红松扦插技术的研究

研究结果表明，红松扦插最佳季节为4月20日－5月1日、7月10日－7月15日；插穗应采集节间插穗，5a生插穗粗细为0．4－0．6cm，长短为3－5cm为宜。     

桂花扦插繁殖技术研究

在粤北对桂花进行扦插繁殖试验,对不同扦插基质、促根素、扦插时间及插条母树年龄的扦插效果进行对比,结果表明：扦插基质以黄心土效果最佳,生根率达90．9％;促根素以NAA＋IBA混合处理效果最佳,成活率达91．0％;扦插时间宜在1～2月进行,插条宜选择3～10年生母树2年生健壮枝条。     

榉树扦插繁殖试验

为了保护珍稀濒危树种榉树，对榉树扦插繁殖进行了研究，结果表明榉树扦插季节以早春扦插比秋插好；枝条宜粗壮饱满，以径粗大于1.2cm的枝条为佳；插前宜用激素处理，其中以浓度为100mg/L的ABT1号处理效果最佳.     

苦丁茶扦插育苗技术的研究

通过苦丁茶不同枝条的扦插、不同扦插季节及激素处理等方法进行随机区组对比试验，得出：3～5年生插条成活率最大；最佳扦插季节为初夏5月和冬季11月，扦插成活率最高分别达到88．9％和83．5％；最佳激素处理为0．1％K2MnO4浸30分钟 500ppmNAA5秒。     

小紫珠硬枝扦插试验研究

按不同年龄、不同直径和不同激素处理对泰山野生小紫珠进行硬枝扦插试验，结果表明：在不采用任何激素处理的情况下，1年生枝条的插穗生根率达48．6％，明显优于多年生枝条；在1年生枝条中，又以直径0．6～0．8cm的插穗为宜，其生根率为67．3％。采用激素处理普遍可以提高扦插生根率，其中以1000mg／L的ABT1号生根粉浸泡插条基部10秒钟的处理效果最好，生根率达95．0％，为清水对照的185．2％。     

灵香草南移试验

灵香草为报春花科常绿草本植物,林下栽培,收效快,易管理,经济效益大。我场于1985年4月12—18日向柳州地区金秀县引种试我,至1985年9月1日观察,成活率达60％,初步认为灵香草南移可以生长。灵香草宜生长在气候荫凉,林下郁闭度为75％的常绿     

竹柏嫩枝扦插育苗试验初报

从竹柏树冠中、上部选取当年或１年生的嫩枝作插穗、，按不同时间、不同浓度的生长激素处理和不同的基质等３方面进行试验，结果表明：竹柏可以进行嫩枝扦插，且成活率高，最高可达９８％以上；扦插时间以３月上、中旬最佳，其次是９月中旬；激素处理有利于竹柏扦插生根，但浓度不宜过大，浸泡时间不宜过长，以ＡＢＴ－１号生根粉０．５h为宜；在基质选择上，应选择肥力条件、透气保水力等都较好的土壤。     

植物生长调节剂对红花檵木扦插影响的试验

对不同植物生长调节剂及其浓度、处理方式和处理时间对红花檵木扦插生根的影响进行研究。结果表明：IBA、IAA、NAA和ABT中，以IBA处理效果最佳。IBA不同处理方式有其对应浓度，IBA浸泡处理以200mg／L扦插效果最佳，速沾浓度以2000mg／L效果最好。而IBA滑石粉稠液蘸沾浓度以100mg／L为宜。IBA处理时间对红花枉木扦插生根的影响具显著差异，用300mg／L的IBA溶液处理红花檵木插条，以60min的效果最佳；用1000mg／L的IBA溶液进行速沾，以608为宜。IBA和NAA两种植物生长调节剂混合使用对红花檵木扦插生根具有桔抗作用。     

几种因素组合对红豆杉扦插成活率的影响

扦插季节、插床基质、药剂的选用及浓度处理等因素对红豆杉（TaxusChinesis（pilger）Rehd）扦插成活生根率及生根速度有明显影响．试验结果表明：春夏扦插试验最优组合都为B2C1D2；春播和县插生根率和生根速度有明显差异，春插需96天才开始生根，生根率最高为36．00％；而夏插只需85天就开始生根，生根率最高为86．00％；药剂类型以奈乙酸100×10－6效果最佳，插床基质以珍珠岩效果最佳．     

杠柳育苗试验初报

杠柳(Periploca sepium Bge)是一野生缠绕灌木，具有保持水土作用，又可用于制造农药j有很大的开发前景。经育苗试验，播种、扦插育苗均可。播种育苗覆土0．5cml为宜，扦插育苗插条长度以15cm为佳。年平均高生长0．8～1．2nl，地径0．7～1．1cm。扦插苗高径生长量较播种苗分别高36％和26％。     

