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1.
One hundred and fifty-four jarrah (Eucalyptus marginata) and 85 marri (Corymbia calophylla) trees were measured and assessed, and the numbers and sizes of hollows in these trees were determined by destructive sampling; 665 hollows were located and measured. The relationship between tree diameter and tree age was determined from counts of annual growth rings on 162 of these trees. Large trees and trees with moderately senescent crowns individually bear the most hollows. Although the number of hollows found in individual trees increased with tree diameter, the distribution of tree diameters in the forest is skewed and the large number of small trees with diameters between 40 and 80 cm contribute approximately 50% of all hollows in the jarrah forest. The distributions of entry size, and of hollow depth, are highly skewed, with small hollows occurring more frequently than large hollows. Although jarrah trees bear more hollows than marri trees and the distribution of entry sizes is similar for both tree species, the hollows in jarrah are significantly smaller than the hollows in marri. Most hollows are cylindrical in shape, vertically oriented and occur in dead wood in the tree crown. Relatively few hollows (14%) occur in the tree bole or at crown break. Counts of hollows made from ground level are inaccurate as estimates of the actual number of hollows in trees.  相似文献   

2.
Information on roosting requirements and responses to forest management is integral to effectively conserve and manage bat populations. Tree hollows are especially important for roosting bats given the long time taken for hollows to form. We used radiotelemetry to compare roost site selection in two species, Vespadelus regulus and Nyctophilus gouldi, in logged jarrah forests of south-western Australia. We compared characteristics of roost trees and forest structure around roost trees (n = 48) with randomly located plots at a local roost tree level (n = 90) in February and March 2009. For landscape features, we compared roost trees with randomly selected trees in the broader landscape that had cavities or exfoliating bark (n = 204). V. regulus roosted solely in hollows that were located predominantly in contemporarily unlogged buffers and mature forest while N. gouldi used a broader range of roost types, located in contemporarily unlogged buffers and mature forest and in retained habitat trees in gap release and shelterwood creation silvicultural treatments. In contrast with N. gouldi, which selected hollows or crevices under bark near the ground and close to vegetation, V. regulus used hollows that were high above ground and had little surrounding vegetation. Both species preferred large trees, in intermediate or advanced stages of decay and crown senescence. Bats changed roosts frequently, with short distances between subsequent roosts, suggesting a degree of spatial fidelity. Contemporarily unlogged buffers and mature forest contained higher densities of trees with hollows than gap release and shelterwood creation areas, potentially providing more alternate bat roosts. Our results demonstrate the importance of mature forest and unlogged buffers as bat roost sites in logged jarrah forests of south-western Australia, but the area of old forest required by these and co-occurring bat species remains to be determined.  相似文献   

3.
Water stress and fire disturbance can directly impact stand structure, biomass and composition by causing mortality and influencing competitive interactions among trees. However, open eucalypt forests of southwest Australia are highly resilient to fire and drought and may respond differently to increased fire frequency and aridity than forests dominated by non-eucalypt species. We measured the variation in stem density, basal area, stand biomass, sapwood area, leaf area and litterfall across 16 mixed jarrah (Eucalyptus marginata) and marri (Corymbia calophylla) forest stands along an aridity gradient in southwest Australia that had variable fire histories. Fire frequency was defined as the total number of fires over a ∼30-year period and aridity as the ratio of potential evapotranspiration to annual precipitation. Total stand biomass and sapwood area were predicted from diameter at breast height of individual jarrah and marri trees using allometric equations. Leaf area was estimated using digital cover photography. More arid and frequently burnt stands had higher stem density, especially of smaller trees, which were mainly jarrah. Overall, both standing biomass and leaf area decreased at more arid sites, while sapwood area was largely unaffected by aridity, suggesting that these stands respond to increased water limitation by decreasing their leaf area relative to their sapwood area. Biomass of marri was reduced at more arid and, to a lesser extent, at more frequently burnt stands. However, total stand biomass (jarrah and marri) and leaf area index did not vary with fire frequency, suggesting that less marri biomass (due to slower growth rates, higher mortality or less recruitment) was compensated by an increase in the density of jarrah trees (regeneration). We conclude that increased fire and drought shift tree species composition towards more fire-resistant species and result in denser stands of smaller trees. In contrast, total stand biomass declines with increasing aridity, but has no association with fire frequency.  相似文献   

