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Mixed Stands (mixed + stand)

Distribution by Scientific Domains

Earth and Environmental Science	55%
Life Sciences	40%

Selected Abstracts

Biological Cycles of Mineral Elements in a Young Mixed Stand in Abandoned Mining Soils

JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 9 2007
Da-Lun Tian
Abstract Phytoremediation as a sustainable and inexpensive technology based on the removal of pollutants from the environment by plants is becoming an increasingly important objective in plant research. In this study, biological cycles of five nutrient elements (N, P, K, Ca, and Mg) and eight heavy metal elements (Fe, Cu, Zn, Mn, Cd, Ni, Pb and Co) were examined in young paniculed goldraintree (Koelreuteria paniculata Laxm) and common elaeocarpus (Elaeocarpus decipens) mixed stands in an abandoned mining area. We found that after vegetation restoration in abandoned mining areas, the organic matter and concentrations of nutrient elements were significantly increased and the heavy metal elements were significantly decreased, the annual retention, uptake and return were 75.0, 115.4, and 40.3 kg/hm2 for nutrient elements, and 1 878.0, 3 231.0 and 1 353.0 g/hm2 for heavy metal elements, respectively, with the utilization coefficient, cycling coefficient and turnover rate of 0.92, 0.35 and 0.32 for nutrient elements, and 1.24, 0.42 and 1.92 for heavy metal elements, respectively. Our results suggested that the vegetation restoration in abandoned mining areas had significant effects in improving environmental conditions, enhancing soil available nutrients, and ensuring human health. [source]

Methane and nitrous oxide fluxes of soils in pure and mixed stands of European beech and Norway spruce

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 5 2006
W. Borken
Summary Tree species can affect the sink and source strength of soils for atmospheric methane and nitrous oxide. Here we report soil methane (CH4) and nitrous oxide (N2O) fluxes of adjacent pure and mixed stands of beech and spruce at Solling, Germany. Mean CH4 uptake rates ranged between 18 and 48 ,g C m,2 hour,1 during 2.5 years and were about twice as great in both mixed and the pure beech stand as in the pure spruce stand. CH4 uptake was negatively correlated with the dry mass of the O horizon, suggesting that this diminishes the transport of atmospheric CH4 into the mineral soil. Mean N2O emission was rather small, ranging between 6 and 16 ,g N m,2 hour,1 in all stands. Forest type had a significant effect on N2O emission only in one mixed stand during the growing season. We removed the O horizon in additional plots to study its effect on gas fluxes over 1.5 years, but N2O emissions were not altered by this treatment. Surprisingly, CH4 uptake decreased in both mixed and the pure beech stands following the removal of the O horizon. The decrease in CH4 uptake coincided with an increase in the soil moisture content of the mineral soil. Hence, O horizons may maintain the gas diffusivity within the mineral soil by storing water which cannot penetrate into the mineral soil after rainfall. Our results indicate that conversion of beech forests to beech,spruce and pure spruce forests could decrease soil CH4 uptake, while the long-term effect on N2O emissions is expected to be rather small. [source]

PATTERNS OF INTERSPECIFIC INTERACTIONS IN THE ULVA -DOMINATED INTERTIDAL COMMUNITY IN A SOUTHERN COAST OF KOREA

JOURNAL OF PHYCOLOGY, Issue 2000
Y.J. Bhang
In the southern coast of Korea, rocky intertidal zones where green tide commonly occurs are dominated by Ulva pertusa, red algal turf (a mixed stand of Gigartina intermedia and Gigartina teedii) and species of Enteromorpha with highly opportunistic occurrence. To investigate their interspecific interactions, a field experiment was carried out using press effect of one species removal from permanent plots (20 x 20cm) set up on two different tidal heights. Mechanisms of interaction were also attempted using artificial plants to test the possible effects of shading, scouring, allelopathy of U. pertusa on the turf algae. The turf-forming red algae lowered the abundance of U. pertusa presumably by inhibiting the recruitment of U. pertusa; this effect was consistent along the tidal height. However, the greater abundance of Enteromorpha was observed in the presence of turf in the upper zone, indicating a positive effect of turf on Enteromorpha. Once U. pertusa was successfully recruited and grown to the adult plant, it inhibited the growth of turf by shading, which was effective both in winter and summer regardless of desiccation stress. No scouring and allelopathic effects of U. pertusa on the turf were detected. When an open substrate was provided, Enteromorpha colonized the space faster than any other species in the upper zone, but the turf was the fastest one followed by U. pertusa and Enteromorpha in the lower zone. Results indicated that patterns of interaction represented a complex network with no ultimate winner and the outcomes of interaction varied over time and space. [source]