意大利214杨合理造林密度的选择

依据17龄意大利214杨随机区组设计的不同密度,根据树高和胸径生长量用林业统计软件进行蓄积计算,用不同密度下的立木蓄积量来确定最佳的造林密度。试验结果表明,4m×6m试验密度尽管单株蓄积不是最高的,但公顷蓄积是最大的,为260．74m^3·hm^-2,该密度林分林木符合大径材标准的株数最多,为87株。因此4m×6m密度是较为丰产的最佳密度。     

杉木单木枯损率与初植密度、竞争和气候因子的关系

【目的】分析杉木单木枯损率与初植密度、竞争和气候因子的关系,为杉木科学经营管理提供决策依据。【方法】以江西杉木密度试验林为研究对象,选取常用的logit、probit和cloglog 3种二分类变量数据结构模型构建杉木单木枯损率基础模型,并进行选择。以选择出的最优模型为基础,引入样地和样木的随机效应构建杉木单木枯损率混合效应模型。【结果】logit模型的AIC值最小(4 700.419),probit模型次之,cloglog模型最差。考虑样地和样木两水平随机效应的混合效应模型模拟精度最高,其AUC值为0.966 8。初植密度、林分优势高越大,杉木单木枯损率越高;相对直径d/D_g越大,杉木单木枯损率越低;气候越干旱,杉木单木枯损率越高;温度升高,杉木单木枯损率减小。【结论】考虑样地和样木两水平的logit模型能够较好分析杉木单木枯损率与初植密度、竞争、立地和气候因子的关系,并且随着气候干旱发生,杉木单木枯损率提高。     

Normalization of wood density in biomass estimates of Amazon forests

Wood density is an important variable in estimates of biomass and carbon flux in tropical regions. However, the Amazon region lacks large-scale wood-density datasets that employ a sampling methodology adequate for use in estimates of biomass and carbon emissions. Normalization of the available datasets is needed to avoid bias in estimates that combine previous studies of wood density that used wood sampling at diverse positions in the bole or with various methods of density determination. This paper examines the question of whether regressions for radial variation and for variation in wood density along the bole, both developed in dense forest in central Amazonia (CA), are suitable for the open forests in southern Amazonia (SA) that are currently the target of most of Amazonia's deforestation activity. The wood density of the heartwood and density of full disks or slices (bark, sapwood and heartwood) in each tree were measured to assess the radial variation. For variation along the length of the bole, wood densities at breast height and at the top of the bole were used. Moisture content of the bole was measured in SA and compared with values reported by studies from CA in similar dense forest. Comparing regressions that predict full-disk density from heartwood density, the pattern of radial variation differs slightly and significantly between the two forest types (ANCOVA p = 0.006); the slopes have similar values but the intercepts differ. Variation along the bole in the two forest types does not differ significantly (p = 0.144), so the CA model for predicting mean bole density from the density of a slice at breast height gives an unbiased estimate of the mean bole density when applied to SA trees. In SA the mean moisture content of the bole was 0.416 (±0.068 S.D.; n = 223 trees). Moisture content of the bole had a strong inverse relationship with basic wood density (r = −0.77), which explains the lower moisture content in the trees in CA relative to SA. A much weaker inverse relationship was found between moisture content and green wood density (r = −0.292). The relationship between wood basic density and green (‘fresh’) density presented in this study provides an alternative means of obtaining basic wood density directly in the field when oven drying of samples is not possible.     

Wood density in forests of Brazil's ‘arc of deforestation’: Implications for biomass and flux of carbon from land-use change in Amazonia