4.
Many invertebrates, birds and mammals are dependent on hollow trees. For landscape planning that aims at persistence of species inhabiting hollow trees it is crucial to understand the development of such trees. In this study we constructed an individual-based simulation model to predict diameter distribution and formation of hollows in oak tree populations. Based on tree ring data from individual trees, we estimated the ages when hollow formation commences for pedunculate oak (Quercus robur) in southeast Sweden. At ages of about 200–300 years, 50% of the trees had hollows. Among trees <100 years old, less than 1% had hollows, while all >400-year-old trees had hollows. Hollows formed at earlier ages in fast-growing trees than in slow-growing trees, which may be because hollows are formed when big branches shed, and branches are thicker on fast-growing trees in comparison to slow-growing trees of the same age. The simulation model was evaluated by predicting the frequency of presence of hollows in relation to tree size in seven oak stands in the study area. The evaluation suggested that future studies should focus on tree mortality at different conditions. Tree ring methods on individual trees are useful in studies on development of hollow trees as they allow analysis of the variability in time for hollow formation among trees.  相似文献   

5.
Hollow-bearing trees are an important ecological resource for many forest-dwelling species throughout the world. Assessments of the abundance and characteristics of tree hollows usually involve ground-based surveys. These are likely to be biased because of the distance over which the assessments are made. We demonstrate the use of double-sampling theory to correct this bias in order to provide the most efficient estimate of hollow abundance. A sample of 40 Eucalyptus leucoxylon (yellow gum) trees located at Yarra Bend Park, Melbourne, were climbed and assessed for hollows through close-up inspection. The results were compared to ground-based surveys conducted by individuals with varying levels of experience in assessing tree hollows. Strong correlations (r=0.57−0.83) were found between climbing and ground surveys and amongst ground surveys. Those ground surveyors who took more time with their surveys generally identified a higher proportion of hollows (Spearman’s r2=0.72), although all ground surveys underestimated hollow frequency. The proportion of hollows identified by each observer (range 0.09–0.44) remained approximately constant across all tree diameter size classes, indicating systematic underestimation of hollow frequency. The relative efficiency of ground surveys in comparison to climbing surveys is dependent on the time taken for each survey method and the strength of the relationship between them. Although climbing surveys provided the standard for hollow detection, in all cases, the quicker ground surveys were found to increase the efficiency of hollow assessments. Therefore, it was determined that efficient surveys of hollow occurrence could be undertaken by inexperienced surveyors with periodic climbing surveys to measure and correct for bias.  相似文献   

6.
The damaging effects of mistletoes Amyema spp. on host eucalypts in rural Australia concern many landholders, but few data are available to evaluate mistletoe impacts or formulate management strategies. We used an experimental disinfection approach to determine the effects of a putative pest mistletoe, Amyema miquelii, on its two principal hosts, Blakely's red gum (Eucalyptus blakelyi) and yellow box (Eucalyptus melliodora), on pastoral properties in northern New South Wales. For each host species, pairs of nearby trees were matched for heigth, diameter at breast height, level of mistletoe infestation and distance to neighbouring trees. One tree per pair was chosen at random and all the mistletoes pruned. After 33 months all treated trees were still alive, but among control trees seven of 29 red gums and one of 20 yellow box trees had died. The difference in survival between treated and control trees was significant for red gum. Among surviving pairs of trees, treated trees of both species had significantly greater diameter increments and significantly more foliage than untreated trees. After 33 months, the average increase in relative host foliage biomass attributable to removal of mistletoes was 22% in red gum and 24% in yellow box, compared with untreated controls. The average increase in radial growth attributable to mistletoe removal was 55% in red gum and 49% in yellow box. Diameter increment was negatively and linearly related to mistletoe infestation level in control trees of both species. The differences between infected and disinfected trees in this experiment may underestimate the impact of Amyema miquelii on host growth because small amounts of host biomass were unavoidably lost during disinfection. In a separate experiment, loss of host biomass had a significant negative impact on diameter increment. Although the results indicate that control of serious Amyema miquelii infestation of individual trees will be worthwhile in terms of immediate host survival and higher growth rate, prudent long-term management may well allow for the loss of small numbers of farm trees to mistletoes when planning tree recruitment and utilisation.  相似文献   

