80 research outputs found
Juvenile growth response of European beech (Fagus sylvatica L.) to sudden change of climatic environment in SE European trials
Modelling the potential distribution of three climate zonal tree species for present and future climate in Hungary = Három klĂmazonális fafaj hazai potenciális elterjedĂ©sĂ©nek modellezĂ©se jelenlegi Ă©s jövĹ‘beni klĂmában
The potential distribution and composition rate of beech, sessile oak and Turkey oak were
investigated for present and future climates (2036–2065 and 2071–2100) in Hungary. Membership
functions were defined using the current composition rate (percentage of cover in forest compartments) of
the tree species and the long-term climate expressed by the Ellenberg quotient to model the present
and future tree species distribution and composition rate. The simulation results using the regional
climate model REMO showed significant decline of beech and sessile oak in Hungary during the 21st
century. By the middle of the century only about 35% of the present beech and 75% of the sessile oak
stands will remain above their current potential distribution limit. By the end of the century beech
forests may almost disappear from Hungary and sessile oak will also be found only along the
Southwest border and in higher mountain regions. On the contrary the present occurrences of Turkey
oak will be almost entirely preserved during the century however its distribution area will shift to the
current sessile oak habitats. | The potential distribution and composition rate of beech, sessile oak and Turkey oak were
investigated for present and future climates (2036–2065 and 2071–2100) in Hungary. Membership
functions were defined using the current composition rate (percentage of cover in forest compartments) of
the tree species and the long-term climate expressed by the Ellenberg quotient to model the present
and future tree species distribution and composition rate. The simulation results using the regional
climate model REMO showed significant decline of beech and sessile oak in Hungary during the 21st
century. By the middle of the century only about 35% of the present beech and 75% of the sessile oak
stands will remain above their current potential distribution limit. By the end of the century beech
forests may almost disappear from Hungary and sessile oak will also be found only along the
Southwest border and in higher mountain regions. On the contrary the present occurrences of Turkey
oak will be almost entirely preserved during the century however its distribution area will shift to the
current sessile oak habitats
The Effect of Soil Moisture on the Reflectance Spectra Correlations in Beech and Sessile Oak Foliage
Reflectance inten
sities of
foliage are mostly due
to
bio
materials
synthesised
by plant
s
.
A
daptation to the continuously changing environment requires the
regulated
alteration of m
etabolic
processes, which
also
influences
the UV
-
VIS
(Ultraviolet
-
Visible)
and IR
(Infra Red)
spectra
of
leaves
.
For the calculation of various Vegetation Indices (VIs), e.g. NDVI
(Normalized Difference
Vegetation Index)
, t
he common practice is to use the reflectance spectrum of the whole foliage
and
when
individual leaves of th
e
same plant are sampled
,
an average
VI
is derived
.
On the contrary
,
our
method exploits the small differences
between
individual leaves of the same plant
,
making use of
the
similar
distribution
s
of
measured
reflectance values
.
Using particular
wavelength pairs, l
inear
regressions of reflectance intensities have been
investigated
.
T
he
parameters
of th
ese
regression
s
(slope and intercept)
have been compared
to the temporal variations of the environmental
factors, such
as
temperature,
vapour pressure deficit a
n
d soil moisture
.
By
assessing
the
sensitivity
of the
regression
coefficient (slope)
to
the
changing
environment
,
wavelength pairs
can be selected
whose
sensitivity
change
reflect
s
the effect of
soil moisture deficit
on the plant
.
B
ased on the
state
-
dependent
correlations of the reflectance
spectra of plant foliage
, a new concept is presented that
is capable
of
indicating
the level of
environmental stress, e.g.
drought stress
Juvenile growth response of European beech (Fagus sylvatica L.) to sudden change of climatic environment in SE European trials
Accelerated Height Growth Versus Mortality of Quercus petraea (Matt.) Liebl. in Hungary
Background and Purpose: Due to climate change, it is important to know to what extent forests will be impacted by atmospheric changes. This study focuses on the height growth response of sessile oak (Quercus petraea (Matt.) Liebl.) to counteracting effects of fostering and interfering changes under contrasting climatic conditions with special attention to the xeric limit zone of this species.
Materials and Methods: Twenty-eight sites were selected along a climatic gradient from the humid region in southwest Hungary to the continental-semiarid region in northeast Hungary where neighbouring old and young sessile oak stands were available for pair-wise comparison of height growth. While these young stands developed entirely in the significantly changed atmospheric conditions, the older trees lived only a part of their life time in such changed environment. The Ellenberg quotient (EQ) was used for describing climate aridity. Stand top height in each pair of old and young stands was measured to calculate the relative stand top height using yield tables of sessile oak for Hungary. Additionally, stand densities of old stands were measured. To demonstrate the height growth differences of old and young stands their relative stand top heights were compared as functions of EQ and stand density.
