Jiri Kučera

One of the giants in Czechoslovakia—now the Czech Republic—in plant water relations, Professor Jan Čermák, passed away on December 23, 2021, in Brno, Czech Republic. Following in the footsteps of earlier noted Czech physiological ecologists—Jiří Čatský, Pavol Eliáš, Josef Huzulák, Zdeněk Šesták and Bohdan Slavík—Jan Čermák carved a reputation in pl...

This work is focused on a comparison of sap flow and tree growth in adult high and overaged coppice oak forests. The main hypothesis is that the older root system of coppice provides better access to soil water, and thus coppice is able to withstand drought stress better than high forest. During two growing seasons (2014–2015), two adult Quercus pe...

Heatwaves exert disproportionately strong and sometimes irreversible impacts on forest ecosystems. These impacts remain poorly understood at the tree and species level and across large spatial scales. Here, we investigate the effects of the record-breaking 2018 European heatwave on tree growth and tree water status using a collection of high-tempor...

In-situ measurements of tree sap flow enable the analysis of derived forest transpiration and also the water state of the entire ecosystem. The process of water transport (by sap flow) and transpiration through vegetation organisms are strongly influenced by the synergistic effect of numerous external factors, some of which are predicted to alter d...

Understanding how natural processes arise from complex interactions between particular processes at small spatiotemporal scales and in turn how these processes form patterns at large spatiotemporal scales is one of the current principal questions in environmental science. The problem is very complicated, as in many cases, key processes are often st...

Soil acidification has constituted an important ecological threat to forests in Central Europe since the 1950s. In areas that are sensitive to acid pollution, where the soil buffering capacity is naturally low, tree species can significantly modulate the extent of soil acidification by affecting throughfall deposition and the composition of litter....

Geodiversity plays an important role in species establishment during spontaneous succession. At post-mining sites in the Czech Republic in 2003, we established plots in which the surface of the heaped overburden was either kept wave-like or leveled. Based on surveys conducted from 2006 to 2015, leveled plots were increasingly dominated by grasses a...

Key message The novel approach for direct parameterization of the Penman–Monteith equation was developed to compute diurnal courses of stand canopy conductance from sap flow. Abstract The Penman–Monteith equation of evaporation is often combined with sap flow measurements to describe canopy transpiration and stomatal conductance. The traditional a...

Expansion of apple growing to dry areas requires reliable approaches to select genotypes tolerant to water stress. We have simulated apple tree transpiration (Ec) from different commercial orchards and compared it with actual transpiration (Ea) derived from sap flow measurements. The modelling approach lies in rearranging a parameterized P–M Equati...

The increasing frequency and severity of extreme weather events, especially droughts, arising from on-going climate changes negatively affect productivity and stability of forest ecosystems. Understanding species responses and suitable ecotypes that are able of adapting to new environmental conditions is increasingly important. The objective of thi...

Over the course of a year, tree physiological processes are not only directly affected by environmental conditions, but also by the tree’s own phenological stages. At the same time, phenological stages should, to a certain degree, reflect tree physiology. However, we have rather poor knowledge of the details of the interplay between phenology and e...

Published results on the growth interactions of non-nitrogen fixing mixed plantations species, and their impact on the regeneration of woody plants are scant. This paper addresses the growth interactions of pure and mixed plantations of Eucalyptus camaldulensis and Cupressus lusitanica and their impact on the regeneration of woody plants in relatio...

Key message We measured sap flow and shoot water potentials in clonally connected parent and daughter trees. We found bidirectional flow patterns in branches mediating the connection between parent and daughter trees. Abstract Layering is an important mode of vegetative reproduction at treeline, in which clonal daughter trees are formed by the r...

The parameterization process is usually based on daily mean values of main environmental factors, namely radiation (R) and vapour pressure difference (VPD). We have rearranged the P–M equation for stomatal conductance and then found the best fit to R and VPD using diurnal courses of variables instead of commonly used daily means. Instead of standar...

Phenological observations and ecophysiological measurements were conducted in a 45-year-old European beech stand in the Drahanská vrchovina (the Czech Republic). Ecophysiological studies included sap flow measurements on stem using trunk heat balance method, transmittance of photosynthetically active radiation (PAR) and stem volume changes. Sap flo...

Layering, in which clonal offsprings are formed by the rooting of lower branches of the parent tree, is an important way of vegetative tree reproduction at treelines. These rooting branches (termed "layering" branches) mediate connection between parent and clonal daughter tree. In this contribution, we aimed to investigate quantity and directions o...

