共查询到19条相似文献,搜索用时 156 毫秒
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基于EDA技术的自动立木整枝机无线遥控发射系统 总被引:4,自引:0,他引:4
立木整枝是优质工业用材林定向抚育的重要环节,采用自动立木整枝机是实现高效、高质量和安全可靠整枝的有效途径。本文综合运用电子电路设计及优化技术、无线遥控及通信编解码技术,创造性地研制了基于CPLD的无线数字编码抗干扰自动立木整枝机无线遥控发射系统,通过优化CPLD内部逻辑电路有效消除了逻辑竞争冒险、降低了噪声干扰,确保了系统逻辑设计的正确性。该系统具有可靠、节能、抗干扰、工作效率高等优点。本研究成果及方法为推进其他林业机械的自动化与智能化进程提供了一种有效的新思路。 相似文献
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间伐抚育是森林经营工作中一项重要技术措施。合理进行抚育采伐;对改善林分卫生状况、减少病虫危害、增加林木抗性等都有好处。同时,通过间伐还能获得部分用材。所以如何结合生产的需要,因地制宜地制定间伐抚育的技术措施,也是当前林业生产上急待解决的问题。一、间伐抚育和各因子的关系1、连年生长量、造林密度、立地条件、林木分化程度、经济效益和间伐的关系幼龄阶段,林木胸径的连年生长量开始下降时期,往往是由于单位面积立木株数过密,林分内林木生长受到抑制。因此,用胸径连年生长量下降时期只能做为间伐抚育的 相似文献
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介绍了杨树无根大苗的苗木培育、整地、造林及抚育技术,通过造林试验,造林成活率达98%,林木生长与常规造林相差无几,减少林木后期管理费用80%。 相似文献
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人工工业用材林整枝机器人无线电遥控系统的研制 总被引:15,自引:0,他引:15
人工工业用材林是解决工业、建筑、家具和家庭装饰等用材的主要途径,整枝是人工工业用材林培育必不可少的环节。传统的整枝机效率低、伤亡率高,难以适应我国大面积工业用材林抚育的需要,而优质、安全和高效的自动化整枝技术是解决问题的关键措施。笔者在参照国外先进整枝技术的基础上,采用遥控、无线电波传播、遥控编解码、系统加密等技术,自行设计研制了一套立木整枝机器人无线电遥控系统。本文重点阐述了该系统的遥控指令输入电路、HS2262/HS2272编解码电路、315MHz无线电发射电路、RX3310A无线接收电路、接口电路等的组成及技术要点。其电路结构简单,工作可靠,抗干扰能力强。 相似文献
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林木整枝技术研究现状及趋势 总被引:2,自引:0,他引:2
对目前的林木自然整枝预测模型和影响因子、人工整枝对林木生长的影响、整枝强度划分等级及表征指标应用现状进行综合整理分析的结果表明:①国内目前的自然整枝规律和人工修枝技术研究主要集中于速生树种和用材林,缺乏对天然林尤其是次生林的研究。需要对生态公益林自然整枝规律、恢复次生林自然整枝能力以及人工整枝技术、创新构建符合生产的整枝强度指标等方面进行深入研究。②对自然整枝规律及机理性研究有待深入。需要研究分枝特性、枝条生长规律、形成枯枝和脱落动态变化与林木年龄增长的关系,建立整枝理论技术和实用技术体系,从而指导林业生产。重点是根据不同经营目标,针对不同区域、林种、树种、林分结构的林木,找到形成枯枝脱落的时间规律、表征整枝强度的指标及变化规律,林分结构因子与整枝强度间的动态变化关系等。③平衡自然整枝与人工整枝,通过调整优化结构,促进伴生树种对目标树的自然整枝,进而有效提升自然整枝能力,减少人工整枝成本。 相似文献
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关于落叶松人工幼中林抚育间伐技术的研究 总被引:1,自引:0,他引:1
兴安落叶松是牙克石林区乡土树种。落叶松人工林郁闭成林后,林木生长到一定阶段,开始分化。据调查15—16年生落叶松人工林被压木占16%,中层木占65%,上层木占19%,林木生长发育受到影响。为了保证立木生长有适应的营养面积,合理调整立木密度,充分利用地力,改善林分环境条件,促进林木迅速生长,缩短培育周期,发挥森林的生产效能,尽快培育出材质好数量多的后备用材林基地。我们于一九七九年秋开展了对落叶松人工林抚育间伐技术的探讨。 相似文献
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河北省塞罕坝机械林场总经营面积140万亩,有林地面积112万亩,以人工落叶松为主的商品林面积39.6万亩。自上世纪80年代开展成林抚育以来,已累计完成抚育间伐作业70余万亩次,目前仍有部分林分由于受地理位置、经济条件的制约,未能得到及时的抚育管理,林内枯死木、病害木、濒危木、风折雪压等自然灾害木数量众多,林相杂乱,林地卫生状况差,林木个体间竞争激烈,自然整枝强烈,林木直径、树高、材积等生长量低,林分的抗逆性、稳定性、生产力明显低于同类立地林分,另有一些中龄林分生长率开始下降,自然整枝明显偏高,按照商品林培育目标,对这些林分进行抚育间伐作业。 相似文献
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Growth of trees and seasonal yields of understory crops were measured over a 5-year period for 4 crops grown under 17 tree
species at 8 × 8 m spacing in wetland rice fields. All tree species grew well in rice fields, at rates comparable to their
growth in forest plantations. Top and root pruning reduced average tree girths by up to 19% and average tree volumes by up
to 41%, depending on intensity of pruning. The crops monitored were Oryza sativa, Triticum aestivum, Corchorus olotorius,
and Lens culinaris. Crop yields under the trees averaged 93% of the corresponding yields outside the tree canopy. The most
