Spatial distribution and regeneration of Quercus semecarpifolia and Quercus floribunda in a subalpine forest of western Himalaya, India

Studies were conducted on population status and regeneration of Quercus semecarpifolia and Quercus floribunda in a subalpine forest of western Himalaya. Saplings of Q. semecarpifolia belonging to the 51-100 cm size class and those of Q. floribunda belonging to the 101-150 cm size class were well represented in studied subalpine forests. Comparable seedling emergence and establishment of both species, either in the habitat dominated by same or different species seems to be an adaptational strategy of these species in subalpine forests. Seedling to tree ratio for Q. semecarpifolia was higher in the stand dominated by Q. floribunda, while comparable pattern was observed for Q. floribunda in the stand dominated by Q. semecarpifolia. Establishment of higher percent of seedlings of one species in the habitats dominated by another species of Quercus appears to indicate an oligarchic nature of oaks in subalpine forests. This study describes regeneration strategies, and spatial distribution of these species in a subalpine forest of Uttarakhand.     

Pathogen induced disturbance and succession in temperate forests: Evidence from a 100-year data set in southern Sweden

Major tree species are declining in many temperate forests due to changing disturbance regimes, including invasive pests and pathogens. We examined the interaction of secondary succession and Dutch elm disease in the Swedish temperate forest reserve Dalby Söderskog, based on five tree surveys made between 1909 and 2011. The forest is characterized by the coexistence of four major European tree species: wych elm (Ulmus glabra), European ash (Fraxinus excelsior), European beech (Fagus sylvatica) and pedunculate oak (Quercus robur). After protection of the forest in 1918, lack of disturbance mainly favoured elm, while the oak population declined due to mortality of old oaks and lack of regeneration. Dutch elm disease has caused high and continuous elm mortality since 1988. As a result, increased light availability at the forest floor favoured abundant regeneration of ash, beech, and lately also oak. The recent arrival of an invasive fungal pathogen causing ash dieback may once again change the course of succession. Open space emerging from loss of elm and ash in forest reserves may be used by reserve managers to favour oak regeneration and biodiversity of semi-open woodlands once lost during succession to closed forest. We conclude that winners and losers change places as an effect of invasive pathogens, resulting in unexpected successions and both losses and gains in valuable ecological niches and habitat structures in temperate broadleaf forests.     

Influence of canopy openness,ungulate exclosure,and low‐intensity fire for improved oak regeneration in temperate Europe

Failed oak regeneration is widely reported in temperate forests and has been linked in part to changed disturbance regimes and land‐use. We investigated if the North American fire–oak hypothesis could be applicable to temperate European oaks (Quercus robur, Quercus petraea) using a replicated field experiment with contrasting canopy openness, protection against ungulate browsing (fencing/no fencing), and low‐intensity surface fire (burn/no burn). Survival, relative height growth (RGR_H), browsing damage on naturally regenerated oaks (≤300 cm tall), and changes in competing woody vegetation were monitored over three years. Greater light availability in canopy gaps increased oak RGR_H (p = .034) and tended to increase survival (p = .092). There was also a trend that protection from browsing positively affected RGR_H (p = .058) and survival (p = .059). Burning reduced survival (p < .001), nonetheless, survival rates were relatively high across treatment combinations at the end of the experiment (54%–92%). Most oaks receiving fire were top‐killed and survived by producing new sprouts; therefore, RGR_H in burned plots became strongly negative the first year. Thereafter, RGR_H was greater in burned plots (p = .002). Burning altered the patterns of ungulate browsing frequency on oaks. Overall, browsing frequency was greater during winter; however, in recently burned plots summer browsing was prominent. Burning did not change relative density of oaks, but it had a clear effect on competing woody vegetation as it reduced the number of individuals (p < .001) and their heights (p < .001). Our results suggest that young, temperate European oaks may respond similarly to fire as their North American congeners. However, disturbance from a single low‐intensity fire may not be sufficient to ensure a persistent competitive advantage—multiple fires and canopy thinning to increase light availability may be needed. Further research investigating long‐term fire effects on oaks of various ages, species‐specific response of competitors and implications for biodiversity conservation is needed.     

