天然公益林抚育间伐技术探讨

我省国家重点公益林抚育间伐是从去年开始的，在省市林业局的支持和帮助下我场已进行了两次。通过实际工作，我们对天然公益林抚育间伐技术进行了有益探索。由于公益林的经营目的改变了，所以抚育间伐技术也应随之进行更新。现就抚育间伐中常遇到的几个技术问题谈几点看法。     

侧柏人工林抚育间伐效果的研究

针对济南南部石灰岩山地侧柏人工纯林急待抚育间伐的实际，采用设立固定标准地定位观测动态检测的方法，对侧伯人工林5年来的抚育间伐效果进行了分析和研究。探讨了不同间伐强度对林分各种生长因子的影响及不同间伐强度下林分的稳定性及病虫害发生发展情况，提出了适宜的间伐强度。     

谈抚育间伐的目的和方法

文中对抚育间伐的目的进行了分析，并从有利于森林培育出发，提出了在抚育间伐作业中应执行的几点原则。     

我区中幼林抚育间伐成绩可观

从1992年到1996年，我区着重抓好宣传、工程项目管理和服务工作，中幼林抚育间伐取得可喜成绩：完成中幼龄林抚育间伐面积269．2万亩、蓄积379．6万立方米，出商品材187．万立方米，按当年销售间伐材统计，共销售122．4万立方米，总产值43亿元，扣除投入1．6亿元，上交各种税费1．4亿元外，纯收入1．3亿元。抚育间伐试验标准地证明：抚育间伐比不抚育间伐的林分，胸径、蓄积都有明显的增加。宣传发动。区林业厅转发了林业部《关于加强中幼龄林抚育工作的决定》，要求各地认真学习贯彻，并在全州、龙胜、融安等县召开全区营林工作会议，参观…     

黑松人工林抚育间伐效果分析

在刘公岛林场设置４块黑松人工林固定标准地，进行间伐强度为０、１５％、２０％和２５％的抚育间伐试验，分别在１９７４年和１９８３年以相同处理实施间伐。１９９３年的调查结果表明，抚育间伐能显著地促进林木生长，林分蓄积量可提高１２％～２８％，以间伐强度为２０％和２５％的效果较好；间伐使林分结构有明显改善，林内幼树幼苗的生长表现也均显著优于不间伐林。     

汤山林场松树,杉木林分人工抚育间伐技术

根据汤山林场现有松树、杉木林分的实际情况，经常运用林分的下层抚育间伐、上层抚育间伐、综合抚育间伐和机械抚育间伐等４种方法，伐后加强管理，较好地促进了林木的生长。     

小陇山林区日本落叶松人工商品林抚育间伐技术及经济效益研究

通过分析，确定了小陇山林区日本落叶松人工商品林抚育间伐的时间，抚育间隔期及抚育强度，预测了抚育间伐的经济效益。     

搞好抚育间伐 培育后备资源

满归林业局在企业经营中,认真抓好天然幼、中龄林的抚育间伐生产,加速培育后备森林资源。目前已抚育间伐2.4万多公顷,占应抚育间伐面积的53％。满归林业局是1966年投产开发的林业企业,经营的幼、中龄林面积占用材林面积的42％,抚育间伐任务相当繁重。1968年,这个局就开始了抚育间伐生产,但由于人力、物力等客观条件的限制,抚育间伐生产的速     

茶陵举全县之力 搞好松林间伐

编者按：茶陵县松林中幼林面积大，急需抚育间伐。近3年来，茶陵县委、县政府把抚育间伐当作一件大事来抓，已间伐松林近7万亩。他们的做法和措施值得各地借鉴和推广。从某种意义上来说，抓现有林分的抚育间伐就是抓荒山造林，甚至胜过荒山造林。在目前造林任务不大的情况下，各地要象抓荒山造林一样抓抚育间伐，以提高林分质量，巩固造林成果。茶陵县有松林面积70万亩，林分密度普遍较大，分化严重，生长减弱，林分质量和产量下降，急需抚育间伐。为切实抓好这项工作，县委、县政府从1997年开始，把松林间伐列入林业建设的重要内容，计划用…     

杉木人工林抚育间伐成效分析

以17年生杉木人工林为研究对象,分别设置3块抚育间伐样地和3块对照样地,并于试验前(2013年9月)和试验4年后(2017年9月)对样地进行调查。结果表明:抚育间伐在一定程度上促进了杉木人工林胸径、树高的生长,但在短期内对林分蓄积量的促增效果不明显;抚育间伐促进了杉木人工林林下植被的更新生长,抚育间伐样地灌木和草本的种类、高度和盖度的变化量均大于对照样地,抚育间伐样地物种多样性指数Simpson指数、Shannon-Weiner指数的变化量大于对照样地,且Shannon-Weiner指数的变化量抚育间伐与对照间差异达到了显著水平(P<0.05)。     