Spatial variability of O layer thickness and humus forms under different pine beech,forest transformation stages in NE Germany

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 1 2006
Oliver Bens
Abstract Spatial variability of humus layer (O layer) thicknesses can have important impacts upon soil water dynamics, nutrient storage and availability, as well as plant growth. The purpose of the present study was to elucidate the impact of forest-transformation practices on the spatial variability of O layer thicknesses. The study focused on the Kahlenberg forest area (NE Germany) with stands of Scots pine (Pinus sylvestris) and European beech (Fagus sylvatica) of different age structures that form a transformation chronosequence from pure Scots pine stands towards pure European beech stands. Topsoil profiles including both, the O layer and the uppermost humic mineral soil horizon were excavated at intervals of 0.4 m along 15,20 m long transects, and spatial variability of O layer thicknesses was quantified by variogram analysis. The correlation lengths of total O layer thickness increased in the sequence consisting of pure pine stand (3.1 m) , older mixed stand (3.7 m) , pure beech stand (4.5 m), with the exception of the younger mixed stand, for which no correlation lengths of total O layer thickness could be determined. The degree of spatial correlation, i.e., the percentage of the total variance which can be described by variograms, was highest for the two monospecies stands, whereas this percentage was distinctly lower for the two mixed stands. A similar minimum for the two mixed stands was observed for the correlation lengths of the Oh horizon. These results suggest that the spatial structures of forest-transformation stands may be interpreted in terms of a disturbance (in the form of the underplanting of beech trees). After this disturbance, the forest ecosystem requires at least 100 y to again reach relative equilibrium. These findings are in line with the results of other soil-related investigations at these sites. Räumliche Variabilität der Humuslagenmächtigkeit und Humusformen in verschiedenen Stadien des Waldumbaus von Kiefer zu Buche in NO-Deutschland Die räumliche Variabilität der Humusauflagenmächtigkeit kann einen bedeutenden Einfluss auf die Bodenwasserdynamik, Nährstoffspeicherung und -verfügbarkeit sowie das Pflanzenwachstum haben. Ziel dieser Studie war es, die Auswirkungen von Waldumbaumaßnahmen auf die räumliche Verteilung der Auflagehumusmächtigkeiten zu untersuchen. Im Forstrevier Kahlenberg, mit Beständen von Kiefer (Pinus sylvestris) und Buche (Fagus sylvatica) unterschiedlichen Alters, welche eine Transformations-Chronosequenz von einem Kiefern-Reinbestand hin zu einem reinen Buchenbestand darstellen, wurden Humusprofile entlang von 15,20 m langen Transekten in Abständen von 0,4 m aufgenommen. Die räumliche Variabilität der Mächtigkeiten der Auflagehumushorizonte wurde durch Variogramm-Analysen quantifiziert. Die Korrelationslängen der Mächtigkeiten des gesamten Auflagehumus stiegen in der Reihenfolge reiner Kiefernbestand (3,1 m) , älterer Mischbestand (3,7 m) , reiner Buchenbestand (4,5 m) an. Aus dieser Reihe fällt der jüngere Mischbestand heraus; für ihn konnten keine Korrelationslängen ermittelt werden. Der Grad der räumlichen Korrelation, d. h. der Anteil der gesamten Varianz, der durch Variogramme beschrieben wird, ist für die beiden Reinbestände am höchsten, während er für die beiden Mischbestände deutlich geringer ist. Ein ähnliches Minimum für die beiden Mischbestände ergibt sich, wenn nur die Korrelationslängen der Oh-Mächtigkeiten betrachtet werden. Diese Ergebnisse deuten darauf hin, dass die räumlichen Strukturen von Waldumbaubeständen im Sinne einer Störung gedeutet werden können (wobei die Umbaumaßnahme und der Unterbau mit Buchen die Störung darstellt). Diese Störung dauert offenbar mindestens 100 a an. Dieser Befund stimmt mit den Ergebnissen aus Studien zu weiteren relevanten Bodeneigenschaften an Forststandorten im nordostdeutschen Tiefland überein. [source]