A Neighborhood Analysis of the Consequences of Quercus suber Decline for Regeneration Dynamics in Mediterranean Forests

In forests, the vulnerable seedling stage is largely influenced by the canopy, which modifies the surrounding environment. Consequently, any alteration in the characteristics of the canopy, such as those promoted by forest dieback, might impact regeneration dynamics. Our work analyzes the interaction between canopy neighbors and seedlings in Mediterranean forests affected by the decline of their dominant species (Quercus suber). Our objective was to understand how the impacts of neighbor trees and shrubs on recruitment could affect future dynamics of these declining forests. Seeds of the three dominant tree species (Quercus suber, Olea europaea and Quercus canariensis) were sown in six sites during two consecutive years. Using a spatially-explicit, neighborhood approach we developed models that explained the observed spatial variation in seedling emergence, survival, growth and photochemical efficiency as a function of the size, identity, health, abundance and distribution of adult trees and shrubs in the neighborhood. We found strong neighborhood effects for all the performance estimators, particularly seedling emergence and survival. Tree neighbors positively affected emergence, independently of species identity or health. Alternatively, seedling survival was much lower in neighborhoods dominated by defoliated and dead Q. suber trees than in neighborhoods dominated by healthy trees. For the two oak species, these negative effects were consistent over the three years of the experimental seedlings. These results indicate that ongoing changes in species’ relative abundance and canopy trees’ health might alter the successional trajectories of Mediterranean oak-forests through neighbor-specific impacts on seedlings. The recruitment failure of dominant late-successional oaks in the gaps opened after Q. suber death would indirectly favor the establishment of other coexisting woody species, such as drought-tolerant shrubs. This could lead current forests to shift into open systems with lower tree cover. Adult canopy decline would therefore represent an additional factor threatening the recruitment of Quercus forests worldwide.     

Ecological dynamics of Quercus dominated woodlands in California and southern Spain: a state-transition model

There are many similarities between Spanish and Californian Quercus woodlands and savanna. Both are located in Mediterranean climate zones, and are used predominantly for livestock grazing. The Californian overstory is dominated by one or a combination of five Quercus species and their hybrids: Quercus douglasii H.&A., Q. agrifolia Nee., Q. wislizenii A.DC., Q. lobata Nee., and Q. englemennii Greene (blue, coast live, interior live, valley, and Englemann oaks). In southern Spain and Portugal, Quercus woodland overstory is predominantly one or a combination of two Quercus species, Quercus ilex L. (holm oak) and Quercus suber L. (cork oak). The underlying natural and semi-natural ecological dynamics of the Quercus woodlands of Spain and California are different, and it follows that the management practices employed also differ. The greatest point of contrast between California and Spain is in the intensity and diversity of management goals and practices. A state-transition model for comparing the ecological dynamics of Quercus woodlands and savanna in California and southern Spain is developed and examined. The highly simplified model is an analytic tool of use in organizing research and developing management practices. States are reached and maintained in different ways in Spain and California, but their appearance and their function in each landscape are quite similar.     

Population dynamics and growth patterns for a cohort of northern red oak (Quercus rubra) seedlings

Summary I studied the survival and development of a 1986 cohort of northern red oak (Quercus rubra L.) seedlings growing under a variety of overstory and microsite conditions in a northern hardwood forest dominated by northern red oak, red maple (Acer rubrum L.) paper birch (Betula papyrifera Marsh.), and scattered white pine (Pinus strobus L.). Fifty naturally regenerating seedlings of oak were randomly selected in each of three canopy classes: no overstory, partial overstory, and complete overstory. Growth and mortality were measured for six years. Seedling height growth decreased with overstory density, with less growth evident with even a partial overstory. Seedling survival also declined with overstory density and depended on microtopography to a lesser extent. After six years, 92% of the seedlings survived in the open, compared to 54% under the partial overstory, and 36% under the complete overstory. The open environment, in which woody and herbaceous regrowth formed a low canopy reducing light intensities to about 50% of full sunlight, provided a favorable site for the growth and survival of northern red oak.     

