Abies Alba Forests Research Articles

Neighborhood effects on tree growth in a Fagus sylvatica - Abies alba forest following an ice storm

Ice storms can cause substantial damage to tree crowns and lead to growth reduction. However, in uneven-aged stands, the growth of an individual tree may also increase due to crown release caused by the damage or mortality of neighboring trees. Three years after the devastating ice storm in 2014 in mixed uneven-aged Dinaric forests (Croatia), we cored 156 European beech (Fagus sylvatica) and 85 silver fir (Abies alba) trees across 20 permanent sample plots to study the post-storm growth response as a function of tree, stand, site, spatial arrangement and local competition factors. The ice storm damaged over 84% of trees on the sampled plots. Among the cored trees, 52.7% exhibited growth reduction, which on average amounted to −3.1% relative to the pre-disturbance average. Trees with less than 40% crown damage maintained their pre-disturbance growth rates or experienced only minor growth suppression. While 60% of beech trees suffered a growth reduction at an average rate of −7.2%, the average radial increment of fir after the storm was 14.0% higher compared to the pre-storm rate. A linear mixed-effects model suggests that the growth response can largely be explained by the focal and neighboring tree species identity, tree competition pressure, focal and neighboring tree damage, crown size, slenderness index and stoniness. Growth release was positively associated with fir, inverse distance-weighted crown damage of the nearest neighbor, shorter crowns, slenderness, less stony sites and less damaged trees. The analysis suggests that at the same level of local competition load, trees with a broadleaved and damaged nearest neighbor are more likely to experience growth release than those with a coniferous or undamaged nearest neighbor. This implies that uneven-aged stands with a substantial presence and mingling of both conifers and broadleaves are expected to be more resilient to ice storms and are less likely to suffer growth reduction.

Causes and mechanisms of synchronous succession trajectories in primeval Central European mixed Fagus sylvatica forests

Abstract Natural succession trajectories of Central European forest ecosystems are poorly understood due to the absence of long‐term observations and the pervasive effects of past human impacts on today's vegetation communities. This knowledge gap is significant given that currently forest ecosystems are expanding in Europe as a consequence of global change. Annually laminated sediments were extracted from two small lowland lakes (Moossee 521 m a.s.l.; Burgäschisee 465 m a.s.l.) on the Swiss Plateau. We combine high‐resolution palaeoecological and quantitative analyses to assess changes in vegetation during the Neolithic. We test for regionally synchronous land‐use phases and plant successional patterns that may originate from complex interactions between human and climatic impacts. Mixed Fagus sylvatica forests dominated the Swiss Plateau vegetation over millennia. During the period 6,500–4,200 cal year bp, pronounced forest disruptions accompanied by increased fire and agricultural activities occurred at c. 6,400–6,000 cal year bp, 5,750–5,550 cal year bp, around 5,400 cal year bp and at 5,100–4,600 cal year bp. Biodiversity increased during these land‐use phases, likely in response to the creation of new open habitats. After decades to centuries of land‐use, arboreal vegetation re‐expanded. In a first succession stage, heliophilous Corylus avellana shrubs were replaced by pioneer Betula trees. These open arboreal communities were out‐competed within 150–200 years by late‐successional F. sylvatica and Abies alba forests. Most strikingly, cross‐correlations show that these successions occurred synchronously (±11 years) and repeatedly over large areas (>1,000 km2) and millennia. Synthesis. First notable human impact shaped the primeval mixed Fagus sylvatica forests in Central Europe from c. 6,800–6,500 cal year bp on. Agrarian societies were susceptible to climate changes and we hypothesize that climate‐induced, simultaneous agricultural expansion and contraction phases resulted in synchronous regional forest successions. Currently, forests are expanding in Central Europe as a result of land abandonment in marginal areas. Our results imply that mixed Fagus sylvatica forests with Abies alba and Quercus may re‐expand rapidly in these areas, if climate conditions will remain within the range of the mid‐Holocene climatic variability (with summers c. +1–2°C warmer than today).

