•Temperature negatively affects Scots pine and Norway spruce at lower latitudes but positively at higher latitudes.•Summer precipitation has a positive impact on the species at lower latitudes but a ...negative impact at higher latitudes.•The resistance of pine and spruce to drought increased linearly with latitude.•Compared to spruce, pine attained pre-drought growth levels faster and was independent of latitude.
Pinus sylvestris L. (Scots pine) and Picea abies L. H. Karst. (Norway spruce) are the most important economic tree species in Sweden. However, like every other tree species, they are affected by climate change, especially drought conditions. In this study, we analysed the effect of climate variability on the radial growth of Scots pine and Norway spruce in Sweden. Sixteen sites of pairwise monospecific stands of Scots pine and Norway spruce distributed across latitudinal gradients in Sweden (55 – 67 ° N) were used. In each site, we sampled at least 15 dominant/codominant Scots pine and Norway spruce trees without any defect in the sampled plots’ buffer zone (3 – 5 m wide). We performed a correlation analysis between climate variables and the radial growth of the species using different timescales; and regressed the coefficients with latitudes. Thereafter, important climate variables for both species were identified. Our results showed that temperature is the main climate factor affecting the radial growth of Scots pine while Norway spruce is more sensitive to early summer precipitation. The impact of summer precipitation on the radial growth of both species transitioned from a positive to a negative trend across a latitudinal gradient. Conversely, a contrasting pattern was noted in the relationship with summer temperature. The radial growth of both species responded positively to spring temperature, particularly at lower latitudes. The resistance of pine and spruce to drought showed a clear linear increase with latitude (p < 0.001). Compared to spruce, pine showed a better capacity to attain pre-drought growth levels (i.e., resilience) and was independent of latitude. Our findings contribute to the understanding of the spatial patterns of the growth-climate relationship of Scots pine and Norway spruce in Sweden; and could offer useful guidance on adaptive forest management in the face of climate change.
The growth of a tree depends on the size, shape, and functioning of the crown. The length of the crown is a somewhat subjective value because the base of the crown is often difficult to determine. ...The aim of this study was to develop an allometric model to calculate the crown length of Pinus sylvestris L., which might serve as an alternative to the current equations used especially for stands of variable density. The model used three predictive variables, i.e., diameter at breast height, tree height, and density. The developed crown length model showed high compatibility with empirical data within the studied stands differing in diameter at breast height, height, age, biosocial position, and, above all, density (SD = 1.786). The correlation coefficient between the empirical crown length for the stand (Hsub.emp sup.* ) and the calculated model (Hsub.cal sup.* ) was r = 0.974, with a discrepancy of (±) 3.17%. The derived crown length model can be one of the components used to estimate the mass of needles or leaf area index (LAI) and, consequently, the amount of transpiration or the amount of carbon dioxide bound, which is crucial in the context of climate change.
Abstract
Nitrogen (N) added through atmospheric deposition or as fertilizer to boreal and temperate forests reduces both soil decomposer activity (heterotrophic respiration) and the activity of roots ...and mycorrhizal fungi (autotrophic respiration). However, these negative effects have been found in studies that applied relatively high levels of N, whereas the responses to ambient atmospheric N deposition rates are still not clear. Here, we compared an unfertilized control boreal forest with a fertilized forest (100 kg N ha
−1
yr
−1
) and a forest subject to N‐deposition rates comparable to those in Central Europe (20 kg N ha
−1
yr
−1
) to investigate the effects of N addition rate on different components of forest floor respiration and the production of ectomycorrhizal fungal sporocarps. Soil collars were used to partition heterotrophic (
R
h
) and autotrophic (
R
a
) respiration, which was further separated into respiration by tree roots (
R
tr
) and mycorrhizal hyphae (
R
m
). Total forest floor respiration was twice as high in the low N plot compared to the control, whereas there were no differences between the control and high N plot. There were no differences in
R
h
respiration among plots. The enhanced forest floor respiration in the low N plot was, therefore, the result of increased
R
a
respiration, with an increase in
R
tr
respiration, and a doubling of
R
m
respiration. The latter was corroborated by a slightly greater ectomycorrhizal (
EM
) fungal sporocarp production in the low N plot as compared to the control plot. In contrast,
EM
fungal sporocarp production was nearly eliminated, and
R
m
respiration severely reduced, in the high N plot, which resulted in significantly lower
R
a
respiration. We thus found a nonlinear response of the
R
a
components to N addition rate, which calls for further studies of the quantitative relations among N addition rate, plant photosynthesis and carbon allocation, and the function of
EM
fungi.
