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1.
LAWRIE  J.; CLAY  D. V. 《Forestry》1994,67(4):287-295
There is a need for selective foliar-acting herbicides for transplantlines in forestry nurseries and new forestry plantings. Toleranceof 2-year-old pot-grown trees of beech, birch, sycamore, ash,cherry, oak, red alder, Japanese larch and Sitka spruce to contactherbicides applied at different dates in the growing seasonwas investigated.Clopyralid was safe to use on all species apartfrom some fresh weight reduction in Japanese larch. Bentazoneand phenmedipham caused initial necrosis on most species tested;however, most trees outgrew the effect of phenmedipham in thefollowing season. Bentazone, generally, had a long-term inhibitoryeffect on growth of alder and at the highest dose tested (5.2kg ha–1 ) also affected ash and beech.Metsulfuron-methyland tribenuron-methyl were safe on most species tested.However,fresh weight reductions were caused by metsulfuron-methyl inash and cherry and by tribenuron-methyl in alder. Mecoprop damagedall species, apart from Sitka spruce.  相似文献   

2.
Due to the dieback caused by invasive fungus Hymenoscyphus pseudoalbidus, ash is threatened in many regions of Europe. In order to predict the situation with ash ecosystems, it is important to examine forest regeneration in areas formerly dominated by ash with long disease history and known management. The main aim of the present study was, therefore, to evaluate forest self-regeneration following clear-felling of ash dieback-devastated stands, focusing on ash. In Lithuania, during 2011, a forest regeneration inventory was performed on twenty clear-cuts, initially dominated by stands of ash, but severely damaged by the dieback caused by H. pseudoalbidus and clear-felled 1–10 years previously. In subsequent forest regeneration, grey alder and birch dominated. Ash regeneration was scarce, and its proportion decreased from 40–100 % in pre-dieback stands to 0–21 % in current stands. Of all observed ash trees (n = 775), 53.9 % were diseased, 16.8 % were dead, and only 29.3 % were visually healthy. Moreover, ash was among the slowest growing species, while grey alder, aspen and birch were the fastest. The regeneration and health condition of ash in forests, where previous to the dieback ash was dominant, demonstrated a sharp decrease in occurrence of this species and a clear shift in species composition towards grey alder and birch.  相似文献   

3.
Climate varies along altitudinal gradients and species performance may be affected in response to these variations. Climate change can modify these gradients and, at the lower limit of species distributions, individuals may become stressed and their general health and reproductive performance may decrease. Study and prediction of the effects of climate change on the distribution of species along these gradients is therefore necessary. Our model study species, Pinus pseudostrobus, is a widely distributed pine in Mexico, ranging from 1600 to 3200 masl in altitude. In order to explore changes in health condition and reproductive investment along an altitudinal gradient, ten reproductive trees were selected in each of four populations (at 2300, 2400, 2700 and 2900 masl). As a proxy of individual health, we conducted a rapid visual assessment for each tree, based on crown defoliation, dead branches and foliage discoloration. This stress condition index (SCI) ranges from zero to fifteen, and lower values indicate low stress and therefore better health conditions. We also evaluated reproductive (cone weight, number/weight of seeds) and progeny (germination/seedling growth) traits. In addition, the relationships between SCI and the reproductive/progeny traits were assessed. The lowest altitude population presented poor health, with higher values of SCI (mean ± SE = 6.3 ± 0.9) that reduced up to 4.8-fold in higher-altitude populations. Cone weight also differed among altitudes, with lighter cones in the lower population (mean ± SE = 38.2 ± 4.3 g), and 1.5-fold heavier cones found in the higher populations. In general, all of the reproductive/progeny traits differed among altitudes. The population of intermediate altitude (2700 masl) presented the highest values for all traits evaluated, indicating higher performance at this altitude. Finally, a negative relationship was found between stress condition and cone weight. Based on our results and climate change models and their predictions, an increase in physiological stress can be expected in individuals of low altitude populations. Furthermore, possible increases in pests and pathogens are likely to contribute to the decline of this population. It is therefore necessary to maintain efforts of stress condition assessment and population dynamics, as well as to permanently monitor the climate along altitudinal gradients.  相似文献   