important factor affecting the yields of undercrops was tree size (height and/or girth). Differences among tree species and
the interaction with species of undercrops were not significant after controlling for tree size. Pruning of roots and branches
significantly improved crop yields under trees by amounts proportional to the intensity of root or top pruning.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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杨树修枝理论和技术研究进展 总被引:4,自引:0,他引:4
杨树修枝是杨树速生丰产后期经营管理中一项重要的措施,本文综述了修枝对杨树生长、材质以及林下经济的影响。修枝对杨树树高、材积生长量的影响因树种、立地、修枝强度的不同规律不同;修枝会降低胸径的生长量,提高萌枝数量,但可以提高材质。修枝对材质的影响表现在尖削度减小、节子减少、形数和形率增加等。修枝可以增强林下作物光合作用,促进林下植物生长,提高产量;实践中,修枝强度、起始年龄、修枝季节应因树种而异。目前,对于杨树修枝的研究多为短期的、单方面的,系统综合研究尚需进一步加强。 相似文献
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以怀宁县皖河滩地杨树林为研究对象,对修枝前后林木与土壤中的养分含量进行了研究。结果表明:(1)一定修枝强度下,修枝对杨树的树高和胸径生长影响显著(P〈0.05),但随着修枝强度增大对树高生长的影响是先增大后减小,而对胸径的影响是一直增大。(2)修枝会降低林地土壤全氮含量,但对土壤全氮、全磷、速效磷和钾含量影响不显著(P〉0.05)。(3)修枝对不同土层深度土壤养分影响不显著(P〉0.05),但全氮、全磷、速效磷含量均随着土层深度的加深而逐渐减少,钾、钙、镁含量基本相同;同一修枝强度下,各种养分含量在不同方向基本持平,只有钙的含量在每个方向都是以轻度修枝最大。(4)植物各器官中,全氮含量以根最高,3种修枝强度下,随着年龄增大枝的全氮含量降低,根的全氮含量增加。同时,修枝对上部枝的全氮含量影响显著(P〈0.05);修枝强度对中部枝和大于5mm根的全氮含量影响显著(P〈0.05);修枝对植物各组分全磷含量影响不显著(P>0.05);除中部枝的钙含量在轻度修剪与强度修剪有显著差异外(P〈0.05),修枝对植物钾、钙、镁的影响不显著(P〉0.05),但随着枝的生长钾、钙、镁的含量有降低的趋势;随着根的生长,钾、钙、镁的含量变化规律不明显。 相似文献
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Integration of trees on farms may exert complementary or competitive effects on crop yield. This 4 year study examined novel
systems in which Alnus acuminata (alnus), Calliandra
calothyrsus (calliandra), Sesbania sesban (sesbania) or a mixture of all three were grown on the degraded upper part of bench terraces in Uganda; beans or maize were
grown on the more fertile lower terrace during the short and long rains. Three pruning treatments (shoot, root or shoot + root
pruning) were applied to the tree rows adjacent to the crops; shoot prunings were applied as green manure to the woodlot from
which they came. Pruning increased survival in calliandra and reduced survival in sesbania; alnus was unaffected. Pruning
reduced tree height and stem diameter in alnus, but did not affect calliandra or sesbania. Maize yield adjacent to unpruned
calliandra, alnus and sesbania or a mixture of all three was reduced by 48, 17, 6 and 24% relative to sole maize. Shoot pruning
initially sustained crop performance but shoot + root pruning became necessary when tree age exceeded 2 years; shoot + root
pruning increased maize yield by 88, 40, 11 and 31% in the calliandra, alnus, sesbania and tree mixture systems relative to
unpruned trees. Bean yield adjacent to unpruned calliandra, alnus, sesbania and the tree mixture was 44, 31, 33 and 22% lower
than in sole crops and pruning had no significant effect on crop yield. The results suggest that sesbania fallows may be used
on the upper terrace without reducing crop yield on the lower terrace, whereas pruning of alnus is needed to sustain yield.