7.
Tidal freshwater forested wetlands occupy a relatively narrow range, occurring where wind and lunar tides interact with coastal river systems, causing freshwater flooding onto the floodplain. A prominent component of this wetland type is hummock and hollow microtopography. Tidal freshwater forested wetlands along the Savannah River were differentiated into backswamp and streamside areas, and the degree to which trees occupied hummocks and hollows were compared at three scales: landscape (backswamp vs. streamside), tree community, and species (within community). The community- and species-level analyses were extended to determine whether trees were using either hummocks or hollows in a nonrandom manner. Trees in the backswamp setting were found to use hummocks more than trees in the streamside setting. At the community scale, three of the five treatment groups investigated differed based on the degree to which trees on hummocks outnumber trees in hollows. Further examination of microtopography usage confirmed that hummocks are used significantly more than hollows in two communities, both of which are located in the backswamp setting. Though no tree community used hollows significantly more than hummocks, species-level analyses confirmed that, within a specific tree community in the streamside setting, alder (Alnus serrulata [Ait.] Willd.) is found more in hollows than on hummocks. Fourteen different species between the two communities in the backswamp setting are found on hummocks more than in hollows, and only one species, sweetgum (Liquidambar styraciflua L.), is found more on hummocks than in hollows in the tree community in the streamside setting.  相似文献   

8.
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9.
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10.
Detailed studies have been undertaken to define pruning regimes for Eucalyptus nitens, but little is known of E. globulus responses to pruning although this is a more commonly planted species. This paper describes experiments that aimed to identify (a) levels of pruning that reduce E. globulus growth, (b) physiological processes contributing to those growth responses, (c) the incidence of decay and factors influencing decay incidence following pruning of E. globulus, and (d) comparative responses of E. nitens and E. globulus to live branch pruning. Results of a field experiment indicated that removal of between 30 and 50% of the crown length was appropriate for E. globulus plantations verging on canopy closure. The significant reduction in height growth associated with removal of 50 or 70% of crown length suggested pruning should remain below 50% of crown length if reduced stem growth of pruned trees was to be avoided. Stem volume was only significantly reduced over the period of the experiment by 70% pruning, but it was estimated that standing volume following removal of 50% of crown length would be reduced by 82 m3 ha−1 over a 20-year rotation if there were no other silvicultural interventions. The growth responses observed were probably related to large reductions in leaf area following 50 or 70% removal of crown length. Trees responded to pruning by changing patterns of biomass partitioning to favour stem growth at the expense of branch growth. A glasshouse study determined that light-saturated net CO2 uptake (Amax) increased following pruning. E. nitens seedlings had both a higher baseline Amax and higher Amax following pruning than did E. globulus, which could partially explain the greater effect of pruning on E. globulus growth than has been observed for E. nitens in other studies. This result, as well as apparently different patterns of foliage distribution through the crowns of E. globulus and E. nitens, suggested that models of pruning responses need to be parameterised for both species. In addition, a more conservative pruning regime may be appropriate for E. globulus than E. nitens. Pruning increased the frequency of branch traces with decay infection, and there was a trend towards increasing decay outbreaks with increasing pruning severity. Decay outbreaks were more likely to occur following pruning of high angle or larger diameter branches.  相似文献   

11.
We examined the vertical profiles of leaf characteristics within the crowns of two late-successional (Fagus crenata Blume and Fagus japonica Maxim.) and one early-successional tree species (Betula grossa Sieb. et Zucc.) in a Japanese forest. We also assessed the contributions of the leaves in each crown layer to whole-crown instantaneous carbon gain at midday. Carbon gain was estimated from the relationship between electron transport and photosynthetic rates. We hypothesized that more irradiance can penetrate into the middle of the crown if the upper crown layers have steep leaf inclination angles. We found that such a crown has a high whole-crown carbon gain, even if leaf traits do not change greatly with decreasing crown height. Leaf area indices (LAIs) of the two Fagus trees (5.26-5.52) were higher than the LAI of the B. grossa tree (4.50) and the leaves of the F. crenata tree were more concentrated in the top crown layers than were leaves of the other trees. Whole-crown carbon gain per unit ground area (micromol m(-2) ground s(-1)) at midday on fine days in summer was 16.3 for F. crenata, 11.0 for F. japonica, and 20.4 for B. grossa. In all study trees, leaf dry mass (LMA) and leaf nitrogen content (N) per unit area decreased with decreasing height in the crown, but leaf N per unit mass increased. Variations (plasticity) between the uppermost and lowermost crown layers in LMA, leaf N, the ratio of chlorophyll to N and the ratio of chlorophyll a to b were smaller for F. japonica and B. grossa than for F. crenata. The light extinction coefficients in the crowns were lower for the F. japonica and B. grossa trees than for the F. crenata tree. The leaf carbon isotope ratio (delta(13)C) was higher for F. japonica and B. grossa than for F. crenata, especially in the mid-crown. These results suggest that, in crowns with low leaf plasticity but steep leaf inclination angles, such as those of F. japonica and B. grossa trees, irradiance can penetrate into the middle of the crowns, thereby enhancing whole-crown carbon gain.  相似文献   

