Sensitivity of bud burst in key tree species in the UK to recent climate variability and change

Analysing the relationship between the changing climate of the UK and the spatial and temporal distribution ofspring bud burst plays an important role in understanding ecosystem functionality and predicting future pheno-logical trends. The location and timing of bud burst of eleven species of trees alongside climatic factors such as,temperature, precipitation and hours of sunshine (photoperiod) were used to investigate: i. which species’ bud bursttiming experiences the greatest impact from a changing climate, ii. which climatic factor has the greatest influenceon the timing of bud burst, and iii. whether the location of bud burst is influenced by climate variability. Winterheatwave duration was also analysed as part of an investigation into the relationship between temperature trendsof a specific winter period and the following spring events. Geographic Information Systems (GIS) and statisticalanalysis tools were used to visualise spatial patterns and to analyse the phenological and climate data through re-gression and analysis of variance (ANOVA) tests. Where there were areas that showed a strong positive or negativerelationship between phenology and climate, satellite imagery was used to calculate a Normalised Difference Veg-etation Index (NDVI) and a Leaf Area Index (LAI) to further investigate the relationships found. It was expectedthat in the north of the UK, where bud burst tends to occur later in the year than in the south, that the bud burstswould begin to occur earlier due to increasing temperatures and increased hours of sunshine. However, initial re-sults show that for some species, the bud burst timing tends to remain or become later in the year. Interesting resultswill be found when investigating the statistical significance between the changing location of the bud bursts andeach climatic factor.