Accuracy of the Rotfinder instrument in detecting decay on Norway spruce (Picea abies) trees

Rotfinder is a non-destructive decay-sensing apparatus based on resistance measurements in standing trees. The accuracy of Rotfinder in detecting decay was evaluated in 500 standing trees in three Norway spruce (Picea abies) plots. Trees were measured at three heights, 0.30, 0.66 and 1.30 m. Sections were later inspected for the presence of decay and reaction zones. Inspected trees were mostly infected by Heterobasidion annosum and showed a large variation in the amount of decay present, ranging from 0.1% to 88.0% of the section. Correctly and incorrectly classified trees were compared in terms of ion and element concentration, density and moisture. Measurements at stump level (0.30 m) were more accurate than measurements at breast height (1.30 m) where the reaction zone and decay columns showed lower moisture content. The accuracy of Rotfinder increased when trees with small decay columns were regarded as ‘non-decayed’. When only trees with more than 15% of the section decayed were regarded as ‘decayed’, Rotfinder had an accuracy of 0.86 when performing assessments at stump level. False negatives, as opposed to true positives, corresponded to trees with smaller and drier decay columns, drier reaction zones and lower K⁺ (potassium) concentration in the decay column. False positives corresponded to trees with large sapwood and high sodium content in the sapwood. Rotfinder represents an alternative to the standard method of using increment core observations to assess decay in living trees.     

Growth–climate responses of high-elevation conifers in the central Hengduan Mountains,southwestern China

Improved understanding of tree-growth responses to climate is needed to model and predict forest ecosystem responses to current and future climatic variability. We applied dendroclimatological techniques to assess the effects of inter-annual climate variations on radial growth of high-elevation conifers in the central Hengduan Mountains, southwestern China. Eight tree-ring width chronologies of the major tree genera Abies and Picea that are aligned along an elevation gradient from 3200 to 4200 m a.s.l. were developed. Correlation and principal component analyses for the eight chronologies identified three groups of sites, representing different patterns of growth–climate relationships. Correlation and redundancy analyses with regional climate data revealed that radial growth of fir growing at high-elevation sites is enhanced by normal or warm summer temperatures (June and July) during the current growing season. In addition, radial growth of trees growing from high to middle elevations is sensitive to low temperatures during winter season. At low-elevation sites, trees display low sensitivity to temperature variation. However spring moisture availability becomes crucial for radial growth regardless of tree species. High- to middle-elevation conifers in the central Hengduan Mountains may benefit from the current climate warming, especially from rising winter temperatures.     

Stem deformation in young plantations of black spruce (Picea mariana (Mill.) B.S.P.) and jack pine (Pinus banksiana Lamb.) in the boreal forest of Quebec,Canada

Stem deformation has often been observed in young black spruce (Picea mariana (Mill.) B.S.P.) and jack pine (Pinus banksiana Lamb.) plantations. Whenever important stem deformations are observed at the time of harvesting, timber value is negatively affected especially during the wood transformation process. The present work was undertaken to quantify and qualify the importance of stem deformation of black spruce and jack pine in the boreal forest of central Quebec at the stand and tree levels. In 30 black spruce and jack pine plantations, approximately 22% of spruce trees and 27% of pine trees exhibited stem deformation. The proportion of deformed trees was higher in the youngest plantations and decreased with the age of the plantations. Stem deformation caused the formation of compression wood which is another factor that can reduce the value of wood products. Thirty-nine black spruces and 34 jack pines were analysed at the tree level. On average, compression wood represented 14% and 20% of stem volume in 7- and 10-year old black spruce plantations, respectively. These proportions ranged from 18% in the youngest jack pine plantation to 26% in the oldest one. Stems of both species classified as normal contained a lower volume of compression wood than stems classified as deformed or very deformed. Annual percentages of compression wood and annual shoot length increased significantly with tree age (p < 0.0001 for both variables). Statistically significant correlations were also found between the range of displacement of the stem and the percentage of compression wood. The fewer number of trees with deformed stems in older plantations combined with high compression wood formation suggests that, over time, a deformed tree can become normal and straight in appearance.     