4.
CO2 concentrations in different plant communities (larch, birch, lilac, and grassland) were measured during the growing season in the Heilongjiang Forest Botanical Garden to study diurnal variation, seasonal and annual dynamics and factors that impact CO2 concentration in different spaces. CO2 concentration in different communities in green lands had an obvious diurnal variation, chronically decreasing, and temperature influenced the lilac area and the grassland. Seasonally, CO2 was lowest in the larch green land (344.03 ± 23.03 μmol/mol) and highest in the grassland (360.13 ± 22.43 μmol/mol). The overall trend in CO2 concentration was autumn > spring > summer; temperature is the main factor controlling variation in CO2 concentrations during the growing season; the CO2 concentration at the larch, birch, lilac, and grassland types of sites was negatively correlated with land surface temperature and air temperature, and the CO2 concentration at the larch and birch sites was positively correlated with atmospheric pressure. Without any obvious annual change law, further study and observation are needed.  相似文献   

5.
The widely observed advance in spring budburst across a range of temperate forest species due to climatic warming has received considerable attention. This change in forest phenology has important implications for the choice of species and provenances currently being planted, which need to be suited to both current and future climatic conditions. Using a provenance trial in the south of England, this study assessed variation in the timing of budburst across 23 different European provenances of oak (Quercus robur L. and Q. petraea (Matt.) Liebl.) over 8 years of observations. The order in which the different provenances reached budburst was related to provenance source latitude: the southern provenances were always earlier than those from more northerly latitudes. The statistical technique partial least squares regression was used to identify critical periods of both chilling and warming. A General Linear Model and three-dimensional temperature response surfaces were used to analyse the temporal trends in budburst. There was a negative correlation between the date of budburst and mean daily air temperature in both the chilling and warming periods for all provenances, which was statistically significant for a majority. Spring warming had a larger effect on budburst than winter chilling with a mean spring temperature-driven advance of 3.61 days/°C (standard error = 0.17 days/°C) and mean winter period temperature-driven advance of 0.99 days/°C (standard error = 0.17 days/°C). Surprisingly, there was no statistically significant interaction between mean air temperatures during the chilling and warming phases on the date of budburst.  相似文献   

6.
崔晓阳 《林业研究》1997,8(4):206-210
InterspecificdiffernceIntr0ducti0nFornutrientandwaterseeking,tinerootsrepresentafuncti0nallyimportantpartofthebiomassoftbresttrees.lnforeststands,wherefinero0tsaredenselvpackedinsurfaces0iI,strongcompetitionfornutrientsandwatermaybeexpectedam0ngrootIetsan…  相似文献   

7.
关帝山次生林区典型植物群落物种多样性垂直分布研究   总被引：6，自引：0，他引：6  
高俊峰  张芸香 《林业研究》2006,17(2):111-115
为了分析和探讨海拔对植物多样性的影响,沿海拔梯度(1600–2600m),设定14个样地,对每个样地内对植物物种进行调查。结果表明:随海拔升高,群落优势种变化依次为:辽东栎、油松、白桦、红桦、华北落叶松和云杉。群落内乔木树种的平均树高和胸径表现为先增大后减小,最大树高和胸径表现为单峰变化。群落内不同生活型树种(针叶树和阔叶树)的最大树高表现为先增大后减小.阔叶树最大胸径无明显变化规律,针叶树最大胸径不断减小。中海拔群落内,针叶树种的最大树高和胸径高于阔叶树种。群落的Shannon-wiener指数和Margalef指数均表现为单峰变化,中海拔群落(1900–2200m)植物多样性最高,高于低海拔群落(1600–1900m)和高海拔群落(2200–2600m)。Shannon-wiener指数和Margalef指数反映出的植物α多样性变化与海拔高度显著相关。在研究地区,植物多样性变化与群落所处的海拔显著相关,此外,还与群落结构、物种组成、树种特性和人为干扰有关。图8表3参13。  相似文献   

