Forest ecosystems in Europe undergo cyclic fluctuations with alternating periods of forest prosperity and disturbances. Forest disturbances are caused by large-scale calamities (climate-induced and ...unforeseen events) resulting in an increased volume of salvage logging. In recent decades, climate change (warming, long-term droughts, more frequent storms, bark beetle outbreaks) has contributed to an increased frequency of salvage logging. However, until now, it has not been revealed what triggers national-scale forest calamities. All of the above-mentioned natural disturbances are connected to solar activity, which is the driver of climate change. This research relates the total volume of harvested timber and salvage logging to the climate and cosmic factors in the Czech Republic, Central Europe. Data of total and salvage logging are compared with air temperatures, precipitation, extreme climatic events, sunspot areas, and cosmic ray intensities. The results document a significant effect of average annual temperatures on the total and salvage logging for the entire period of observations since 1961. A significant correlation of salvage logging to the sunspot area and cosmic ray intensity was observed. The link between salvage logging and sunspots and cosmic ray intensity is supported by spectral analysis in which a significant 11-year cycle was observed since 1973. The results also show an increasing significant effect of sunspots and cosmic ray intensity on logging in recent years in connection with synergism of extreme climate events and the subsequent bark beetle outbreaks. Space and cosmic effects are factors that substantially influence forest ecosystems. Therefore, this paper provides new knowledge about, and possible predictions of, the forest response under climate change.
•Positive effect of species mixing on stand production, diversity and tree growth.•Higher production potential of mixed stands compared to monospecifics.•Decreasing resilience of tree species to ...climatic extremes and air pollution with its increasing share.•Increasing radial growth of beech and spruce in mountain areas.•Higher ecological and economic benefits of mixture in conifer-broadleaved stands.
Mixed forests play a key role in terms of stability, production potential and adaptation to climate change. Norway spruce PA, Picea abies (L.) Karst and European beech (FS, Fagus sylvatica L.) are among the most important tree species in Europe. The aim of the study was to determine the influence of the species composition of these two tree genera on the production, structure, diversity and growth of mixed Fageto-Piceetum acidophilum stands in the Krkonoše Mountains, in the Czech Republic. The following 5 variants (ratios) of mixture were compared in 6 replications (30 research plots in total): PA 100%, PA 75:25 FS, PA 50:50 FS, PA 25:75 FS and FS 100%. Based on 178 tree core samples, the research also focused on the influence of climatic factors (temperature, precipitation) and air pollution (SO2, NOX, AOT40F) on the radial growth of these tree species of particular variants. Mixed forests showed a timber production higher by 7.7% (-10.8 to 31.5%) in comparison to spruce monocultures, and by 47.3% (21.9–79.7%) compared to beech monocultures. The largest production as well as the highest diameter increment were documented in PA 75:25 FS (656 m3 ha−1). In addition, this variant had the lowest extreme decreases/fluctuations in radial growth in both tree species. Over the last 50 years, the increment in beech increased by 7.9% and by 2.5% in spruce. The cyclical behavior in the radial growth of both tree species occurred in the short-term solar cycles of 9–11 and long-term periods of 50–75 years, while the spruce showed higher cyclic intensity. The concentration of both SO2 and NOX had a significant negative effect on the radial growth of spruce. In both tree species, the negative effect of air pollution lessened with their decreasing share in the stand. Similarly, precipitation and temperature had a more significant effect on the growth of monospecific variants in both tree species, especially in beech. Temperatures, when compared to precipitation, had a greater effect on the radial growth of both tree genera, especially during the vegetation period. In terms of diversity, mixed stands achieved significantly higher structural (diameter, height, crown) differentiation and overall diversity compared to monospecific variants. In general, mixed stands can achieve higher production potential, diversity and especially resistance to climate extremes and air pollution in relation to climate change in the water-sufficient highland and mountain areas of the Czech Republic. Differences between mixed stands vs. monocultures, i.e. the effect of tree species mixing, depend on suitable ratios of tree species and their spatial pattern.