Regeneration of oaks (Quercus robur/Q. petraea) and three other tree species during long-term succession after catastrophic disturbance (windthrow)

In broadleaved temperate forests in Europe, oak (Quercus robur/Q. petraea) regeneration is reported to be weak or absent. However, most work concern seedlings or saplings, studied relatively few years. We studied a Picea abies stand in Sweden, windthrown and logged (all stems harvested) in 1969, testing the hypothesis that oaks regenerate in the long term among competing tree species after catastrophic disturbance. In 2011, after 40 years/growth seasons, we recorded live and dead trees in the new stand and investigated the surroundings, competition, and succession. The following trees, up to 26 m tall, colonized: Sorbus aucuparia, Betula pendula/B. pubescens, Fagus sylvatica, Q. robur/Q. petraea, and Corylus avellana (a shrub). Betula dominated, and only Fagus was regenerating in 2011. Sorbus had produced most of the dead trees, mainly or partly through intraspecific competition. In the stand, compared to the surroundings, Quercus, Picea, and Alnus glutinosa were under-represented, and Sorbus, Betula, and Fagus were over-represented. Yet, the density of Quercus was far from negligible; 48 large trees/ha. Most of the oaks (74 %) were co-dominant trees and many grew near Sorbus. Thus, oaks can survive and grow fast among pioneer trees and browsing animals, a conclusion which is supported by the literature (nine studies identified). High mortality of Sorbus is part of a long-term succession, where Fagus might come to dominate. However, Quercus likely will persist, in low density. We propose three key traits contributing to long-term persistence of Q. robur/Q. petraea in European temperate forests: long life span, ecological plasticity, and resistance to disturbances.     

锐齿槲栎林的天然更新——坚果、幼苗库和径级结构

对四川茂县地区的锐齿槲栎(Quercus aliena var.acuteserrata)天然次生林进行研究,发现(1)坚果完好比例约在14%～26%之间,完好坚果的发芽率和发芽势都比较高,但在天然状况下能够留存到隔年5月的坚果几乎没有.因此,实生幼苗的天然补充就受到了严重的限制.(2)林缘的幼苗密度低于所有其它生境的(p＜0.05),林中的幼苗密度最高,和林窗的比较有显著差异(p＜0.05),而和灌丛的比较则没有差异.在灌丛幼苗密度和林中以及林窗的比较都没有差异.动物对坚果的取食速度则是林中的最慢(10.0%),林窗和林缘的相同(分别为61.1%和66.5%),都比较快(p＜0.01).(3)林中的幼苗在小于100 cm的各高度内都有大量分布,说明在林中树冠下幼苗是可以长期存在的,在幼苗和种子阶段的锐齿槲栎可能是耐荫的.(4)在林中缺失幼树,在林缘则有包括幼树在内的完整的更新大小系列,表明林缘也可以成为更新的关键地点.(5)在栎林的每一个大小级别上,萌生个体和实生个体都按各种比例伴生,说明导致萌生的干扰一直在发生,并可能在森林的更新中扮演重要角色;也说明该地区的锐齿槲栎林由萌生和实生起源的个体混合组成.     

