大兴安岭猞猁冬季生境选择

采用机械布点法随机设置样线,对猞猁冬季生境选择进行了研究.包括海拔、植被类型、隐蔽度、坡度、坡位、坡向、距水源距离、距人为干扰距离等因素进行了调查,并利用栖息生境的偏爱指数进行计算分析.结果显示:猞猁冬季喜欢栖息在海拔800～1 000m,食物丰富度＞100 gDM/100 m2、隐蔽度≤0.3、水源距离＜1000m、人为干扰距离＞2 000 m的针阔混交林或针叶林中活动,喜欢活动于坡度较陡的生境,且多集中与上坡位.猞猁对坡向和雪深无明显的选择性.     

广西宜州龙江河畔赤腹松鼠春季栖息地选择

2008和2009年3—5月,采用直接观察法对广西宜州龙江河畔赤腹松鼠春季栖息地的选择进行调查和分析,结果表明：赤腹松鼠喜欢郁闭度好、水源距离10-50m、坡度20—40°、避风性良好、坡向东坡和南坡、坡位中坡位或上坡住、食物因子良好,人为干扰距离10-20m,海拔50—150m,乔木密度〈50株,灌木密度50～200株,乔木距离1～4m,灌木距离〈2m的栖息地;水源距离、坡度、海拔、灌木距离、人为干扰距离和灌木密度无显著差异（P〉0．05）,郁闭度、避风性、坡向、坡位、食物因子、乔木密度和乔木距离存在显著差异（P〈0．05）。     

广西元宝山自然保护区黑熊春季栖息地选择

2009年2～4月,对元宝山自然保护区黑熊春季栖息地选择进行调查分析,Vanderloeg选择系数Wi和Scavia选择指数Ei表明：黑熊喜欢郁闭度〉50%、水源距离〈30 m、坡度小于20°～40°、避风性良好、坡向为南坡、坡位中坡位或上坡位、树径〉0.4 m,人为干扰距离〉100 m、海拔1 600～2 000 m...     

大山包自然保护区越冬黑颈鹤对觅食地选择的初步研究

对云南大山包黑颈鹤国家级自然保护区越冬黑颈鹤种群所选用的觅食地进行了调查和初步研究。研究结果表明:在其越冬黑颈鹤的家庭鹤与集群鹤两种类群中对觅食地的8种生境因子(坡度、坡向、坡位、植被型、植被盖度、植被高度、最近水源距离和最近干扰距离)及其相对应的项目均表现出有相同的选择性。除家庭鹤更偏好选用上坡位(54.4%)作觅食地,而集群鹤更偏好选用下坡位(44.5%)作觅食地外;对其他因子的选择频次相差不大。对大山包自然保护区越冬黑颈鹤觅食地进行了因子分析,提取了主成分。其结果表明:对越冬黑颈鹤觅食地影响较大的生境因子为植被盖度、植被高度、水源距离和干扰距离。对其两种类群而言,对家庭鹤影响较大的生境因子为植被盖度、坡向、干扰距离和植被高度;而对集群鹤影响较大的生境因子为水源距离、坡向和植被高度。越冬黑颈鹤所选择的觅食地的主要特征具体表现为开阔(植被高度3~10 cm,上坡位(54.5%))、距离水源较近(100~500 m)、植被盖度适中(>40%~<60%)、背风〔东北坡向(45.4%)和西南风(63.6%)〕、缓坡(<30°)、附近有人类活动(距100~700 m)的鸭茅草草地。大山包自然保护区越冬黑颈鹤中家庭鹤与集群鹤对觅食地选用的差别主要表现在水源距离、植被盖度和干扰距离上。     

大兴安岭林区雪兔冬季生境选择研究

在冬季,雪兔在非生物环境因子的选择中,偏好山体的坡下位和谷底,坡向为阳坡,坡度较小及小于10 cm雪深的生境;在生物环境因子的选择中,偏好针阔混交林和灌丛、乔木株数较少、灌木低于2 m、灌丛隐蔽度为30%-60%、杂草高度小于50 cm和含有倒木的生境;冬季雪兔对生境选择是基于保存自身能量、获取食物和躲避天敌基础上的。     