Early human impact (5000–3000 BC) affects mountain forest dynamics in the Alps

Summary The resilience, diversity and stability of mountain ecosystems are threatened by climatic as well as land‐use changes, but the combined effects of these drivers are only poorly understood. We combine two high‐resolution sediment records from Iffigsee (2065 m a.s.l.) and Lauenensee (1382 m a.s.l.) at different elevations in the Northern Swiss Alps to provide a detailed history of vegetational changes during the period of first pastoralism (ca. 7000–5000 cal. BP, 5000–3000 BC) in order to understand ongoing and future changes in mountain ecosystems. We use palaeoecological methods (fossil pollen, spore, microscopic charcoal and macrofossil analysis) as well as ecological ordination techniques and time‐series analysis to quantify the impact of fire and grazing on natural mountain vegetation at Iffigsee. Fire was used by Neolithic people to create pastures at timberline and clear forests for arable farming in the valley. This had a significant, long‐term effect on the mountain vegetation and a negative impact on keystone forest species such as Abies alba, Larix decidua and Pinus cembra. The mass expansion of Picea abies at ca. 5500 cal. BP (ca. 3500 BC) was facilitated by anthropogenic disturbance (fire, grazing and logging) causing an irreversible decline in Abies alba. Temperate Abies alba forests, which existed under warmer‐than‐today conditions, might be better adapted to projected climate change than today's drought‐sensitive Picea abies forests, especially under low anthropogenic disturbance following land abandonment. Synthesis. Human impact for millennia has shaped mountain vegetation in the Alps and still continues to have a large effect on today's species composition and distribution. Fire and traditional pastoralism have the potential to mitigate the effects of climate change, maintain species‐rich high‐alpine meadows and prevent biodiversity losses.

Climatic and human impacts on mountain vegetation at Lauenensee (Bernese Alps, Switzerland) during the last 14,000 years

Lake sediments from Lauenensee (1381 m a.s.l.), a small lake in the Bernese Alps, were analysed to reconstruct the vegetation and fire history. The chronology is based on 11 calibrated radiocarbon dates on terrestrial plant macrofossils suggesting a basal age of 14,200 cal. BP. Pollen and macrofossil data imply that treeline never reached the lake catchment during the Bølling–Allerød interstadial. Treeline north of the Alps was depressed by c. 300 altitudinal meters, if compared with southern locations. We attribute this difference to colder temperatures and to unbuffered cold air excursions from the ice masses in northern Europe. Afforestation started after the Younger Dryas at 11,600 cal. BP. Early-Holocene tree- Betula and Pinus sylvestris forests were replaced by Abies alba forests around 7500 cal. BP. Continuous high-resolution pollen and macrofossil series allow quantitative assessments of vegetation dynamics at 5900–5200 cal. BP (first expansion of Picea abies, decline of Abies alba) and 4100–2900 cal. BP (first collapse of Abies alba). The first signs of human activity became noticeable during the late Neolithic c. 5700–5200 cal. BP. Cross-correlation analysis shows that the expansion of Alnus viridis and the replacement of Abies alba by Picea abies after c. 5500 cal. BP was most likely a consequence of human disturbance. Abies alba responded very sensitively to a combination of fire and grazing disturbance. Our results imply that the current dominance of Picea abies in the upper montane and subalpine belts is a consequence of anthropogenic activities through the millennia.

Phylogenetic position of the ectomycorrhizal basidiomycete Tricholoma dulciolens in relation to species of Tricholoma that produce “matsutake” mushrooms

Tricholoma dulciolens is an ectomycorrhizal basidiomycete that produces “matsutake”-like mushrooms in association with Picea abies in Fennoscandia. The phylogenetic position of T. dulciolens relative to matsutake species is, however, unknown. In the present study, we demonstrated that T. dulciolens is phylogenetically independent from T. matsutake and its allied species. In addition, herbarium specimens identified as T. caligatum from Abies alba forests in Spain were phylogenetically related to but distinct from T. dulciolens. Based on ribosomal internal transcribed spacer DNA sequence data, T. dulciolens appears to exist in North America, as well. This is the first phylogeny of T. dulciolens in Fennoscandia and its related species in southern Europe.

