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Conifers and other trees are constantly adapting to changes in light conditions, water/nutrient supply and temperatures by physiological and morphological modifications of their foliage. However, the relationship between physiological processes and anatomical characteristics of foliage has been little explored in trees. In this study we evaluated needle structure and function in Norway spruce families exposed to different light conditions and transpiration regimes. We compared needle characteristics of sun-exposed and shaded current-year needles in a control plot and a thinned plot with 50% reduction in stand density. Whole-tree transpiration rates remained similar across plots, but increased transpiration of lower branches after thinning implies that sun-exposed needles in the thinned plot were subjected to higher water stress than sun-exposed needles in the control plot. In general, morphological and anatomical needle parameters increased with increasing tree height and light intensity. Needle width, needle cross-section area, needle stele area and needle flatness (the ratio of needle thickness to needle width) differed most between the upper and lower canopy. The parameters that were most sensitive to the altered needle water status of the upper canopy after thinning were needle thickness, needle flatness and percentage of stele area in needle area. These results show that studies comparing needle structure or function between tree species should consider not only tree height and light gradients, but also needle water status. Unaccounted for differences in needle water status may have contributed to the variable relationship between needle structure and irradiance that has been observed among conifers.
- MeSH
- aklimatizace MeSH
- dehydratace MeSH
- dusík metabolismus MeSH
- listy rostlin anatomie a histologie metabolismus fyziologie MeSH
- půda analýza MeSH
- sluneční záření MeSH
- smrk anatomie a histologie metabolismus fyziologie MeSH
- transpirace rostlin MeSH
- vlhkost MeSH
- voda analýza fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
Activity concentrations of (137)Cs were detected in more than 400 outer spruce bark samples collected at sites variably affected by Chernobyl fallout across the Czech Republic in 1995 and 2010. The temporal changes in the (137)Cs activities were found. The mean effective half-life (TEF) for (137)Cs in spruce bark was 9.6 years, and the mean environmental half-life (TE) was 14 years. The effective half-lives were significantly higher in areas with higher long-term annual precipitation sums. Coefficient a in linear regression y = ax + b of half-lives on precipitation sums was 0.015 y mm(-1) for TEF and 0.036 y mm(-1) for TE. The aggregated transfer factor of (137)Cs from soil to bark was determined and the pre-Chernobyl bark contamination related to year 2010 was estimated.
- MeSH
- kůra rostlin chemie MeSH
- monitorování radiace MeSH
- poločas MeSH
- radioaktivní spad analýza statistika a číselné údaje MeSH
- radioaktivní znečišťující látky analýza MeSH
- radioizotopy cesia analýza MeSH
- smrk chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
Spring drought episodes are becoming more frequent and intensive in European temperate forests. To study tree resilience to spring drought, Norway spruce seedlings were exposed to three levels of drought stress (well-watered (W), moderately stressed (M) and severely stressed (S)) for 42 days and then fully irrigated for 14 days. Drought strongly reduced gas exchange parameters for both M and S seedlings. After 42 days, stomatal conductance was lower by 83 and 97% in M and S, respectively, than in W seedlings. Respiration prevailed over photosynthesis in S seedlings at the end of the drought period. Drought mostly reduced longitudinal growth, especially in shoots and needles. Xylem growth reduction was caused mainly by a lower number of newly produced tracheids, not by changes in their size. Norway spruce seedlings showed good resilience to spring drought, as the observed physiological parameters started to recover after rewatering and seedlings started to sprout and form new tracheids. In M seedlings, all physiological traits recovered to the level of W seedlings during the 14-day irrigation period but the recovery took longer in S seedlings. Shoots and needles did not regrow in length but leaf mass per area increased during the recovery phase. To conclude, Norway spruce seedlings showed good resilience to spring single-drought event, but time necessary to full recovery from stress could make seedlings more vulnerable to recurrent drought events.