8.
The effects of the interaction between tree species composition and altitude on soil microbial properties are poorly understood. In this study, soil samples (0–20?cm) were collected in August 2011 from Betula platyphylla and Picea crassifolia forests along two different altitudinal gradients. Soil microbial activity and biomass were measured using Biolog-ECO plates and phospholipid fatty acid analysis. Both of the forest soils were characterized by a significantly lower soil pH (p?p?相似文献   

9.
The changes in species composition, abundance and forest stand structure were analyzed across altitudinal regimes in tropical for- ests of Eastern Ghats of northern Andhra Pradesh, India. Three 1-ha plots were established with one each in low, medium and high altitudes. A total of 153 species, 2129 stems (709 stems ·ha -1 ) of ≥10 cm girth were enumerated. Species richness and diversity pattern varied along altitud- inal gradient and increased with the altitude. Species richness varied from 52 to 110 species·ha -1 and stand density from 639 to 836 stems·ha -1 with average basal area of 34.39 m 2 ·ha -1 . Shannon-Wiener index (H’) ranged from 4.55 to 5.17. Low altitude (i.e., Site 1) is dominated by Xylia xylocarpa (59.22) and Lagerstroemia parviflora (23.90), medium altitude (i.e., Site 2) by Xylia xylocarpa (45.50) Bursera serrata (17.29), and high altitude (i.e., Site 3) has Schleichera oleosa (28.25) Pterocarpus marsu- pium (26.55) as predominant species. Taxonomically, Rubiaceae (12 species), Fabaceae (12), Euphorbiaceae (11), Rutaceae (7) and Lauraceae (7) were dominant families. Density-wise, Fabaceae, Combretaceae, Euphorbiaceae, Anacardiaceae and Myrtaceae were abundant. Thus, conservation assessment based on altitudinal regimes and the information on species structure and function can provide baseline information for monitoring and sustaining the biodiversity.  相似文献   

10.
CANNELL  M. G. R.; SMITH  R. I. 《Forestry》1984,57(2):177-197
The probability of frost damage at the time of budburst on thelateral shoots of young trees of Picea sitchensis in Scotland,and at Masset on the Queen Charlotte Islands, was determinedfrom (a) the dates of budburst, predicted from past temperaturerecosds using a thermal time / chilling model, and (b) the datesof last air frosts of –2.5°C. The mean date of budburst occurred between 6 and 13 May at arange of Scottish sites up to about 250 m altitude, but it occurredabout 6 days later for each further 100 m increase in altitudeup to 550 m. This resulted from an interplay between chillingand thermal time requirements for budburst. In different years,budburst dates ranged from mid-April to early June. From 1920to 1960 there was a trend towards warmer springs and earlierdates of budburst, which has been reversed since 1960. Potentially damaging frosts have occurred near the date of budburstonce every 3 years (on average) at Eskdalemuir and Braemar duringthe last 66 to 107 years, and once every 3 to 5 years in manyupland plantation regions of Scotland. The probability of damagingfrosts was greatest in the period 1930 to 1960 when budburstoccurred relatively early, and has been relatively small since1960, because budburst has occurred relatively late. Renewedwarming of the climate in future may increase the probabilityof damaging frosts coinciding with the time of budburst. Masset, on the Queen Charlotte Islands, from where Britain hasimported most P. sitchensis seed, has relatively cool springsso that budburst occurs relatively late (averaging 18 May).Also there are few damaging frosts at Masset after late April.Consequently, potentially damaging spring frosts have occurredthere only once in 65 years.  相似文献   

11.
A phenological time series of the date of budburst of birch (Betula pendula) was constructed using data from the years 1907-1950. Data for the years 1908, 1910-1915 and 1930 are missing. The phenological observations were made at Saarij?rvi (62 degrees 42' N, 25 degrees 44' E) in Central Finland. Different models describing the rate of development in the spring were analyzed using temperature data from the city of Jyv?skyl? about 60 km to the southeast of Saarij?rvi. The models based on temperature sum gave more accurate predictions of the date of budburst than the model based on time. Differences between different development rates seemed to be negligible when computing the temperature sum.  相似文献   