Similarities between predator mite populations (Acari: Gamasina) from natural forests in the Bucegi Massif, Romania

Ecological research of gamasid mites was carried out in three natural forest ecosystems with Picea abies (1350 m a.s.l.), Abies alba (950–1000 m a.s.l.) and Fagus sylvatica (1200 m a.s.l.) situated in the Bucegi Massif, Southern Carpathians, Romania during 2001–2003. In the studied forest ecosystems, the taxonomic structure of gamasids was represented by 11 families (Epicriidae, Parasitidae, Veigaiidae, Ameroseiidae, Aceosejidae, Rhodacaridae, Macrochelidae, Pachylaelapidae, Laelapidae, Eviphididae and Zerconidae), with 39 genera and 97 species. The maximum number of species was recorded in the ecosystem with Abies alba (80), followed by the ecosystem with Fagus sylvatica (73), while the minimum in the ecosystem with Picea abies (68). 2,016 samples, 97 species with 23,441 individuals were analysed. In order to show similarities between predator mite populations from these areas, the vegetation and some abiotic parameters of the soil (temperature, humidity, pH) were analysed and described. Similarities between gamasid mite populations from the investigated ecosystems were analysed using the Jaccard index (q). The highest similarity index (q = 0.706) was recorded between gamasids identified in Picea abies and Abies alba forests, at soil level, in comparison with those from Abies alba and Fagus sylvatica forests (q = 0.656). Based on the similarity index, it is discussed that the gamasid population structure was influenced by the type of soil, the specific composition of the herbaceous, shrub and tree layers, the microclimatic factors, all characteristic for each studied ecosystem.

Forest plant community changes during 1989-2007 in response to climate warming in the Jura Mountains (France and Switzerland)

Question: How strong are climate warming-driven changes within mid-elevation forest communities? Observations of plant community change within temperate mountain forest ecosystems in response to recent warming are scarce in comparison to high-elevation alpine and nival ecosystems, perhaps reflecting the confounding influence of forest stand dynamics. Location: Jura Mountains (France and Switzerland). Methods: We assessed changes in plant community composition by surveying 154 Abies alba forest vegetation releves (550-1,350 m a.s.l.) in 1989 and 2007. Over this period, temperatures increased while precipitation did not change. Correspondence analysis (CA) and ecological indicator values were used to measure changes in plant community composition. Releves in even- and uneven-aged stands were analysed separately to determine the influence of forest stand dynamics. We also analysed changes in species distribution to detect shifts along the elevation gradient by focusing on the lowest, central and highest positions of lowland and mountain species altitudinal ranges. Results: We found significant shifts along the first CA axis, which reflected a change in plant community composition towards a greater frequency of lowland species. Analyses of ecological indicator values indicated increases in temperature and light availability in A. alba stands, particularly in even-aged stands. However, no major changes in overall species distribution were found. Conclusions: The community-level changes are consistent with effects of climate warming and local stand dynamics. Changes in species distribution were small in comparison to observed local temperature increases, perhaps reflecting dispersal limitation, phenotypic plasticity or microclimatic buffering by the tree canopy. Causality cannot rigorously be inferred from such a descriptive study; however, we suggest that recent warming is now driving plant community change in the climatically more moderate mid-elevation forest setting.

Structural characteristics and aboveground biomass of old‐growth spruce–fir stands in the eastern Carpathian mountains, Ukraine

Temperate old‐growth forests are known to have ecological characteristics distinct from younger forests, but these have been poorly described for the remaining old‐growth Picea abies–Abies alba forests in the eastern Carpathian mountains. In addition, recent studies suggest that old‐growth forests may be more significant carbon sinks than previously recognized. This has stimulated interest in quantifying aboveground carbon stocks in primary forest systems. We investigated the structural attributes and aboveground biomass in two remnant old‐growth spruce–fir stands and compared these against a primary (never logged) mature reference stand. Our sites were located in the Gorgany Nature Reserve in western Ukraine. Overstory data were collected using variable radius plots; coarse woody debris was sampled along line intercept transects. Differences among sites were assessed using non‐parametric statistical analyses. Goodness‐of‐fit tests were used to evaluate the form of diameter distributions. The results strongly supported the hypothesis that old‐growth temperate spruce–fir forests have greater structural complexity compared to mature forests, including higher densities of large trees, more complex horizontal structure, and elevated aboveground biomass. The late‐successional sites we sampled exhibited rotated sigmoid diameter distributions; these may reflect natural disturbance dynamics. Old‐growth Carpathian spruce–fir forests store on average approximately 155–165 Mg ha−1 of carbon in aboveground tree parts alone. This is approximately 50% higher than mature stands. Given the scarcity of primary spruce–fir forests in the Carpathian region, remaining stands have high conservation value, both as habitat for late‐successional species and as carbon storage reservoirs.