12.
Crown dimensions are important for the quantification of tree interactions in some growth models. This study investigates the potential for structural indices and other spatial measures to improve the prediction of crown radius and crown length for birch (Betula spp.) and Sitka spruce (Picea sitchensis (Bong.) Carr.) in forests in Wales. Crown dimensions were measured for 125 birch and 154 spruce in six fully stem-mapped research plots. These data were used to test the performance of a crown radius model and a crown length model which estimated crown dimensions on the basis of allometric relationships with stem dimensions. Spatial data from the six plots were used to calculate the structural indices mean directional index, diameter correlation index, species mingling, dbh and height dominance, and dbh differentiation, as well as the Hegyi competition index, and basal area of neighbours and larger neighbours, for each crown measurement sample tree, using various numbers of nearest neighbours. Two non-spatial indices, BAL and BALMOD, were also calculated for all sample trees for comparison. These spatial and non-spatial variables were then incorporated into modified crown dimension models. Model performances, in terms of efficiency and relative bias, were compared to determine whether the inclusion of spatial or non-spatial variables resulted in any improvements over models using tree dimensions alone. Crown length and radius were found to be correlated with most of the spatial measures studied. Models incorporating spatial variables gave improvements in performance over allometric models for every data set, and performed more consistently than models containing non-spatial variables. The greatest improvements were achieved for suppressed birch in unthinned forests which had irregularly shaped and strongly displaced crowns. The spatial variable contributing to the most efficient model for each data set varied widely. This points to the complexity of tree spatial interactions and indicates that there is a great deal of scope for investigating other structural indices and crown dimension model forms.  相似文献   

13.
In recent years unusual high mortality of Scots pine (Pinus sylvestris) has been observed in the Swiss Rhone Valley. The exact causes, however, are not known. At a 2‐ha monitoring plot, tree mortality and crown condition have been monitored since 1996. Between 1996 and 2004, 59% of the Scots pines died, most of them following the drought periods 1996–1998 and 2003–2004, while only 15% of the deciduous trees died. Crown transparency, needle discolouration, dead branch percentage, mistletoe (Viscum album ssp. austriacum) rating, Tomicus sp. shoot feeding, male flowering effect, tree stem diameter, crown shading and social tree class assessed in 1998 were used in a logistic regression model to predict tree mortality. Crown transparency, mistletoe rating and percentage of dead branches were found significant in the model and the probability of tree mortality increased with increasing rankings of these parameters. Needle discolouration could be used to substitute ‘dead branch percentage’ as predictor. While crown transparency increased with mistletoe rating, for trees in the same transparency class, trees with medium and heavy mistletoe infection were two to four times more likely to die than trees with no or only low mistletoe infection. For the surviving trees we found that trees with mistletoes showed a significantly higher increase in transparency in the year following a drought than trees without, while in a drought year the opposite was true. At the beginning of the observations no significant differences in transparency had been found between the trees with and without mistletoe. However, by the end of the observation period trees with mistletoe had significantly higher crown transparency. We conclude that mistletoe infection can be considered as both a predisposing factor for tree death, by increasing needle loss following drought and a contributing factor by increasing water stress during drought.  相似文献   