Soil biochemical and chemical changes in relation to mature spruce (Picea abies) forest conversion and regeneration

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2003
Zheke Zhong
Abstract To investigate soil changes from forest conversion and regeneration, soil net N mineralization, potential nitrification, microbial biomass N, L-asparaginase, L-glutaminase, and other chemical and biological properties were examined in three adjacent stands: mature pure and dense Norway spruce (Picea abies (L.) Karst) (110 yr) (stand I), mature Norway spruce mixed with young beech (Fagus sylvatica) (5 yr) (stand II), and young Norway spruce (16 yr) (stand III). The latter two stands were converted or regenerated from the mature Norway spruce stand as former. The studied soils were characterized as having a very low pH value (2.9 , 3.5 in 0.01 M CaCl2), a high total N content (1.06 , 1.94,%), a high metabolic quotient (qCO2) (6.7 , 16.9 g CO2 kg,1 h,1), a low microbial biomass N (1.1 , 3.3,% of total N, except LOf1 at stand III), and a relatively high net N mineralization (175 , 1213 mg N kg,1 in LOf1 and Of2, 4 weeks incubation). In the converted forest (stand II), C,:,N ratio and qCO2 values in the LOf1 layer decreased significantly, and base saturation and exchangeable Ca showed a somewhat increment in mineral soil. In the regenerated forest (stand III), the total N storage in the surface layers decreased by 30,%. The surface organic layers (LOf1, Of2) possessed a very high net N mineralization (1.5 , 3 times higher than those in other two stands), high microbial biomass (C, N), and high basal respiration and qCO2 values. Meanwhile, in the Oh layer, the base saturation and the exchangeable Ca decreased. All studied substrates showed little net nitrification after the first period of incubation (2 weeks). In the later period of incubation (7 , 11 weeks), a considerable amount of NO3 -N accumulated (20 , 100,% of total cumulative mineral N) in the soils from the two pure spruce stands (I, III). In contrast, there was almost no net NO3 -N accumulation in the soils from the converted mixed stand (II) indicating that there was a difference in microorganisms in the two types of forest ecosystems. Soil microbial biomass N, mineral N, net N mineralization, L-asparaginase, and L-glutaminase were correlated and associated with forest management. Chemische und biochemische Veränderungen der Bodeneigenschaften durch Verjüngung und Waldumbau eines Fichtenaltbestandes Um die durch den Waldumbau und die Regeneration bedingten Standortsveränderungen zu untersuchen, wurden die Netto-Stickstoffmineralisierung, die potenzielle Nitrifikation, der mikrobiell gebundene Stickstoff (Nmic), L-Asparaginase, L-Glutaminase sowie weitere chemische und biologische Parameter an drei benachbarten Standorten untersucht: Standort I, reiner Fichtenaltbestand (Picea abies (L.) Karst ,110 Jahre); Standort II, Fichtenaltbestand mit Buchenunterbau (Fagus sylvatica , 5 Jahre); Standort III, reine Fichtenaufforstung (16 Jahre). Die Standorte II und III entstanden infolge des Waldumbaus aus reinen Fichtenaltbeständen. Die untersuchten Böden sind gekennzeichnet durch sehr niedrige pH-Werte (pH(H2O) 3, 7 , 4, 2, pH (CaCl2) 2, 9 , 3, 5), hohe Gesamtstickstoffgehalte (1, 06 , 1, 94,%), hohe metabolische Quotienten (6, 7,16, 9g CO2 kg,1 h,1), geringe Nmic -Gehalte (1, 1 , 3, 3,% des Gesamt-N, ausgenommen LOf1 von Standort III) und eine relativ hohe N-Nettomineralisation (175 , 1213 mg N Kg,1 in LOf1 und Of2, nach 4 Wochen Inkubation). Am Standort II nahm das C,:,N-Verhältnis und der qCO2 im LOf1 -Horizont deutlich ab, wohingegen der Gehalt an austauschbarem Ca sowie die Basensättigung im Mineralboden geringfügig zunahmen. Am Standort III nahm der N-Vorrat (Auflagehumus + Mineralboden 0 , 10,cm) um 30,% ab. In den LOf1 - und Of2 -Lagen des Auflagehumus dieses Standortes traten eine hohe N-Nettomineralisation (1, 5- bis 3fach höher als in den Standorten I und II), hohe Gehalte an mikrobiell gebundenem C und N, eine erhöhte Basalatmung sowie erhöhte qCO2 -Werte auf. In den Oh-Lagen hingegen nahm die Basensättigung ab. Alle untersuchten Standorte zeigten in der ersten Periode der Inkubation (0 bis 2 Wochen) eine geringe Netto-Nitrifikation. An den Standorten I und III fand in der späteren Periode (7. bis 11. Woche) eine Anreicherung an NO3 (20 , 100,% des gesamten mineralischen N-Vorrates) statt. Im Gegensatz dazu wurde am Standort II keine NO3 -N- Anreicherung festgestellt. Dies deutet auf einen Unterschied in der Zusammensetzung der mikrobiellen Gemeinschaften in den zwei verschiedenen Forstökosystemen hin. Nmic, N-Nettomineralisation, L-Asparaginase und L-Glutaminase korrelieren miteinander und zeigen eine enge Beziehung zu den Bewirtschaftungsformen. [source]