An increase in the upper tree-limit of silver fir (Abiesalba Mill.) in the Alps since the mid-20th century: A land-use change phenomenon

Global environmental changes observed during recent decades are likely to have had an impact on the distribution of species. Currently, silver fir (Abies alba) is becoming established in the subalpine forests of the west central Alps at elevations higher than 2000 m a.s.l.; prior to the 1970s its upper altitudinal limit was 2000 m. Several hypotheses could explain this recent expansion of the upper tree-limit. Silver fir regeneration could be linked (1) to land-use changes or (2) to current climatic warming. Using dendrochronology, the age structure of 31 forest plots containing at least one silver fir was examined in order to elucidate the population dynamics of subalpine communities. This allowed us to decipher the timing of fir regeneration in relation to the mean age of the stands examined and of the other tree-canopy species present. The majority of the firs germinated sporadically since 1950, before the regional temperature increase. The pattern of fir recruitment did not appear to relate to altitude, but followed a pattern characteristic of secondary succession. The age structures identified showed an exponential increase in tree-density during the 20th century; the stands were first dominated by Larix decidua during the 18th and 19th centuries, and then by Pinus cembra during the 20th century. In most stands, fir regeneration occurred after Larix and before P. cembra dominated, following a similar pattern to Picea abies regeneration. The number of local inhabitants and temperature both exhibited a negative relationship with fir tree recruitment, thus supporting the land-use change hypothesis. There has been a significant upward shift of the altitudinal range of fir, amounting to an increase of about 300 m since 1950. This followed the abandonment of low-productivity land. This trend is likely to continue during the 21st century, because of new agricultural and forestry practices which involve limited intervention in low-productivity areas and may be because of the effects of global warming.     

Elevation patterns of woody taxa richness in the evergreen Afromontane vegetation of Ethiopia

Plant species distributions show patterns along elevation gradients. Regardless of the diverse Afromontane vegetation in Ethiopia(AFE), studies of elevation patterns of woody plants are limited and they are restricted to small areas or single/few Mountains. Moreover, there is no general consensus on the patterns of woody taxa distribution by elevation. The objectives of this study were to examine the elevation patterns of woody taxa richness and their relationship with elevation in the AFE. Data were collected and compiled from the Flora of Ethiopia and Eritrea(Vols. 1–7). About 5918 plant species of 243 families were examined and their elevational distributions were recorded. The distributional ranges of woody taxa were aggregated at 19 points(sites) at 100 m intervals starting from 1500 to 3400 m a.s.l. Single-factor analysis of variance(one-way ANOVA) was used to test the hypothesis that mean species richness of woody taxa decreases from the lower to the upper limit of AFE. Simple linear correlation and regression were used to show the relationships of woody taxa richness with elevation. We documented the presence of 505 woody taxa(441 species,31 subspecies and 33 varieties) representing 267 genera and 90 families in the AFE. In terms of habit, 279 taxa are shrubs, 178 are trees and 48 are lianas. The distribution of woody taxa(trees, shrubs and lianas) showed a slight increase at the lower portion and a monotonic decline with increasing elevation. Species richness of trees, shrubs and lianas was negatively and significantly correlated with elevation(r =-0.985,-0.984,-0.981, respectively; all p 0.001). Our hypothesis was accepted because mean richness significantly decreased from the lower to the upper limit of AFE(p 0.001). Generally, monotonic patterns of decline in richness were observed for trees, shrubs and lianas. The contribution of shrubs to total richness increased with increasing elevation whereas that of trees and lianas decreased.     

Evidence that longer needle retention of spruce and pine populations at high elevations and high latitudes is largely a phenotypic response

There is abundant evidence that evergreen conifers living at high elevations or at high latitudes have longer-lived needles than trees of the same species living elsewhere. This pattern is likely caused by the influence of low temperature in combination with related factors such as a short growing season and low nutrient availability. Because it is not known to what degree such patterns result from phenotypic versus genotypic variation, we evaluated needle longevity for common-garden-grown lowland populations of European Scots pine (Pinus sylvestris L.) of wide latitudinal origin and Norway spruce (Picea abies L.) of wide elevational origin. Nine-year-old trees of 16 Scots pine populations ranging in origin from 47 degrees to 60 degrees N were studied in Kórnik, Poland (52 degrees N) and 18-year-old trees of 18 Norway spruce populations ranging in origin from 670 to 1235 m elevation in southwestern Poland were studied near Morawina, Poland (51 degrees N, 180 m elevation). There was no tendency in either species for populations from northern or high elevation origins to retain needles longer than other populations. All of the Scots pine populations had between 2.5 to 3.0 needle age cohorts and all of the Norway spruce populations had between 6.4 and 7.2 needle age cohorts. Thus, extended needle retention in Scots pine and Norway spruce populations in low-temperature habitats at high elevations and high latitudes appears to be largely an environmentally regulated phenotypic acclimation.     