Wood density is an important variable in estimates of forest biomass and greenhouse-gas emissions from land-use change. The mean wood density used in estimates of forest biomass in the Brazilian Amazon has heretofore been based on samples from outside the “arc of deforestation”, where most of the carbon flux from land-use change takes place. This paper presents new wood density estimates for the southern and southwest Brazilian Amazon (SSWA) portions of the arc of deforestation, using locally collected species weighted by their volume in large local inventories. Mean wood density was computed for the entire bole, including the bark, and taking into account radial and longitudinal variation. A total of 403 trees were sampled at 6 sites. In the southern Brazilian Amazon (SBA), 225 trees (119 species or morpho-species) were sampled at 4 sites. In eastern Acre state 178 trees (128 species or morpho-species) were sampled at breast height in 2 forest types. Mean basic density in the SBA sites was 0.593 ± 0.113 (mean ± 1 S.D.; n = 225; range 0.265–0.825). For the trees sampled in Acre the mean wood density at breast height was 0.540 ± 0.149 (n = 87) in open bamboo-dominated forest and 0.619 ± 0.149 (n = 91) in dense bamboo-free forest. Mean wood density in the SBA sites was significantly higher than in the bamboo dominated forest but not the dense forest at the Acre site. From commercial wood inventories by the RadamBrasil Project in the SSWA portion of the arc of deforestation, the wood volume and wood density of each species or genus were used to estimate average wood density of all wood volume in each vegetation unit. These units were defined by the intersection of mapped forest types and states. The area of each unit was then used to compute a mean wood density of 0.583 g cm⁻³ for all wood volume in the SSWA. This is 13.6% lower than the value applied to this region in previous estimates of mean wood density. When combined with the new estimates for the SSWA, this gave an average wood density of 0.642 g cm⁻³ for all the wood volume in the entire Brazilian Amazon, which is 7% less than a prior estimate of 0.69 g cm⁻³. These results suggest that current estimates of carbon emissions from land-use change in the Brazilian Amazon are too high. The impact on biomass estimates and carbon emissions is substantial because the downward adjustment is greater in forest types undergoing the most deforestation. For 1990, with 13.8 × 10³ km² of deforestation, emissions for the Brazilian Amazon would be reduced by 23.4–24.4 × 10⁶ Mg CO₂-equivalent C/year (for high- and low-trace gas scenarios), or 9.4–9.5% of the gross emission and 10.7% of the net committed emission, both excluding soils.     

Carbon density and accumulation in woody species of tropical dry forest in India

We studied the carbon density and accumulation in trees at five sites in a tropical dry forest (TDF) to address the questions: how is the TDF structured in terms of tree and carbon density in different DBH (diameter at breast height) classes? What are the levels of carbon density and accumulation in the woody species of TDF? Is the vegetation carbon density evenly distributed across the forest? Does carbon stored in the soil reflect the pattern of aboveground vegetation carbon density? Which species in the forest have a high potential for carbon accumulation? The WSG among species ranged from 0.39 to 0.78 g cm⁻³. Our study indicated that most of the carbon resides in the old-growth (high DBH) trees; 88-97% carbon occurred in individuals ?19.1 cm DBH, and therefore extra care is required to protect such trees in the dry forest. Acacia catechu, Buchanania lanzan, Hardwickia binata, Shorea robusta and Terminalia tomentosa accounted for more than 10 t ha⁻¹ carbon density, warranting extra efforts for their protection. Species also differed in their capacity to accumulate carbon indicating variable suitability for afforestation. Annually, the forest accumulated 5.3 t-C ha⁻¹ yr⁻¹ on the most productive, wettest Hathinala site to 0.05 t-C ha⁻¹ yr⁻¹ on the least productive, driest Kotwa site. This study indicated a marked patchy distribution of carbon density (151 t-C ha⁻¹ on the Hathinala site to 15.6 t-C ha⁻¹ on the Kotwa site); the maximum value was more than nine times the minimum value. These findings suggest that there is a substantial scope to increase the carbon density and accumulation in this forest through management strategies focused on the protection, from deforestation and fire, of the high carbon density sites and the old-growth trees, and increasing the stocking density of the forest by planting species with high potential for carbon accumulation.     

Leaf gas exchange of understory spruce-fir saplings in relict cloud forests, southern Appalachian Mountains, USA

The southern Appalachian spruce-fir (Picea rubens Sarg. and Abies fraseri (Pursh) Poir.) forest is found only on high altitude mountain tops that receive copious precipitation ( > 2000 mm year(-1)) and experience frequent cloud immersion. These high-elevation, temperate rain forests are immersed in clouds on approximately 65% of the total growth season days and for 30-40% of a typical summer day, and cloud deposition accounts for up to 50% of their annual water budget. We investigated environmental influences on understory leaf gas exchange and water relations at two sites: Mt. Mitchell, NC (MM; 35 degrees 45'53' N, 82 degrees 15'53' W, 2028 m elevation) and Whitetop Mtn., VA (WT; 36 degrees 38'19' N, 81 degrees 36'19' W, 1685 m elevation). We hypothesized that the cool, moist and cloudy conditions at these sites exert a strong influence on leaf gas exchange. Maximum photosynthesis (A(max)) varied between 1.6 and 4.0 micromol CO(2) m(-2) s(-1) for both spruce and fir and saturated at irradiances between approximately 200 and 400 micromol m(-2) s(-1) at both sites. Leaf conductance (g) ranged between 0.05 and 0.25 mol m(-2) s(-1) at MM and between 0.15 and 0.40 mol m(-2) s(-1) at WT and was strongly associated with leaf-to-air vapor pressure difference (LAVD). At both sites, g decreased exponentially as LAVD increased, with an 80-90% reduction in g between 0 and 0.5 kPa. Predawn leaf water potentials remained between -0.25 and -0.5 MPa for the entire summer, whereas late afternoon values declined to between -1.25 and -1.75 MPa by late summer. Thus, leaf gas exchange appeared tightly coupled to the response of g to LAVD, which maintained high water status, even at the relatively low LAVD of these cloud forests. Moreover, the cloudy, humid environment of these refugial forests appears to exert a strong influence on tree leaf gas exchange and water relations. Because global climate change is predicted to increase regional cloud ceiling levels, more research on cloud impacts on carbon gain and water relations is needed to predict future impacts on these relict forests.     