唐家河国家级自然保护区藏酋猴(Macaca thibetana)的生境选择

2013年3月至2014年2月,在唐家河国家级自然保护区毛香坝区域对对一群数量50只～60只的野生藏酋猴生境选择进行了研究.根据藏酋猴的活动位点,设置了96个20 m×20 m的植物样方,测定了植被类型、乔木密度、乔木胸径、乔木高度、郁闭度、灌丛盖度、地理性、海拔、坡向、坡度、坡位、水源距离、干扰距离等13个生态因子.对该群藏酋猴生境选择喜好程度分析表明,唐家河国家级自然保护区的藏酋猴偏好利用常绿落阔混交林、落叶阔叶林.猴群选择在乔木平均胸径20 cm ～30 cm和平均高度为11 rn～20 m的森林活动.它们不选择郁闭度＜20％的树林,主要位于海拔1 500m～2000m的地带活动.该群藏酋猴主要栖息于山坡面的森林,活动地点的坡度多介于20°～40°之间.该群藏酋猴对水源距离和干扰距离没有严格要求.     

基于GIS大熊猫活动区域环境特征分析——以大熊猫国家公园(四川)为例

基于GIS,以地形因子(海拔、坡度)、生物因子(植被类型、植被盖度、可食竹)、水源分布、人为干扰(道路、矿山、居民点耕地)等因素,分析国家公园内大熊猫活动痕迹点的环境特征。结果表明:国家公园内大熊猫主要栖息活动的范围集中在海拔1 800 m~3 400 m的针阔混交林和常绿落叶阔叶混交林,林分郁闭度0.2~0.7之间,林下有主食竹分布,活动点距离水源1 000 m以内,距离居民点(耕地)距离1 000 m~5 000 m。矿山开采和道路分布密度对大熊猫分布影响较明显。通过对大熊猫生境特点分析,为下一步开展大熊猫栖息地恢复及廊道建设提供基础参考。     

三江自然保护区丹顶鹤春季觅食生境初步研究

采用样方因子测定法对三江国家级自然保护区丹顶鹤春季觅食生境进行调查研究的结果表明:丹顶鹤春季主要在以苔草、小叶章为主的沼泽湿地中觅食;觅食地植被高度小于40 cm,植被密度低于400株/m2,植被盖度为0～25%,觅食地水深多为5～15 cm,人类干扰距离大于1 500m;人为活动严重影响着丹顶鹤的觅食;春季丹项鹤有在...     

狗獾夏季生境选择

在黑龙江省方正林业局新风林场,通过痕迹检验法和洞穴辨别法对狗獾夏季生境选择进行研究的结果表明：狗獾夏季利用样方法和对照样方在乔木密度、乔木距离、灌木密度、植被盖度、距水源距离生态因子方面差异极显著（P〈0．001）,在乔木高度上差异显著（P〈0．05）,其余的生态因子无显著差异（P〉0．05）;相对于对照样方而言,狗獾夏季更偏爱在海拔322m左右、优势乔木为紫椴、乔木密度6．81左右、乔木高度在12m以上、乔木距离大于4．5m、乔木盖度小、灌木密度较高、植被盖度较低、距水源距离较近、坡位为中坡位的生境下活动;运用皮尔逊相关性检验模型的预测率达到97．2％,说明模型能够很好的反应狗獾夏季生境选择的基本情况。     

陕西黄龙山自然保护区冬季褐马鸡沙浴地选择

2006年11—12月和2007年1月,在陕西黄龙山采用样带法对褐马鸡冬季沙浴地选择进行研究。在选定的8条样带上测定54个利用样方以及96个对照样方。结果表明:褐马鸡沙浴地偏好利用下坡位、阳坡和半阴半阳坡以及山坡面和山脊,对中坡位是随机选择,避免选择中上坡位、阴坡和山沟。对林型的利用无选择性。对利用样方和任意样方进行比较,褐马鸡冬季通常选择水源距离、林边距离和人为干扰距离较小的低海拔地方作为其沙浴地,且其沙浴地以乔木数量低及其盖度、高度和直径较小、灌丛数量和高度较小但盖度大、草本盖度和高度较大以及可视度高为主要特征。褐马鸡也选择岩洞作为沙浴地,占总沙浴地的35.19%。对19个岩洞和35个非岩洞沙浴地进行比较,表明岩洞沙浴地具有人为干扰距离大、坡度大、可视度低、乔木数量和盖度较大而直径小、灌丛数量和盖度大、草本高度较高的特征。逐步判别分析表明:人为干扰距离、坡位、林边距离、海拔、可视度、灌丛盖度和乔木数量具有重要作用,由这7个变量构成的方程在对冬季沙浴地利用样方和对照样方进行区分时,正确判别率可以达到93.60%。     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Biogeochemical impacts of clearfelling and reforestation on blanket-peatland streams: II. major ions and dissolved organic carbon

