共查询到20条相似文献，搜索用时 203 毫秒
1.
2.
针对辽西地区油松纯林多、小老树多、生长量低、病虫害严重的问题对30年生的油松纯林实施带状皆伐工程,皆伐带与保留带比例为1：1,带宽50m,同年在皆伐迹地上栽植山杏、刺槐。土壤为栗褐土,土层厚度45～50cm,坡度6°,年平均降水量450mm。对油松×山杏混交林、油松×刺槐混交林、油松纯林三种模式的树木生长状况、林下植物多样性、林下土壤物理性状和养分状况、水土保持效益等方面进行分析评价。结果表明：山杏、刺槐与油松混交后,可改善油松林分结构,形成人工针阔混交林,促进了油松生长,混交林林下植被盖度增加,植物种类增多,枯落物的厚度加大,林地的渗透性及土壤理化性质有所改善,减少了地表径流量和土壤侵蚀量。 相似文献
3.
油松纯林改造试验研究 总被引：1，自引：0，他引：1
本文在调查了油松纯林及采用带状皆伐改造后形成的混交林的生长情况后,从混交后林分的稳定性及生态效益等方面,论述了油松纯林的改造是可行的,也是成功的。 相似文献
4.
5.
半干旱地区油松纯林改造成混交林效益分析 总被引：4，自引：0，他引：4
半干旱地区大面积的油松纯林，不仅生产力水平低、抗性差，林分的涵养水源、防止水土流失等重要生态功能也因林分结构单一，缺乏灌木覆盖而不尽理想。为改善林分生态条件，提高林木生长量和林分的综合效益，于１９８３年分别在凌源市、喀左县、建平县对２８年生的油松纯林进行了改造试验。结果表明，选择刺槐、沙棘、柠条、黄栌等阔叶树种，在带状皆伐的砍伐带上造林，经多年研究效果显著。油松混交林与油松纯林相比，相对湿度提高０２％～２２％，林内温度降低０１～１℃，土壤有机质含量提高００３％～０７３％，减轻容重００５～０２ｇ／ｃｍ３，有虫株率降低５０％，虫口密度降低８４％，林分虫害明显减弱，油松树高、胸径生长量比对照分别提高１４９％、２２９％。 相似文献
6.
人工成过熟纯林具有林分组成单一、群落结构简单、综合效益低下等弊端。可通过渐伐、群团状皆伐、带状皆伐,人工补植珍贵树种等方法将其改造培育为近自然林。 相似文献
7.
天然更新油松林木生长进程分析 总被引：1，自引：0，他引：1
《山东林业科技》2016,(1)
本文通过对油松林皆伐后天然更新29年林分平均木树干解析,分析得到了不同于普通油松人工林的生长进程,从而得出结论:油松天然落种、自然出苗能力很强,只要条件具备,就能实现天然更新;依靠天然更新形成新的油松林林地生产力得到较大的提高。 相似文献
8.
9.
赤松纯林更新为油松麻栎混交林的试验 总被引：2，自引：0，他引：2
采用伐前更新和伐后更新相结合，播种和植苗造林相结合的方法，成功地将赤松纯林更新为以油松为优势树种的油松、麻栎单层混交林。更新后的混交林分，土壤理化性质得到改善，土壤有机质含量达到３．０５％，是油松纯林的１．９２倍；林地生产力有明显提高，混交林油松的平均树高和直径分别是纯林的１．２４和１．１５倍，混交林林木蓄积量是油松纯林的１．６５倍。 相似文献
10.
11.
Broad-lcavedKoreanpincforcstisthcclimaticclimaxconinunitVofnortheastmoun-tainousregionsofChina.AsthemaintreesPecies,Koreanpinehasexccllentwood.AgreatattentionbasbccnpaidtorecoveringtheseforesttyPesafterharvesting.Additional1y,KoreanpineisoneofkeyregcncrationtreesPeCiesinthisregion.TherehasbeenlargeareaofKorcanpincplantations.Howevcr,thercaresomeproblemsncedingtobestUdicdfwtheramongwhichoneistoselectsuitabIeropenerationapproacl1esofKoreanpincforesls.WHATISTHEPROBLEM?ThcnatUralregen… 相似文献
12.
经对沙地樟子松人工林进行不同方式的结构调整试验,结果表明:对40年生左右染病较重的沙地樟子松人工林进行卫生伐引导成疏林草地,7年间疏林处理的胸径生长量比对照的高62.96%,疏林处理和对照的蓄积收获总量差异不大,疏林的树势得到增强,病害防控效果明显。对30年生左右的沙地樟子松人工林进行改造后,伐1留1从伐后第3年胸径生长量显著超过对照;伐1留1的总蓄积最大;伐1留1和伐2留2改造措施均对病害有抑制作用,且伐1留1效果更明显。处理的冠层结构发生了明显的变化,群落的透光率上升。疏林模式和林分改造措施有利于改善林分水分状况,在干旱年份效果更加明显。对30年生左右的沙地樟子松带状人工林,选用6个树种进行树种结构调整,建立了5种混交模式林,增加了树种多样性,改善了林分树种、年龄结构,丰富了沙地樟子松人工林景观,提高了林地生产力。 相似文献
13.