Bowen ratio energy balance (BREB) is one of the most widely used indirect methods for deriving latent heat (LE) and sensible heat fluxes. The BREB technique relies on net radiation, ground heat flux, and air temperature and humidity gradients measurements. Whilst the first two mentioned can be practically considered as point measurements, the sourc...

This effort is aimed to derive a simple tool for separating soil evaporation and transpiration from evapotranspiration, measured by Bowen ration energy balance method (BREB) in short rotation coppice (SRC). The main idea is to utilize daily data of actual evapotranspiration (ETa) measured above bare soil (spring 2010 - first year following harvest)...

This effort is aimed to derive a simple tool for separating soil evaporation and transpiration from evapotranspiration, measured by Bowen ration energy balance method (BREB) in short rotation coppice (SRC). The main idea is to utilize daily data of actual evapotranspiration (ETa) measured above bare soil (spring 2010 – first year following harvest)...

Maize (Zea mays L.) water regime was monitored in the pot experiment in four variants of irrigation. The aim of the study was to identify the influence of air temperature, drought and intensity of solar radiation on the plant water regime. Potential evapotranspiration calculated according to Penman-Monteith transpiration equation was compared with...

The main aim of this study was to derive stomatal conductance (gs) from sap flow measurements and explore some of possible applications of this method. Sap-flow and other meteorological variables were continuously monitored in poplar-based short rotation coppice (SRC) plantation in Bystřice nad Pernštejnem during growing season 2012. Sap flow of 8...

Evapotranspiration of the Czech hop cultivar Agnus (Humulus lupulus L.) plantation was investigated during three consecutive growing seasons. We measured two components of the water balance: total evapotranspiration (using the Bowen ratio energy balance method) and transpiration of the bines (using the stem heat balance sensors type EMS SF 62). Act...

The aim of this contribution is to describe the step-wise improvement of the trunk heat balance method (THB) from the first idea to the actual sophisticated instrumentation. Both technical and theoretical aspects of the development of the method are considered. The original idea of heating trunk tissues with an electrical current passing between in...

This text presents results of a study focusing on differences of water balance between two contrasting cultures -short rotation poplar coppice and grass plot in conditions of Czech-Moravian Highlands. Actual evapotranspiration (by Bowen ratio energy balance method), precipitation and soil moisture in two layers (0 – 0.45 m and 0.45 – 0.90 m) were m...

Tree water use and growth increment were studied in a north-facing forest edge of a 70-year-old monospecific Scots pine (Pinus sylvestris L.) stand growing on poor sandy soils in the northern boreal zone of Sweden. The forest edge in this study bordered a 20-year-old clearcut. There were differences in water use and growth increment during the grow...

The plantations of short rotation coppice (SRC) usually based on poplar or willow species are promising source of biomass for energy use. To contribute to decision-making process where to establish the plantations we evaluated the water consumption and its relation to biomass yields of poplar hybrid clone J-105 (Populus nigra x P. maximowiczii) in...

The paper deals with the study of damage to the assimilatory apparatus of silver birch (Betula pendula Roth) using the study of changes of epicuticular waxes in the period 1997 to 2009. During the period, changes in the air pollution spectrum occurred in the area of the Ore Mountains. At the beginning of the monitoring, above-limit concentrations o...

This study reports on evapotranspiration and tree water use in short rotation coppice culture of hybrid poplar (Populus nigra x P. maximowiczii) for biomass energy in the Czech Republic. The high density poplar plantation (10 000 trees per ha) was established in 2003 on arable land in Czech-Moravian Highland (49°32´ N, 16°15´ E, 530 m a.s.l.) and h...

The principle of Bowen ratio is one of the available techniques for measurements of actual evapotranspiration (ETa) as one of essential water balance fractions. The main aims of submitted study were: (i) to compare the water balance of selected crops, (ii) to compare outputs of SoilClim model with observed parameters (including ETa on Bowen ratio b...

Presented study is focused on 50 years of phenological observations (1961-2010) of five wild plant shrubs and its phenological phases that create a continuous phenological sequence covering the whole spring aspect of floodplain forest. The phases were observed for Cornelian cherry (Cornus mas), English hawthorn (Crataegus oxyacantha), Midland hawth...

The main objective of submitted study was to calibrate and verify the simple model for net radiation (Rn) estimates during the growing periods of selected agricultural crops. In the same time the soil heat flux (G) measurements were analysed. The model needs incoming solar radiation, air temperature, vapor pressure measurements and information abou...

There are presented results of a study of soil moisture dynamics, its spatial patterns and soil water availability under poplar coppice (Populus nigra × P. maximowiczii). The study took place in a short rotation poplar coppice culture (SRC) situated in the locality Domanínek (the Czech Republic, 49°32' N, 16°15' E, 530 m a.s.l.). Generally, the soi...