巨桉、尾叶桉及其无性系在思茅地区引种栽培适应性论证

通过对巨桉、尾叶桉生物学特性、省外栽培情况、思茅地区小面积引种情况、省外栽植地点和引种地的立地条件进行分析比较，选择气候因子进行相似优先比论证，得出思茅地区在一定范围内大面积引种巨桉、尾叶桉是可行的结论。     

湖南常德不同杨树品种造林生长调查

调查近2～4年常德引种的16个杨树品种造林生长和抗逆性情况，以及不同立地条件、培管措施等因素对杨树品种生长的影响，从中筛选出适应当地发展的杨树品种，并对杨树造林提出建议。     

贵州米槁的栽培与病虫害防治技术

米槁是贵州省名贵中药材之一，其应用广泛，功效奇特。米槁资源市场紧俏，人工栽培市场前景看好。详细叙述其良种采集、苗木繁殖、植苗造林、果实的采收与加工等人工栽培技术。介绍了5种病害和2种虫害的防治技术。提出加强基础研究，扩大种苗繁殖，实行开发与保护相结合等扩大米槁资源的对策措施。     

非灭菌条件下VA菌根菌对肉桂苗生长发育的影响

研究了在非灭菌条件下接种木薯球囊霉 (GlomusmanihotisHoweler ,Sieverding&Schenck)对肉桂 (CinnamomumcassiaPresl.)营养袋幼苗生长的影响。结果表明 ,接种组幼苗具有较高的VA菌感染率 ,幼苗的高、径、冠幅生长及根长、叶片数、生物量、叶绿素含量均比非接种对照组高 ,差异达显著水平。     

黄精林下生态种植技术

黄精为天门冬科黄精属植物,以干燥根茎入药,是一种用途非常广泛的药食同源植物。本文在生产实践与科研相结合的基础上,从适生条件、种苗繁育、林下种植、抚育管理、病虫害防治、采收等技术环节,将黄精林下生态种植技术进行了总结。     

Estimating aboveground biomass in forest and oil palm plantation in Sabah, Malaysian Borneo using ALOS PALSAR data

Conversion of tropical forests to oil palm plantations in Malaysia and Indonesia has resulted in large-scale environmental degradation, loss of biodiversity and significant carbon emissions. For both countries to participate in the United Nation’s REDD (Reduced Emission from Deforestation and Degradation) mechanism, assessment of forest carbon stocks, including the estimated loss in carbon from conversion to plantation, is needed. In this study, we use a combination of field and remote sensing data to quantify both the magnitude and the geographical distribution of carbon stock in forests and timber plantations, in Sabah, Malaysia, which has been the site of significant expansion of oil palm cultivation over the last two decades. Forest structure data from 129 ha of research and inventory plots were used at different spatial scales to discriminate forest biomass across degradation levels. Field data was integrated with ALOS PALSAR (Advanced Land-Observing Satellite Phased Array L-band Synthetic Aperture Radar) imagery to both discriminate oil palm plantation from forest stands, with an accuracy of 97.0% (κ = 0.64) and predict AGB using regression analysis of HV-polarized PALSAR data (R² = 0.63, p < .001). Direct estimation of AGB from simple regression models was sensitive to both environmental conditions and forest structure. Precipitation effect on the backscatter data changed the HV prediction of AGB significantly (R² = 0.21, p < .001), and scattering from large leaves of mature palm trees significantly impeded the use of a single HV-based model for predicting AGB in palm oil plantations. Multi-temporal SAR data and algorithms based on forest types are suggested to improve the ability of a sensor similar to ALOS PALSAR for accurately mapping and monitoring forest biomass, now that the ALOS PALSAR sensor is no longer operational.     