对日本冲绳岛北部相同土壤条件下的琉球松纯林及其混交林的土壤氮素及有机碳素、地表凋落物量、枯枝落叶量以及土壤氮素矿化速率进行了比较研究。结果表明 ,琉球松纯林的地表凋落物层氮、碳平均贮量分别为133kg·hm- 2 和 7199kg·hm- 2 ,混交林则分别为 10 5kg·hm- 2 和 6 14 3kg·hm- 2 。然而 ,混交林地表 10cm矿质土层的氮、碳贮量则显著高于纯林 ,氮素比纯林多 4 93kg·hm- 2 ,碳素多 5 5 5 4kg·hm- 2 。在 30d的实验室培养实验中 ,混交林表层土壤的氮素矿化速率高于纯林 18% ;而且 ,混交林的落叶和土壤的碳氮比值亦明显低于松纯林。混交林土壤的年平均矿化氮素 (NH4 NO3- )浓度高于纯林 2 2 %。与松纯林相比 ,混交林通过枯枝落叶年平均氮素归还量多 4 3 7kg·hm- 2 ,碳素归还量多 16 5 5kg·hm- 2 。混交林具有较高的氮素归还量 ,主要是混交林的针叶含氮含量较高以及大量的高含氮量的阔叶落叶所致。上述结果充分说明针阔混交导致了林分氮素循环的变化。 相似文献
14.
试验选用木麻黄4个优良无性系来改造低效防护林。试验表明,在海岸前沿基干林带改造中,采用隔行带状改造效果较好,木麻黄低效林经过改造,6 a后可以达到生长快、短期内恢复基干林带的目的。在后沿片林内通过采用木麻黄优良无性系等综合措施块状改造后的林分与保留老林带相比,除了平均胸径生长略低1.2 cm外,其保存率、树高和冠幅生长量显著高于保留低效林的51.17%、2.3%和25.71%。 相似文献
15.
Frederick Cubbage Patricio Mac Donagh José Sawinski Júnior Rafael Rubilar Pablo Donoso Arnaldo Ferreira Vitor Hoeflich Virginia Morales Olmos Gustavo Ferreira Gustavo Balmelli Jacek Siry Mirta Noemi Báez José Alvarez 《New Forests》2007,33(3):237-255
Timber investment returns were estimated for the principal exotic and selected native species in the Southern Cone of Latin
America and in the Southern United States. Exotic eucalyptus plantations in South America were most profitable, with internal
rates of returns (IRRs) ranging from 13% to 23%, followed by exotic loblolly pine, with IRRs from 9% to 17%. Average loblolly
pine plantation returns in the US South were less profitable, with an IRR of about 9.5%, and natural forest management in
the South had IRRs of 4% to 8%. Subtropical native species plantations of the best araucaria and nothofagus species had reasonable
financial returns, with IRRs ranging from 5% to 13%. Subtropical or tropical native forests had fewer commercial timber species,
and had much lower growth rates and returns. Their IRRs were less than 4%, or even negative for unmanaged stands. State subsidy
payments for forest plantations or for timber stand improvements increased IRRs somewhat and reserving areas for environmental
protection reduced their IRRs slightly. Including land costs in the cash flows decreased these internal rates of return substantially.
Natural stand returns in Latin America were much less than those of plantations, but management of those stands offered better
rates of return than only holding the land. 相似文献
16.
Plantations cover a substantial amount of Earth's terrestrial surface and this area is expected to increase dramatically in the coming decades. Pinus plantations make up approximately 32% of the global plantation estate. They are primarily managed for wood production, but have some capacity to support native fauna. This capacity likely varies with plantation management. We examined changes in the richness and frequency of occurrence of bird species at 32 plots within a Pinus radiata plantation (a management unit comprising multiple Pinus stands) in south-eastern Australia. Plots were stratified by distance to native forest, stand age class and thinning regime. We also assessed the landscape context of each plot to determine relationships between bird assemblages and stand and landscape-level factors. Bird species richness was significantly higher at plots ≥300 m from native forest and in mature (∼20 years since planting) and old (∼27 years since planting) thinned pine stands. We were able to separate the often confounding effects of stand age and thinning regime by including old stands that had never been thinned. These stands had significantly fewer species than thinned stands suggesting thinning regime, not age is a key factor to improving the capacity of pine plantations to support native species (although an age × thinning interaction may influence this result). At the landscape level, species richness increased in pine stands when they were closer to native riparian vegetation. There were no significant differences in species composition across plots. Our study indicates the importance of stand thinning and retention of native riparian vegetation in improving the value of pine plantations for the conservation of native fauna. 相似文献
17.