The article presents the results of thermo-mechanical densification tests conducted on Scots pine timber. The densification process was carried out in industrial conditions with a high-pressure ...press, which allowed flat compression of boards that were up to 2.5 m long. A phenomenon of elastic redeformations was observed in the densified boards after each pulse of compression. As a result of thermo-mechanical compression, the average timber moisture content dropped to 9%, and the average density increased by 13.5%, from the level of 547 to 621 kg/msup.3 . As a result of thermo-mechanical densification, the strength class C of most Scots pine timber pieces improved. Most timber pieces that were subjected to thermo-mechanical densification have improved their strength class, C, by one (72.7% of the tested batch) or two C classes (3.6% of the batch under study).
Genetic diversity is important for the long-term survival of species and plays a critical role in their conservation. To manifest the adaptive potential, it is necessary to preserve the allelic ...diversity of populations, including both typical and region-specific alleles. Molecular genetic analysis of 22 populations of Scotch pine (Pinus sylvestris L.; Pinaceae) in 10 subjects of the Russian Federation in the East European Plain and the Middle Urals was carried out. Molecular genetic analysis of 22 populations of P. sylvestris revealed 182 polymorphic PCR fragments. The studied populations are characterized by a medium level of genetic diversity. A high subdivision coefficient (GST) of the studied populations was established; the intensity was 0.559. At the same time, the level of subdivision differed for different regions; for the populations from the Middle Urals, it was 15.5% (GST = 0.155), and for the populations from the East European Plain, it was 55.8% (GST = 0.558). The dendrogram of genetic similarity shows five clusters of the studied populations of P. sylvestris according to their geographical location. The populations from the East European Plain are mostly characterized by typicality, while the populations from the Middle Urals, on the contrary, are more specific in gene pools. The use of the coefficient of genetic originality to identify populations with typical and specific alleles allows for solving the problem of selecting populations for the conservation of forest genetic resources. The data obtained on genetic diversity, and the structure of populations growing in areas of active logging, are important for determining the geographical origin of plant samples, which is an integral part of the control of illegal logging.
•Tree species leaf litter decay rates are relatively low on post-mining sites.•Decay rates are most often higher in home stands than in Scots pine stands.•Decay rates are higher on the western slope ...than on the plateau of the spoil heap.•Proper species selection for afforestation can accelerate soil restoration.•This is high in importance from both biological and economical points of view.
Tree litter decomposition on disturbed post-mining sites has been mainly studied within successional gradients, whereas almost no results were shown from afforested spoil heaps. Litterfall and its decomposition rate are considered the most important ecological processes for soil restoration during stand development on such initial forest habitats. These processes allow development of a functional ecosystem and productive forest stands. Moreover, the pedogenesis process on such “soilless”’ habitats can be significantly improved and accelerated by tree species selection during afforestation.
The main aim of the study was to determine litter decomposition rates of nine tree species used for afforestation of a lignite mine spoil heap. We assumed that leaf litter decomposition rates would differ among tree species studied and that the site conditions would significantly influence this process.
Our study was conducted on the spoil heap of the lignite open cast mine in Bełchatów, central Poland. We studied leaf litter decomposition of Alnus glutinosa, Betula pendula, Pinus sylvestris, Quercus robur, Q. rubra and Robinia pseudoacacia in pure stands of these species (home stands), and litter decomposition of Acer pseudoplatanus, A. glutinosa, Fagus sylvatica, Prunus serotina, Q. rubra, and R. pseudoacacia in Scots pine stands. We used the litterbag method. The experiments lasted for three years and the samples were collected every three months.