Effect of seed source elevation on bud opening of Yezo spruce (<Emphasis Type="Italic">Picea jezoensis</Emphasis>)

Spring frost damage is one of the obstacles to be overcome in establishing a Yezo spruce (Picea jezoensis Carr.) plantation. The timing of bud opening of Yezo spruce seedlings cultured from seeds collected at three different elevations (420, 700, and 1200m) in the Tokyo University Forest in Hokkaido was observed at two planting site elevations (610 and 750m) to investigate whether seed source elevation or planting site elevation affects the bud opening date. At both planting sites the bud opening dates were not significantly different among the seedling groups from different seed source elevations. On the other hand, bud opening dates of seedlings planted at the lower elevation site were significantly earlier than those planted in the higher elevation site. It could be deduced from this study that the environment of the planting site rather than seed source elevation affects the bud opening date of Yezo spruce.     

Snow-packing as a potential harmful factor on Picea abies,Pinus sylvestris and Betula pubescens at high altitude in northern Finland

Snow-packing, a combination of ice, hoarfrost and snow on trees, and the subsequent tree damage by snow, were estimated on Norway spruce (Picea abies), Scots pine (Pinus sylvestris), and pubescent birch (Betula pubescens) in the winter of 1993-94 in southern Lapland, northern Finland, near the local alpine timberline around 400 m a.s.l. Snow-packing on each fully sized tree increased from a few hundred kilograms at 150–250 m a.s.l. to a maximum of 3290 kg at 300–350 m a.s.l. At 300 m a.s.l., snow-packing per metre of stem increased from 30 to 50 kg on trees < 5 m in height up to 180–200 kg on 20-m trees. There was 300 000-480 000 kg/ha of snow accumulated on tree crowns. No stem breakage by snow-packing occurred at or below 250 m a.s.l., whereas at 290–350 m a.s.l., 0-46%, 39-100%, and 0–33% of the spruce, pine and birch trees, respectively, had broken tops. Birch appeared to be the most resistant and pine the most susceptible to snow breakage.     

Biomass functions and expansion factors in young Norway spruce (Picea abies [L.] Karst) trees

Roots, stems, branches and needles of 160 Norway spruce trees younger than 10 years were sampled in seven forest stands in central Slovakia in order to establish their biomass functions (BFs) and biomass expansion factors (BEFs). We tested three models for each biomass pool based on the stem base diameter, tree height and the two parameters combined. BEF values decreased for all spruce components with increasing height and diameter, which was most evident in very young trees under 1 m in height. In older trees, the values of BEFs did tend to stabilise at the height of 3–4 m. We subsequently used the BEFs to calculate dry biomass of the stands based on average stem base diameter and tree height. Total stand biomass grew with increasing age of the stands from about 1.0 Mg ha⁻¹ at 1.5 years to 44.3 Mg ha⁻¹ at 9.5 years. The proportion of stem and branch biomass was found to increase with age, while that of needles was fairly constant and the proportion of root biomass did decrease as the stands grew older.     

The importance of seedling competition in the segregation of spruce and fir in the southern Appalachians

Fraser fir (Abies fraseri [Pursh] Poir.) and red spruce (Picea rubens Sarg.) are codominants of southern Appalachian spruce-fir forests. Fraser fir generally dominates above 1740 m, while red spruce usually dominates below this elevation. This study was designed to determine whether the present segregation of the two species along elevational gradients is associated with seedling competition or contrasting physiological responses to environmental factors. Seedlings were grown for two years in a replacement series experiment along two elevational transects extending from 1300 m to 1900 m, and harvested for growth analysis.Competition increased with decreasing elevation and Fraser fir was apparently the stronger competitor. Mortality was inversely correlated with elevation and was most evident in red spruce in May, and in fir in late summer. Fir growth increased with elevation and red spruce grew most at the middle elevation (1600 m). Neither competitive interactions nor growth responses completely explained the elevational segregation of red spruce and Fraser fir. We hypothesize that the early-successional Fraser fir quickly dominates at higher elevations following disturbance and that continued disturbance will favor its dominance at higher elevations. However, the late-successional noncompetitive red spruce slowly establishes itself and, while consistently present, may only dominate in the absence of disturbance and where other species are at the margins of their distribution.     