Gap regeneration and replacement patterns in an old-growth Fagus–Abies forest of Bosnia–Herzegovina

We examined the influence of small-scale gap disturbances on stand development and tree species coexistence in an old-growth Fagus sylvatica–Abies alba forest in the Dinaric Mountains of Bosnia–Herzegovina. The structure and composition of tree regeneration in gaps were compared to the forest as a whole, and the influence of gap size on the density and composition of regeneration was assessed. Transition probabilities were also calculated from gapfillers in different life stages to examine canopy replacement patterns. The structure and composition of tree regeneration were similar between gaps and the forest as a whole, and there was no relationship between overall regeneration density and gap size, indicating most individuals established prior to gap formation. Likewise, there was no strong evidence of gap-size partitioning for shade tolerant F. sylvatica and A. alba, although less tolerant Acer pseudoplatanus only recruited to taller life stages in larger gaps. Transition probabilities calculated from the seedling and sapling data suggest that most gaps will be captured by F. sylvatica, while probabilities based on pole-sized gapmakers indicate both A. alba and F. sylvatica will be maintained in the canopy. We suggest that gaps primarily play a role in reorganizing advance regeneration, and that coexistence of shade tolerant F. sylvatica and A. alba is more likely related to their differential ability to tolerate shaded understory conditions, particularly during larger life stages, rather than gap-size partitioning.

Historia paleoecológica y modelo de idoneidad de <i>Abies Alba</i> Mill. en la cordillera pirenaica.

A phytogeographic approach of Abies alba Mill. populations in the Spanish side of the Pyrenees Range is provided. The methodology is based on “Species distribution models” (SDMs) and palaeopalynological Quaternary records from Pyrenees. Articulating the results derived from the SDMs (topo-climatic perspective), and a review of the Quaternary fossil record (climate and anthropic approach), we try to build a historical understanding of the dynamics of these forests. Both tools reveal that Abies alba only occupy a small proportion of their potential distribution range (30%) and offer geographic evidence demonstrating that these populations had a wider altitudinal distribution in the past. We suggest the use of SDMs to reinforce assumptions about the Quaternary distribution of the Iberian Abies alba forest, and to locate refugia for the long-term persistence.

Landscape dynamics of Abies and Fagus in the southern Pyrenees during the last 2200 years as a result of anthropogenic impacts

The vegetation landscape dynamic is derived from the relationship established between a society and its environment through time, and the current landscape has never been seen in the previous 2000 years. The pollen study of a core from a peat bog in València d'Àneu (Lleida, NE Iberian Peninsula) shows a maximum extension of Abies alba forest about 2200–2000 cal. yr BP. Later on, there is evidence of selective actions affecting this forest and the expansion of Fagus sylvatica at about 2000–1300 cal. yr BP. Beginning in 1300 cal. yr BP, deforestation due to agricultural activities expanded and beech definitively disappeared at 800 cal. yr BP. Natural and human disturbances affected the dynamics of A. alba and F. sylvatica from their first appearance to the current vegetation landscape. Human impact on the silver fir forest, which reached its maximum in the last millennium, favoured the beech population. Pollen data from this region support our finding that human impact, not climate, is the most important influential factor in the development of beech forests.

