叶型对马尾松幼苗生长及叶绿素荧光特征的影响

【目的】研究叶型对马尾松幼苗生长及叶绿素荧光特征的影响,以期为马尾松苗木选择及栽培提供参考。【方法】以出圃时呈现为全初生条形叶、全次生针形叶和中间型的马尾松1年生幼苗为试验材料,分析其生长指标、光合色素含量及叶绿素荧光参数,研究初生叶和次生叶叶绿素荧光特征差异及对幼苗生长的影响。【结果】全次生叶幼苗出圃时苗木质量指数(QI)、干物质积累量及造林1年后净生长量均显著高于全初生叶幼苗;次生叶的叶长、体积和表面积等指标均显著大于初生叶;初生叶中叶绿素a、叶绿素b和总叶绿素含量均显著高于次生叶,两者间的类胡萝卜素含量无显著差异。初生叶的F_m、F_v/F_m、F_v/F_o均显著高于次生叶,F_o在2种叶型间无显著差异;初生叶的PSⅡ反应中心参数Y(Ⅱ)和F_v’/F_m’、淬灭参数q_P和NPQ、能量耗散参数Y(NPQ)和Y(NO)及光响应参数ETR_max、α、β和I_k也均高于次生叶,在高光强条件下,初生叶的非光化学淬灭和调节性能量耗散能力增强。由于次生针叶叶长、体积和表面积等形态指标均显著大于初生叶,因而具有次生针叶的幼苗的光合作用面积更大,干物质量积累较多,出圃时的苗木质量以及造林后的生长表现均高于全初生叶的幼苗。【结论】与次生叶相比,初生叶拥有较高的叶绿素含量,较耐光抑制,有较高的光能转化效率,但高光强条件下会通过热耗散的形式来减少多余光能对光合系统的损害;拥有次生叶的幼苗表现出较好的苗木质量及生长特性。     

浸泡和冷预处理对喜马拉雅长叶松不同种源种子萌发的作用

对喜马拉雅长叶松种子进行24小时GA3和H2O2浸泡预处理和15d的2-3℃低温预处理后,研究了在20℃,25℃和30℃萌发条件下,21个不同种源的喜马拉雅长叶松种子的萌发情况。结果表明,H2O2（1%v/v）和GA3（10mg/L）浸泡预处理,种子萌发率分别是82.39%和78.19%,而未经预处理的种子平均萌发率为70.79%。GA3和H2O2浸泡预处理分别使种子萌发时间缩短了8d和10d。在超过21天的20℃萌发条件下,湿冷处理提高了种子萌发率和缩短了萌发时间 而在25℃和30℃萌发条件下,总的萌发率未受到影响。喜马拉雅长叶松种子因缺少休眠而表现出很好的萌发,但是因为越来越多的造林项目需要大量的种子,播种预处理有利于提高种子萌发率和萌发速率,有助于满足种子需求。     

日本落叶松原生种源和次生种源对比试验研究

为扩大日本落叶松的遗传变异幅度,改善中国日本落叶松的育种状况,提高育种水平和林业生产力。对落叶松种和种源、原生种源试验林建成后10 a的数据进行比较,结果表明:日本落叶松次生种源的胸径、树高、单株材积分别是原生种源的1.10,1.11,1.23倍;选育出了13个优良种源,为我省及辐射推广地区营造日本落叶松速生丰产林找到了优良种源。     

Predicting field performance of Douglas-fir seedlings: comparison of root growth potential,vigor and plant moisture stress

Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] seedlings were evaluated- by three measurements of seedling quality — root growth potential or RGP, vigor, and plant moisture stress or PMS — and the results were correlated with subsequent field performance. Measurements made by each method were significantly (p 0.05) correlated with first- and second-year survival and terminal height growth. Seedlings from lots that grew many new roots during a 28-day interval in a growth room (RGP evaluation) or that survived for 6 weeks in the growth room and initiated rapid budburst (vigor evaluation) or whose plant moisture stress values remained fairly constant during 1 week after potting (PMS evaluation) had the greatest field survival and height growth.The RGP evaluation was the best predictor of first-year height growth, while the vigor evaluation was the best predictor of first- and second-year survival. All evaluations predicted second-year height growth equally well.These results demonstrate that all three evaluations can be successfully used to predict field performance of Douglas-fir seedlings. Each has its advantages and limitations, and none can be considered best. The one used should be selected on the basis of time constraints, equipment and resources available, and specific objectives, such as whether it is considered more important to estimate field survival or growth.When this research was conducted, both authors were affiliated with the Department of Forest Science, College of Forestry, Oregon State University, Corvallis, OR 97331, USA. Mention of commercial products does not imply endorsement by Oregon State University. This is Paper 2145 of the Forest Research Laboratory, Oregon State University.     

