The influence of temperature and precipitation on the growth of Sessile oak in the colder sites of the Djerdap area: First results

U radu su prezentovani rezultati dendroekoloških istraživanja u dvema sastojinama hrasta kitnjaka na toplijim staništima na području Nacionalnog parka „Đerdap”. Za sagledavanje uticaja temperature i padavina na prirast (radijalni prirast – RW, prirast kasnog drveta – LW i prirast ranog drveta – EW) ove vrste drveća korišćena su četiri metodološka pristupa: korelacije između tromesečnih (sezonskih) veličina temperature i padavina i rezidualne hronologije, korelacije između mesečnih temperatura i padavina i rezidualne hronologije, tzv. odzivne funkcije i korelacije između SPEI indeksa suše i rezidualne hronologije. Rezultati su pokazali veliku senzitivnost hrasta kitnjaka prema padavinama u letnjim mesecima, na taj način da veće količine padavina u leto, naročito u julu, prouzrokuju statistički značajno veće iznose prirasta. Variranje prirasta mnogo je manje uslovljeno varijacijama temperature, pri čemu je registrovan slabiji negativan uticaj viših julskih i avgustovskih temperatura na veličinu prirasta. Konstatovano je da je u ukupnoj veličini radijalnog prirasta i u prirastu kasnog drveta detektovan jači klimatski signal nego u prirastu ranog drveta. Utvrđena reakcija hrasta kitnjaka u ovde analiziranim toplijim stanišnim uslovima u pogledu prirasta i njegove zavisnosti od klime slična je reakciji kitnjaka iz sastojina u neposrednom okruženju NP „Đerdap” i iz drugih okolnih zemalja koje se karakterišu srodnim klimatskim uslovima.

In order to assess the impact of climate variations on Austrian pine forest in the Belgrade area, the radial growth of artificially-established Austrian pine trees and its dependence on temperature and precipitation was studied using dendroclimatological methods. The site is classified as Quercetum-frainetto cerris Rudski. Standard and residual chronologies were established and several common statistics were calculated. A dendroclimatic study was carried out using the correlation and response function analysis. The Pearson correlation coefficients between the chronology indices and 13 seasonal (3-month period) precipitation and temperature data were calculated for the period from 1959 to 2014. The applied response function analysis included 24 precipitation and temperature variables from October of the prior year to September of the current year. The results of the correlation analysis pointed out that there was a strong tendency towards a positive response to the summer and late summer/early autumn precipitation and a weak significant negative response to the spring and summer temperatures. Climate-growth relationships were further first studied using the response functions for the significant seasons that were detected from the correlation analysis and then for individual months from previous October to current September. These results also highlighted the findings that higher precipitation in the current summer months has a beneficial effect on the tree-ring width. The conducted correlation between the residual chronology and the Standardised Precipitation Evapotranspiration Index indicated that a high summer value of this drought index had a positive impact on the pine growth and reinforced the previously detected relevance of September as an important month for the Austrian pine growth. These preliminary results point out that some additional climate-Austrian pine growth studies (application of various tree-ring features, growth data with a much longer time span, more sites/stands, etc.) should be performed to obtain new and valuable knowledge important for the sustainable management of Austrian pine forests.

Tree rings, δ13C and climate in Picea glauca growing near Churchill, subarctic Manitoba, Canada

Hydroklimatyczne uwarunkowania przyrostów promieniowych dębu szypułkowego w lasach dolin rzecznych

The life histories of Ameletus celer and A. similior were compared at Ford Creek and Elbow Creek, two sites in the same drainage system that differed in their annual temperature regimes. We used electrophoresis to identify very small larvae and to determine parasitism by a mermithid nematode. Ameletus similior had an overwintering egg diapause and a univoltine summer cycle at both sites. Ameletus celer eggs appeared to take about 1 yr to hatch and larvae took a further year to develop at the warmer site but 2 yr at the colder site. Both species were parasitized by a mermithid nematode, the prevalence of parasitism reaching ∼10% in the A. celer population at the colder site. Parasitism had the effect of prolonging larval life by 2 mo, and parasitized mayflies laid no eggs, even if they survived to adulthood. Temperature and larval size had significant effects on growth rates in the laboratory but larvae of both species of mayfly grew at the same rate at each temperature between 0.6°C and 18°C. The number of day-degrees at the colder site was sufficient to allow the smaller A. similior to mature in one year, but not the larger A. celer. Extension of physiological time to complete the life cycle at the colder site could not be satisfactorily explained by delayed development, a thermal minimum above 0°C, a nonlinear relationship between temperature and growth rate, placement of recruitment within the thermal cycle, food supply, or parasitism. However, some extension of the life cycle in A. celer may be achieved by increase in final size.