Life at the margin: the mating system of Mediterranean conifers

Abstract. Mixed mating, where a single tree progeny results from a mixture of selfing and outcrossing, is widespread in conifers and could be an evolutionary advantage at ecological margins when mating partners become scarce. This study analyzes how the mating system responds to bioclimate and density variations. We surveyed published data on the mating system of Abies, Picea and Pinus species when information on bioclimate and stand density was available. Our survey revealed that Mediterranean species demonstrate a lower selfing rate than other species and that the proportion of selfed versus outcrossed progeny is not fixed within species. The highest variability in mating types within populations was found when stand density was the most variable. To show how density affects the proportion of selfed versus outcrossed progeny, we used isozymes to genotype single tree seeds from a marginal Abies alba forest in Mediterranean France (Mont Ventoux) where low-to high-density stands are found. We then tested the adaptive potential of the different high and low density progenies by sowing them under controlled nursery conditions and measuring germination rate and seedling survival after 4 yr under 3 different water regimes. Although the mean value of outcrossing rate was typical for mixed mating conifers (tm = 0.85), individual outcrossing rates varied from 0.05 to 0.99 and were strongly correlated with stand type and density (tm from 0.87 in high-density to 0.43 in low-density marginal stands). Significantly fewer seeds from the low density marginal stand germinated (32% vs. 53% in the high density mature stand), although seedlings from the marginal stand had a better 4-yr survival (81%) than seedlings from the high-density mature stand (63%) when the three water regimes (from least to most stressful) were averaged. Trees from low density stands may be at a selective disadvantage because they produce more selfed progeny than trees from high-density stands. However, selfed seeds may be purged early on (at the embryo stage) and the remaining seeds tend to produce seedlings with better fitness. Variability of the selfing rate might thus be an adaptive strategy for species in highly contrasted environments where selection of both reproductive assurance and avoidance of inbreeding depression may be density dependent.

Winter habitat selection by wild boar Sus scrofa in southeastern Poland

Research was conducted on habitat selection by the wild-boar population in the Carpathian foothills, southeastern Poland. In two forest districts (Bircza and Krasiczyn) with a total area of forests of 47,000 ha, 21 line transects were designated (total length, 284 km). In February 2001, tracks that wild boar left during the day were counted on five subsequent days. Using a car mileage meter and forest maps, the locations of tracks in seven forest types, forest meadows and agricultural fields situated inside the forests were determined. The Bailey’s test was applied to calculate the boars’ preference for each forest type and non-forest areas. Spatial distribution of 284 wild-boar tracks shows that the animals do indeed prefer European beech–hornbeam Fagus silvatica–Carpinus betulus forest and avoid silver fir Abies alba forest. The hypothesis raised is that in the European beech–hornbeam forests, there are foraging areas and bedding sites crucial for the animals.

Spatial patterns and environmental factors affecting the presence of Melampsorella caryophyllacearum infections in an Abies alba forest in NE Spain

SummaryThe presence of trunk swellings caused by the rust fungus Melampsorella caryophyllacearum was systematically surveyed in an Abies alba forest (Irati, NE Spain), using 1237 circular plots (diameter = 18 m). The relationship between fungal presence and several abiotic (aspect, elevation, distance to the nearest river and slope) and biotic factors (basal area of A. alba and/or Fagus sylvatica, shrub, fern and herb cover) was assessed through correlation and ordination analyses. Additionally, the spatial pattern of the presence of diseased trees was described using Ripley's K function. Southern‐aspect plots had a significantly lower presence of diseased trees than plots‐oriented north, east and west. Plots with diseased trees were located at a significantly lower elevation, and at a shorter distance to the river than plots without infections. Plots with diseased trees had almost twice the average A. alba basal area, and less average F. sylvatica basal area than plots without diseased trees. However, similar mean values of slope and shrub, fern and herb cover were found in both types of plots. The disease showed spatial aggregation in patches with a mean radius of ca. 900 m. The implications of the results for disease management are discussed.

Regeneration patterns after intermediate wind disturbance in an old-growth Fagus– Abies forest in southeastern Slovenia

