毛竹林冬笋开发试验     

胡正坚  张培新 《竹子研究汇刊》1995,14(3):50-53

通过较大面积冬笋开发试验,冬笋每公顷产量达180kg以上,产值达900元以上,不影响春笋、新竹产量。  相似文献   

林火对森林虫害发生影响的研究   总被引：1，自引：0，他引：1  

胡海清  郭福涛 《林业科学》2006,42(12):77-82

对黑龙江省的大兴安岭、黑河、伊春、牡丹江等林区近5年的火灾过火林地进行森林虫害调查分析.结果表明:大兴安岭及黑河林区森林过火后主要虫害为天牛和小蠹类;伊春林区食叶害虫种类较多,但危害较轻;牡丹江林区落叶松毛虫发生程度严重.森林火灾后林内蛀干害虫大量发生,树干熏黑高度是影响虫害发生数量的一个重要因子.火烧强度与虫害发生数量呈正相关性;天牛及小蠹类虫害发生数量与树干熏黑高度线性关系明显;兴安落叶松林、樟子松林、白桦林的虫害发生数量与树干熏黑高度相关性较高,兴安落叶松和樟子松林尤为明显.  相似文献   

Nondestructive test and prediction of modulus of elasticity of veneer-overlaid particleboard composite     

Yingcheng Hu  Fenghu Wang  Jiyou Gu  Yixing Liu  Tetsuya Nakao 《Wood Science and Technology》2005,39(6):439-447

The effects of grain angle, thickness of face veneer, and shelling ratio on dynamic modulus of elasticity (E) of veneer-overlaid particleboard composite (VOP) were examined by using nondestructive test. In this study, the possibility that E of VOP can be predicted by means of some empirical formula was also discussed. This study has shown that grain angle, thickness of face veneer, and shelling ratio have substantial effects on E of VOP. The E at 0° of grain angle of face veneer was the largest, decreasing rapidly with increase in the grain angle. The lowest value of E occurred at 90° of grain angle of face veneer. The relationship between grain angle of face veneer and E of VOP can be expressed in the form of Jenkin’s and Hankinson’s equations. The orthotropic properties of wood and VOP defined as the ratio E ₀/ E ₉₀ were 25.7 for wood and 4.7 for VOP. When the grain direction of face veneer was parallel to the length of the specimens, the E of VOP increased with increasing shelling ratio. VOP increased E from 125 to 179% over that of the particleboard and veneer thickness from 2.1 upto 3.6 mm. However, when the grain direction of face veneer was perpendicular to the length of the specimens, the E of VOP decreased with increasing shelling ratio. VOP decreased E from 23 to 41% over that of the particleboard and veneer thickness from 2.1 upto 3.6 mm. The relationship between E of VOP and face veneer thickness can be expressed in the form of a second-order parabolic equation. Rule of Mixture (ROM) can be used to predict E of VOP from the E of wood element and particleboard element.  相似文献   

基于动态递归神经网络的木材干燥模型辨识   总被引：10，自引：1，他引：10  

张冬妍  胡昆仑  赵真非 《森林工程》2003,19(6):10-12

木材干燥是一个复杂的非线性系统 ,由于木材结构复杂且具有多样性和变异性 ,因此要建立一个理想的符合木材干燥过程的模型是很困难。本文利用动态递归神经网络的特点 ,提出了基于动态递归神经网络的木材干燥模型辨识方法 ,给出了动态递归状态 -输出神经网络的结构和学习算法。并通过对辨识得到的模型的仿真结果 ,表明了本文所建立的模型是有效的  相似文献   

影响松毛虫赤眼蜂种群消长因子研究     

方惠兰  童普元 《林业科学》1995,31(3):233-238

１９８６－１９９０年的研究得知：松毛虫赤眼蜂在浙江于３月下旬开始活动，１０月上旬至１１月陆续以蛹在马尾松毛虫、云南松毛虫等虫卵中越冬在林中常年都可见到该蜂的活动，其种群数量出现的高峰期与松毛虫卵期相一致，林中昆虫卵的多少、蜜源植物的有无、温度的高低、是影响松毛虫赤眼蜂林间种群消长的主要因子。  相似文献   

中国竹文化及竹文化旅游研究的现状和展望   总被引：10，自引：5，他引：10  

胡冀贞  辉朝茂 《竹子研究汇刊》2002,21(3):66-71,75

竹子对中国历史文化、文学艺术、绘画艺术、工艺美术、园林艺术和音乐文化、宗教文化、民俗文化等产生了巨大影响。系统深入研究竹文化对促进精神文明的发展、发扬光大中华民族优良传统、发展特色旅游产业等都具有重要意义。通过对中国竹文化现状的研究，即从文明发展、哲学、专业、生产和艺术等不同角度研究了竹文化的理论和成果，提出和探讨了我国竹文化研究应重视少民族竹文化的发掘种保护、与发展特色旅游产业相结合、开展典型竹文化区研究和区域性竹文化旅游发展规划等问题，包括东亚（中国江南）“毛竹文化”区、东南亚（中国云南）“少数民族竹文化”区、喜马拉雅“高山竹文化”区和拉丁美洲“瓜多竹文化”区。  相似文献   