14.
Cork oak (Quercus suber) forests are acknowledged for their biodiversity and economic (mainly cork production) values. Wildfires are one of the main threats contributing to cork oak decline in the Mediterranean Basin, and one major question that managers face after fire in cork oak stands is whether the burned trees should be coppiced or not. This decision can be based on the degree of expected crown regeneration assessed immediately after fire. In this study we carried out a post-fire assessment of the degree of crown recovery in 858 trees being exploited for cork production in southern Portugal, 1.5 years after a wildfire. Using logistic regression, we modelled good or poor crown recovery probability as a function of tree and stand variables. The main variables influencing the likelihood of good or poor crown regeneration were bark thickness, charring height, aspect and tree diameter. We also developed management models, including simpler but easier to measure variables, which had a lower predictive power but can be used to help managers to identify, immediately after fire, trees that will likely show good crown regeneration, and trees that will likely die or show poor regeneration (and thus, potential candidates for trunk coppicing).  相似文献   

15.
《林业研究》2021,32(1)
Over the past 50 years,crown asymmetry of forest trees has been evaluated through several indices constructed from the perspective of projected crown shape or displacement but often on an ad hoc basis to address specific objectives related to tree growth and competition,stand dynamics,stem form,crown structure and treefall risks.Although sharing some similarities,these indices are largely incoherent and non-comparable as they differ not only in the scale but also in the direction of their values in indicating the degree of crown asymmetry.As the first attempt at devising normative measures of crown asymmetry,we adopted a relative scale between 0 for perfect symmetry and 1 for extreme asymmetry.Five existing crown asymmetry indices(CAIs) were brought onto this relative scale after necessary modifications.Eight new CAIs were adapted from measures of circularity for digital images in computer graphics,indices of income inequality in economics,and a bilateral symmetry indicator in plant leaf morphology.The performances of the 13 CAIs were compared over different numbers of measured crown radii for 30 projected crowns of mature Eucalyptus pilularis trees through benchmarking statistics and rank order correlation analysis.For each CAI,the index value based on the full measurement of 36 evenly spaced radii of a projected crown was taken as the true value in the benchmarking process.The index(CAI_(13))adapted from the simple bilateral symmetry measure proved to be the least biased and most precise.Its performance was closely followed by that of three other CAIs.The minimum number of crown radii that is needed to provide at least an indicative measure of crown asymmetry is four.For more accurate and consistent measures,at least 6 or 8 crown radii are needed.The range of variability in crown morphology of the trees under investigation also needs to be taken into consideration.Although the CAIs are from projected crown radii,they can be readily extended to individual tree crown metrics that are now commonly extracted from LiDAR and other remotely sensed data.Adding a normative measure of crown asymmetry to individual tree crown metrics will facilitate the process of big data analytics and artificial intelligence in forestry wherever crown morphology is among the factors to be considered for decision making in forest management.  相似文献   

16.
Living trees (green trees) are intentionally retained on logged sites for many purposes such as wildlife conservation, future wood potential and aesthetics. Minimizing the risk that these trees collapse in the short-term will improve the chances that green-tree retention meets its objectives. In a retrospective case-control study, we identified factors significantly associated with the collapse of living trees retained on logged and slash-burnt sites in south-eastern Australia within 8 years of harvesting. Trees with incomplete crowns or trees with at least one visible cavity were, on average, at three times greater risk of collapse relative to trees with complete crowns or no visible cavities, respectively. Trees with fire-scarring, trees retained greater than 50 m from intact forest or trees retained in isolation were, on average, around twice the risk of collapse relative to trees without fire-scarring, trees retained within 50 m of intact forest or trees retained among other trees, respectively. When considered jointly, the significant factors in a model predicting the collapse of retained trees – tree height, tree diameter, crown form – were all associated with the health of trees. Choosing the healthiest trees possible for fulfilling their function, protecting trees from damage (e.g. fire) and retaining trees near, or among, other trees are likely to reduce the risk of collapse among retained trees and thus contribute to the effectiveness of green-tree retention in logged eucalypt forests.  相似文献   