Results: The relative top heights of the young stands were significantly higher than of the older stands, which means that the overall growing conditions were better in the last 30-35 years due to atmospheric changes than the mean conditions during the lifetime of old stands. Although extreme drought events associated with climate change caused reduced stand density due to periodic tree mortality at the xeric limit of sessile oak, the synergetic effect of all atmospheric changes was still sufficient enough to accelerate height growth.
Conclusions: There has been an acceleration of height growth during the last decades despite the increased frequency of droughts. It cannot be concluded that height growth acceleration will continue in the future since climate models show an increasing tendency of dry extremes in Hungary that may overrule the positive fostering effect of atmospheric changes
The timing of leaf flush in European beech (Fagus sylvatica L.) saplings
Spring phenology is considered one of the most important determinants of growth and survival in young stands. It is relatively easy to monitor and is expected to respond to climate changes that will affect the favourable period for growth in temperate regions. The response of trees to the environmental cues that govern spring phenology is largely under genetic control and inter-populational differences exist within species. This suggests that the trait undergoes site-specific selection. Data obtained through monitoring of bud burst at multiple beech provenance-trials were compared with specific site and weather data to reveal geographical clines in beech phenology. We fitted the Weibull function to harmonise phenology data collected using various flushing scales and at different intensities of monitoring. By comparing data from 20 annual census of phenology performed across 13 sites throughout Europe, we showed that accumulated temperature sum > 5°C modelled the timing and duration of flushing more consistently than other temperature sum models > 0°C or > 8°C, or simply Julian Day. Inconsistency in the number of degree hours required for flushing among sites, reinforced the need for testing of more complex mechanistic models that include photoperiod, chilling period, and summer drought in addition to temperature sum. South-North, East-West, and low-high elevational clines were confirmed from the analysis. These findings; reinforce the need for caution in planting provenances from the south-east of Europe, suited to warmer-drier summers, in more north-westerly sites; and highlight the location of some potentially valuable late-flushing populations that also tolerate warm dry temperatures.Peer reviewe
ErdĹ‘társulások Ă©s fafajaik átrendezĹ‘dĂ©si lehetĹ‘sĂ©gei a változĂł klĂmában
Kutatásunk sokrĂ©tű megközelĂtĂ©st tĂĽkröz. Honos fafajaink becsĂĽlt reakciĂłi alapján elemeztĂĽk Ĺ‘shonos fafajĂş erdĹ‘társulásaink várhatĂł átrendezĹ‘dĂ©sĂ©t. Az elmĂ©leti becslĂ©seket összedolgoztuk az Ăşjulatra Ă©s mortalitásra vonatkozĂł terepi vizsgálatok eredmĂ©nyeivel. Potenciális, inváziĂłbiolĂłgiai szempontbĂłl alacsony kockázatĂş cserefafajokat kerestĂĽnk a várhatĂłan visszaszorulĂł fafajaink esetleges helyettesĂtĂ©sĂ©re. A honos Ă©s inváziĂłs fafafajok esetĂ©ben országos adatokon nyugvĂł, cserefafajok esetĂ©ben eurĂłpai lĂ©ptĂ©kű modellezĂ©ssel is becsĂĽltĂĽk a fajok potenciális Ă©s prognosztikus elterjedĂ©sĂ©t. Potenciális termĂ©szetes erdĹ‘társulás (PTE) adatbázist Ă©pĂtettĂĽnk fel az ország erdĹ‘terĂĽleteire az Országos Erdőállomány Adattár alapján, a jelenre Ă©s jövĹ‘re vonatkozĂłan egyaránt. EredmĂ©nyeink alapján az erdĹ‘- Ă©s erdĹ‘ssztyep-társulások esetĂ©ben egyaránt a magas összetĂ©teli (elegyessĂ©g) Ă©s szerkezeti diverzitás (gyepekkel, cserjĂ©sekkel mozaikolĂł állományok) jelenthet nagyobb alkalmazkodĂłkĂ©pessĂ©get. A kiválasztott tájidegen fafajok alkalmazására csak az Ăşj körĂĽlmĂ©nyek között is vitális, Ĺ‘shonos taxonok Ă©s az általuk alkotott (akár Ăşjszerű) társulások által nyĂşjtott lehetĹ‘sĂ©gek kimerĂĽlĂ©sĂ©t követĹ‘en kerĂĽlhet sor
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