韦塔桉为母本的控制授粉研究

对2．5年生位于广东江门韦塔桉种质资源库内的母株进行控制授粉试验，结果表明：（1）不同父本花粉在相同母本上的平均座果率、平均单果产种量排序均为：尾叶桉〉韦塔桉〉巨桉，说明花粉类型对果实宿存和平均单果产种量有影响，亲缘关系越远，获得种子的可能性越小；（2）切割花柱法是缩短授粉时间、减少工作量的授粉方法；（3）参试母株W3102的座果率高，但产种量少，W3604座果率高，种子产量也高；（4）全双列育种有利于亲子代遗传关系分析，但花期不遇影响目的种子的获得，从而延长育种年限；（5）花粉对座果率的影响不如母株的影响显著。参试的8株母本座果率排序为：W3102〉W3507〉W3604〉W3401〉W3708〉W3206〉W3103〉W3105。     

马尾松优良种源对初植密度的早期生长反应

在马尾松中心产区之一的闽西地区,利用5个马尾松优良种源在肥力中等立地上设置的种源与密度互作9年生试验林测定材料,初步研究优良种源生长对初植密度的反应式样和互作效应.结果表明,5个参试优良种源对初植密度的反应差异很大,江西崇义和福建武平种源生长对初植密度反应敏感,广西岑溪和广东高州种源生长对初植密度反应较小,而广东信宜种源的生长反应则一般.比较分析发现,广西岑溪、广东高州、广东信宜3个南部种源在1.5 m×2.0 m初植密度下树高和胸径生长量大、单位面积蓄积量高,适宜较高初植密度短周期经营,但也可在2.0 m×2.5 m较稀初植密度下实现大径材培育目标.江西崇义和福建武平两个中部种源在2.0 m×2.0 m中等初植密度下生长表现最好.马尾松种源生长分化与初植密度有关,在较密和较稀初植密度下种源生长分化较大,密植似可提高早期选择效果.研究还发现,种源×初植密度、区组×种源×密度互作显著,应针对不同立地和种源设计不同的初植密度,实现优良种源与初植密度的优化配置.     

基于磁弹性的扭矩测量方法及特性分析

基于磁弹性原理组建扭矩测量系统;归纳出"扭矩与磁感应强度之间存在线性正比例关系"的规律;提出以扭矩与磁感应强度之间的线性正比例关系为基础,利用具有巨磁阻效应的特斯拉计先测量磁感应强度值,再计算出相应扭矩值的扭矩测量新方法,为研发汽车扭矩传感器提供一种新的思路;利用SPSS软件进行数据分析,扭矩测量系统的线性度误差小于0.1%,重复性误差均小于0.1%,符合测量系统的误差要求,验证这种扭矩测量新方法的可行性;总结出扭矩测量系统的主要技术指标有:量程为0～100 N.m、线性度和重复性两个误差指标均为0.1%。     

Influence of initial spacing and tree class on the basic density of Picea abies

The effects of initial spacing and tree class on the basic density of Norway spruce were evaluated in a stand on a fertile site in southwestern Sweden. The basic density at 0 and 4 m above ground level was significantly higher for trees planted with an initial spacing of 1.5 m than for trees planted with wider initial spacings. A decrease in initial square spacing from 2.5 m to 1.5 m had little effect, of small practical importance, on the basic density. The density at 0 and 4 m above ground was significantly higher for the suppressed trees than for the intermediate and dominant ones, and for the intermediate trees compared with the dominant trees. Differences in basic density appeared to be due mainly to differences in growth‐ring width. Basic density decreased outwards from the pith to the bark at 1.3 and 4 m above ground.