Кл.слова (ненормированные):
conductive system in xylem -- Vaccinium arctostaphylos -- Rhododendron -- ponticum -- Ilex colchica -- climate impact -- Strandja
Аннотация: As is clear from weather data, the climate of the inner Strandja, Bulgaria, has grown dryer since 1970. As a result, some relic species having low environmental adaptation potential either have been subjected to the risk of mortality from drought, or have migrated upward, to more humid conditions. The aim of our work was to reveal the effect of recent climatic changes on the vascular systems of relic Vaccinium arctostaphylos L., Rhododendron ponticum L. and Ilex colchica Poj. growing in Strandja. These species are recognized to need conservation. The xylem features were studied by Image Analysis set-up using the dated cross sections of the woody samples. Vessel characters were measured ring by ring. Correlations were calculated between the chronologies of the vessel parameters (mean vessel area and vessel density per a growth ring) and daily average temperature and precipitation recorded at Burgas weather station. These correlations were analyzed using a 20-day moving window technique whereby the climatic variables were shifted at 10-day steps from April 1-st to October 30. It was revealed that from 1996 to 2008, V. arctostaphylos mean vessel area, S, (mu m(2)) was rising while the mean vessel density, N/mm(2), was dropping. The same trends but at considerably lower rates were revealed for R. ponticum in 2001-2008. In I. colchica, the former feature, on the contrary, dropped slightly and the latter rose in 2004-2008. In all three species, relative water conductive area within a growth ring, sw (sum of the vessel areas located in the growth ring /growth ring area), remained constant in R. ponticum, on the contrary, dropped slightly in V. arctostaphylos and rose in I. colchica. Climate signals recorded in vessels showed that April-May air temperatures influenced in xylem of all three species, while June-July temperatures influenced only archaic R. ponticum and V. arctostaphylos. Spring (April) and summer (June 20 - July 10) precipitation had significant positive effect only on these two species but not on I. colchica. The results clearly showed V arctostaphylos, the most ancient species, were extremely vulnerable to unfavorable climate. When available water diminishes and transpiration rises, increasing vessel area is unfavorable for plant health, because it makes embolism in vascular system highly probable.
WOS
Держатели документа:
Univ Forestry, Sofia, Bulgaria.
RAS, VN Sukachev Inst Forest, SB, Krasnoyarsk, Russia.
Доп.точки доступа:
Tashev, Alexander; Benkova, Vera; Benkova, Anna; Tashev, Nikolai