Woodland canopy structure and the light response of juvenile Quercus lobata (Fagaceae)

I investigated competition for light between canopy plants and juvenile valley oaks (Quercus lobata Nee) in a mixed-broadleaf woodland of California's northern Coast Ranges. Canopy effects on understory light supply were separated among the overlying adult valley oak, the adult's woody understory, and neighboring trees and shrubs through a series of light sampling surveys and measurements of the number, size, and spatial distribution of neighboring plants. Light supply in the understory was primarily influenced by neighboring plants, with no detectable effect of the overlying adult valley oak. Light supply in the understory averaged 25% full sun due to a high frequency of canopy gaps and a typically open understory. Seedling response to understory light supply was investigated in an experimental sunfleck gradient (10%, 19%, and 100% full sun). Between 10% and 100% full sun, seedling growth increased by 90% and the shoot:∗∗∗root ratio changed from 1.561 to 0.607. Shade seedlings were also taller and produced fewer, larger, and thinner leaves than seedlings grown in full sun. A field survey of the spatial distribution and crown morphology of saplings and young adults found 1) the distance between young valley oaks and neighboring overstory trees to increase with neighbor size, and 2) crowns of the young oaks to be skewed away from neighbors. Although shading by the canopy was only moderate, canopy effects on understory light supply may restrict juvenile recruitment of valley oak in this woodland.     

Flowering dogwood (Cornus florida L.) as mediator of calcium cycling: new insights are revealed by analysis of foliar partitioning

Flowering dogwood (Cornus florida L.) is an important understory tree species that is thought to enhance ecological calcium (Ca) cycling and soil Ca availability through high foliar Ca concentrations and rapid leaf litter decomposition. Calcium is an essential macronutrient in plants, important for stabilizing cell walls and plasma membranes. It is also an ubiquitous intracellular second messenger, helping plants sense and physiologically respond to numerous environmental cues. Analyses of total foliar Ca can be dominated by chemically sequestered Ca, which is not readily available for cellular processes. Thus, analyses of specific foliar partitions of Ca are more closely tied to Ca-dependent processes such as signal transduction. To further develop our understanding of the role of flowering dogwood in ecological Ca cycling, we evaluated foliar Ca partitioning via sequential acidic extractions. We compared Ca partitioning in flowering dogwood to that of white oak (Quercus alba L.), and found significantly more labile Ca in dogwood and a much greater proportion of Ca sequestration in oak. We compared foliar Ca partitioning in white oak at sites with dogwood to that of oaks at dogwood-absent sites, and found significantly greater labile Ca in oaks where dogwood was present. We also investigated the phenological patterns of Ca partitioning and sequestration in flowering dogwood foliage, and found preferential partitioning of Ca into the more labile and physiologically accessible pools throughout the growing season, with minimal Ca sequestration. This work helps elucidate the mechanisms and consequences associated with Ca cycling by flowering dogwood in forested systems.     

黑龙江省不同地点蒙古栎林生态特点研究

通过对黑龙江省６个地点的天然蒙古栎林的结构和更新特点的分析,蒙古栎林可划分为不同特点的蒙古栎群落,即纯蒙古栎群落、蒙古栎桦树群落、蒙古栎槭树群落、蒙古栎红松群落和蒙古栎松混交林群落,其演替趋势如下：红蒙古栎群落、蒙古栎桦树群落至蒙古栎槭树落、蒙古栎红松群落,再至蒙古栎红松混交林群落,蒙古栎群落类型的多样性主要反应群落不同的演替阶段,造成蒙古栎群落多样的原因是人类活动和自然因素作用的结果,随着群落的演替,蒙古栎的优势地位逐渐被消弱,乔木种类丰富度增多,草本种类丰富度增多;蒙栎的相对密度下降,林内环境由于干燥逐渐变中性至较湿润,蒙古栎幼苗和幼树在总幼苗和幼树中所占的比例下降,耐荫物中色木槭等的幼苗和幼树所占比例上升;在演替过程中,蒙古栎分布格局－聚集分布的聚集程度逐渐降低,并向随机分布的方向发展。     