Leaf litter decomposition calculated for home stands after three years of decomposition was 94.4% of the initial leaf mass for A. glutinosa, 70.9% for R. pseudoacacia, 70.1% for P. sylvestris, 68.3% for B. pendula, 66.9% for Q. rubra and 61.5% for Q. robur. In Scots pine stands, after three years of the experiment, 92.3% of the initial leaf mass decomposed for P. serotina, 85.7% for A. glutinosa, 83.5% for A. pseudoplatanus, 65.2% for R. pseudoacacia, 50.9% for Q. rubra and 40.1% for F. sylvatica. A. glutinosa, R. pseudoacacia and Q. rubra leaves decomposed significantly faster in home stands than in Scots pine stands. Site aspect significantly influenced litter decomposition of the species studied, with higher rates mostly on the western slope.
Our study revealed that the decision on tree species used for afforestation might shorten the period needed for soil restoration and achievement of sustainability of novel ecosystems. Proper selection of main and admixture tree species for afforestation of the post-mining sites might reduce the renewal period of the soilless and newly created habitats, which may provide noticeable ecological and economical effects during stand management.
Forest community structure and function in climate-sensitive regions exhibit uncertain changes under the influence of global warming. Especially in northern Central Asia, the response of pine growth ...to climate change remains unclear. Here, we identified changes in growth trends and climate response in a total of 646 trees for the abundant species Scots pine (Pinus sylvestris) at 30 sites in the Kazakh steppe. We used basal area increment, regional curve standardization and negative exponential curve detrended chronologies to comprehensively analyze trends in pine growth, and linear mixed effects and random forest models were calculated to explore growth-climate relationships. An increase in the overall growth of Scots pine under the influence of global warming, expressed in this region by increasing temperatures and precipitation, was observed during the period 1950–2018. Spatial differences in climate response between the sub-regions were identified showing that pine growth is more influenced by summer precipitation in the eastern compared to the western and central Kazakh steppe. Warm spring temperatures and more precipitation are important common climatic factors affecting pine growth in northern Central Asia. Moreover, increased drought intensity and longer drought duration negatively impact pine growth in this region. The Pacific Decadal Oscillation and North Atlantic Oscillation were identified to be the main atmospheric circulation patterns that influence the spatial differentiation in pine growth in this steppe. Albeit pine growth in northern Central Asia shows an increasing trend currently but also in future climate scenarios, the risks and challenges posed by drought should not be underestimated.
•Global warming leads to growth increase of Scots pine.•Spring precipitation and temperature primarily constrain pine growth.•The intensity and duration of drought has affected Scots pine.•The NAO and PDO are atmospheric forcing factors that impact pine growth.•Scots pine growth increase will be sustained under future scenarios.
Fennoscandian studies of thinning responses are usually limited to low thinning with moderate intensities. We studied here intermediate commercial thinning of different types (low, crown/normal, ...crown/strict, where respectively mostly intermediate and suppressed trees, mostly dominant and co-dominant trees, and only dominant trees were removed) and intensities (moderate and heavy) in Scots pine (Pinus sylvestris L.) dominated stands. We analysed their responses in terms of wood production and carbon balance. We investigated three stands in Southern and Middle Finland at the stage of second or third commercial thinning (age 34–50 years). We observed their development for fifteen years, and then we further simulated it with MOTTI stand simulator until final felling (scheduled either at age 65 or 80 years). We considered various variables of interest related to the thinning outputs, volume production after thinning, simulated final felling, and carbon balance. For all variables of interest, there were negligible differences across thinning types, and strong ones across thinning intensities. Thinning removals were significantly higher in heavy than moderate treatments, although only crown heavy thinnings had significantly higher sawlog output than low moderate. Volume growth post thinning during the 15-years observation was highest in unthinned plots, followed by moderate and then heavy treatments. For both total standing volume at simulated final fellings and carbon balance at any times, there was a similar descending trend from unthinned to moderate to heavy treatments. Concluding, the results suggest that crown/normal thinning could be applied with moderate intensity as alternative to low thinning, while heavy thinnings do not provide commercial benefits in Scots pine stands. Heavy intermediate thinnings in Scots pine stands provides lower total carbon accumulation during rotation, and early higher wood products (although not necessarily in terms of sawlogs) at the expense of later ones. Moderate thinning reached on site carbon neutrality after 5-years, while heavy thinning after 15 years.