We studied patterns of tree regeneration in relation to canopy structure in a 1-ha plot damaged by an intermediate windstorm in 1983 and a 1-ha control plot regulated by small-scale canopy gaps in an old-growth Fagus sylvatica– Abies alba forest, southeastern Slovenia. In the windthrow plot, a maze of interconnected gaps covered 55% of the plot, while more discrete canopy openings covered 27% of the control plot. The different canopy structures resulted in marked differences in the density and spatial patterns of tree regeneration in the two plots. Fagus dominated the regeneration layer in both plots, while Abies occurred infrequently. For Fagus, there were nearly six-fold less seedlings, but twice as many saplings and understory trees in the windthrow plot compared to the control plot. Overall, the spatial patterns of Fagus seedlings, saplings, and understory trees were clumped in both plots, but only saplings and understory trees were aggregated under canopy gaps in the control plot, whereas saplings in the windthrow plot were distributed irrespective of canopy gaps. Abies individuals also had an aggregated spatial distribution, but were growing under a closed canopy. We suggest that infrequent, intermediate windstorm disturbance plays an important role in the structure and dynamics of central European forests by creating more coarse-grained forest structures than in stands regulated by smaller-scale gap processes.

Habitat Assessment, Phytosociology and Conservation of the Tunbridge Filmy-fern Hymenophyllum tunbrigense (L) Sm. in its Isolated Locations in the Vosges Mountains

The Tunbridge Filmy-fern, Hymenophyllum tunbrigense, has been discovered within the last 10 years in several places in a 15 km long by 2 km wide area located in the western part of the Vosges Mountains. After the disappearance of the Saxony and Ardennes sites, these Vosgian locations have to be considered as one of the last continental areas for this fern in Europe, meriting the same level of interest as the well-known Luxembourg locations. In its Vosgian area, the fern occurs in Abies alba forests on small (less than 2.5 m high) and moist sandstone rocks, generally located near running water in wet valleys, at altitudes between 400 and 640 meters a.s.l. As assessed through the impact of the 26 December 1999 storm on one Hymenophyllum location, this fern appears to be sensitive to direct sunlight in the Vosges mountains. Therefore the main measure to ensure its conservation would be to maintain a dense and permanent forest canopy above the Hymenophyllum sites in order to avoid any direct sunlight.

Environmental factors related to damage by Heterobasidion abietinum in Abies alba forests in Southern Italy

A study was carried out in southern Italy to determine the role of some factors in favouring Heterobasidion annosum s. l. spread and damage in eight Silver-fir ( Abies alba Mill.) forests. All the studied stands were colonised by H. abietinum. The presence of the fungus (as carpophores on colonised wood) was detected by means of transects and varied from 7.0 to 56.0% of trees. Stand history, precipitation and forest origin, analysed by the χ 2-test, had a significant effect on rot severity. Damage was more severe in stands more xerophytic where the woods were planted on pasturelands.

The impact of a needleminer (Epinotia subsequana) outbreak on radial growth of silver fir (Abies alba) in the Aragón Pyrenees: A dendrochronological assessment

Summary We report the first dendrochronological assessment on the effects of the Epinotia subsequana (Lepidoptera: Tortricidae) needleminer on Abies alba forests in the Aragon Pyrenees (northeastern Spain), near the southwestern distribution limit of A. alba. We built local residual ring-width chronologies, in fifteen A. alba stands, using dendrochronological techniques. We found a strong decrease in radial growth in the 20th century, during the 1996–98 period, only at the sites AS (Paco Asieso, 42°39' N, 00°17' W) and DI (Diazas, 42°38' N, 00°06' W). There were previous surveys of E. subsequana outbreaks and fir defoliation, in the studied sites area, in 1995–96. They showed that the radial-growth suppression was caused by E. subsequana. We compared radial growth in the non-defoliated stands with mean regional chronology. The greatest decline in radial growth was in 1996–97. Thus, there was a 1–2 year lag in radial growth suppression following the defoliation. The recovery of radial growth occurred in 1998–99.

The genus Tephrocybe Donk in Britain

Tricholoma dulciolens is an ectomycorrhizal basidiomycete that produces “matsutake”-like mushrooms in association with Picea abies in Fennoscandia. The phylogenetic position of T. dulciolens relative to matsutake species is, however, unknown. In the present study, we demonstrated that T. dulciolens is phylogenetically independent from T. matsutake and its allied species. In addition, herbarium specimens identified as T. caligatum from Abies alba forests in Spain were phylogenetically related to but distinct from T. dulciolens. Based on ribosomal internal transcribed spacer DNA sequence data, T. dulciolens appears to exist in North America, as well. This is the first phylogeny of T. dulciolens in Fennoscandia and its related species in southern Europe.