A comparison of annual transpiration and productivity in monoculture and mixed-species Douglas-fir and red alder stands

Although much is known about drivers of productivity in Douglas-fir and red alder stands, less is known about how productivity may relate to stand transpiration and water use efficiency. We took advantage of a 15-year-old experiment involving Douglas-fir (Pseudotsuga menziesii) and red alder (Alnus rubra) in the western Cascade Range of western Oregon to test the following hypotheses: (a) more productive stands transpire more water, (b) the relationship between productivity and transpiration differs between species, and (c) the relationship between productivity and transpiration differs between sites varying in soil moisture and fertility. Furthermore, the experimental design included alder, a facultative nitrogen-fixing species, which could also affect fertility. Fixed area plots (20 × 20 m) were planted as monocultures of each species or in mixtures at a common density (1100 trees ha⁻¹) in a randomized-block design. Transpiration of Douglas-fir and red alder was measured using heat dissipation sensors installed in eight trees per plot and scaled to the plot level based on sapwood basal area for each species. Although up to 53% of the variability in tree transpiration was explained by basal area, irrespective of species or site conditions, the two stands with the highest biomass and sapwood basal area did not transpire the most. Instead of more productive stands transpiring more water, the greatest variability in both productivity and transpiration was determined by site conditions and to a lesser degree, species composition. For example, 70% of the variation in tree biomass increment (TBI) was determined by leaf area index, which was much higher at the site with higher fertility and soil moisture (p < 0.05). Despite marked phenological and physiological differences, Douglas-fir and red alder performed similarly. Only 19% of annual water use of Douglas-fir occurred between October and March when alder was leafless. Also, there was no evidence of a fertilization effect of the nitrogen-fixing red alder on the Douglas-fir: the nitrogen concentration and N-isotopic ratio of Douglas-fir needles did not differ whether trees were grown in monoculture or in mixtures with red alder. We conclude that lower soil fertility and contrasting microclimate at one site relative to the other suppressed NPP while maintaining higher transpiration, thus reducing water use efficiency.     

珍稀保护竹种筇竹引种育苗研究

利用3个种源的筇竹种实开展引种育苗试验研究,对其发芽、保存和生长状况进行了探索.结果表明:不同种源的筇竹种实在引种地的发芽率为50%以上,种实大小与发芽率和保存率未成比例.相对于裸地育苗没有保存率的情况,遮荫条件下筇竹苗均得以保存,不同遮荫度对比分析的结果表明:以50%左右的遮荫度为好,遮荫度过高或过低不利于筇竹苗的生长和保存.筇竹种实能够适应引种地天然发育的山地黄壤,夏季病虫害防治等抚育措施是保证筇竹成活保存的重要环节,冬季极短低温没有对筇竹苗的保存造成威胁.短时间(2 h内)浸种对发芽势有一定的促进作用,但长时间浸种(5 h以上)会降低发芽势.GA3对苗高生长有显著促进作用,适宜浓度的6-BA对地径生长有一定的效果,低浓度的矮壮素对叶宽生长有促进作用.筇竹实生群体苗高、地径的遗传力较高,而叶长、叶宽和萌孽的遗传力较低,群体性状存在一定变异,具有选育潜力.加强引种育苗技术探索,开展育苗和炼苗,培育优质苗木用于造林有望实现筇竹迁地保护和培育利用.     