A phenological study on the onset and duration of particular phenological stages of European beech (Fagus sylvatica L.) was carried out using sample trees growing in a research area of the Faculty of Forestry and Wood Technology, MENDELU Brno for a period of 17 years (1991-2007). The paper describes the onset and duration of particular phenological...

Significant influence of weather conditions on alpha acid contents in hop cones is generally accepted. Long-term monitoring of alpha acid content in hops cultivated in the region of central Europe shows notable year to year differences. Mathematical models of the relationship between alpha acid content and meteorological parameters were worked out...

The canopy transpiration of mountain mixed forest was investigated during summer 2006 at research plot Smrekovec in Tatra National Park in Slovakia after heavy windstorm in November 2004 on the area of 12,000 hectares. The research plot is situated in untouched forest at altitude 1249 m on the southern-east oriented slope. The forest is mixed with...

This study analyses the effects of thinning on stand transpiration in a typical mixed spruce and pine forest in the southern boreal zone. Studies of transpiration are important for models of water, energy and carbon exchange, and forest management, like thinning, would change those processes. Tree transpiration was measured by the tissue heat-balan...

1,3 Ústav ekologie lesa Lesnická a dřevařská fakulta, Mendelova zemědělská a lesnická uni-verzita v Brně 2 EMS Brno Environmental measuring system Abstract: European beech spring phenological stages observation in mixed forest stand based on automatic camera equipment The paper presented is aimed at results of monitoring phenological phenomena of E...

For the research of irrigation optimization and nitrate leaching it is important to know the short-term soil moisture variation during percolation episodes as well as its seasonal pattern. Dielectric soil moisture sensors Virrib (AMET - Consortium) and ThetaProbe ML2x (Delta-T) were used for this purpose over several years for measuring soil moistu...

Diurnal and seasonal tree water storage was studied in three large Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) trees at the Wind River Canopy Crane Research site. Changes in water storage were based on measurements of sap flow and changes in stem volume and tissue water content at different heights in the stem and branches. We measured sap f...

Canopy transpiration (Ec) of a 50-year old Pinus canariensis Chr. Sm. Ex DC. stand in Tenerife, Canary Islands was estimated continuously throughout 1 year from August 2000 to July 2001 by means of xylem sap flow measurements. Although there was pronounced seasonal trend in soil water availability and evaporative demand, Ec did not show any clear s...

The underlying physics of three specific thermal methods to measure tree sap flow was investigated. All these methods utilize local heating and measure heat dissipation caused by moving water. The application of heating was specific for each of the methods tested, herewith distinguishing the following alternatives: (1) thin needle perpendicular to...

Sap flow measurement techniques and evaluation of data are reviewed. Particular attention is paid to the trunk segment heat balance (THB) and heat field deformation (HFD) methods based on 30 years experience. Further elaboration of sap flow data is discussed in terms of integrating flow for whole stems from individual measuring points, considering...

Sap flow of model beech trees was estimated by direct, non-destructive and continuous measurements by tree-trunk heat balance method (THB) with internal heating and sensing of temperature. The consumption of water for the model beech trees transpiration as well as approximate model beech stand transpiration were estimated on the basis of these meas...

We extended the applicability of the ecosystem model BIOME-BGC to floodplain ecosystems to study effects of hydrological changes on Quercus robur L. stands. The extended model assesses floodplain peculiarities, i.e., seasonal flooding and water infiltration from the groundwater table. Our interest was the tradeoff between (a). maintaining regional...

Several the most commonly applied methods of tree stem sap flow measurement are based on stem local heating and measuring of heat transfer by moving water. Qualitatively the basic physical idea of these methods (decreasing of temperature of heated wood with the increasing of water mass flow) is evident, but the equations applied in these methods fo...

Seven sample trees of Norway spruce of different social position were chosen for analysis of needle biomass distribution in the crown profile in a 19-year-old stand. Vertical needle dry mass distribution was approximated with a one-peak-curve according to equation Q = A. exp [-B. (h(0.5) - C)(2)]. Crown zone with the maximum of needle dry mass did...

Phenological phases at forest tree species arc distinctly periodic, but their onset and duration depend considerably on the course of a whole complex of environmental conditions, above all on the weather. In the presented study there is a comparison of the onset and duration of phenological phases at two forest stands of Picea abies [L.] K a r s t....

Transpiration of fully grown floodplain forests growing on heavy alluvial soils in southern Moravia was studied during 10 years over the period of 27 years under changing environmental conditions and impacts of water management measures. The study period characterized the situation under last regular floods in early seventies, about 20 year long tr...