Tree rings show competition dynamics in abandoned Castanea sativa coppices after land-use changes

JOURNAL OF VEGETATION SCIENCE, Issue 1 2006
Patrick Fonti
Abstract Questions: As a consequence of socio-economic changes, many Castanea sativa coppices have been abandoned and are now developing past their usual rotation length. Do we have to expect changes in stand structure and composition of abandoned Castanea sativa coppice invaded by other species? Is a tree ring-based approach adequate to early recognise changes in inter-specific competitive interaction? Location: Lowest alpine forest belt of the southern Swiss Alps. Methods: We selected a 60-year old abandoned Castanea sativa coppice stand with sporadic Fagus sylvatica and Quercus cerris mixed in. Using tree-ring based indices we analysed differences in the species-specific response to competition. Analyses were performed by comparing how subject dominant trees (10 Castanea, 5 Fagus, 5 Quercus) have differently faced competition from their immediate Castanea coppice neighbourhood, taking into account the changes over time and space. Results: Although no species appears yet to have made a difference in the surrounding coppice mortality, there are species-specific differences in growth dominance, which indicate potential successional processes. Castanea sativa growth dominated in the early stages of stand development. However, after approximately 30,35 yr Fagus sylvatica and Quercus cerris became much more dominant, indicating a change in competitive potential that does not favour Castanea sativa. Conclusions: Without interventions this coppice will develop into a mixed stand. A tree-ring based approach allows an early recognition of forthcoming changes in stand composition and structure and is likely to be an important tool for forest landscape management. [source]

Modeling above-ground litterfall in eastern Mediterranean conifer forests using fractional tree cover, and remotely sensed and ground data