•Scots pine forests vs. reclaimed sites with Scots pine showed significant growth differences.•Standard forests showed higher stand volume (by 22%) and biomass production (by 19%).•Out of reclamation ...variants, highest production potential was on reclaimed coal-mine.•Climatic factors had higher effect on radial growth on reclamation sites compared to forest sites.•Lack of precipitation and droughts in growing season were the main limiting factors for growth.
As a result of human population growth and human need for resources, the landscape has been increasingly transformed and devastated by mining activities. Subsequent reactivations are thus extremely important in the process of restoring the disturbed biosphere. The objective of this study was to determine differences between original forest sites and reclamation sites afforested with Scots pine (Pinus sylvestris L.) in terms of stand structure, diversity, biomass, productivity and climatic resistance. Three different types of reclamation were compared in the Czech Republic – (1) a post-mining coal site, (2) a former sand quarry and (3) a reclaimed sand dune that had been used for pasture. At the comparable stand age of 40–46 years, the stand volume and biomass were higher by 22% and 19%, respectively, on original forest sites (370–500 m3 ha−1, 332–422 t ha−1) compared to reclamation sites (318–371 m3 ha−1, 287–325 t ha−1). On the contrary, structure and diversity were more complex and richer in reclaimed areas. Climatic factors had a higher effect on radial growth on reclamation sites compared to original forest sites, but no significant differences were observed between the variants in terms of the occurrence of negative pointer years (extreme deflection in growth). A lack of precipitation and long-term droughts in vegetation periods were the main limiting factors of growth. Comparing all reclamation variants, the highest productivity was found on the reclaimed coal-mine, and the lowest differences between forest and reclamation sites were documented in the reclaimed sand quarry case. In relation to climate change, Scots pine proved a very adaptive and suitable tree species whose wood production on reclaimed post-mining sites is comparable to the original forest sites. Pine afforestation of reclamation sites brings invaluable environmental and production benefits.
•Bark stripped trees were studied from the point of extent of damage, production characteristics and radial growth in relation to climatic factors.•The stand volume of heavily damaged trees was ...50–71% lower compared to healthy trees.•The vertical stem decay reached maximally up to 4.5–6.0 m (mean 1.9–3.1 m) with the mean speed of vertical spreading of 5.7–9.6 cm yr−1. Decayed wood accounted for 30–39% of the stem volume.
Bark stripping damage and the resultant stem rot to Norway spruce (Picea abies L. Karst), one of the most important tree species, poses a serious problem for forest management in Europe. Our research objective was to determine the effect of bark stripping, the subsequent rot decay and the impact of climatic factors in young (42–49 years) spruce stands. Moreover, we compared the differences between damage caused by red deer (Cervus elaphus L.) and sika deer (Cervus nippon Temminck). In all the cases studied, game damage was lower in forest stands when caused by sika deer (SD − 77.3%) compared to red deer (RD − 88.8%); 27.8% (SD) – 32.0% (RD) of stem circumference was damaged in average. Damaged trees showed higher growth variability and were more sensitive to a lack of precipitation and droughts, while air temperature had a higher effect on the growth of healthy trees. The initial game damage was observed in the 11 (SD) – 14 (RD) year of the mean tree age. The stem volume was lower by 25% (SD) – 28% (RD) in lightly damaged trees, and 50% (SD) – 71% (RD) in heavily damaged trees compared to healthy trees. The vertical stem decay reached a maximum of up to 4.5 m (SD) – 6.0 m (RD) (mean 1.9–3.1 m) with the mean speed of vertical spreading of 5.7 cm yr−1 (SD) – 9.6 (RD) cm yr−1. The mean decayed wood accounted for 30% (SD) – 39% (RD) of the stem volume. The peripheral stem damage by bark stripping and the age of the first occurrence were significant factors in predicting damaged crosscut area and vertical rot spreading in the stem. During this time of climate change, the stability of damaged spruce stands has been significantly disturbed by deer game.