黄河三角洲柽柳与芦苇光合特性比较

选取黄河三角洲典型植被优势种柽柳(Tamarix chinensis)和芦苇(Phragmites australis),以全天自然光的日变化为光照梯度,研究两者对光强的响应规律,比较它们的光合荧光特性。结果显示,柽柳具有较高的光补偿点和光饱和点,在高光强时蒸腾依然旺盛,并且气孔调节能力较强,以反应中心状态转换和可逆失活进行能量调节,最大可能减少无谓的能量散失,光系统有效量子产量高,从而保证了较高的电子传递速率;芦苇气孔调节和光能利用能力较柽柳低,在高光强时出现净光合速率和蒸腾速率的降低及电子传递饱和现象,随光照增加,光系统有效量子产量下降较大,采取热耗散的方式散失过剩光能以避免光损伤。本次光响应研究的尝试证明其具有一定的合理性,但仍有待进一步验证。     

Stand structure of hemiboreal old-growth forests: Characteristic features,variation among site types,and a comparison with FSC-certified mature stands in Estonia

To improve the silvicultural targets for ecologically sustainable forestry, we quantified functionally important structural features for the first time in a representative set of old-growth forests in hemiboreal Europe. Altogether, 23 old-growth stands of four site-type groups were compared with mature commercial stands nearby in the Estonian state forests that hold the Forest Stewardship Council (FSC) certificate of sustainable forestry. These two treatments did not differ significantly in terms of tree-species diversity, volumes of woody debris of <20 cm diameter (including fine woody debris) and its decay-stage composition. However, mature stands had many more early-successional trees and lacked late-successional deciduous species; they also had a higher overall density and volume of live trees, due to abundant individuals of 10–39 cm diameter at breast height. Old-growth stands had at least twice as many live trees ≥40 cm, standing dead trees ≥30 cm and lying wood ≥20 cm in diameter, any freshly fallen debris, and regeneration. For lying wood ≥20 cm in diameter, the treatment effect depended on site type: both treatments of Vaccinium-type dry boreal forests were remarkably deadwood-poor (indicating historical management of the old-growth stands), while mature eutrophic stands of Aegopodium-type were most impoverished relative to old-growth levels. We conclude that many functional characteristics of old growth were present in the FSC-certified, mostly naturally regenerated, commercial stands. The main problem is the lack of very large trees, particularly of late-successional deciduous species, which should be addressed by their well-planned retention in cut areas and reconsideration of salvage logging strategies. A dense regeneration in old-growth stands also indicated the potential of selection cuttings. The study highlighted the need for region- and site-type specific numerical targets for sustainable forest management, which in the hemiboreal region should address the characteristic occurrence of late-successional deciduous trees on fertile soils and higher natural deadwood volumes than in typical boreal forests. For certification, the issues of structural impoverishment revealed both the inadequacy of some silvicultural practices and some indicators set by the national FSC-standard in Estonia.     

Driving forces of stability and change in woodland structure: A case-study from the Czech lowlands

This paper presents how long-term socioeconomic processes influenced the management and structure of a lowland ancient wood in the south-eastern Czech Republic from the 14th century to the present. The analysis draws on a wide range of historical documents to establish that the size, management and structure of Děvín Wood was remarkably stable throughout the study period except for the last 60 years. It is argued, however, that the long-term stability of woodland management and structure contrasts with the multiple changes that can be observed in the driving forces behind this stability. Four kinds of driving forces are distinguished (business, need for firewood, nature conservation and forestry policy), whose various combinations maintained the coppice structure of the Wood for six centuries. It is concluded that landscape ‘stability’ and ‘change’ are highly context-dependent, and that socioeconomic driving factors are a crucial link between forest ecology and history, representing a means to understand and control current ecosystems and future changes. The paper also demonstrates that in European historical ecology it is necessary to integrate qualitative and quantitative sources in order to study periods before ca. 1800 AD, i.e. the appearance of modern quantitative sources, because societal processes have exerted their influence on landscapes much longer than 200 years.     

湖南舜皇山常绿阔叶林群落主要结构特征--Ⅳ.乔木物种多样性

生物多样性是当代生态学研究的三大重点领域之一,而物种多样性既是遗传基因的载体,又是生态系统的核心组成部分,所以它在生物多样性研究中所占地位最为重要.以湖南舜皇山常绿阔叶林为研究对象,通过3个生境梯度,33个中样方,99个小样方的叠加和群落重构资料,采用7个测度公式,对物种多样性开展了研究.结果表明舜皇山常绿阔叶乔物种比较丰富,丰富度指数为11.006,信息度指数为3.666 1;α多样性指标中的丰富度指数dGL和Shanmon-Wiener指数,以及β多样性指标中的群落系数和欧氏距离,能较好地反映亚热带常绿阔叶林乔木物种多样性的特征.     