Germination of Quercus ilex and Q. pubescens in a Q. ilex coppice

Quercus ilex L. (holm oak) coppices, widespread around the Mediterranean basin, are probably the result of 5 000 years of prolonged human disturbance of the original Quercus pubescens Willd. (downy oak) forests. Since disturbance has almost ceased in recent years, a question arises as to the development of these coppices: will the Q. pubescens forests return, or will Q. ilex remain the dominant species? To investigate the phenomenon, we analyzed the first stages, i.e. germination of the two species in holm oak coppices. Our experiments show that both species germinated better in coppices than in clearings or clear-cuts. Moreover, Q. pubescens appears to be slightly favored above Q. ilex and it is suggested auto-allelopathy is involved, at least partially inhibiting the germination of Q. ilex.     

Quercus species divergence is driven by natural selection on evolutionarily less integrated traits

Functional traits are organismal attributes that can respond to environmental cues, thereby providing important ecological functions. In addition, an organism’s potential for adaptation is defined by the patterns of covariation among groups of functionally related traits. Whether an organism is evolutionarily constrained or has the potential for adaptation is based on the phenotypic integration or modularity of these traits. Here, we revisited leaf morphology in two European sympatric white oaks (Quercus petraea (Matt.) Liebl. and Quercus robur L.), sampling 2098 individuals, across much of their geographical distribution ranges. At the phenotypic level, leaf morphology traditionally encompasses discriminant attributes among different oak species. Here, we estimated in situ heritability, genetic correlation, and integration across such attributes. Also, we performed Selection Response Decomposition to test these traits for potential differences in oak species’ evolutionary responses. Based on the uncovered functional units of traits (modules) in our study, the morphological module “leaf size gradient” was highlighted among functionally integrated traits. Equally, this module was defined in both oaks as being under “global regulation” in vegetative bud establishment and development. Lamina basal shape and intercalary veins’ number were not, or, less integrated within the initially defined leaf functional unit, suggesting more than one module within the leaf traits’ ensemble. Since these traits generally show the greatest species discriminatory power, they potentially underwent effective differential response to selection among oaks. Indeed, the selection of these traits could have driven the ecological preferences between the two sympatric oaks growing under different microclimates.Subject terms: Quantitative trait, Evolutionary biology     

Ecological behavior of Quercus suber and Quercus ilex inferred by topographic wetness index (TWI)

The ecological behaviors of a network of pure evergreen oak stands (Quercus suber L. and Quercus ilex L.) in the Central-Western Mediterranean Basin were investigated toward climatic and edaphic factors implemented with the application of topographic wetness index (TWI). A Categorical Principal Component Analysis (Catpca) using climatic and soil physico-chemical parameters was performed on 23 cork oak and holm oak pure stands with the aim to understand better the effectiveness of TWI for characterizing soil ecology of the two species. Catpca pointed out that, although cork oak and holm oak are able to growth in similar Mediterranean conditions, they show different behaviors in terms of needs and tolerance to soil water content. TWI confirmed such results at local scale, allowing highlighting some interesting features of the species differential ecology. Although both species confirmed to be drought-tolerant, the heliophilous cork oak revealed to dominate the landscape on wettest soils with high TWI values—indicating the capacity to tolerate stresses due to periods of waterlogging—, while the shade-tolerant holm oak prevails for low-medium TWI values—drier and mesophilous sites. Despite the application of TWI to vegetation science and ecology is relatively recent, results are encouraging and suggest considering this user-friendly and synthetic index in ecological investigations and modeling.     