APPLIED VEGETATION SCIENCE, Issue 4 2010
Sibel Taskinsu-Meydan
Abstract Question: How can we model above-ground litterfall in Mediterranean conifer forests using remotely sensed and ground data, and geographic information systems (GIS)? Location: Eastern Mediterranean conifer forest of Turkey. Methods: Above-ground litterfall from Mediterranean forest stands of Pinus nigra, Cedrus libani, Pinus brutia and Juniperus excelsa and mixed Abies cilicica, C. libani and P. nigra was modeled as a function of fractional tree cover using a regression tree algorithm, based on IKONOS and Landsat TM/ETM+data. Landsat TM/ETM+images for the study area were used to map actual stand patterns, based on a land-cover map of species stands using a supervised classification. Results: Total amount of annual above-ground litterfall for the entire study area (12 260 km2) was estimated at 417.2 Mg ha,1 for P. brutia, 291.1 Mg ha,1 for the mixed stand, 115.5 Mg ha,1 for P. nigra, 54.6 Mg ha,1 for J. excelsa and 45.9 Mg ha,1 for C. libani. The maps generated indicate the distribution of the seasonal amount of total above-ground litterfall for different species and the distribution of species stands in the study area. There was an increase in the amount of above-ground litterfall for P. brutia stand in summer, for J. excelsa in autumn and for C. libani, P. nigra and the mixed stand of A. cilicica, P. nigra and C. libani in winter. Conclusion: Application of this model helps to improve the accuracy of estimated litterfall input to soil organic carbon pools in the Mediterranean conifer forests. [source]

Spatiotemporal changes of beetle communities across a tree diversity gradient

DIVERSITY AND DISTRIBUTIONS, Issue 4 2009
Stephanie Sobek
Abstract Aim, Plant and arthropod diversity are often related, but data on the role of mature tree diversity on canopy insect communities are fragmentary. We compare species richness of canopy beetles across a tree diversity gradient ranging from mono-dominant beech to mixed stands within a deciduous forest, and analyse community composition changes across space and time. Location, Germany's largest exclusively deciduous forest, the Hainich National Park (Thuringia). Methods, We used flight interception traps to assess the beetle fauna of various tree species, and applied additive partitioning to examine spatiotemporal patterns of diversity. Results, Species richness of beetle communities increased across the tree diversity gradient from 99 to 181 species per forest stand. Intra- and interspecific spatial turnover among trees contributed more than temporal turnover among months to the total ,-beetle diversity of the sampled stands. However, due to parallel increases in the number of habitat generalists and the number of species in each feeding guild (herbivores, predators and fungivores), no proportional changes in community composition could be observed. If only beech trees were analysed across the gradient, patterns were similar but temporal (monthly) species turnover was higher compared to spatial turnover among trees and not related to tree diversity. Main conclusions, The changes in species richness and community composition across the gradient can be explained by habitat heterogeneity, which increased with the mix of tree species. We conclude that understanding temporal and spatial species turnover is the key to understanding biodiversity patterns. Mono-dominant beech stands are insufficient to conserve fully the regional species richness of the remaining semi-natural deciduous forest habitats in Central Europe, and analysing beech alone would have resulted in the misleading conclusion that temporal (monthly) turnover contributes more to beetle diversity than spatial turnover among different tree species or tree individuals. [source]

Soil water dynamics along a tree diversity gradient in a deciduous forest in Central Germany

ECOHYDROLOGY, Issue 3 2010
Inga Krämer
Abstract This study aimed to investigate whether soil water dynamics differ along a tree species diversity gradient. The 12 study plots in the Hainich National Park, Germany, were composed of up to 11 tree species. Fagus sylvatica formed the monospecific plots. Mixed forest plots consisted of a variable admixture of other broad-leaved deciduous tree species such as Tilia spp., Fraxinus excelsior, Carpinus betulus, and Acer pseudoplatanus. Volumetric soil water content and soil water potential were measured for about two and a half years. Overall patterns of soil water dynamics were similar in all study plots. However, during a desiccation period in summer 2006, significant correlations between soil water in the upper soil and tree species diversity of the 12 study plots were observed. At the beginning of this period, soil water was extracted at higher rates in the species-rich plots than in the beech-dominated plots. However, later during the desiccation period, when atmospheric evaporative demand was higher, only the beech-dominated stands were able to increase soil water extraction. In plots of high tree species diversity, soil water reserves were already low and soil water extraction reduced. Possible explanations for high water extraction rates in mixed species plots at the beginning of the desiccation period include species-specific characteristics such as high maximum water use rate of some species, enhanced exploitation of soil water resources in mixed stands (complementarity effect), and additional water use of the herb layer, which increased along the tree species diversity gradient. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Methane and nitrous oxide fluxes of soils in pure and mixed stands of European beech and Norway spruce