Patterns of fine root biomass, production, and distribution were estimated for pure stands and mixtures of three-year-old loblolly pine (Pinus taeda L.) with red maple (Acer rubrum L.) or black locust (Robinia pseudoacacia L.) on the Virginia Piedmont to determine the role of fine roots in interference between pine and hardwood tree species. Estimates were based on amounts of live and dead fine roots separated from monthly core samples during the third growing season after planting. Live and dead fine root biomass and production varied by species, but mixtures of loblolly pine and black locust generally had greater fine root biomass and fine root production than pure stands or loblolly pine-red maple mixtures. Hardwood species had greater live fine root biomass per tree in mixtures with pine compared to pure stands. Greater live fine root biomass in pine-locust stands may be attributed to differential utilization of the soil volume by fine roots of these species. For all stands, approximately 50% of live five root biomass was located in the upper 10 cm of soil. 相似文献
18.
Two contrasting trajectories for vegetation restoration in agricultural landscapes are secondary succession following cropland abandonment that can regenerate woodlands (passive restoration) and conversion of cropland to tree plantations (active restoration), which have mostly focused on pine species in the Mediterranean Basin. We compared the effects of these two contrasting trajectories of vegetation restoration on bird assemblages in central Spain. Vegetation structure differed in the two restoration trajectories, pine plantations attaining higher tree cover and height (31% and 4.1 m, respectively) but lower strata complexity than secondary shrubland and holm oak woodland (which attained 10% and 1.4 m of tree cover and height, respectively). Bird species richness differed in stands under active or passive restoration trajectories, the former collecting a higher total number of species (4.2 species per 0.78 ha plot) than the latter (3.5 species per plot). The number of forest species increased with vegetation maturity in both restoration trajectories, but especially in stands under active restoration. The occurrence of woodland generalist species increased and of species inhabiting open habitats decreased in actively restored stands, being some of these latter species of high conservation priority in the European context but relatively common at the regional level. Bird species inhabiting pine plantations had broader habitat breadth at the regional level than those inhabiting secondary shrublands and woodlands. Maximum regional density did not differ between both restoration trajectories, but it increased with development of the herbaceous layer only at the secondary succession trajectory. The relative importance of species of European biogeographic origin was higher in mature pine plantations (58.9% of total bird abundance) than in mature holm oak woodlands (34.4%), whereas that of Mediterranean species was considerably higher in the latter (40.1%) than in the former (20%). Bird assemblages of relatively small patches of pine plantations are unable to reflect the regional avifauna, in contrast with the relationships between local and regional assemblage characteristics that can be found in isolated natural forests. We conclude that programs of vegetation restoration should base upon a range of approaches that include passive restoration, active restoration with a variety of tree and shrub species, and mixed models to conciliate agricultural production, vegetation restoration and conservation of target species. 相似文献
19.
马尾松枫香混交林生长及其效应研究 总被引：23，自引：0，他引：23
本文从林木生长及其与生态环境之间相互关系入手，对马尾松枫香混交林与马尾松纯林进行了长期定位研究。结果表明：混交林生长优势明显，有利于维持地力和形成稳定的人工林群落。与对照相比，１２年生混交林蓄积量提高１３．９％－７２．５％：土壤有机质含量增加５２．３％，全氮量增加２４．１％，速效氮、磷、钾含量分别增加１３．７％．２５．２％和２６．８％；改善了林内小气候条件，提高了林地土壤肥力和蓄水保水能力。混交林增加了马尾松针叶内叶绿素的积累，其日平均净光合速率为７．７２ｍｇＣＯ２·ｄｍ－２·ｈ－１，高于对照的２０．８％。营造马尾松枫香混交林以带行状和星状混交为宜；补植枫香是改造马尾松低产林的有效措施。 相似文献
20.
《Forest Ecology and Management》1999,113(1):11-21
A methodological approach to the identification of biodiversity indicators in commercial forest stands is illustrated by analysis of the relationships between syrphid (hoverflies) and carabid (ground beetles) community composition and diversity, and stand structure and field layer vegetation. Data were collected from 12 commercial forest sites encompassing a range of climatic conditions and different crop types (Scots pine, Sitka spruce, Norway spruce and Corsican pine) across the UK. Comparisons were also made between unmanaged semi-natural Scots pine woods and Scots pine plantations. For both syrphids and carabids, no differences in species richness and diversity were recorded between semi-natural stands and plantations; one rare syrphid considered to be restricted to semi-natural pine stands was also found in spruce. Syrphid species diversity and richness was higher in southern spruce sites than in the northern sites. Northern sites had distinctive carabid communities, as did sites in the New Forest, a large ancient woodland in southern England. Of the measured habitat variables, vertical stand structure showed the best correlation with species richness and diversity of both carabids and syrphids. Richness and diversity were less in stands with high vertical cover values for canopy layers. Stands with higher field layer cover supported greater syrphid diversity, but lower carabid diversity. Measures of stand structure could be used as potential indicators of syrphid and carabid diversity, but additional habitat parameters also need to be tested. 相似文献