- MeSH
- fotosyntéza MeSH
- období sucha * MeSH
- semenáček MeSH
- smrk * MeSH
- voda MeSH
- xylém MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- elektrochemie metody MeSH
- esterasy analýza MeSH
- finanční podpora výzkumu jako téma MeSH
- financování organizované MeSH
- glutathion analýza MeSH
- kadmium škodlivé účinky MeSH
- klíčení MeSH
- látky znečišťující půdu MeSH
- počítačové zpracování obrazu MeSH
- semenáček cytologie enzymologie genetika MeSH
- smrk genetika růst a vývoj MeSH
Daily ozone deposition flux to a Norway spruce forest in Czech Republic was measured using the gradient method in July and August 2008. Results were in good agreement with a deposition flux model. The mean daily stomatal uptake of ozone was around 47% of total deposition. Average deposition velocity was 0.39 cm s(-1) and 0.36 cm s(-1) by the gradient method and the deposition model, respectively. Measured and modelled non-stomatal uptake was around 0.2 cm s(-1). In addition, net ecosystem production (NEP) was measured by using Eddy Covariance and correlations with O3 concentrations at 15 m a.g.l., total deposition and stomatal uptake were tested. Total deposition and stomatal uptake of ozone significantly decreased NEP, especially by high intensities of solar radiation.
- MeSH
- biomasa MeSH
- chemické modely MeSH
- látky znečišťující vzduch analýza metabolismus MeSH
- ozon analýza metabolismus MeSH
- počasí MeSH
- průduchy rostlin metabolismus MeSH
- smrk růst a vývoj MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
Nitrogen leaching owing to elevated acid deposition remains the main ecosystem threat worldwide. We aimed to contribute to the understanding of the highly variable nitrate losses observed in Europe after acid deposition retreat. Our study proceeded in adjacent beech and spruce forests undergoing acidification recovery and differing in nitrate leaching. We reconstructed soil microbial functional characteristics connected with nitrogen and carbon cycling based on community composition. Our results showed that in the more acidic spruce soil with high carbon content, where Acidobacteria and Actinobacteria were abundant (Proteo:Acido = 1.3), the potential for nitrate reduction and loss via denitrification was high (denitrification: dissimilative nitrogen reduction to ammonium (DNRA) = 3). In the less acidic beech stand with low carbon content, but high nitrogen availability, Proteobacteria were more abundant (Proteo:Acido = 1.6). Proportionally less nitrate could be denitrified there (denitrification:DNRA = 1), possibly increasing its availability. Among 10 potential keystone species, microbes capable of DNRA were identified in the beech soil while instead denitrifiers dominated in the spruce soil. In spite of the former acid deposition impact, distinct microbial functional guilds developed under different vegetational dominance, resulting in different N immobilization potentials, possibly influencing the ecosystem's nitrogen retention ability.
- MeSH
- Bacteria klasifikace metabolismus MeSH
- buk (rod) růst a vývoj MeSH
- denitrifikace * MeSH
- dusičnany analýza MeSH
- koncentrace vodíkových iontů MeSH
- mikrobiota * MeSH
- půda chemie MeSH
- půdní mikrobiologie * MeSH
- smrk růst a vývoj MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Evropa MeSH
This study presents results from continuous measurements of stem CO2 efflux carried out for seven experimental seasons (from May to October) in a young Norway spruce forest. The objectives of the study were to determine variability in the response of stem CO2 efflux to stem temperature over the season and to observe differences in the calculated relationship between stem temperature and CO2 efflux based on full growing season data or on data divided into periods according to stem growth rate. Temperature sensitivity of stem CO2 efflux (Q10) calculated for the established periods ranged between 1.61 and 3.46 and varied over the season, with the lowest values occurring in July and August. Q10 calculated using data from the full growing seasons ranged between 2.30 and 2.94 and was often significantly higher than Q10 calculated for the individual periods. Temperature-normalized stem CO2 efflux (R10) determined using Q10 from growing season data was overestimated when the temperature was below 10 °C and underestimated when the temperature was above 10 °C, compared with R10 calculated using Q10 established for the individual periods. The differences in daily mean R10 calculated by these two approaches ranged between -0.9 and 0.2 μmol CO2 m-2 s-1. The results of this study confirm that long periods for determining the temperature dependence of stem CO2 efflux encompass different statuses of the wood (especially in relation to stem growth). This may cause bias in models using this relationship for estimating stem CO2 efflux as a function of temperature.
- MeSH
- biologické modely MeSH
- lesy MeSH
- meteorologické pojmy MeSH
- oxid uhličitý metabolismus MeSH
- roční období MeSH
- smrk fyziologie MeSH
- stonky rostlin růst a vývoj metabolismus MeSH
- stromy fyziologie MeSH
- teplota MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