Afforested farmland is a phenomenon of Central Europe. In this study, we evaluate the radial growth of Norway spruce
Picea abies
(L.) Karst. and European larch (
Larix decidua
Mill.) in forest ...stands established on abandoned agricultural land compared to forest stands on standard forest soils. As the quality of wood from such sites is often challenged, we also focused on wood quality of those species. The following characteristics of wood were evaluated: wood density, bending strength, impact bending strength, modulus of elasticity and radial growth in relation to climatic factors. The radial growth of both tree species showed higher radial increment to tree age of 19–23 years on former agricultural land compared to forest land. Norway spruce growing on forest land was significantly (
p
< 0.05) more sensitive to climatic factors than on agricultural land (7 significant moths vs. 3 months), while there were low differences in larch. Spruce produced wood with significantly higher density on agricultural land (399 kg m
−3
), while larch had higher density on forest land (583 kg m
−3
). In other characteristics, significant differences were found only in the case of larch. Higher values were detected for impact bending strength (4.5 J cm
−2
) and bending strength (87 MPa) on forest land. The detected differences between wood characteristic were not important for industrial purposes and final usage of the wood. Therefore, afforested agricultural lands provide wood of similar quality and also showed higher resistance in relation to climatic change compared to permanent forest lands.
Presently, the forests of one of the most economically important tree species in Europe—Norway spruce Picea abies (L.) Karst.—have been disrupted and are in rapid decline due to a combination of ...several natural factors: extreme drought, heatwaves, and secondary damage caused by bark beetle outbreaks. The vulnerability of these forests has increased considerably over the past decade, and remote sensing methods can theoretically improve the identification of endangered forest stands. The main objective was to determine the relationship between remotely sensed characteristics of vegetation (using the normalized difference vegetation index—NDVI) and annual tree-ring growth in 180 trees through precipitation and air temperature. The research was conducted at six research plots in lowland spruce forests (319–425 m a.s.l.) in the central Czech Republic. No significant correlation between NDVI and annual ring width was observed. The primary factor limiting radial growth was lack of precipitation in the growing season; subsequently, spruce trees reacted negatively to air temperatures. A higher correlation with NDVI was observed on sites susceptible to drought, but overall, NDVI and RWI did not show similarities. This result describes that NDVI is a poor indicator for identifying low radial growth in Norway spruce stands on non-native localities in the studied area.
Many studies have examined the relationships between the effects of the sunspot area and growth of trees; however, none of them considered European beech (
Fagus sylvatica
L.). We investigated the ...relationships between the sunspot area, climate factors (temperature and precipitation) and radial growth of beech in the Krkonoše Mts. in the Czech Republic. We used the core samples of 199 beech trees representing the century-long growth, two sets of climate data (local short-term data and general long-term climate data), and more than a century-long sunspot area dataset acquired from the National Oceanic Atmospheric Administration. Our results showed the significant effects of the sunspot area, temperature and precipitation on the radial growth of beech. The correlations between sunspot area and tree-ring width index varied from 0.9 to 0.5 in the period between 1986 and 2017, a period during which none of the significant anthropogenic disturbances occurred in the study area. The strong correlations were found between the sunspot area and climate factors for a longer period. The largest effect of the sunspot area on the radial growth was observed in the previous year, especially in growing season. Structurally diversified (heterogeneous) beech stands were less affected by the sunspot area compared to the homogeneous stands. In conclusion, the sunspot area is one of the important factors that significantly influence the radial growth of beech in the Krkonoše Mts. Our results will be useful for understanding beech forests in the context of global change, and will have an important contribution to the knowledge for predicting potential impact of the sunspot area on the Earth’s surface.
