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Transpiration and biomass increment in short rotation poplar coppice
Orság, Matěj ; Fischer, Milan ; Trnka, Miroslav ; Kučera, J. ; Žalud, Zdeněk
This paper deals with interaction between amount of water lost by tree transpiration and aboveground biomass increment in poplar based short rotation coppice in conditions of CzechMoravian highlands. Stem sap-flow measured on 8 poplar trees by Granier heat dissipation method was put in relation with biomass increments measured both with automated dendrometers so with manual measurements with caliper gauge. Transpiration totals ranged between 28.3–175.6 liters per tree in executed period 3.8.–31.8.2011. Above-ground biomass increments in this period varied between 30.07–519.28 g per tree and mean value of water use efficiency of all monitored trees reached 2.76 g.kg–1. Mean diurnal sap-flow total of all sampled trees was 3.25 liters. Results show that it is possible to establish relationship between transpiration totals and biomass increments (coefficient of determination R2 = 0.90) and also relationship between transpiration totals and stem diameter (R2 = 0.81). These results (especially after obtaining experimental data from spring growth conditions) can be further used for calculations of biomass increments and transpiration as scaling factors from tree level to whole stand level.
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Evapotranspirace vybraných druhů zemědělských a lesních porostů
Kučera, J. ; Urban, J. ; Trnka, Miroslav ; Fischer, Milan ; Krofta, K. ; Duffková, R.
Cílem článku je porovnat evapotranspiraci (ET) z porostů různých plodin (trávník, jetel luční (Trifolium pratense), ozimá pšenice (Triticum aestivum), chmel (Humulus lupulus) a plantáž topolu (J-105, Populus nigra x Populus Maximowiczii) s potenciální evapotranspirací (PET) a rámcově popsat vývoj ET těchto porostů v průběhu vegetační sezóny. Druhým cílem je stanovit podíl transpirace na celkové ET u dvou kontrastních porostů – chmele a plantáže topolu. Denní suma ET trávníku, stejně jako většiny dalších porostů, dosahovala maximálně 5 – 6 mm, což odpovídá 85 – 93 % PET. Výrazně vyšší ET byla naměřena v porostu jetele, naopak nejnižší v porostu topolu v prvním roce po jeho smýcení. Podíl transpirace na ET činil u chmelu 40 - 70 %, kdežto u topolu 80 - 90 %.
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Water balance in short rotation poplar coppice and reference grass-plot in conditions of Czech-Moravian Highlands
Orság, Matěj ; Fischer, Milan ; Trnka, Miroslav ; Hlavinka, Petr ; Kučera, J. ; Balek, J. ; Žalud, Zdeněk
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 measured on both plots during seasons 2008 – 2010. The seasonal water lost through evapotranspiration was higher for the grass (560.4 and 508 mm for grass and 523.8 and 351.8 mm for poplar during growing season 2009 and 2010 respectively), but generally the observed amounts of ETa are comparable for both cultures and within the range of values described in literature. Results of soil moisture measurements expressed as soil water availability [mm] were compared with simulations obtained from water balance model SoilClim. The model a little bit underestimated the amount of available water in the system, since based on water balance closure we suggest that there is a higher water income than was recorded from precipitation. This extra water found in observed systems may be supplied probably by lateral underground water inflow from the upper fields.
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