旅游风景区景观格局变化及其驱动机制——以庐山风景名胜区为例

在3S技术支持下,以2000年和2004年的TM影像为主要数据源.采用景观格局指数分析方法,探讨了庐山风景区两期景观格局特征及动态变化情况.结果表明:庐山风景区的旅游景观生态系统内,林地景观类型占有绝对的优势,但耕地的规模仍维持在较高的水平.从2000年到2004年,各景观类型的面积发生了较大的变化.总量减少的景观类型为耕地、林地和其他土地,园地、草地、城镇村及工矿用地、交通运输用地、水域及水利设施用地的面积则大幅增加,其中交通运输用地的年均增幅最为显著.庐山各景观类型基本处于动态变迁过程中,林地保留的比率最高,草地和其他土地的原始保留比率都很低,表明自然景观生态系统受到了较大的外力压迫,庐山风景区内各景观类型的斑块数量极不平均,年变动幅度很大.在8种景观类型中,城镇村及工矿用地和交通运输用地是变化最显著的人为干扰斑块,表明了人类干扰能力的快速增加,人为景观斑块对于自然斑块的影响力可能产生了较大的负面作用.林地、园地等斑块形状渐趋简单,表明受干扰程度越大,生态系统的脆弱性也越明显.导致庐山风景区内景观格局快速变化的驱动力主要源于自然因素、城市化的快速推进和旅游业的快速发展三大直接动因.     

Biological diversity indicators: A comparison of Swedish forest commons and other forest ownership categories

Abstract

Research indicates that natural resources managed in common, resembling traditional commons such as the Swedish forest commons, could be a type of regime with the potential to stimulate successfully sustainable use conditions. This is supported by findings regarding the characteristics of Swedish forest commons, their claimed concern for the environment and relatively high proportion of old forest in two out of three regions. Swedish environmental policy is directed towards environmental quality objectives and the Sustainable Forests objective states, among other things, that biological diversity must be maintained and enhanced. Swedish National Forest Inventory data for the period 2003–2006 were used to analyse differences between forest commons in northern Sweden and other ownership categories regarding the proportion of forestland with a large deciduous element, the proportion of forest older than 80 years with a large (> 25%) deciduous element, the volume of dead wood and the proportion of forest older than 140 years, parameters corresponding to the interim targets for enhanced biological diversity. The results show no consistent differences in indicator variables between the forest commons and other ownership categories, signifying that forests managed in common have been conducted in ways promoting biodiversity more effectively than in other ownership categories. Further studies of different ownership categories regarding driving forces and forest status are warranted.     

湖南舜皇山常绿阔叶林种类组成数量综合特征Ⅲ群落结构图解

群落结构图解不仅能反映物种在群落中的地位,也能在一定程度上反映物种的动态及群落的演替趋势,所以它能较全面地比较天然混交林中各种树种在森林中的作用.用第V级大树结构图解和林木结构图解两种方法分别测定了中亚热带常绿阔叶林乔木层物种在森林组成中的优势度.结果表明:第V级大树结构图解能较客观地反映已进入稳定阶段群落的组成结构特征;林木结构图解能较好地反映处于顺向演替阶段群落的组成结构特征.     

湖南舜皇山常绿阔叶林种类组成数量综合特征I.乔木物种重要值

研究森林群落种类组成的数量综合特征,以期为揭示森林群落结构规律、营建以及保护或利用多功能的森林生态系统提供依据.用3个特征指标数值综合为重要值的定量方法,分层测定亚热带常绿阔叶林各物种在群落组成中的地位和作用.结果表明:经过顺向演替,中亚热带常绿阔叶林的种类组成比较丰富,在1000m2左右的3个样地内有乔木22～30种.乔木层的优势种主要由壳斗科、樟科、木兰科、槭树科等常绿树种所组成,大多为珍贵的用材树种和庭园绿化树种.乔木层中含有常绿、半常绿、落叶3个层片,攀援或附生多种层间植物,已形成多层的立体群落结构,表现出向更高阶段演替的外貌特征.     