Calliandra woodlots appear to be unsuitable as crop yield was reduced even after pruning. 相似文献
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Daniel Moreno-Fernández Mariola Sánchez-González Juan G. Álvarez-González Andrea Hevia Juan P. Majada Isabel Cañellas Guillermo Gea-Izquierdo 《European Journal of Forest Research》2014,133(5):833-843
Pruning allows knot-free timber to be obtained, thereby increasing the value of the highest-value wood products. However, the effect of pruning on growth is under discussion, and knowledge about the tree response to the simultaneous development of thinning and pruning is scarce. The objective of this study was to analyze the effect of the interaction of thinning and pruning on tree and stand level and the annual radial growth of two pine species native to Mediterranean mountains. We used long-term data of three trials installed in pine stands where several combinations of pruning and thinning were developed. Five inventories were carried out for each trial, and the mean dasometric features of the different treatments were compared using linear mixed models including a competition index. In addition, we collected cores from ten trees per plot in order to evaluate the annual response of trees to the thinning and pruning. We analyzed the annual radial growth using a semiparametric approach through a smooth penalized spline including rainfall and temperature covariates. Pruning did not show any effect on growth. However, larger diameter and increased annual radial growth were found in thinned plots, both with and without pruning, as compared to unthinned plots. Also, we found significant effects of climate on annual radial growth. We recommend the application of thinning and pruning in stands of Mediterranean mountains in order to get knot-free timber since growth reduction was not found in thinned stands. 相似文献
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Pruning effects on root distribution and nutrient dynamics in an acacia hedgerow planting in northern Kenya 总被引:2,自引:0,他引:2
Tree pruning is a common management practice in agroforestry for mulching and reducing competition between the annual and perennial crop. The below-ground effects of pruning, however, are poorly understood. Therefore, nutrient dynamics and root distribution were assessed in hedgerow plantings of Acacia saligna (Labill.) H.L. Wendl. after tree pruning. Pruning to a height of 1.5 m was carried out in March and September 1996. In July and October 1996, the fine root distribution (< 2 mm) and their carbohydrate contents were determined at three distances to the tree row by soil coring. At the same time, foliar nutrient contents were assessed, whereas nutrient leaching was measured continuously. The highest root length density (RLD) was always found in the topsoil (0–0.15 m) directly under the hedgerow (0–0.25 m distance to trees). Pruning diminished the RLD in the acacia plots at all depths and positions. The relative vertical distribution of total roots did not differ between trees with or without pruning, but live root abundance in the subsoil was comparatively lower when trees were pruned than without pruning. In the dry season, the proportion of dead roots of pruned acacias was higher than of unpruned ones, while the fine roots of unpruned trees contained more glucose than those of pruned trees. Pruning effectively reduced root development and may decrease potential below-ground competition with intercropped plants, but the reduction in subsoil roots also increased the danger of nutrient losses by leaching. Leaching losses of such mobile nutrients as NO3– were likely to occur especially in the alley between pruned hedgerows and tended to be higher after pruning. The reduced size of the root system of pruned acacias negatively affected their P and Mn nutrition. Pruning also reduced the function of the trees as a safety net against the leaching of nutrients for both NO3– and Mn, though not for other studied elements. If nutrient capture is an important aim of an agroforestry system, the concept of alley cropping with pruning should be revised for a more efficient nutrient recycling in the system described here.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
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Due to the lack of knowledge about ponderosa pine performance under silvopastoral systems (SPS) conditions, the objective
of this study was to determine the effect of stand density and pruning on the growth magnitude of ponderosa pines growing
in NW Patagonia (SPS with 350 and 500 pines ha−1 vs. commercial densities of 1,300 trees ha−1, HPP). Individual growth rate was higher in SPS 350 trees than in SPS 500 trees, being both higher than in HPP plots, indicating
a higher sensitivity of this drought resistance species to relative water availability. The higher individual growth compensated
the lower amount of trees per land unit, being the whole stand growth similar or even higher in both SPS treatments than in
the HPP stand. Pruning reduced diameter growth in both SPS treatments, at least until 2 years after pruning, with a more marked
effect in the pruning treatment with the higher amount of extracted foliage. Carbon fixation reduction in addition to changes
in carbon allocation within different plant parts after pruning could be the responsible of observed stem growth reductions.
We suggest that higher growth rates in combination with frequent pruning in low density plantations can be applied to shorten
the rotation period producing high quality timber in comparison with plantations managed under conventional conditions in
Patagonia. Additional advantages could be associated to the lower environmental impact of low canopy cover plantations compared
to high density stands. 相似文献