Water use of Acacia mangium trees grown in plantations was measured by a heat balance method in two stands that largely differed in tree density. Tree sap flow was closely coupled to climatic drivers and responded with minimal time delay. Using no time shift, sap flow rate could be tightly fitted to a simple equation that combined a parabolic respo...

Changes in leaf physiology with tree age and size could alter forest growth, water yield, and carbon fluxes. We measured tree water flux (Q) for 14 ponderosa pine trees in two size classes (12 m tall and ∼40 years old, and 36 m tall and ∼ 290 years old) to determine if transpiration (E) and whole-tree conductance (g t) differed between the two size...

Transpiration of 22 individual trees in a mature plantation of spruce in Drahanska Vrchovina uplands, Moravia (Querci-fageta abietis forest-type group) was studied through the measurement of sap flow by the stem section heat balance method over six years. Relative transpiration of trees was calculated as the ratio of daily totals of their actual tr...

Long-term measurements of sap flow were performed to estimate actual transpiration of a mixed pine/spruce sub-boreal stand. There was a variation in water use for the growth periods of 1994–1996 that reflected the hydro-climatic conditions in these years. The variability of water fluxes at tree level was generally high. This forced an application o...

Tree sap flow rate was continuously measured, using the tissue heat balance technique in six trees of Myrica faya at the experimental site of laurel forest in Agua Garcia mountains, Tenerife, Canary Islands, over a whole year in 1995. Sample trees were of different sizes covering the whole range of the species. A linear relation based on the diamet...

 We investigated whole tree water relations in 56–65m tall, old-growth Pseudotsuga menziesii trees within the Wind River Canopy Crane site, Carson, Washington, USA. We measured at predawn and solar noon the vertical gradients in xylem pressure potential using a pressure chamber. On an Abies amabilis sapling located in the understory at the base of...

We estimated the reduction of transpiration from drought for tree species in a mixed boreal 60-year-old stand in central Sweden. Actual transpiration was estimated from direct measurements of sap flow rate in Pinus sylvestris and Picea abies trees during two consecutive years with contrasting precipitation. Drought-induced reduction of transpiratio...

Estimation of areal evapotranspiration is crucial for the parameterization of the soil-vegetation-atmosphere interface in climate models and for the assessment of land-use changes on water resources. Present knowledge on how areal forest evapotranspiration depends on forest species composition and age is insufficient. In this study, transpiration o...

We measured whole-tree sap flow in a 43-year-old Abies amabilis (Dougl. ex Loud.) Dougl. ex J. Forbes - Tsuga heterophylla (Raf.) Sarg. forest in western Washington, U.S.A. We calculated whole tree crown conductance to water vapor (g(crown)) by substituting the sap flow data and meteorological measurements into the inverted Penman-Monteith equation...

We measured,whole-tree sap flow in a 43-year-old Abies amabilis (Dougl. ex Loud.) Dougl. ex J. Forbes ñ Tsuga heterophylla (Raf.) Sarg. forest in western Washington, U.S.A. We calculated whole-tree crown conductance to water vapor (gcrown) by substituting the sap flow data and meteorological measurements,into the inverted PenmanñMonteith equation....

Sap flow rate was continuously measured in six trees of Laurus azorica at the experimental site of laurel forest in Agua García mountains, Tenerife, Canary Islands, over 1 year from June 1993 to May 1994. Sample trees were of different sizes and covered the whole range of species. A sigmoid-like relationship based on basal area was applied to scale...

The introduction of rapidly growing trees in so-called short-rotation forestry requires knowledge about their water use in order to select suitable land for plantations and to manage the stands in a proper way. In Sweden, different clones of Salix are usually used in short-rotation forestry today. The diameter of trees in such stands is much smalle...

Transpiration in a mixed old stand of sub-boreal forest in the Norunda region (central Sweden) was estimated on the basis of direct measurement of sap flow rate in 24 large Scots pine and Norway spruce trees in July and August 1993. Sap flow rate was measured using the trunk tissue heat balance method based on internal (electric) heating and sensin...

Transpiration, pre-dawn shoot water potential and growth of Norway spruce trees were measured for one growing season, under three water regimes, giving a seasonal water input of 696 mm (irrigated), 579 mm (control) and 270 mm (drought). Potential transpiration was calculated from the Penman-Monteith equation, using maximal canopy conductance as a f...

We studied water flux in a four-year-old stand of hybrid Populus during midsummer 1992. Study trees ranged in height from 11.0 to 15.1 m and in diameter from 8.3 to 15.1 cm. The large-leafed Populus hybrid was relatively poorly coupled to the atmosphere. The average value of the stomatal decoupling coefficient, Omega, was 0.66, indicating that, on...