We assessed the pools of non-structural nitrogen compounds (NSNC) through a year, thereby addressing the question of whether mature sessile oak [Quercus petraea (Matt.) Liebl.] and beech (Fagus sylvatica L.), which differ in wood anatomy and growth patterns, exhibit contrasting seasonal dynamics of NSNC pools as previously shown for non-structural carbohydrate (NSC) pools. Seasonal fluctuations of NSNC (amino acids and soluble proteins) and NSC (starch and soluble sugars) pools were analyzed in the inner and the outer stem sapwood. In oak, NSC showed marked seasonal variation within the stem sapwood (accumulation during winter and decrease during bud burst and early wood growth), whereas in beech seasonal fluctuations in NSC were of minor amplitude. Even if the distribution and intensity of the NSNC pools differed between the two species, NSNC of the stem sapwood did not show seasonal variation. The most significant change in NSNC pools was the seasonal fluctuation of protein composition. In both species, two polypeptides of 13 kDa (PP13) and 26 kDa (PP26) accumulated during the coldest period in parallel with starch to sugar conversion and disappeared with the onset of spring growth. The absence of seasonal changes in total soluble protein concentration suggests that the polypeptides are involved in the internal nitrogen (N) cycling of the stem rather than in N storage and remobilization to the other growing organs of the tree.

We tested the hypothesis that broad-leaved forest species with contrasting wood anatomy and hydraulic system (ring-porous versus diffuse-porous) also differ in distribution and seasonal dynamics of carbohydrate reserves in stem wood. Total nonstructural carbohydrate (TNC) reserves (starch and sugars) were measured enzymatically in the 10 youngest stem xylem rings of adult oak (Quercus petraea (Matt.) Liebl.) and beech (Fagus sylvatica L.) trees during an annual cycle. Radial distribution of carbohydrates was investigated according to ring age. On all dates, oak trees had twofold higher TNC concentration than beech trees (41 versus 23 mg g(DM)(-1)), with starch accounting for the high TNC concentration in oak. Seasonal dynamics of TNC concentration were significantly (P < 0.05) more pronounced in oak (20-64 mg TNC g(DM)(-1)) than in beech (17-34 mg TNC g(DM)(-1)). A marked decrease in TNC concentration was observed in oak trees during bud burst and early wood growth, whereas seasonal fluctuations in TNC concentrations in beech trees were small. The radial distribution of TNC based on ring age differed between species: TNC was restricted to the sapwood rings in oak, whereas in beech, it was distributed throughout the wood from the outermost sapwood ring to the pith. Although the high TNC concentrations in the outermost rings accounted for most of the observed seasonal pattern, all of the 10 youngest xylem rings analyzed participated in the seasonal dynamics of TNC in beech trees. The innermost sapwood rings of oak trees had low TNC concentrations. Stem growth and accumulation of carbon reserves occurred concomitantly during the first part of the season, when there was no soil water deficit. When soil water content was depleted, stem growth ceased in both species, whereas TNC accumulation was negligibly affected and continued until leaf fall. The contrasting dynamics and distribution of carbohydrate reserves in oak and beech are discussed with reference to differences in phenology, early spring growth and hydraulic properties between ring-porous trees and diffuse-porous trees.

Tree species have a remarkable impression on the physical, chemical and microbial properties of the soil. Some tree species like alders create a favorable environment for microbes in their soil–root interface in addition to carrying out soil reclamation. This study, conducted in the Western Black Sea Region of Turkey, compared the N-fixing in the roots of the black alder [Alnus glutinosa (L.) Gaertn.] and the non-N-fixing in those of the sessile oak [Quercus petraea (Matt.) Liebl.] species in terms of physical, chemical and microbiological soil characteristics. Samples of topsoil (0–6.5 cm) were collected randomly from under the black alder and the sessile oak trees, respectively, at seven different sites in the study area. Soil microbial biomass C and N were established by the chloroform fumigation extraction method. Basal respiration of soil was retained by the sodium hydroxide (NaOH) trap method. Contrary to expectations, the average organic C (2.59%), total N (0.22%), microbial biomass C (738.48 µg g−1) and N (99.56 µg g−1) were higher under the sessile oak trees, demonstrating the positive effect of sessile oak on soil microflora. The black alder and sessile oak tree soils exhibited significant differences in their content of organic C (Corg), total N, microbial biomass C (Cmic), and N. In addition, significant positive linear correlations were found between organic C and microbial biomass C, and also between organic C and basal respiration; however, the correlation between the metabolic quotient (qCO2) and Cmic/Corg percentages was negative for the black alder and sessile oak (r = − 0.589 and r = − 0.474, respectively), likely due to the fact that relatively more C was being utilized for growth than for respiration. These results indicated that, compared to the sessile oak, the relatively lower organic C and total N and subsequently, the microbial biomass C and N content under the black alder were most likely due to shallow and deep groundwater flow and thus, the loss of plant nutrients was probably brought about by weathering.