Reflectance of Alaskan black spruce and white spruce foliage in relation to elevation and latitude

Leaf reflectance at visible and near-infrared wavelengths (400-1000 nm) is related primarily to pigmentation, leaf structure and water content, and is an important tool for studying stress physiology and relationships between plants and their growth environment. We studied reflectance of two co-occurring Alaskan conifers, black spruce (Picea mariana (Mill.) BSP) and white spruce (Picea glauca (Moench) Voss), at elevations from 60 to 930 m a.s.l. along a latitudinal gradient from 61 degrees to 68 degrees N. Black spruce samples were collected from 24 sites and white spruce from 30 sites. Overall, reflectance spectra of the two species were similar, but from 400 to 700 nm, needle reflectance was consistently higher in black spruce than in white spruce (all P 相似文献   

Growth and population structure of the tree species Malouetia tamaquarina (Aubl.) (Apocynaceae) in the central Amazonian floodplain forests and their implication for management

The long-term success of forest management depends primarily on the sustainability of timber production. In this study we analyse the population structure, tree age and wood increment of Malouetia tamaquarina (Aubl.) (Apocynaceae) to define a species-specific minimum logging diameter (MLD) and felling cycle by modelling volume growth. Contrary to other timber species in the nutrient-rich white-water floodplains forests (várzea), M. tamaquarina grows in the subcanopy of old-growth várzea forests. The wood of this species is utilized by local inhabitants in the floodplains for handicraft. In 35 plots of 25 m × 50 m we measured diameter at breast height (DBH) and tree height of all trees taller than 150 cm height. From 37 individuals with DBH > 15 cm we sampled two cores by increment borers to determine the wood density, tree age and diameter increment rates. In the management area of a várzea settlement with about 150 ha recently harvested trees of M. tamaquarina have been recorded and DBH was measured. The species presents an inverse J-shaped diameter distribution indicating that the species is obviously regenerating in the old-growth forests. Tree-ring analysis indicates a mean age of 74.5 years for a DBH of 22.7 cm for a studied population comprising 37 trees with maximum ages of up to 141 years for an individual with a DBH of 45.7 cm. The tree species has low annual diameter increment rates (3.16 ± 0.6 mm) despite a low wood density (0.36 ± 0.05 g cm⁻³). The volume growth model indicates a MLD of 25 cm and a felling cycle of 32.4 years. In the management area 35 trees with a mean DBH of 24 cm were recorded, similar to the defined MLD. The abundance of trees above the MLD is 2.7 trees ha⁻¹, or 405 trees, when extrapolated to the whole management area. Considering a felling cycle of 32.4 years (annual production unit of 4.63 ha) this results in total of 12.5 harvestable trees, almost three times less than actually harvested. The actual practice of harvesting M. tamaquarina risks the overexploitation of this slow-growing species.     

Drought sensitivity of Norway spruce is higher than that of silver fir along an altitudinal gradient in southwestern Germany

Context

For Central Europe, climate projections foresee an increase in temperature combined with decreasing summer precipitation, resulting in drier conditions during the growing season. This might negatively affect forest growth, especially at sites that are already water-limited, i.e., at low elevation. At higher altitudes trees might profit from increasing temperatures.

Aims

We analyzed variations in radial growth of silver fir (Abies alba Mill.) and Norway spruce (Picea abies (L.) Karst.) along an altitudinal gradient from 400 until 1,140 m a.s.l. in the Black Forest, to assess climate responses with increasing elevation.

Methods

Climate–growth relationships were analyzed retrospectively using tree-ring and climate data. In total, we sampled stem discs of 135 trees to build 27 species- and site-specific chronologies (n _fir?=?13, n _spruce?=?14).

Results

Our results indicate distinct differences in climate–growth relations between fir and spruce along the gradient. Growth of high-altitude fir was positively related to temperature from January till March. Growth of low-altitude fir and spruce at all elevations was positively related to precipitation and negatively to temperature during the growing season, particularly in July. A self-calibrating Palmer drought severity index underlined summer drought sensitivity of these trees.

Conclusion

Overall, we found that climatic control of tree growth changes over altitude for fir. For spruce, a remarkable synchrony in growth variation and climate response was shown, which indicates that this species is drought sensitive at all studied elevations. In a future warmer climate, the growth of low-altitude fir and spruce along the entire studied gradient may be negatively affected in the Black Forest, if an increased evaporative demand cannot be compensated by increased water supply.     