Nutrient dynamics in decomposing forest leaf litter: A comparison of field and laboratory microcosm approach

The effect of incubation setting (greenhouse: GM and field: FM microcosms) on nutrient element dynamics during decomposition of Japanese Konara Oak (Quercus serrata Murray) and Japanese Red Pine (Pinus densiflora Sieb et. Zucc.) litter was studied. Results show a disparity in relative concentrations and amounts of the same type of litter when incubated in different settings. The nutrient mobility, however, showed similar trend. The order of elemental mobility after 12 months forQuercus in FM was: P>K>Mg>C>Mn>Ca>N>Al>Cu>Zn>Fe; for GM it was: P>K>Mn>Mg>C>Ca>N>Al>Cu>Zn>Fe. ForPinus, elemental mobility in FM was: K>Mg>C>Mn>N>P>Cu>Zn>Al>Fe; while for GM was: K>C>Mn>N>Ca>Mg>Cu>Al>P>Zn>Fe. The elements inQuercus that lost their mass were P, K, Mg, Ca, Mn and C while those that increased were N, Cu, Al, Fe and Zn. ForPinus, K and Mg lost their nutrient mass while the other elements had increased or fluctuated but tended to increase. Three patterns of nutrient mobility were observed: first, the concentration increased while the nutrient mass (absolute amount) decreased; second, both concentration and nutrient mass increased; third, the concentration and nutrient mass decreased. On tracing nutrient mobility over time, the linear regression of nutrient element mass and litter element mass was preferred over the carbon to element ratios because the former gave a clearer picture of the relationship. On the over-all, the pattern of nutrient changes in greenhouse microcosms were different from those observed in the field, hence nutrient cycling studies using greenhouse-microcosm approach alone may give inaccurate results. This study was conducted while the senior author holds a Japanese government scholarship (MONBUSHO Grant No. 920205).     

Competitive interactions between juvenile trembling aspen and lodgepole pine: A comparison of two interior British Columbia ecosystems

To facilitate ecosystem-specific management of juvenile mixtures of lodgepole pine (Pinus contorta Dougl. Ex Loud. Var. latifolia Engelm.) and trembling aspen (Populus tremuloides Michx.) in south-central British Columbia, we compared the characteristics of pine–aspen competition between a moist sub-boreal spruce and a dry interior Douglas-fir ecosystem. A total of 252 lodgepole pine and their neighbourhoods were examined across four untreated stands, each of which was sampled three times between ages 12 and 24 years. Pine diameter and height decreased with increasing density of trembling aspen at least as tall as the target pine (tall aspen) in both ecosystems. Regression analysis was used to examine the ability of tall aspen density and four competition indices (CIs) to predict pine size. Tall aspen density, which is easily assessed in the field, accounted for 63% and 69% of the variation in pine diameter and height in 20–24 year-old stands, respectively. The most successful competition index, based on the basal diameter ratio (BDR) of trembling aspen to pine accounted for, respectively, 78% and 73% of the variation. In the same stands, R² values were 1–5% lower when tall aspen density and BDR at age 15–19 years were used to predict size of 20–24-year-old pine.     

Automatic grading of sawlogs: A comparison between X-ray scanning,optical three-dimensional scanning and combinations of both methods

As sawmills become increasingly efficient, the importance of focusing on value recovery becomes obvious. To maximize value recovery, sawmills require the ability to sort logs according to quality. This study compares four different combinations of three-dimensional (3D) and X-ray scanning that can be used to grade logs automatically. The study was based on 135 Scots pine (Pinus sylvestris L.) logs that had been scanned with both a 3D scanner and an X-ray scanner with two X-ray sources. The percentage of boards with correct grade sawn from automatically graded logs varied from 57% when using only 3D scanning to 66% when using a combination of 3D scanning and X-ray scanning in two directions. The highest possible result, with ideal log grading, was 81%. The result also shows that the combination of a 3D scanner and one X-ray direction results in higher accuracy than a scanner based on two X-ray directions.     