Brazil nut conservation through shifting cultivation

The regeneration of Brazil nut trees depends on tree-fall gaps in the forest. However, shifting cultivation fallows also create comparable biotic and abiotic opportunities for the dispersion and establishment of this gap-loving species. At the same time, the ability of Brazil nut trees to resprout enables fallow individuals to survive successive slash-and-burn cycles. Recognizing the importance of shifting cultivation for the food security of forest dwellers, we investigated whether the high level of Brazil nut regeneration found in cultivation fallows could be explained by the resprouting capability of Brazil nut trees, the number of cultivation cycles, past agricultural use and distance to the nearest conspecific productive adults. We found that the Brazil nut tree population density increased from 8.86 trees ha⁻¹ to 13.69 trees ha⁻¹ and 27.09 trees ha⁻¹ at sites after one, two and three or more shifting cultivation cycles, respectively. As a consequence of resprouting, after a certain number of shifting cultivation cycles, the fallows become dominated by Brazil nut trees, and the landholders may decide to preserve them and to exclude enriched sites from future agricultural use. Protected for their extractive value, the secondary forests spontaneously enriched with Brazil nut trees are allowed to develop into nut-producing forests that have reduced chances of conversion into crops or pastures, thus reversing the classical process of Amazon forest degradation.     

A shifting cultivation land use system under population pressure in Zambia

The status of chitemene shifting cultivation, in northern Zambia was investigated and reviewed. This paper presents results concerning (a) changes in soil nutrients under chitemene shifting cultivation, (b) the relationship between population density and deforestation and (c) how the chitemene shifting cultivation system has survived under conditions of overpopulation relative to the critical population density.In the chitemene shifting cultivation system crops are grown in a small ash garden made by burning a pile of wood cleared from a larger area. The burning increased soil NH₃–N content by 40–50%, with a further increase of 15% after 262 mm of rainfall. In contrast, the soil in unburnt plots lost up to 30% NH₃–N. The content of other major nutrients, such as, P,K, Ca, Mg, and Na also increased in the top soil immediately after burning. The increase in soil NH₃–N after burning is attributed to the reduction in microbacterial activity. These soil nutrient changes appear essential in the production of finger millet.However, the growing rural population in the chitemene shifting cultivation region of northern Zambia has caused deforestation which has resulted in the reduction of (a) the length of the fallow period from 25 years to 12 years, (b) the per person woodland requirement of m 1.1 ha to 0.53 ha and (c) the frequency of clearing new chitemene gardens from yearly to once in two years. These responses to diminishing wood resources have artificially increased the population carrying capacity from 2.4 to 18.7 persons per km². This has enabled the survival of the chitemene shifting cultivation land use system in northern Zambia.     

Changes in soil carbon and nitrogen stocks after conversion of subtropical natural forest to loblolly pine plantations

Pinus plantations have increased in Brazil, and native forest areas have been converted for timber production. The clearing and the long-term loblolly pine (Pinus taeda L.) land-use effects on soil carbon and nitrogen stocks were evaluated in a natural broadleaved forest and in loblolly pine sites cultivated for 29, 35, 38 and 49 years, as well the soil contribution as ecosystem carbon pool. According to the exponential-decay model fitted to changes in carbon stock, the initial soil carbon stock of 200 Mg ha^?1 to a depth of 100 cm in the natural forest decreased by 36% over 49 years of pine cultivation (around 72.4 Mg ha^?1 of C). Around two-thirds of this decrease occurred in the top 30 cm of the soil and intensively in the first 12 years of cultivation, but slowly faded as carbon stock tended to reach a new steady state after approximately 49 years of cultivation. The soil nitrogen stock in the natural forest was 14.2 Mg ha^?1 to a depth of 100 cm and decreased by 36% over the 49 years. This decrease was linear according to the fitted model, especially in the top 30 cm where nitrogen decline was 83% and was proportionally more intense than the carbon decline. Despite the soil carbon decrease, soil remained the largest carbon reservoir in the ecosystem for the growing rotation time of loblolly pine in this region.

     

Mineral nitrogen dynamics following soil compaction and cultivation during hoop pine plantation establishment

The effects of soil compaction and cultivation on soil mineral N dynamics were investigated through an 18-month, in situ N mineralisation experiment during the inter-rotation and early establishment period of a second rotation (2R) hoop pine (Araucaria cunninghamii Aiton ex A. Cunn) plantation in southeast Queensland, Australia. Treatments were 0, 1 and 16 passes of a fully laden forwarder (gross weight, 40.2 Mg) and cultivation by disc plough (zero cultivation and cultivation). Nitrate N was the dominant form of mineral N throughout the 18-month sampling period in both non-cultivated and cultivated soils, varying between 10 and 40 kg ha⁻¹ whilst ammonium N remained <10 kg ha⁻¹. Compaction had no significant effect on N mineralisation or nitrification. However, the remediation of the effects of compaction on soil through the use of the disc plough had significant impacts on N mineralisation, nitrification and N leaching. On a seasonal basis, the mean net N mineralisation increased from around 30 to 53 kg ha⁻¹, nitrification from 28 to 43 kg ha⁻¹ and nitrate N leaching from around 10 to 73 kg ha⁻¹ following cultivation.