Interactions of ecological factors and natural regeneration in an altimontane Norway spruce (Picea abies (L.) Karst.) stand (original) (raw)
Annals of Forest Science
& Key message Natural regeneration of P. abies (L.) H. Karst. may reach high densities in lower mountain elevations. The highest densities were found in sites with moderate light availability, with low pH, and not near the riverbank. However, age-height classes differed in the predicted magnitude of response, but were consistent in response directions. Mosses and understory species typical of coniferous forests were positively correlated with regeneration density. & Context Norway spruce Picea abies (L.) H. Karst. in Central Europe is at risk under climate change scenarios, particularly in mountain regions. Little is known about the impact of environmental factors on the natural regeneration of P. abies in lowelevation mountain forests. & Aims We aimed to assess impacts of distance from the riverbank, soil pH, and light availability on natural P. abies regeneration. We hypothesized that (1) natural P. abies regeneration would depend on light availability and soil pH and (2) there are understory plant species which may indicate the microsites suitable for natural regeneration of P. abies. & Methods The study was conducted in the Stołowe Mountains National Park (SW Poland, 600-800 m a.s.l.). We established 160 study plots (25 m 2) for natural regeneration, light availability, soil pH, and understory vegetation assessment.
Forest Ecology and Management, 2002
Conversion of Norway spruce (Picea abies (L.) Karst.) plantations is a great challenge for silviculture in Europe today. While complex problems with these stands are widely recognised, methods to regenerate or convert them to mixed stands are not yet well established. The purpose of this study was to determine favourable combinations of site factors (diffuse solar radiation (DIFF) and direct solar radiation (DIR), forest ground vegetation cover, thickness of humus horizons, browsing) for development of tree regeneration within gaps of different size and age, located in a Norway spruce plantation on a silver ®r (Abies alba Mill.) and common beech (Fagus silvatica L.) forest site. Fifteen fenced and ®fteen unfenced gaps with nine plots each were placed on the north slope of Mount Krasica, in the mountain vegetation belt, on limestone parent material. From 1993 to 1998 woody seedlings and saplings were observed. A successful development of Norway spruce, sycamore (Acer pseudoplatanus L.) and other frequently seed-bearing broad leaves was determined for the ®rst years. Further development of seedlings was hindered by dense forest ground vegetation and browsing impact. Beech and silver ®r regeneration was insuf®cient due to a lack of seed-bearing trees. On the basis of direct and DIFF radiation four groups of microsites were separated. This satisfactorily explained the differences in regeneration patterns among tree species. Norway spruce seedlings were most frequent in the group with high levels of diffuse and low levels of DIR, while sycamore saplings were most frequent in the group with high levels of both radiation components. Results obtained suggest that natural regeneration success and composition can be successfully in¯uenced by managing the incidence of radiation in context with gap geometry (shape, size and orientation). #
Regeneration in experimental gaps of subalpine Picea abies forest in the Slovenian Alps
European Journal of Forest Research, 2005
In 1998, we analysed regeneration success in four 20 year old medium-sized (600–800 m2) and four small experimental gaps (100–200 m2) in subalpine Norway spruce forest in Triglav National Park, Slovenia. We assessed the influence of site (depressions, slopes), gap size, and position within gap (centre, gap south, and north edge) on regeneration success and interactions between regeneration density, height, height increment, direct and diffuse light, ground vegetation, soil depth, thickness of humus horizons, presence of woody debris, and microrelief. Seedling density was higher in depressions, where more seedlings developed in central positions of gaps in both gap sizes, and in microsites with deeper soils, less competition from ground vegetation and convex microsites. On slopes, a higher seedling density was found in small gaps, and at the northern edge of gaps regardless of gap size. Here, seedling density was negatively influenced by diffuse radiation and positively by soil depth. The results suggest that regeneration should be initiated from medium to large gaps in depressions and small gaps on slopes. Development of established seedlings was enhanced by higher radiation levels on both sites, therefore favourable extension of the gaps would be lateral to northwards.
Natural regeneration of Norway Spruce (Picea abies (L.) Karst.) stands on northern Velebit
Background and Purpose: Natural regeneration is a natural phenomenon that depends on numerous factors. Regeneration of virgin forests is successful even without any human interference. For the regeneration of economic forests we do not have that much time and thus try to speed up the process. The study of factors involved in natural regeneration as the most perfect system of forest ecosystem regeneration requires long lasting research. Material and Methods: Numbers and heights of seedlings and new growths, as well as the species participating in natural regeneration were measured on four test plots over the period of four years (1995, 1998, 1999, 2000). The plots were located at different elevations and contained different plant communities. The Norway spruce seed yield and its quality (germination) were also researched. Results: Very poor appearance of seedlings and new growth and even the decline in the numbers were observed on all test plots. This can be directly correlated to ma...
Forest Ecology and Management, 1997
In the absence of reliable and representative data on the frequency of seed years, seed amounts, germination and survival of seeds, the data of the observation period 1992-1996 of the permanent national forest inventory of Austria are used to develop a model describing the probability for the occurrence, density and height of Norway spruce (Picea a&es (L.) Karst) natural regeneration in the forests of Austria. The forest inventory provided data on natural regeneration (saplings between 10 and 130 cm height) on clusters within a 3.89 km square sampling grid. A logistic equation is used to predict the probability for natural regeneration occurrence. Input parameters for this equation are the variables that describe the site, with slope and azimuth as continuous variables, and growth districts and vegetation types as discrete variables; the crown competition factor describes density and the quadratic mean diameter describes the stage of development of the stand. The same equation type is used to predict the probability for the occurrence of Norway spruce, conditional on the occurrence of some regeneration. An additional variable in this species specific model is a dummy variable which is set to 1 if Norway spruce occurs in the overstory and otherwise zero. Additional site variables entering this model are elevation and vegetation types characterizing soil fertility and moisture. Because the density and height of spruce regeneration depends on the stand's susceptibility to browsing, the probability for browsing is also modelled as a logistic equation depending on elevation, vegetation type, and stand density. Finally the probability distribution for height and density of the regeneration is described by two bivariate Weibull-distributions, each one describing browsed and unbrowsed Norway spruce regeneration respectively. 0 1997 Elsevier Science B.V.