Beech regeneration of seed and root sucker origin: A comparison of morphology, growth, survival, and response to defoliation

American beech (Fagus grandifolia Ehrh.) reproduces sexually, and vegetatively by root suckers. Although many studies have investigated its regeneration response, most did not account for differences that may exist between its two modes of reproduction. This study was performed in an old-growth Acer - Fagus forest in southern Quebec, where beech bark disease had only a minor effect at the time of the study. We compared the density and frequency of occurrence of beech seedlings and root suckers (height < 30 cm), as well as their morphology, growth, survival, and response to experimental defoliation. Root suckers accounted for 13% of beech regeneration at our site. Density and frequency of occurrence were greater for seedlings than suckers, but did not vary with light availability, which was low at our study site (mean: 2.9%). Seedlings and suckers did not differ in leaf characteristics, but several differences were observed in terms of plant morphology, growth, and survival. Root suckers showed more lateral growth than height growth, and had a lower leaf area index than seedlings. Root suckers had both a greater growth in height and diameter, and a higher survivorship than seedlings (height and diameter growth were, respectively, five and two times greater for suckers than seedlings, and 74% of suckers survived more than 1 year, compared to 52% for seedlings). Defoliation treatments, which included levels of defoliation of 50% and 100% (1) did not affect current-year extension growth of seedlings and suckers; (2) did not affect seedling diameter growth, but had a negative impact on sucker diameter growth; and (3) affected survivorship for both origins, but had a much greater negative impact on seedling survivorship (none of the completely defoliated seedlings survived over one year, while 55% of the suckers did). This study showed that several differences exist between small beech seedlings and root suckers in traits that are important determinants of a species’ competitive ability. We therefore expect that variation in the relative importance of root suckering among sites might have several community-level implications.     

Key roles of leaves, stockplant age, and auxin concentration in vegetative propagation of two African mahoganies: Khaya anthotheca Welw. and Khaya ivorensis A. Chev

Leaf area, IBA concentration and age of stockplants were all found to be important factors for successful rooting for vegetative propagation using single-node cuttings of the two main African mahogany species: Khaya anthotheca and K. ivorensis. Cuttings with leaf area of 30–50 cm² had the best rooting percentage and cuttings with about 30 cm² had the most number of roots per cutting in K. anthotheca. Khaya ivorensis, cuttings with 10–30 cm² leaf area had the highest rooting percentage. Cuttings collected from 1-year-old stockplants recorded the highest rooting percentage and largest number of roots per cutting. Cuttings from 3-year-old stockplant of the same seeds sources had the lowest rooting suggesting aging negatively impacted rooting ability. The effect of auxin concentration, on rootability was examined with cuttings of K. anthotheca. An IBA concentration of 0.8% was the best exogenous auxin concentration for percentage rooting, number of roots per cutting and the length of the longest root per cutting.     

Prediction of pine mistletoe infection using remote sensing imaging: A comparison of the artificial neural network model and logistic regression model

In this study, the prediction of pine mistletoe distribution in Scots pine ecosystems was explored using remote sensing variables to compare the multilayer perceptron (MLP) artificial neural network (ANN) and logistic regression (LR) model performances. For this purpose, 109 sample plots were distinguished in pure Scots pine forests (natural) in the Eastern Black Sea Region of Turkey. Distinguishing mistletoe-infected stands (69) and uninfected stands (40) was performed with field observations. The variables acquired from Landsat 8 (Level 1) images were used as independent variables for independent-sample t-test, MLP ANN and LR models. Remote sensing variables indicated that mistletoe-infected stands were in drier areas with a lower vegetation-leaf area index. Based on the performance results of both models, the sensitivity (SEN), specificity (SPE), positive predictive value (PPV), negative predictive value (NPV) and accuracy of the MLP ANN model were superior to those of the LR model. The prediction percentages (SEN, SPE, PPV and NPV) of mistletoe-infected stands were better than the prediction percentages of uninfected stands. The prediction accuracies of LR and MLP ANN models were 74.3% and 89.6%, respectively. However, all remote sensing variables were included in the prediction equation of the MLP ANN model, while the thermal infrared 1 (TIRS1) variable was included in the LR model. In the MLP ANN model, the TIRS1 variable also had the highest normalized importance (100%). The area under the curve (AUC) value for identifying the mistletoe-infected stands of Scots pine forests used by the MLP ANN model (0.892 ± 0.034) was higher than in the LR model (0.838 ± 0.039), explaining the more accurate predictions obtained from the MLP ANN model. The MLP ANN model showed much better performance than the LR model. The results of this study are expected to make important contributions to the identification of potential mistletoe-infected areas.