Leaf-level resource use for evergreen and deciduous conifers along a resource availability gradient

FUNCTIONAL ECOLOGY, Issue 3 2000
B. D. Kloeppel
Abstract 1.,We compared leaf-level carbon, nitrogen and water use for a deciduous (Larix occidentalis Nutt.) and sympatric evergreen (Pseudotsuga menziesii, Beissn., Franco, or Pinus contorta Engelm.) conifer along a resource availability gradient spanning the natural range of L. occidentalis in western Montana, USA. 2.,We hypothesized that leaf photosynthesis (A), respiration (r), specific leaf area (SLA) and foliar nitrogen concentration (N) would be higher for deciduous than sympatric evergreen conifers in mixed stands, and that these interspecies differences would increase from high to low resource availability. We also hypothesized that leaf-level nitrogen and water-use efficiency would be higher for the co-occurring evergreen conifer than L. occidentalis. 3.,In general, mass-based photosynthesis (Am) was significantly higher for L. occidentalis than co-occurring evergreen conifers in the drier sites, but Am was similar for evergreen and deciduous conifers at the mesic site. 4.,Mass-based foliar nitrogen concentration (Nm) was positively correlated to SLA for all species combined across the gradient (R2 = 0·64), but the relationship was very weak (R2 = 0·08,0·34) for evergreen and deciduous species separately. Mass-based Am and rm were poorly correlated to Nm for all species combined across the gradient (R2 = 0·28 and 0·04, respectively). 5.,For each site-species combination, daily maximum Am was negatively correlated to vapour pressure deficit (VPD) (R2 = 0·36,0·59), but was poorly correlated to twig predawn water potential (R2 < 0·04). 6.,Instantaneous nitrogen-use efficiency (NUEi; Am divided by Nm) and water-use efficiency (,13C) increased significantly (P = 0·05) from high to low resource availability for both evergreen and deciduous conifers, except for NUEi in L. occidentalis. [source]

Hybridization dynamics of invasive cattail (Typhaceae) stands in the Western Great Lakes Region of North America: a molecular analysis

JOURNAL OF ECOLOGY, Issue 1 2010
Steven E. Travis
Summary 1.,By increasing vigour and broadening ecological tolerances, hybridization between native and introduced species may serve as a primary driver of invasiveness. 2.,Cattails (Typha, Typhaceae) are clonal wetland graminoids that are known to hybridize where anthropogenic influences have resulted in distributional overlap. 3.,In order to gauge the relative performance of hybrid vs. pure Typha, we characterized hybridization and clonal growth where native Typha latifolia and introduced Typha angustifolia occur together in the Western Great Lakes Region of North America. 4.,Based on microsatellite markers, we documented F1 hybrids as the most common class at five intensively sampled sites, constituting up to 90% of the genets and 99% of the ramets. Backcrosses to one or the other parent constituted 5,38% of the genets. Pure T. latifolia was rare and never constituted more than 12% of the genets. 5.,F1 hybrid genets achieved the highest mean ramet numbers at three sites, and were second in size only to T. angustifolia at two sites; however, these differences were not significant based on site-specific one-way anovas. 6.,F1 hybrids exhibited little height advantage over other Typha classes, although there was a general tendency for hybrids in relatively mixed stands to be among the tallest genets in shallow water, but among the shortest genets in deeper water. 7.,Native T. latifolia was found growing at the shallowest water depths at the only site where it was sufficiently abundant to be included in statistical comparisons. 8.,Synthesis. The role of hybridization in plant invasions can be difficult to confirm in the absence of molecular data, particularly for clonal species where the boundaries separating individuals are otherwise difficult to discern. Here, we used molecular markers to document the prevalence and performance of hybrid genets in five invasive Typha stands covering a broad area of the Western Great Lakes Region. We found an extremely high prevalence of F1 hybrids within mixed Typha stands. This, coupled with the typically larger sizes of hybrid genets, suggests that hybrids are capable of outperforming other Typha spp. and that hybridization has played an influential role in the North American cattail invasion. [source]