The aim of this study was to assess the effects of bark stripping caused by sika deer (Cervus nippon Temminck) on the production and structure of young Norway spruce (Picea abies L. Karst) forest ...stands (41–43 years). Production parameters, structure, diversity, and the dynamics of radial growth in selected forest stands in relation to climatic conditions were evaluated. Similar to other production parameters, stand volumes showed lower values on research plots heavily damaged by bark stripping (290 m3 ha−1) compared to stands with lower tree stem damages (441 m3 ha−1). A significant decrease in stem volume was recorded for trees with stem circumference damage higher than 1/3 of the stem circumference. In most cases, the trees were damaged between the ages of 10–23 years, specifically the radial growth was significantly lowered in this period. The diameter increment of damaged trees dropped to 64% of the healthy counterparts in this period. Bark stripping damages reached up to 93% of the stem circumference with a mean damage of 31%. Stem rot was found on 62% of damaged trees. In our study area, with respect to the terms of climatic conditions, precipitation had a higher effect on radial growth of the Norway spruce compared to temperature. The main limiting climatic factor of tree growth was the lack of precipitation within a growing season, particularly in June of the current year.
The growth, structure and production of mixed beech (Fagus sylvatica L.) forests were analysed in the Broumovsko Protected Landscape Area, Czech Republic. The objective of the paper was to evaluate ...stand structure, timber production and dynamics of forests with historically different silvicultural practices in relation to climate conditions, management and game damage. The results indicate that scree forests (coppices and coppices with standards) were stands with high-rich species diversity and structure compared to herb-rich beech forests (high forests) with higher timber production. The Norway spruce (Picea abies L. Karst.) was the most sensitive tree species compared to low growth variability in European beech. The climate factors had the highest effect on radial growth from June to August. Natural regeneration showed great density potential (13,880–186,462 recruits·ha–1), especially in expansion of maples and European ash (Fraxinus excelsior L.). However, recruits were seriously limiting by damage caused by hoofed game, especially in silver fir (Abies alba Mill.; 53% browsing damage), wych elm (Ulmus glabra Hudson; 51%) and rowan (Sorbus aucuparia L.; 50%).
In the time of ongoing climate change and the increasing area of post-mining landscape, the successful afforestation of reclamation sites by suitable adaptive tree species is gaining in importance. ...One of possible ways may be the use of introduced tree species, which is, however, a controversial topic in relation to risks for forest management and nature conservation. The objective of this study was to comprehensively evaluate the forest stands (age 48 years) of 9 introduced and 3 native coniferous tree species in lowland post-mining coal site of the Czech Republic. The research was focused on production potential, health status, resistance to climate change, carbon sequestration, biodiversity and soil properties. The highest timber production, biomass and carbon stock (49–95% above average), was observed in case of
Pinus sylvestris, P. nigra
and
Pseudotsuga menziesii
. On the other hand, unsuitable habitat, insect and pathogens caused poor health status and extremely low production parameters (by 55–62% than average) in
Pinus strobus
and
P. rotundata
. In terms of climate,
Pinus sylvestris, P. nigra
,
Larix decidua
,
Pseudotsuga menziesii
and
Picea omorika
were the most resistance tree species in relation to climatic extremes. Conversely,
Pinus rotundata
,
P. strobus
,
P. ponderosa
,
Picea pungens
and
P. abies
were very sensitive to climate events, especially to the lack of precipitation in vegetation period with synergism of high temperature. In terms of soil parameters, the content of plant available nutrients (K, Ca, Mg) was adequate except P deficiency. The highest soil reaction was detected for
Pinus nigra
and
P. sylvestris
(pH 6.9–7.1) compared to
Picea mariana
(pH 4.8). The benefits of “suitable” introduced tree species (
Pinus nigra, Pseudotsuga menziesii
) are high timber production potential and good adaptation and mitigation of the changing climate; however, native tree species (
Pinus sylvestris
,
Larix decidua
) can provide better environmental benefits on reclamation sites.
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