12.
林利民  王戈 《林业科技》1995,20(5):43-45
本文描述了落叶松脲醛树脂胶合板的开发试验，试验结果表明，落叶松胶合板比椴木胶合板，桦木胶合板，水曲柳胶合板和杨木胶合板的耐老化性能和耐水性能强，并且强度较高。  相似文献   

13.
Tree adaptation to environment has been extensively studied. However, little is known about the variations in structure and chemical composition of lignocellulosic biomass (LB) in relation to altitudinal gradient. We wonder, are there significant variations in the LB in the wood across an altitudinal gradient? To answer this, we carried out a study of Abies religiosa. Wood samples were collected from 36 trees, grown between 3000 and 3500 masl, and then subjected to gravimetric and FTIR (Fourier Transform Infrared) spectroscopic analyses. The gravimetric results showed a proportion of 54.81 ± 2.20 % cellulose, 12.37 ± 1.33 % hemicellulose and 24.68 ± 1.16 % of insoluble lignin. Using the principal components analysis with analysis of variance (ANOVA), significant differences were found at 3100 and 3200 masl in two independent components related to both hemicellulose and lignin, through gravimetry as well as the spectroscopic bands assigned to the carbonyl groups of these polymers, respectively. However, the observed changes in chemical composition of LB did not follow a linear relationship with respect to the altitudinal gradient, which suggests that complex environmental interactions could also be playing an important role. Also, there were significant differences (p < 0.05) in two of the empirical indexes calculated from the FTIR analysis.  相似文献   

14.
Many second growth forests have poor regeneration and in some spatial and economic context, such as post-agricultural forests, it may be beneficial to increase tree diversity. We planted seedlings of yellow birch (Betula alleghaniensis) and bur oak (Quercus macrocarpa) in strip openings of 3, 6 and 9 m width to control light. Individual mesh sleeves were used to reduce browsing pressure but they also reduced available light for seedlings: a large mesh and a small mesh sleeves were tested in each opening. Available light for seedlings ranged from 5 to 46% of full sunlight. First year growth was almost non-responsive to all treatments for both species, but birch showed strong responses during second year. Birches in the large mesh sleeve and the 9 m opening had the largest height and diameter increments, while those in the small mesh sleeve and the 3 m opening had the smallest increments. Small mesh sleeves increased the height over stem diameter ratio for both species. Treatments affected several other morphometric variables of birch but none of the oak. More time is needed to assert if bur oak can be a candidate species for enrichment planting. We recommend strip openings of 9 m width and large mesh sleeves, for protection against deer browsing, while controlling neighbouring competition, to promote artificial regeneration of hardwood species.  相似文献   

15.
水曲柳落叶松混交林中细根空间分布   总被引：4，自引：0，他引：4  
王庆成 《林业研究》2002,13(4):265-268
采用根钻取样方法对年生水曲柳落叶松混交林中细根空间分布状况进行了研究。结果表明,水曲柳落叶松地下生物量的空间分配差异显著。在林分水平上,水曲柳的根生物量密度高于落叶松(分别为4442.3和2234.9g/m3)。两树种在相邻区域中分配的细根生物量较高,表明种间根系竞争较弱。落叶松行间的水曲柳细根生物量密度和根长密度均高于水曲柳行间的落叶松细根,表明水曲柳地下部分具有较强能力。根系的空间分布有利于混交林中水曲柳的生长。图1表4参19。  相似文献   