Field study of beech (t Fagus sylvatica L.) and melojo oak (t Quercus pyrenaica Willd) leaf litter decomposition in the centre of the Iberian Peninsula

The effect of the canopy on leaf decomposition of beech (t Fagus sylvatica) and melojo oak (t Quercus pyrenaica) was studied during a period of 660 days in a mountain forest of central Spain; response of leaves to leaching was also studied to determine the effects of rainfall after leaf fall. Beech leaves lost 5.8% of their weight by leaching, whereas melojo oak leaves lost 13%. Under both types of canopy, beech leaves showed almost no difference in their decomposition patterns, with decay constants of 0.31 and 0.32 respectively. Melojo oak leaves showed quite a different behaviour under both canopies; decay constant was 0.47 under t Quercus pyrenaica and 0.77 under beech canopy. Total immobilization of nitrogen was less in the melojo oak forest. Effects of summer dryness were sharper in the melojo oak forest, where decomposition stopped during the summer. This delay in the decomposition might have been due to the lower canopy density in the melojo oak forest. The decomposition patterns of the leaves of both species, under the canopy of the other species, suggests what might happen in mixed stands. Thus, the presence of melojo oaks in beech forest would increase decay and decrease nitrogen immobilization. The presence of beech trees in melojo oak forests would improve microclimatic conditions and increase decay, whereas beech litter on the soil would immobilizate more nitrogen.     

Hollow oaks and beetle conservation: the significance of the surroundings

In this study we investigated hollow oaks (Quercus robur, Q. petrea) situated in open landscapes and in forests in Norway in northern Europe, and compared their importance for rare and threatened beetles (Coleoptera). Old, hollow oak trees, both in parks and in forests, were extremely rich in red-listed beetles, and hosted a high proportion of threatened species. The proportion of oak associated species and the mean number of red-listed beetle species per tree was similar in the two site types, but rarefaction showed that for a certain number of individuals, oaks in forests had more threatened and near-threatened species than oaks in parks. The species composition also differed between site types: Park oaks had a higher proportion of species associated with hollows and animal nests, whereas in forests, there was a higher proportion of species depending on dead oak wood in general. Four factors were significant in explaining the richness of red-listed beetles in our study: Tree circumference, cavity decay stage, proportion of oak in the surroundings, and coarse woody debris (CWD) in the surroundings. Forest oaks were smaller, but they still trapped a species richness comparable to that of the larger park oaks—probably a result of high amounts of CWD in the surroundings. We show that oaks in open landscapes and oaks in forest have only partly overlapping beetle assemblages and, thus, cannot be substituted in conservation. Planning for conservation of red-listed beetles associated with this key habitat demands a large scale perspective, both in space and time, as the surroundings have important effects on associated threatened and near threatened species.     

Effect of a red oak species gradient on genetic structure and diversity of Quercus castanea (Fagaceae) in Mexico

Incipient reproductive barriers are a common characteristic of oak species. Disruption of these barriers promotes changes in diversity and genetic structure of the species involved. Quercus castanea is a red oak with wide geographic distribution in Mexico, which presents atypically high morphological variability when it occurs in sympatry with other red oak species, suggesting that hybridization may explain the observed variation. We tested if the genetic structure and diversity levels of Q. castanea are related to the number of red oak species growing in sympatry. In total, 14 microsatellite (SSRs) primers (six nSSRs and eight cpSSRs) were used in 120 Q. castanea individuals (20/site) belonging to six populations, where the number of red oak species associated varied from zero to five. Results showed a positive and significant relationship between the genetic diversity of Q. castanea and the number of red oak species growing in sympatry, regardless of the marker type or the parameter of genetic diversity analyzed. Also, we found a higher genetic differentiation of Q. castanea populations using cpSSRs in comparison with nSSRs. Our results suggest that temperate forests with high red oaks species richness co-dominated by Q. castanea promote the increase in this species genetic diversity. From a conservation perspective, high genetic diversity levels of foundation species such as Q. castanea may have positive cascade effects extending to other species in the community.     