Streams and drains in blanket-peatland forest in western Ireland were sampled weekly over 5 years, 1996–2000, using continuous, depth-proportional passive sampling. Analysis was for pH, alkalinity by Gran titration, anions by IC, metals by ICP, aluminium speciation by loaded-resin exchange, and dissolved organic carbon (DOC) by absorbance at 320 nm.

Effects of felling are identified graphically from two forest drains whose catchments (both about 1 ha) were clearfelled, and partial clearfelling of one larger catchment (somewhat over 1 km²), in summer 1999. Calcium concentrations and alkalinity were increased in the drain- and streamwater from the felled areas. The pH was increased in drains, while in the larger stream, pH range decreased while the mean increased. Phosphorus increased markedly with clearfell, in the absence of recent fertilising, and also increased with fertilising; these results are reported in an accompanying paper. Ammonium-nitrogen concentrations were increased in the two drains with felling, and temporarily decreased in the larger stream. Nitrate increased in some cases. Potassium and manganese concentrations also increased. Concentrations of DOC and organic monomeric aluminium increased gradually, subject to a continuing strong annual cycle. There were no clearfelling effects on concentrations of solphate, suspended solids or inorganic monomeric aluminium. In the two drains (fully clearfelled), concentrations of sodium, chloride and magnesium, and conductivity, were all reduced after felling. Fertilising effects other than for phosphorus were indistinct.

Effects of the combined clearfell–reforestation treatment were testable statistically, using randomised intervention analysis, between two larger streams (1 km²) as a treatment–control comparison. There were statistically significant positive responses in streamwater concentrations of nitrate, potassium, calcium, DOC and aluminium fractions. The implications for management practice depend on whether the loss of nutrients is sustainable for future crop productivity, and whether critical limits and loads of receiving ecosystems are exceeded.     

Effect of Drought on Growth and Mortality of Actively Growing Norway Spruce Container Seedlings Planted in Summer

Survival, root egress and height growth of 13-month-old actively growing Norway spruce ( Picea abies (L.) Karst.) container seedlings exposed to preplanting drying treatments (0, 4, and 8 days) and postplanting drought periods (1, 2, 3, and 4 weeks) were studied in the field between 5 July and 18 August 1999. The mortality of seedlings increased and the height growth and root egress decreased throughout the postplanting drought period. Postplanting performance was also affected by preplanting drying treatments. The results indicate that no risk of excessive mortality and growth restrictions occurs when actively growing seedlings are planted in summer, provided that seedlings are well watered before planting and the drought period does not exceed 3 weeks.     

Rehabilitation of diseased cacao fields in Peru through shade regulation and timing of biocontrol measures

The objective of this case study was to test the effectiveness of biocontrol for the rehabilitation of abandoned, diseased (moniliasis, witches' broom and black pod) cocoa and to develop testable hypotheses regarding the effect of shade and biocontrol timing. Three trial fields differed in their shade regimes. Biocontrol was administered starting either at flowering or pod filling. Disease incidence and yield were compared with cultural control alone. Biocontrol reduced moniliasis from 49% to 25%, independent of the shading regime and application time. Witches' broom was most severe without shade and unaffected by biocontrol. No significant effects on black pod were observed. Although biocontrol increased percentage healthy fruit independent of shading and timing, only the shaded plot with biocontrol from flowering onwards responded with increased yield. Our hypothesis is: 'In the rehabilitation of abandoned cacao, only fields under sustainable shade management and early onset of biocontrol can realise their production potential.' This revised version was published online in June 2006 with corrections to the Cover Date.