Altitudinal differences in bark stripping by sika deer in the subalpine coniferous forest of Mt. Fuji

Deer expansion is a growing concern for forest ecosystem management. In Japan, upward expansion to subalpine and alpine areas has reached alarming proportions in recent years. We examined bark stripping by sika deer along an altitudinal gradient in the subalpine coniferous forest at three altitude ranges (1800-2000 m, 2000-2200 m, and 2200-2400 m) on the southern slope of Mt. Fuji. We tested differences in densities and diameter at breast height (DBH) of trees and those with bark-stripped stems of all tree species among the three altitude ranges. Then, we compared the relative densities of deer, based on pellet counts, to determine the impact of deer in relation to deer use and forest stand patterns across the altitudinal range studied. The results of the study show that differences in bark stripping by sika deer depended largely on the elevation and the species. Larger stems were sparsely distributed in the lowest elevation zone between 1800 and 2000 m. The relative density of deer was highest in the areas exhibiting high bark-stripping intensity on small regenerating trees of the dominant coniferous species, Abies veitchii, and on broadleaf species. In the highest elevation zone between 2200 and 2400 m, smaller stems were densely distributed, and the relative deer density was lowest where the bark-stripping intensity on small stems was lower for all three species studied. The damage to subalpine tree stems corresponded to the availability of palatable tree species with a small diameter, as reflected by the successional stage along the elevational gradient of subalpine forest on Mt. Fuji. These results suggest that the continuous impact of bark stripping on the dominant tree species might cause severe changes in forest succession.     

Seasonal changes in shoot water relations of Picea rubens at two high elevation sites in the Smoky Mountains

Seasonal changes in water relations of current-year shoots of red spruce (Picea rubens Sarg.) were examined in relation to climatic conditions in trees growing at elevations of 1720 and 1935 m on Clingman's Dome, Tennessee, USA, where increment core data have shown that red spruce decline increases with elevation. Relative height growth of trees at 1720 m was 68% greater than in trees at 1935 m. Following two weeks in July with only traces of precipitation, trees at both sites showed decreased saturated osmotic potentials. The magnitude of the reduction was greater in trees at the high elevation site than in trees at the low elevation site. However, during August and September, shoot water relations of trees at both sites were similar. Precipitation patterns and water relations measurements suggested that, at both sites, trees experienced water stress only briefly during the growing season and to a degree that could not account for the lower growth rates of trees at the high elevation site. During the period of cold hardening in October and November, trees at the low elevation site exhibited saturated osmotic potentials that were lower by 0.2 MPa and solute accumulation (osmol kg(dw) (-1)) that was 48% greater than in trees at the high elevation site.     

Comparison of fractal characteristics of species richness patterns among different plant taxonomic groups along an altitudinal gradient

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]     

Sustainability of wild pistachio (Pistacia atlantica Desf.) in Zagros forests,Iran

Wild pistachio (Pistacia atlantica Desf.) is the most economically important tree species in many rural areas in the west of Iran. The species produces resin used for a wide variety of traditional uses. Because the resin can be harvested non-destructively, the trees are maintained until mortality occurs from natural causes. The result is that natural, managed stands include a variety of age classes. In recent years, a lack of smaller size classes has been observed in the Qalajeh forest, which is located in the Zagros Mountain region of western Iran. We established a series of plots in an area typical of Qalajeh forest to characterize the diameter distribution of the wild pistachio component. We confirmed a deficit of stems <30 cm dbh, based in the expectation that the landscape-level diameter distribution should be characterized by a negative exponential curve. For trees ≥30 cm dbh, de Liocourt's equation closely fit the diameter distribution (r² = 0.93), translating to a q-factor of 1.34. We used this curve to estimate the deficit number of stems in diameter classes <30 cm. We estimate that this forest should have 19–24 wild pistachio trees/ha in the 5–25 cm classes, as compared to about 5 trees/ha found currently. Based on local conditions, we recommend that at least 30 seedlings/ha should be planted to allow 6–8 trees to reach to the 5 cm class.     

Altitudinal variability of stand structure and regeneration in the subalpine spruce forests of the Pol’ana biosphere reserve,Central Slovakia