Large-Scale Patterns of Quercus ilex, Quercus suber, and Quercus pyrenaica Regeneration in Central-Western Spain

In Central-Western Spain, forests and woodlands composed of Quercus sp. support outstanding levels of biodiversity, but there is increasing concern about their long-term persistence due to a lack of regeneration. We hypothesize that this regenerative lack is operating on a large geographic scale; that there are differences in the abundance of regeneration between three oak species; that oak regeneration is governed mainly by forest management and structure; and that shrubs act as important physical protectors of seedlings and saplings. We analyzed whether densities of oak seedlings and saplings in several size classes were related to stand-structure, understory, and physiographic variables potentially affecting regeneration. Data collected at a regional level (1 km × 1 km grid) by the Spanish Forest Inventory were evaluated from 2,816 plots. Results revealed that regeneration failure was common for all size categories, from small seedlings to large saplings, and for the three oak species studied, especially the evergreens. Of the Quercus ilex, Q. suber, and Q. pyrenaica plots studied, 49%, 62%, and 20% were lacking any small seedlings, and 82%, 96%, and 56% did not have any large saplings, respectively. Regeneration was positively correlated with tree cover and density, especially of small and medium-sized trees, and negatively correlated with the presence of large trees, indicating that regeneration failure is mostly associated with more open, uniform, and/or aged woodlands. Regeneration densities of Q. ilex and Q. suber were positively correlated with all understory variables, suggesting that the presence of pioneer shrubs represent a major safe site for early tree recruitment, independent from specific shrub species.     

Seed germination and seedling performance of two Mediterranean tree species,holm oak (shape Quercus ilex L.) and Aleppo pine (shape Pinus halepensis Mill.): a multifactor experimental approach

A two-level multifactor experimental approach was used to compare seed germination and seedling performance of two Mediterranean tree species: the early successional Aleppo pine (Pinus halepensis Mill.) and the late successional holm oak (Quercus ilex L.). In a first experiment germination rate was evaluated under the combined effects of shade, nitrogen availability, and pine or holm oak leaf litter. In a second experiment we tested for the effects of shade, nutrient availability, and litter type on seedling survival, growth and biomass allocation. Holm oak showed higher germination rates under shaded than under unshaded conditions, while Aleppo pine showed no differences between shaded and unshaded conditions. Nitrogen availability and litter type had no significant effect on germination of either species. Both species showed increased RGR, but also higher mortality rates, when grown in an enriched nutrient environment. While Aleppo pine showed no differences in RGR and mortality rate under different shading levels, RGR decreased and mortality increased for holm oak in full light. Increased radiation decreased LAR, SLA and height:diameter ratio, and increased RWR and R/S in both species, although Aleppo pine showed more pronounced changes. Unlike Aleppo pine, holm oak responded to increased nutrient availability by decreasing R/S and increasing LAR. From these results, no seed-seedling conflicts were found in either species, but a trade-off does seem to exist for holm oak between biomass allocation traits deployed in response to increased nutrient availability and radiation. Aleppo pine outperformed holm oak under most environmental conditions tested and showed a wider regeneration niche.     

Growth, regeneration and shade tolerance of the Wild Service Tree (Sorbus torminalis (L.) Crantz) in aged oak coppice forests

Sorbus torminalis L. (Crantz) is a rare species in Central European forests with very limited quantitative information on its regeneration and growth dynamics. Since coppicing is no longer practiced in the most parts of Central Europe, it is unclear whether S. torminalis, which has usually a shorter end height than companion species, can persist in high forest systems. Here, we quantified species frequency on three 1 ha sample plots of former oak coppice forest. To determine whether S. torminalis regenerated continuously and how it might compete with oaks, the age of 80 trees was determined, and diameter and height growth were reconstructed for the 20 largest trees by stem analysis. To assess its shade tolerance, photosynthesis was measured for leaves located in high and low light conditions. Dendrochronological data demonstrated that, over the last 80 years, continuous recruitment of S. torminalis occurred. Growth patterns and photosynthesis measurements suggest that S. torminalis is a highly shade-tolerant species. We conclude that abandonment of coppicing in these forests does not threaten the status of S. torminalis, which can persist beneath the canopy of oaks.