•There were only small differences across low and crown thinning types.•Heavy thinning decreased growth rate and final standing volume.•Moderate thinning reached on site carbon neutrality in 5 years.•Heavy thinning reached on site carbon neutrality after 15 years.
•We studied resistance and resilience to drought in Scots pine–sessile oak forest.•Sessile oak was more affected by spring droughts.•Scots pine was more affected by summer droughts.•Stand composition ...did not affect species’ response to drought.•Small pines performed better during droughts than large ones.
The IPCC previsions for the upcoming decades include an increase in frequency and intensity of drought events in several regions worldwide, including Northern Europe. Drought significantly affects forest ecosystems through decreased productivity, increased vulnerability to biotic disturbances and increased subsequent mortality. How forest ecosystems maintain resistance and resilience to drought events are important questions. Our study aimed to assess whether species mixture or an individual tree size within a stand alters a given tree’s resilience and resistance to drought. A retrospective study of tree-ring widths allowed us to calculate resistance, resilience and recovery indices for five recent drought events: 1976, the 1990–1992 period, 2003, 2006 and 2010. These drought events were selected based on the SPEI (Standardized Precipitation Evapotranspiration Index) drought index. Our study sample consisted of 108 individual sessile oak (Quercus petraea (Matt.)) or Scots pine (Pinus sylvestris L.) trees sampled in 2012 and 2013 (Orleans forest, central France) in pure and mixed stands, divided into three diameter classes corresponding to three sizes: large, medium and small trees. Scots pine performed better than sessile oak during the 1990–1992 and 2010 droughts while the contrary was observed for the 2003 and 2006 droughts. They performed equally in 1976. We suggest that the differing sensitivity of the two species to spring and summer drought explained this result. In our study, stand composition had no effect on resilience or resistance for either species. The size effect in oaks was unclear as small oaks displayed either a better performance or a worse performance than large oaks. Small pines displayed better resistance and resilience than pines of a larger size. This work stressed the importance of taking into account stand composition and trees size as well as soil and climatic conditions for each drought events to achieve a better understanding of the diversity of responses to climatic variations among forest ecosystems.
Climate change increases the occurrence of prolonged drought periods with large implications for forest functioning. Scots pine (
) is one of the most abundant conifers worldwide, and evidence is ...rising that its resilience to severe drought is limited. However, we know little about its ability to recover from drought-induced embolism. To analyze postdrought hydraulic recovery, we investigated stress and recovery dynamics of leaf gas exchange, nonstructural carbohydrates, and hydraulic properties in 2.5-year-old Scots pine seedlings. We quantified the degree of xylem embolism by combining in vivo x-ray microtomography with intrusive techniques including measurements of hydraulic conductivity and dye staining during drought progression and short-term (2 d) and long-term (4 weeks) recovery. Seedlings were grown under controlled conditions, and irrigation was withheld until stomata closed and xylem water potential declined to -3.2 MPa on average, causing a 46% loss of stem hydraulic conductivity. Following drought release, we found a gradual recovery of leaf gas exchange to 50% to 60% of control values. This partial recovery indicates hydraulic limitations due to drought-induced damage. Whereas xylem water potential recovered close to control values within 2 d, both x-ray microtomography and intrusive measurements revealed no recovery of stem hydraulic conductivity. Moreover, we did not find indications for nonstructural carbohydrate reserves limiting hydraulic recovery. Our findings demonstrate that Scots pine is able to survive severe drought and to partially recover, although we assume that xylem development during the next growing season might compensate for some of the hydraulic impairment. Such drought-induced legacy effects are important when considering vegetation responses to extreme events.
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