Fruit quality of ‘Gala’ and ‘Fuji’ apples cultivated under different environmental conditions

Height growth-related competitiveness of oak (Quercus petraea (Matt.) Liebl. and Quercus robur L.) under climate change in Central Europe. Is silvicultural assistance still required in mixed-species stands?

Spatial and temporal differences in the response of Larix sibirica to climate change in the central Altai Mountains

Assessing the characteristics and limiting factors of tree growth is of practical significance for environmental studies and climatic reconstruction, especially in climate transition zones. In this study, four sites of Pinus armandii Franeh are investigated to understand regional climate-tree growth response in Mt. Yao, central China. Based on the high similarity of four residual chronologies and high correlations between chronologies and climatic factors, we analyzed the correlations of regional residual chronology with monthly climatic factors and the self-calibrating Palmer Drought Severity Index (scPDSI) from 1961–2016. The results indicate that the hydrothermal combination of prior August and current May and the scPDSI in May are main limiting factors of regional tree growth in Mt. Yao. The results of stepwise regression models also show that temperature and scPDSI in May are the main limiting factors of tree growth, but the limiting effect of scPDSI is more than temperature in this month. Through the analysis of the number of tree growth years corresponding to high temperature and high scPDSI, it was further confirmed that scPDSI in May is the main limiting factor on the growth of P. armandii in Mt. Yao. However, the influence of scPDSI in May has weakened, while temperature in May has increasingly significant influence on tree growth. The above findings will help improve our understanding of forest dynamics in central China under global climate change.

Who is the new sheriff in town regulating boreal forest growth?

In this article, the dependence of the sessile oak (Quercus petraea (Matt.) Liebl.) radial growth (tree-ring, earlywood, and latewood widths) on climate (the mean monthly temperature and precipitation totals) was studied in the Majdanpek area, north-eastern Serbia. The growth response of the oak trees to the prevailing climate conditions was dendroecologically investigated, by applying the correlation and response function, as well as by pointer years analysis. The site chronology covered 159 years (1855-2013). We found that latewood and total tree-ring width contain the imprinted positive response to the amount of precipitation in summer months (June and July) of the current growing season. The earlywood width showed no direct dependence on climate data, but it was significantly affected by the previous-year latewood width. Moreover, 40 % of the variation in the latewood width is explained by the earlywood variation in the same season. The temperature was not found to have any significant effect on the growth of oak at the study site. The use of pointer years, determined by applying several calculation procedures, has highlighted previous results, indicating that the precipitation in summer months was the deciding climate factor leading to the occurrence of the years with exceptionally wide or narrow tree-rings and latewood. To enhance our understanding of the response of the sessile oak growth at south-oriented sites with a shallow soil profile to precipitation and temperature variations, and expand the current database and knowledge, future studies should be undertaken.

The presence of Cryphonectria parasitica (Murrill) M.E. Barr was studied in six natural and planted stands of sweet chestnut in Serbia. The fungus was detected on the sweet chestnut in five localities and on the sessile oak in one locality. In total, 77 isolates from the sweet chestnut and five isolates from the sessile oak were obtained. Based on the culture morphology, all the obtained isolates were proven to be free from Cryphonectria (Saccardo) Saccardo &amp;amp; D. Saccardo hypovirus. The isolates of C. parasitica from the sweet chestnut were compatible with three different vegetative compatibility types, EU-12, EU-2, and EU-1, while the isolates from the sessile oak belonged to EU-12. After inoculation in laboratory conditions, the isolate from the sweet chestnut and sessile oak caused the decline in 88 and 76% of the sweet chestnut plants, respectively. In the case of the sessile oak, both isolates caused the decline in 52% of the plants. In field conditions, both isolates were aggressive to sessile oak trees after previous bark wounds and they were statistically significantly different compared to the control trees. The isolate from the sweet chestnut caused significantly larger cankers compared to both the isolate from the sessile oak and the control.