The structure of natural subalpine spruce forest in the Zadná Pol’ana massif of the Western Carpathians was analysed. We focused on the variability of different aspects of stand structure, tree decay and regeneration processes in altitudinal gradient. We used systematic sampling, covering an area of 2 km², to detect even subtle changes in stand structure within one forest type over a range of less than 200 m in elevation. Mean stand density was 290 trees (>7 cm DBH) per hectare, average basal area was 41 m² ha⁻¹, and the volume accumulation in living trees amounted to 500 m³/ha⁻¹. Stand volume decreased by more than 50% between 1,260 and 1,434 m a.s.l. This means for an increase of altitude of 100 m that stand volume decreased by nearly 200 m³. Neither stand density nor basal area was related to elevation. Maximum tree height was strongly correlated to elevation, and it decreased on average by 6 m for each 100 m increment of altitude. No significant changes in the maximum spruce diameter were recorded in relation to the elevation gradient. Spatial distribution of trees was biased toward regularity at lower altitudes. Tree clustering increased with increasing altitude. The stock of coarse woody debris (CWD) decreased slightly along the altitudinal gradient, but changes were not significant. Density of spruce saplings and their number growing on CWD significantly increased across the elevation gradient. Despite the fact that the analysed forest tract was relatively large, highly variable in respect to environmental factors, and that stand volume, spatial structure, and tree height displayed strong variability along the elevation gradient, the diameter structure of stands and regeneration measures were uniform. Our results suggest that the recruitment of new trees in the Zadná Pol’ana subalpine spruce forest is not temporally continuous even at a scale of several square kilometres.     

Water relations of Yezo spruce and Todo fir in declined stands of boreal Forest in Hokkaido, Japan

Recently, symptoms of decline have been widely observed in Yezo spruce (Picea jezoensis) and Todo fir (Abies sachalinensis) in Hokkaido. In order to clarify the mechanism of decline, the water status of Yezo spruce and Todo fir trees in the Tokyo University Forest in Hokkaido were investigated. The decline is observed mainly in stands damaged by Typhoon XV of 1981 (D-stands), but is not observed in undamaged stands (C-stands). Sampled trees in both types of stands were selected, the severity of their decline estimated, diurnal water potentials measured and water relation parameters such as water potential at turgor-loss point ( ) and osmotic potential at full saturation ( ) were estimated by pressure-volume analysis. The diurnal trends of leaf water potential and midday water potential ( ) of the sample trees were clearly different between the D-stands and the C-stand. Water stress in trees was much more severe in the D-stands than in the C-stand. and of the declining trees were lower in the D-stands than in the C-stand. However, and were not significantly different between declining trees and healthy-looking trees in D-stands. It was concluded that stand-level water stress, induced by the destruction of the canopy by the typhoon, was associated with the decline symptoms. The measurement of water relation parameters proved to be useful for diagnosis and prediction of decline at a stand level in this area.     

Effects of Filtered Air and Misting Treatments on Cuticles of Red Spruce Needles on Whiteface Mountain,N.Y.

Two sets of large (8-20 m tall) red spruce (Picea rubens Sarg.) trees growing on Whiteface Mountain, N.Y., were used in branch chamber experiments. In the summer of 1988, the treatments were made on four healthy trees and consisted of: (1) open branches (N), and in chambers that were supplied with either: (2) ambient air (A); (3) charcoal-filtered air (T); or (4) charcoalfiltered air and deionized water misting when the forest was immersed in ambient cloud water (M). Each tree had all of the treatments. The treatments for the second year (summer of 1989) were made on four declining trees and consisted of: (1) open branches (NC) and chambers supplied with either (2) ambient air and mist (AA), (3) synthetic acid mist and ambient air (SA), (4) distilled water mist and ambient air (DA), (5) synthetic acid mist with filtered air (SF), and (6) distilled water mist with filtered air (DF). Foliar properties measurcd included: (1) microreflectivity, a measure of surface wax properties; (2) cuticle thickness; (3) cutinized cell wall thickness; (4) total cuticular layer thickness: (5) the mass of surface wax extracted from needle samples; and (6) contact angles, a measure of surface wetting. In addition, needles were collected and measured from healthy trees at lower and higher elevations. In the first experiment, reflectance from the wax in the stomata1 antechambers in treatment M was statistically significantly greater than all the other treatments. The cuticles of needles in treatment M were also statistically significantly thicker than the cuticles measured in all the other treatments (40% thicker than for the open branches). A plot of cuticular layer against elevation showed that the two filtered chambers (M and T) provided environments for cuticle development that mimic lower elevations. In 1989 the weather was cooler and more moist, and although the trees used in 1989 were declining, the results were similar to those of 1988. However, the additional treatments with synthetic acid mist resulted in reduced cuticle thickness. While the cuticles of the chamber trees growing at 1,170 m were, except for treatment M and T, generally thicker in 1989 than in 1988, they were still considerably thinner than those of spruce trees growing at the lower elevations. These results suggest regional scale air and precipitation quality have detrimental effects on red spruce needles at Whiteface Mountain.