16.
In most woody plants, leaf morphological and physiological characteristics are extremely variable across environmental gradients, particularly across altitudinal gradients. Hippophae rhamnoides L., a dioecious and deciduous shrub species, occupies a wide range of habitats in the Wolong Nature Reserve, southwest China. We measured growth, sex ratio and morphological and physiological characteristics of leaves in male and female H. rhamnoides individuals along an altitudinal gradient. Shoot height (HT), leaf N concentration per unit dry mass (N(mass)), leaf N concentration per unit area (N(area)) and leaf carbon isotope composition (delta(13)C) were higher in males than in females, whereas females had higher specific leaf area (SLA), stomatal length (SL) and stomatal index (SI) (i.e., total stomatal length per unit leaf area) than males along the altitudinal gradient. Females also had higher values of stomatal density (SD) at all altitudes except 2800 m. The male:female ratio (MFR) was biased toward males at all altitudes except at 2800 m. Changes in HT, MFR, SLA, SD, SL, SI, N(mass), N(area) and delta(13)C along the altitudinal gradient were nonlinear. Below 2800 m, HT, SLA, SD, SL and SI increased with increasing altitude, but above 2800 m they decreased with increasing altitude. In contrast, MFR, N(mass), N(area) and delta(13)C showed the opposite patterns with altitude. Consequently, we confirmed our hypotheses: (1) stressful environments have a more negative impact on females than on males in a variety of ways; (2) under optimal growth conditions the sex ratio is even, but becomes male-biased as resources become limited; and (3) there is an optimum altitudinal range at around 2800 m for the growth of H. rhamnoides in the Wolong Nature Reserve.  相似文献   

17.
对河北省塞罕坝机械总场第三乡林场的植物多样性进行研究,于2007年7～8月份展开调查。通过对调查资料的统计分析,得出海拔及坡向对植物丰富度、多样性及均匀度的影响程度。测定分析结果表明：海拔对物种丰富度影响不甚明显,但总体上随着海拔的升高物种丰富度呈现下降趋势;总个体数的变化起伏比较大;植物多样性与均匀度的变化与物种丰富度的变化近乎相反。坡向对各多样性指数的研究结果表明：物种丰富度、多样性及均匀度3个指数在半阴坡是最高的,而总个体数随坡向的变化不大。这些研究结果将对如何更好的保护和合理利用生物多样性资源、发挥林区生态效益、促进人工林的可持续经营具有重要的理论和现实意义。  相似文献   

18.
Temperature and freeze-thaw events are two key factors controlling litter decomposition in cold biomes.Predicted global warming and changes in freeze-thaw cycles therefore may directly or indirectly impact litter decomposition in those ecosystems. Here, we conducted a2-year-long litter decomposition experiment along an elevational gradient from 3000 to 3600 m to determine the potential effects of litter quality, climate warming and freeze-thaw on the mass losses of three litter types [dragon spruce(Picea asperata Mast.), red birch(Betula albosinensis Burk.), and minjiang fir(Abies faxoniana Rehd. et Wild)]. Marked differences in mass loss were observed among the litter types and sampling dates. Decay constant(k) values of red birch were significantly higher than those of the needle litters. However, mass losses between elevations did not differ significantly for any litter type.During the winter, lost mass contributed 18.3–28.8 % of the net loss rates of the first year. Statistical analysis showed that the relationships between mass loss and litter chemistry or their ratios varied with decomposition periods. Our results indicated that short-term field incubations could overestimate the k value of litter decomposition.Considerable mass was lost from subalpine forest litters during the wintertime. Potential future warming may not affect the litter decomposition in the subalpine forest ecosystems of eastern Tibetan Plateau.  相似文献   

19.
Pine wilt disease is caused by the pine wood nematode [Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle]. In East Asia, an important vector of the nematode is Monochamus alternatus Hope. We determined the tolerance and reproductive ability of sawyer beetles and the nematode to altitude and temperature at elevations between 850 and 1,450 m on Mt. Fuji in Japan. The number of emergent adults decreased markedly along the altitudinal gradient, but the beetle could still reproduce at 1,050 m (8.2 °C annual mean temperature). Beetles with a 2-year life cycle increased rapidly in number with increasing altitude. The pine wood nematode survived through winter at all altitudes tested (850–1,450 m). The beetle population decreased between 950 (9.1 °C) and 1,150 m (8.3 °C). Therefore, the beetle population seems to be stable at 850 m (10.2 °C) and lower altitudes (higher temperatures) but cannot be maintained from 950 (9.1 °C) to 1,150 m (8.3 °C) without constant immigration of beetles from lower altitudes. The beetles could not reproduce at altitudes above 1,150 m (lower than 8.2 °C). From the mean and effective cumulative temperatures, we concluded that the beetle (and its population) can endure temperatures lower than those previously reported. Pine wilt disease also occurred at lower temperatures and higher altitudes than expected. We have summarized the principal strategies for controlling the disease at high altitudes based on these results.  相似文献   