Performance of the potentially invasive Siberian moth Dendrolimus superans sibiricus on coniferous species in Europe

AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 3 2009
Natalia I. Kirichenko
Abstract 1,The native range of the Siberian moth extends from the Pacific Ocean (Russian Far East, Japan and Northern Korea) across Siberia, Northern China and Mongolia to the Ural Mountains. At the beginning of the 21st Century, this species was documented west of the Ural Mountains in the Republic of Mari El, indicating range extension toward the west. 2,The Siberian moth has recently been suggested for regulation as a quarantine pest for European and Mediterranean Plant Protection Organization member countries. However, no specific report on European host plants for this pest has been published so far. 3,In the present study, larval host plant choice and performance was tested for the first time on coniferous tree species that are widely distributed and of commercial value in Europe. 4,Based on dual-choice tests on neonates and mortality, developmental duration and relative growth rates of the first- to sixth-instar larvae, we found European larch Larix decidua to be the most suitable host for the moth larvae, whereas European black pine Pinus nigra and Scots pine Pinus sylvestris were the poorest hosts. The remaining conifer species tested, European silver fir Abies alba, Nordmann fir Abies nordmanniana, and Norway spruce Picea abies, were intermediate host plants. Douglas-fir Pseudotsuga menziesii, originating from North America, was chosen by the larvae to the same extend as European larch, and was also highly suitable for larval development. 5,If the moth is introduced to European countries, it will become damaging in stands of European larch and Douglas-fir, mixed stands of fir and spruce; however, it will be less damaging in forests dominated by two-needle pines. 6,We predict that Dendrolimus superans sibiricus will be able to survive and develop on the main European coniferous tree species, including non-native coniferous tree species, resulting in severe damage to large areas of forests. [source]

Biological Cycles of Mineral Elements in a Young Mixed Stand in Abandoned Mining Soils

Spatial variability of O layer thickness and humus forms under different pine beech,forest transformation stages in NE Germany

Radial growth responses to drought of Pinus sylvestris and Quercus pubescens in an inner-Alpine dry valley

JOURNAL OF VEGETATION SCIENCE, Issue 6 2007
Pascale Weber
Abstract Question: Lower montane treeline ecotones such as the inner Alpine dry valleys are regarded as sensitive to climate change. In the dry Valais valley (Switzerland) the composition of the widespread, low altitude Pinus forests is shifting towards a mixed deciduous state. The sub-boreal P. sylvestris shows high mortality rates, whereas the deciduous sub-mediterranean Quercus pubescens is spreading. These species may act as early indicators of climate change. We evaluate this hypothesis by focusing on their differences in drought tolerance, which are hardly known, but are likely to be crucial in the current forest shift and also for future forest development. Methods: We used dendroecological methods to detect species-specific patterns in the growth response to drought. The relationship between radial growth of 401 trees from 15 mixed stands and drought was analysed by calculating response functions using yearly tree-ring indices and monthly drought indices. PCA was applied to the response ratios to discover spatial patterns of drought response. Results: A species-specific response to moisture as well as a sub-regional differentiation of the response patterns were found. While Quercus showed a response mainly to the conditions of the previous autumn and those of current spring, Pinus did not start responding before May, but showed responses throughout the whole summer. Quercus may restrict physiological activity to moist periods; growth of Pinus was much more dependent on prior growth. Conclusions: Given that the climate is changing towards (1) longer summer drought periods, (2) higher mean temperatures and (3) shifted seasonally of moisture availability, Quercus may benefit from adapting better to drier conditions. Pinus may increasingly face problems related to drought stress as it depends on summer moisture and has a smaller adaptive capacity due to its long-lived photosynthetic tissue. [source]