The majority of Norway spruce (Picea abies (L.) Karst.) forests is currently affected by humans, and natural processes of regeneration, growth and mortality are deeply influenced by direct or indirect anthropic activities. However, understanding natural dynamics is critical for a proper management of forests. In this sense, forest reserves are fundamental for the study of natural processes. The overall objective of this thesis was to study forest dynamics in Norway spruce stands withdrawn from regular management. In particular, the thesis is focused on growth and mortality processes and patterns. The analyses have been carried out in different areas: (1) Paneveggio forest, into the Valbona Forest Reserve, Trentino Alto Adige, Eastern Italian Alps; (2) four Forest Reserves in Friuli Venezia Giulia and Trentino Alto Adige, Eastern Italian Alps; (3) Trillemarka Nature Reserve, Buskerud county, Southern Norway. Depending on the objectives of each study case, different methodologies have been used. For the growth analysis, we basically adopted a dendrochronological approach, as it allows to reconstruct the tree radial growth with annual resolution. Moreover, we studied competition effect on growth through competition indices, while climate-growth relationships were investigated through dendroclimatological techniques. For the mortality processes, multivariate statistics and spatial pattern analyses were employed. In Paneveggio forest and in the four Forest Reserves in Friuli Venezia Giulia and Trentino Alto Adige, silvicultural activities ceased between 50 and 15 years ago. Such situation is quite common in Italian Alps, and in several European countries, due to economical and social changes occurred after the second world war. In these stands, tree growth, mortality processes and accumulation of deadwood were still influenced by past human activities. Natural processes that mainly influenced forest dynamics were related to competition between trees, while allogenic disturbaces had a slight effect. In Trillemarka forest, in high elevation stands close to the altitudinal forest limit, human disturbances and competition scarcely influenced tree growth patterns and mortality processes, which were more related to age-size related trends. Tree growth and mortality are influenced by tree individual characteristics, autogenic and allogenic disturbances, and climate. Different variables emerged as main factors influencing forest dynamics in the study cases analyzed herein. However, all these factors are interconnected, and relationships between these variables have to be considered for a complete understanding of forest processes.
iForest - Biogeosciences and Forestry
Norway spruce (Picea abies [L.] Karst.) occurred rarely at submountain altitudes before reaching its present position as the most important economic tree species in Central Europe. Spruce cultivation outside of natural sites is under constant threat from harmful agents. In this study, we focused on the indication of potentially suitable planting sites for Norway spruce in areas of protected submountain (< 700 m a.s.l) populations using linear discriminant analysis (LDA) of soil properties in oak-beech, mixed and spruce stands in the territory of the Czech Republic. The soil A-horizon properties in mixed stands were more similar to those in spruce than in broadleaved stands; stand mixtures resulted in lower soil property separability than the localization of individual populations (57% and 85%, respectively). The suitable sites were defined by acid phosphomonoesterase > 151 µg hour-1 , soil porosity > 63%, aeration > 53%, bulk density < 0.86 g cm-3 , cation exchange capacity < 18 cmol + kg-1 , Corg< 9% and Ntot< 0.5% in clusters comprising the Bohemian highlands, North Bohemian rock cities and the Outer Western Carpathians. The LDA of soil properties offered a useful tool for assessing both naturalness and forest threats to support sustainable management.
2014
Knowledge gaps still exist concerning the resilience of Norway spruce growth to changing climate conditions especially outside their natural range. We used a dendroecological approach to assess growth resilience of Norway spruce to changing moisture availability on different sites in southwest Germany near the xerothermic range limits of this species. We described the temporal and spatial variation of Norway spruce tree-ring width, comparatively assessed the response of tree-ring width to changes in moisture availability between different study sites and assessed the capacity of Norway spruce growth to absorb disturbance by drought. To assess the capacity, we applied the concept of resilience and the concept of early-warning signals to tree-ring width data. The results indicated no adequate short-term adaptive capacity to changing climate conditions for the respective Norway spruce trees within the study period. Furthermore the results showed an enhancement of growth synchronicity among the trees at each study site which is highly correlated with changes in moisture availability. Critical slow down, loss of buffering ability and simultaneous increase in spatial correlation are indicative of a loss in growth resilience of Norway spruce. We assume that the capacity of Norway spruce trees to absorb disturbance in terms of their growth response to moisture deficits decreased presumably as a consequence of a series of drought events in the more recent past.
Forest Ecology and Management, 2002
Regional and temporal growth variation of Norway spruce (Picea abies (L.) Karst.) and its dependence on air temperature and precipitation were compared in stands across latitudinal and altitudinal transects in southwestern and eastern Germany, Norway, and Finland. The temporal variation of radial growth was divided into two components: medium-and high-frequency variation, i.e. decadal and year-to-year variation, respectively. The medium-frequency component was rather different between regions, especially the southern and northern ones. However, within each region the medium-frequency growth variation was relatively similar, irrespective of altitudinal and latitudinal differences of the sample sites. A part of the high-frequency variation was common to all four regions, which suggests that some factors synchronising tree growth are common for the entire study area. The high-frequency component of growth was more strongly related to monthly air temperature and precipitation than was the medium-frequency variation. The limiting effect of low temperatures was more significant at northern as well as high-altitude sites, while the importance of precipitation increased in the south and at low altitudes. #