫的发生和危害呈明显上升趋势。1993年森林病虫害发生面积为25．24万ha，1996年上升到了27．29万ha，预计1997年发生面积将达到33．33万ha。其发生的主要特点具体表现为：一是马尾松毛虫、竹… 相似文献
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沈洪华 《中南林业调查规划》1992,(4)
怀化地区是湖南省重点林区,蓄积约占全省四分之一。全区辖十二个县(市)276万ha,其中林业用地193万ha(有林地118万ha)。“四五”森林资源清查活立木蓄积为6266万m~3,而“六五”清查只剩4507万m~3,十一年纯减1759万m~3,年平160万m~3。加上当时的林木生长量,这个时期的年森林资源消耗量在560万m~3左右, 相似文献
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日本甜柿在陕西省发展的前景 总被引：2，自引：0，他引：2
1 日本的甜柿生产 日本有果树面积34.4万ha,其中柿子约有3万ha,占果树面总积的8.57％,仍次于柑桔、苹果和板栗,居第4位,年产鲜柿30万t。甜柿在日本主要分布在山阳、四国等州和歌山、爱知等12个府县,栽培总面积约1.5万ha。日本甜柿专家认为:决定甜柿分布的关键是温度,年平均温度要求在13℃以上;生长期4—10月温度在17℃以上:果实成熟期8—10月 相似文献
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一、吕梁森林经营局残次林分改造的概况山西省吕梁森林经营局地处吕梁山脉南端,总面积31.39万ha,国有经营面积20.13万ha,其中有林地面积7.35万ha。在有林地面积中,约有3.67万ha为阔叶低质次生林分,约占全局有林地总面积的50%左右。这些低质次生林分,主要以栎类树种为主(占蓄积量的50%以上),树形多呈灌木状,主干低、分叉多,弯曲度大。单位面积蓄积量每亩平均3m~3左右,规格材出材率约为8%,而且规格材的材种主要是坑木,只有少量的民用建筑椽材、檩材和加工用原木。这就是低质阔叶天然次生林分,称之谓“残次林分”。根据这种资源状况,吕梁森林经 相似文献
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浙江山核桃丰产栽培技术 总被引：4，自引：0，他引：4
山核桃(Carya cathayensis)是重要的干果类树种,主要分布于浙、皖交界处的天目山区,总面积约1.8万ha。临安县是主产区,已有200年左右的栽培历史,现有林面积1.27万ha,最高年产量达5000t。 相似文献
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调整松林密度控制清源山松突圆蚧危害的试验 总被引：5，自引：0，他引：5
通过对发生区内松林进行间伐、修枝等营林措施将郁闭度调整至0 5左右,松林中松突圆蚧的虫口密度从调整松林密度前的每束2 61头下降至0 63头,虫口密度下降75 86%,表明调整松林密度能有效地控制松突圆蚧对松林的危害;同时发现,阳坡上松林的虫口密度较阴坡上松林的虫口密度大,从阳坡向阴坡逐步过渡,松突圆蚧的虫口密度也随之下降,表明松突圆蚧的虫口密度与坡向有关,在景区绿化规划设计上应针对不同的坡向营造不同的树种,以防止松突圆蚧的发生和危害。 相似文献
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The change of pine scale (Hemiberlesia pitysophila Takagi) population density on pine forest in urban park between treatment (tending operations) and CK (no tending operations) was researched in this paper. The results were shown as follows: population density declined to 0.63 head per bundle from 2.61 heads per bundle when crown density of pine in urban park had become 0.5 or so by means of cultivation activities such as felling, pruning and thinning and so on, and drop got to 75.86 percent. The pinewoods would soon get revived once using these cultivation activities, so tending operations was main measures controlling over harm of pine scale in urban park; At the same time, population density of pine scale on pinewoods in the sunny slope was more than that in the somber slope and it had become less and less from sunny slope to somber slope. Therefore, tree species must be chosen in the planning and design of urban park for preventing harm and happening of pine scale. 相似文献
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松突圆蚧危害程度的划分是以2年生枝条上松针的保存率，枝梢形状和生势作为依据，用60株平均木树干解析连年生长量验证，准确率达87．735，对患东，深圳等6个县（市）9个调查区60块标准地的综合调查结果：危害轻度和中等的林下植物多为草本植物群丛组、桃金娘群丛，其土层松厚肥沃；危害较严重和严重的林下植物多为芒萁群丛、马唐＋芒萁群丛及山的上部，其土壤酸度大、瘠薄、林分因子中，郁闭度与危害程度呈多项式二次幂关系，郁闭度0．5－0．65的危害最轻；水汽压与郁闭度也呈多项式二次幂关系，郁闭度0．5－0．6的水汽压最低。合理的修枝间伐，控制林分郁闭度在0．5－0．65之间。可提高林木的抗虫性。 相似文献
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连续3年对广东省西江林业局直属9个林场的马尾松林分设立标准地进行松突圆蚧的虫情调查,同时调查胸径生长情况。结果表明：被调查标准地所在的高要、德庆、云城、新兴、云安、郁南等区县均为松突圆蚧发生区;各标准地因受害时间及危害程度不同,造成虫口密度有极显著差异;不同龄组的马尾松均受到松突圆蚧的危害,同一时期,林龄越大,虫口密度越大;除通门林场外,其他各标准地由于受到松突圆蚧的危害,森林资源增长缓慢。建议将西江林业局受松突圆蚧危害的马尾松林纳入广东省林分改造工程建设范畴,间伐或皆伐后套种或全面更新阔叶树种,从根本上遏制松突圆蚧的虫情升级和蔓延。 相似文献
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Richy J. Harrod David W. Peterson Nicholas A. Povak Erich K. Dodson 《Forest Ecology and Management》2009
Forest thinning and prescribed fires are practices used by managers to address concerns over ecosystem degradation and severe wildland fire potential in dry forests. There is some debate, however, about treatment effectiveness in meeting management objectives as well as their ecological consequences. The purpose of this study was to assess changes to forest stand structure following thinning and prescribed fire treatments, alone and combined, in the eastern Cascade Mountains of Washington State. Treatments were applied to 12 management units, with each treatment combination replicated three times (including untreated controls). Thinning modified forest structure by reducing overall tree density by >60% and canopy bulk density by 50%, and increased canopy base height by ∼4 m, thereby reducing susceptibility to crown fire. The prescribed fire treatment, conversely, did not appreciably reduce tree density or canopy fuel loading, but was effective at increasing the density of standing dead trees, particularly when combined with thinning (37 snags/ha increase). Prescribed fire effects were more pronounced when used in combination with thinning. Thinning was more reliable for altering stand structure, but spring burning was lower in intensity and coverage than desired and may have led to results that downplay the efficacy of fire to meet forest restoration goals. 相似文献