17.
Long-term forest development programs in Germany aim on an increase of close-to-nature broadleaf forest stands. This means that the economic importance of European beech is expected to increase. The economic potential of a tree basically consists of the stem as well as the economically viable wood volume in the crown. Due to the high morphological variability of European beech crowns, taper models are often not satisfactory for predicting the economically viable wood volume arising from crowns. Prediction models with a higher precision are recently still lacking. Aim of this study is thus the development of prediction model for the economically viable crown wood volume of European beech trees.We determined the distribution of the wood volume in the crown over the branch diameters using the multistage ‘randomized branch sampling’ method (RBS). The tree-specific wood volume distribution on the branch diameters were used to cluster all sampled trees into 3 groups. Additionally, we developed a method able to distinguish between economically viable and unviable crown branches. Basing on the RBS measurements as well as revenues and processing costs, we modeled the economically viable wood volume from the crown for each tree. To calculate the wood volume under bark, we parameterized a bark thickness function from disk samples of the trees.We showed that the European beech crowns could be clustered into 3 groups differing in their wood volume distribution. The economically viable wood volume in the crown significantly depended on this grouping parameter as well as diameter at breast height (DBH). By contrast, the total amount of wood in the crown only depended on DBH. The differing viable wood volumes in the crowns were thus explained by different wood distributions and not by differing total crown wood volume. To make the results applicable in practice forestry, the modelling results were used to develop a regression formula able to predict the economically viable wood volume in the crown depending on the DBH and the crown type. As the crown type can also be predicted via measurable tree covariates, the regression model of the viable wood volume in the crown can be used as a support tool for the management of European beech stands. Sensitivity analysis quantifies how harvest revenues and costs translate into different viable tree volume.  相似文献   

18.
The success of multiple forest management systems is contingent on a variety of social, economic, biophysical, and institutional factors, including the integration of timber and non-timber forest product (NTFP) extraction and management. Selective logging for timber is increasingly taking place in forests where the collection of Brazil nuts, a high-value Amazonian NTFP, also occurs. We report on logging damage to Brazil nut trees in three certified timber concessions in Northern Bolivia from which timber is harvested using reduced-impact logging (RIL) guidelines and nuts are gathered yearly from the ground by local people. Observed frequencies of logging damage to Brazil nut trees were low, likely mirroring the low intensity of timber harvesting (∼0.5 trees/ha and ∼5 m3/ha) being currently applied across the study area. Of the trees ≥10 cm in diameter at breast height about 0.1 Brazil nut trees and 0.4 timber species per hectare suffered some degree of logging damage. Crown loss was the predominant damage type for Brazil nut trees accounting for 50% of all damage. In spite of the observed low rates of tree damage, we further recommend that RIL guidelines be amended to include the pre-harvest marking of pre-reproductive Brazil nut trees along with the future crop trees of commercial timber species. Further refining directional felling to reduce crown damage to Brazil nut trees would also serve to help maintain nut yields in the long term.  相似文献   

19.
Competition for canopy space is a process of major importance in forest dynamics. Although virgin and old-growth European beech (Fagus sylvatica L.) forests in Europe have been studied for many years, there are to date no studies of individual-tree crown plasticity and the way this is influenced by local neighborhood interactions in these forests. In this study, we analyzed crown plasticity and local neighborhood interactions of individual trees in the upper canopy of the old-growth beech forests of Serrahn, northeast Germany. In a 2.8-ha sample plot, we measured crown radii of all upper canopy trees and analyzed the direction and extent of crown asymmetry. Size, relative position, and distance of neighboring trees were used to construct vectors of neighborhood asymmetry within different distances from target trees. The crowns of beech trees showed strong morphological plasticity. Mean absolute and relative displacement of crown centers from the stem base were 1.95 m and 0.37, respectively. Circular–circular rank correlation coefficients between the direction of crown displacement and the direction of neighborhood pressure showed that trees strongly positioned their crowns away from local neighbors. Highest correlation coefficients were obtained when basal area and relative position of neighboring trees within a radial distance of 12 m were considered. Clark and Evans index and Ripley’s K-function showed that crowns were more regularly distributed than stems. Projected canopy cover was about 10% higher than canopy cover with simulated circular crowns. We conclude that the crowns of older beech trees have a high ability to plastically respond to changes in the local canopy conditions, enabling very effective exploitation of canopy space.  相似文献   

20.
Crown form, vertical changes in branch inclination and vertical distribution of foliage density in a young sugi (Crytomeria japonica D. Don) stand were analyzed using allometric equations. Tall trees had deeper crowns than short trees, whereas the crown diameters of both tall and short trees were similar. Apical roundness was more pronounced in the lower-story trees, which were characterized by umbrella-shaped crowns. The vertical distribution of foliage density was approximated by a nearly symmetrical curve. Tall trees had higher spatial densities of foliage than short trees. Branch inclination also varied significantly with tree height. The middle-story trees had the largest branch inclinations and the lower-story trees had the smallest branch inclinations. Even in young uniform stands, crown morphology and structure were modified in response to the light environment.  相似文献   

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