20.
This study was done using the non brown fractal model to quantify and compare the variations in the species richness of trees, shrubs, herbs and all plants along an altitudinal gradient and to characterize the dominating ecological processes that determine the variations. Two transects were sampled far away from any anthropogenic disturbances along the shady slopes of the Dongling mountains in Beijing, China. Both transects were continuous and 2 m wide, and every individual tree and shrub was recorded in each of them. Discrete quadrats of 1 m × 1 m were located along the transects A and B for estimation of the herb species richness along the altitudinal gradients. The level interval between the quadrats was 10 m and 25 m respectively. In this study, transects A and B were combined into one transect AB, and 40 m was selected as the optimal quadrat length along the altitudinal gradients for measuring the plant species richness patterns. Species richness in each quadrat was calculated using a program written in Matlab 6.0. Direct gradient analysis was used to describe the overall trends in the species richness of trees, shrubs, herbs and other plants with change in altitude, while the non-brown fractal model was used to detect more accurately their variations at various scales along the gradient. The model assumed that each class of ecological processes affecting the distribution of a variable could be represented by an independent spatial random function. Generally, ecological phenomena are determined not by a single ecological process but by multiple ones. These processes act on ecological patterns within their own spatial scales. In the non-brown fractal model, the spatial random functions are nested within a larger range of spatial scales. The relative contribution of the spatial random functions to the spatial variation of a variable is indicated by a weighting parameter that has to be greater than or equal to zero. In this paper, we reached the following results and conclusions. Firstly, the direct gradient method describes the general trends of trees, shrubs, herbs and all plants along the altitudinal gradient but is unable to provide further details on the altitudinal variations in the species richness. The non-brown fractal model brought out the altitudinal variations in the species richness of trees, shrubs and herbs at various scales and related them to the ecological processes. The sharp changes in the double-log variograms suggest that the non-brown fractal model is suitable for characterizing the altitudinal patterns in the species richness of trees, shrubs and herbs at various scales but is not appropriate for explaining the variations in the plant species richness, since no significant changes were found in the double-log variograms in this case. Secondly, for the trees, the double-log variogram was divided into two scale ranges (0–245 m and 245–570 m), with a fractal dimension of 1.83 and 1.10, respectively, implying that changes in the tree species richness were random at small scales (0–245 m) and almost linear at large scales (245–570 m) along the altitudinal gradients. This suggests that altitudinal variations in the tree species richness are dominated by short-range processes at small scales and by long-range processes at large scales. Thirdly, for shrubs and herbs, the double-log variograms exhibited three ranges (0–101 m, 125–298 m and 325–570 m), and the fractal dimensions were 1.78 and 1.97, 1.56 and 1.43, and 1.08 and 1.25, respectively. The results indicate that, as in the case of trees, species richness of shrubs and herbs are distributed randomly at small scales and change in a linear manner at large scales although variations in the herb species richness is less heterogeneous than shrub species richness at large scales. These results also indicate that species richness of shrubs and herbs change approximately like brown movement at middle scales. The results also suggest that altitudinal variations in the specie richness of shrubs and herbs are dominated by three ecological processes, short-range ecological processes at small scales, long-range ecological processes at large scales, and brown fractal processes at middle scales. Interestingly, comparisons of the variations in the species richness of shrubs and herbs reveal that shrubs and herbs present the same scale range in spatial variation in species richness but display different trends in species richness along the altitudinal gradient, i.e. the shrub species richness decreased with increasing elevation whereas the herb species richness peaked at the mid-high elevation. These patterns suggest that although the scales at which the main processes affect patterns in species richness are the same, the processes are completely different, or the processes are similar but the responses of the shrubs and herbs to the ecological processes are different. Finally, the plant species richness did not show any obvious pattern along the altitude gradient and maintained a constant fractal dimension across all scales, this is perhaps because the processes defining the patterns of plant species richness had similar weights and acted over closely related scales. __________ Translated from Acta Phytoecologica Sinica, 2005, 29(6): 901–909 [译自: 植物生态学报]  相似文献   

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