粤西乐昌含笑种源试验分析_*     

黄越茂  王润辉  郑会全  晏姝  韦如萍  胡德活  植毓永  蔡维就  郭刚 《广东林业科技》2015,31(3):6-10

以大坑山林场乐昌含笑种源试验林7年生观测数据作遗传变异分析,表型变异分析结果表明树高、胸径、材积、树干通直度、叶片大小、树冠浓密度和冠幅等7个性状种源间都存在较大的差异;方差分析结果表明大部分性状种源间差异达极显著或显著水平;遗传参数估计结果表明生长性状的种源遗传力处于中等偏下水平,形质性状处于中等水平,材积的遗传变异系数最大;根据多重比较结果,以材积为选择目标,选出6个速生种源,增益介于11.1%～35.1%之间。粤西乐昌含笑优良种源主要集中在广东和江西交界的多个县市。  相似文献   

China's role in the global forest sector: how will the US recovery and a diminished Chinese demand influence global wood markets?     

Yanjie Hu  John Perez-Garcia  Alicia Robbins  Ying Liu  Fei Liu 《Scandinavian Journal of Forest Research》2015,30(1):13-29

Over the last decade, while the size of China's economy more than doubled, China has simultaneously become a major producer and exporter of forest products. Although China's domestic supply of wood is significantly constrained both by a limited natural supply and by conservation-oriented policies, the country is increasingly regarded as the world's “wood workshop.” Furthermore, China is the largest driver of demand for the trade in tropical logs and is becoming a significant driver of demand for trade in coniferous logs. In this paper, we describe a spatial equilibrium model adapted to study forest sector markets and policies that affect them. We present the model and the result of two alternative future scenarios. The first scenario analyzes the impact on global forest products markets of a US recovery in wood markets. The second scenario examines the effect on global forest products markets of decelerating growth in Chinese demand for wood products. Through these two scenarios, the modeling output sheds light on the role China's wood products markets have on resource supply and trade around the world. The trade model shows substantial potential changes in global prices, production, and trade activity associated with the recovery in domestic demand in the USA.  相似文献   

Plant diversity of secondary forests in response to anthropogenic disturbance levels in montane regions of northeastern China   总被引：4，自引：0，他引：4  

Jiaojun Zhu  Zhihong Mao  Lile Hu  Jinxin Zhang 《Journal of Forest Research》2007,12(6):403-416

The effects of anthropogenic disturbances on forest structure and plant diversity of secondary forest ecosystems were evaluated based on the classification by site factors in the montane regions of northeastern China. Forty-five sample plots containing 720 sub-plots of overstory species (8 m × 8 m), 1,440 quadrats of understory species (2 m × 2 m), and 1,440 quadrats of herbaceous layer species (1 m × 1 m) were clustered into five groups (G1, G2, G3, G4 and G5) by site variables with Hierarchical Cluster Analysis. Meanwhile, the disturbance levels corresponding to the five groups were determined according to the factors influencing human disturbances (D0-G2, D1-G1, D2-G3, D3-G5, and D4-G4). Species diversities of overstory, understory, herbaceous layer and overall species were evaluated using species number, Margalef index, Pielou index, Shannon–Wiener index, and Simpson index; and β-diversities (Whittaker index, Cody index). Basal area of stands exhibited a decreasing trend along the disturbance level due to a gradual increase in the extraction of timber by the human disturbances. The indices of species diversity suggested that overstory and understory species were distributed evenly among the groups or disturbance levels. There were no absolutely dominant tree species in the secondary forest ecosystems. The differences in site factors and the current disturbance intensities were not intense enough to lead to loose changes in overstory and understory species. The species diversity indices exhibited the maximum values at D3 (G5) for herbaceous layer species; this may suggest that the current disturbance intensities were intense enough to lead the changes of herbaceous layer species. Three rare and endangered species (Juglans mandshurica, Fraxinus mandshurica and Acanthopanax senticosus) were found within the secondary forests. These rare and endangered species appeared in each clustered group or disturbance level, which suggested that the current disturbance intensity in the study area was not strong enough to influence the distribution of rare and endangered species. The current disturbances in the secondary forests may not lead to a decrease in stability and complexity of the overstory and understory species, but the higher disturbance level may be intense enough to change the habitat fitness for the herbaceous species. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized authors.  相似文献   

Locating and identifying sound knots and dead knots on sugi by the rule-based color vision system     

Chuanshuang?Hu  Chiaki?TanakaEmail author  Tadashi?Ohtani 《Journal of Wood Science》2004,50(2):115-122

Knowledge of the occurrence of sound and dead knots on the surface of sugi is important for the classification and application of the material. This study examined a color vision system for detecting sound and dead knots on sugi. The system can be conceptually divided into three components: a CCD-camera scanning system, an image-segmenting module, and a rule-based defect identifying module. The results showed that the potential defect regions could be located by Otsus threshold algorithm in conjunction with t-test analysis. The accuracies of locating sound knots and dead knots were 92.6% and 97.1%, respectively. The rule-based approach was used to identify sound and dead knots and the identifying accuracies for sound knots and dead knots were 92.0% and 94.1%, respectively. The overall detection accuracy of the system was 87.6%. The results indicated that the rule-based color vision system is an efficient means of detecting sound knots and dead knots on sugi.  相似文献