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Thinning treatments in second-growth forest may be a practical means of accelerating the development of certain old-growth structural features in regions where old stands are presently uncommon. We used CANOPY, an individual-tree model calibrated with data from thinned and unthinned stands, to simulate effects of thinning on growth rates and development of old-growth structural features in second-growth northern hardwoods. Three simulated, moderately heavy thinnings over a period of 45 years nearly doubled the predicted mean radial increment of canopy trees, percent of stand basal area in large trees, and area of canopy gaps. Compared to untreated stands, thinned stands had fewer dead trees per ha, but the dead trees were larger in size and the overall volume of snags and logs was little affected. In a 77-year old even-aged stand, moderately heavy thinning was predicted to reduce the time needed to attain the minimum structural features of an old-growth forest from 79 to 36 years. Simulated treatments in an older, uneven-aged stand gave mixed results; the moderately heavy treatment stimulated individual tree growth, but the removal of some medium-sized canopy trees in conjunction with natural mortality delayed the development of old-growth structure. Total volume of dead wood may still be deficient under the thinning regimes investigated in this study, but predicted live-tree structure 45 years after moderately heavy thinning was typical of stands in the advanced transition and steady-state stages of old-growth development. Results suggest that thinning can substantially accelerate the development of old-growth structure in pole and mature northern hardwoods, but response in older, uneven-aged stands is more modest, and treatments in these stands may need to be more conservative to achieve restoration goals. 相似文献
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We sought to quantify changes in tree species composition, forest structure and aboveground forest biomass (AGB) over 76 years (1930-2006) in the deciduous Black Rock Forest in southeastern New York, USA. We used data from periodic forest inventories, published floras and a set of eight long-term plots, along with species-specific allometric equations to estimate AGB and carbon content. Between the early 1930s and 2000, three species were extirpated from the forest (American elm (Ulmus americana L.), paper birch (Betula papyrifera Marsh.) and black spruce (Picea mariana (nigra) (Mill.) BSP)) and seven species invaded the forest (non-natives tree-of-heaven (Ailanthus altissima (Mill.) Swingle) and white poplar (Populus alba L.) and native, generally southerly distributed, southern catalpa (Catalpa bignonioides Walt.), cockspur hawthorn (Crataegus crus-galli L.), red mulberry (Morus rubra L.), eastern cottonwood (Populus deltoides Bartr.) and slippery elm (Ulmus rubra Muhl.)). Forest canopy was dominated by red oak and chestnut oak, but the understory tree community changed substantially from mixed oak-maple to red maple-black birch. Density decreased from an average of 1500 to 735 trees ha(-1), whereas basal area doubled from less than 15 m(2) ha(-1) to almost 30 m(2) ha(-1) by 2000. Forest-wide mean AGB from inventory data increased from about 71 Mg ha(-1) in 1930 to about 145 Mg ha(-1) in 1985, and mean AGB on the long-term plots increased from 75 Mg ha(-1) in 1936 to 218 Mg ha(-1) in 1998. Over 76 years, red oak (Quercus rubra L.) canopy trees stored carbon at about twice the rate of similar-sized canopy trees of other species. However, there has been a significant loss of live tree biomass as a result of canopy tree mortality since 1999. Important constraints on long-term biomass increment have included insect outbreaks and droughts. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(5):446-459
The mean tree height of 73 forest stands in a 1000 ha forest area was determined from canopy heights generated by automatic image matching using a digital photogrammetric workstation and digitized panchromatic aerial photographs with a scale of 1:15 000. First, the mean height of each stand was computed as the arithmetic mean of the quantile corresponding to the 75th percentile of the distribution of the canopy heights from the image matching within square grid cells with cell sizes of 236-400 m2. The mean heights from the image matching underestimated the true heights by 5.42 m. Secondly, field-measured mean tree heights of 165 georeferenced sample plots distributed systematically throughout the 1000 ha forest area were regressed against the mean heights derived from the image matching. The regression equations were used to predict the mean heights of the 73 stands. In very young forest stands, the predicted mean heights overestimated the true heights by 0.4 m and the precision was 0.9-1.0 m. In young and mature stands, the average difference between predicted height and ground-truth ranged between -1.6 and 0.5 m, and the precision ranged from 1.1 to 2.1 m. 相似文献