Realized gene flow within mixed stands of Quercus robur L. and Q. petraea (Matt.) L. revealed at the stage of naturally established seedling

MOLECULAR ECOLOGY, Issue 10 2010
I. J. CHYBICKI
Abstract The estimates of contemporary gene flow assessed based on naturally established seedlings provide information much needed for understanding the abilities of forest tree populations to persist under global changes through migration and/or adaptation facilitated by gene exchange among populations. Here, we investigated pollen- and seed-mediated gene flow in two mixed-oak forest stands (consisting of Quercus robur L. and Q. petraea [Matt.] Liebl.). The gene flow parameters were estimated based on microsatellite multilocus genotypes of seedlings and adults and their spatial locations within the sample plots using models that attempt to reconstruct the genealogy of the seedling cohorts. Pollen and seed dispersal were modelled using the standard seedling neighbourhood model and a modification,the 2-component seedling neighbourhood model, with the later allowing separation of the dispersal process into local and long-distance components. The 2-component model fitted the data substantially better than the standard model and provided estimates of mean seed and pollen dispersal distances accounting for long-distance propagule dispersal. The mean distance of effective pollen dispersal was found to be 298 and 463 m, depending on the stand, while the mean distance of effective seed dispersal was only 8.8 and 15.6 m, which is consistent with wind pollination and primarily seed dispersal by gravity in Quercus. Some differences observed between the two stands could be attributed to the differences in the stand structure of the adult populations and the existing understory vegetation. Such a mixture of relatively limited seed dispersal with occasional long distance gene flow seems to be an efficient strategy for colonizing new habitats with subsequent local adaptation, while maintaining genetic diversity within populations. [source]

Carbon isotope discrimination and wood anatomy variations in mixed stands of Quercus robur and Quercus petraea

PLANT CELL & ENVIRONMENT, Issue 8 2001
S. Ponton
Abstract The two most common oak species in western Europe, Quercus robur and Quercus petraea, display different ecological behaviours, particularly with respect to their responses to drought. The ecophysiological basis of this niche difference is not understood well. Here we test the hypothesis that these two species present distinct water use efficiencies (WUEs), using the carbon isotope discrimination approach. Leaves and 13 dated ring sequences were sampled in 10 pairs of adult trees growing side by side. Carbon isotope composition was measured on cellulose extracts. In addition, relationships between carbon isotope discrimination and wood anatomy were assessed at the tree level. Quercus robur displayed a 1·0, larger isotopic discrimination than Q. petraea, and therefore a lower intrinsic WUE (,13%). This interspecific difference of isotopic discrimination was quite stable with time and independent of tree radial growth and climate fluctuations. A strong positive correlation was observed between average tree values of earlywood vessel surface area and 13C isotopic discrimination. This correlation was even higher with 13C of the 1976 dry year (r = 0·86). These observations led to the hypothesis that hydraulic properties of xylem could exert a constraint on leaf gas exchange, resulting in a larger WUE for individuals with smaller vessel cross-section area. [source]

Modelling Tree Roots in Mixed Forest Stands by Inhomogeneous Marked Gibbs Point Processes

BIOMETRICAL JOURNAL, Issue 3 2009
Stefanie Eckel
Abstract The aim of the paper is to apply point processes to root data modelling. We propose a new approach to parametric inference when the data are inhomogeneous replicated marked point patterns. We generalize Geyer's saturation point process to a model, which combines inhomogeneity, marks and interaction between the marked points. Furthermore, the inhomogeneity influences the definition of the neighbourhood of points. Using the maximum pseudolikelihood method, this model is then fitted to root data from mixed stands of Norway spruce (Picea abies (L.) Karst.) and European beech (Fagus sylvatica L.) to quantify the degree of root aggregation in such mixed stands. According to the analysis there is no evidence that the two root systems are not independent. [source]