Determinsimul climatic al producerii fenofazelor la specii forestiere cu serii maximale din România [Climatic determinism in the occurrence of phenophases for forest species with maximum time series from Romania]

• Main Author: Tedosiu Marius
• Format: Article
• Language: English
• Published: ”Ștefan cel Mare” University of Suceava, Faculty of Forestry and “Marin Drăcea” National Research-Development Institute in Forestry - Station Câmpulung Moldovenesc 2015-08-01
• Series: Bucovina Forestieră
• Subjects: phenology; NAO; temperature; chilling; forcing; PLS regression; Castanea sativa
• Online Access: http://www.bucovina-forestiera.ro/arhiva/2015/15(1)/03_teodosiu-2-2.pdf
• ISSN: 1582-0769; 1582-3725

The paper analyze the relationship between phenophase timming of different forest species and climate (large scale circulation expressed by NAO and the local climate expressed by temperatures), for 40 phenological time series between 1946-1965 and 1962-1971 from Romania. The dependencies of bud burst and flowering on temperatures were modelled also with the Dynamic Model and the Growing Degree Hours model, using the PLS regression, for two varieties (early, late) of Castanea sativa. The results indicated negative relationship with the NAO values for all the phenophases, the best covariable being the mean of the vaues for the first three winter months. The same relationship was with the temperatures, the combined delay for all the phenophases being 1.3 days/oC, with differences between phenophases (2.5 days/oC - bud burst, 2.3 days/oC - leafing and 2.1 days/oC leaf out). The growing season length increased with 5.5 days/oC. Among months, the best predictors were the mean values of April or of February-April, explaining about 55% of variability. The chilling requirements were identical between varieties (36.12±5.22 CP in bud burst and 18.29±5.92 CP in flowering), while differing in heating. Dependencies of the phenophases timming on the mean temperatures of the chiling/forcing periods indicated mixed effects of the two, excepting the bud burst of the early variety, which related only on the forcing mean temperatures.