Greening-up in full swing! - News and Discussion - European Phenology Campaign

Greening-up in full swing
 
Here we come with a fresh update from our phenology scientist Lenka Hajkova:

The birch woods (Betula pendula) have been turning green in Czech Republic since beginning of April. The process of leaf unfolding is monitored and described by scientists as an onset of the phenology phase of first leaf emergence. The stage of 100% first leaf emergence was identified at many phenological stations already around 9th -15th April. As a result, the lush green of birch can be seen in woods across the country, with the exception of high altitude mountain regions.
 
Lime (Tilia cordata) and beech (Fagus sylvatica) started to green up a bit later than birch.  The initial phase with first leaves of lime developed at 10% - 50% of canopy was monitored in the lowlands around Mid-April. At the same time beech reached the 10% of the first leaf emergence.
 
Oaks started to green up slowly in few places of lowlands where the climate is the mildest, while in the rest of the country they barely progressed into a bud-burst last weekend (April 29th-30th).
                                                                                  
How to identify the phenological phase of first leaf emergence:
The midrib and veins are visible at the upper part of the leaf and the leaf is unfolded partially, however not in its full size yet. To determine the progress of the phenological phase of first leaf emergence, scientists distinguish 3 stages, each of them describes to which extent the emerging leaves cover the tree: 10%, 50% or 100% leaves of a tree are developed.
 

• Look around you and tell us whether you can see lime/beech/oak leaves emerging! 
• Do you see green woods of birch in your country by the beginning of May as we could see it in Czech Republic?
  
• Find a lime tree and with the help of the picture below identify if the tree is already in the stage of first leaf emergence. 

Picture:
Lime (Tilia cordata) – leaf unfolding

Observations in Switzerland

In Switzerland the observed stages are a bit different.  Concerning the leaf development there is the stage "Begin of leaf unfolding"
(From 3 buds at three places in the tree (not on the same branch), first leaves have appeared and unfolded. The total surface of the leaf and the leaf blade is visible), which is followed by

Full leaf unfolding - 50% of the leaves on the tree are unfolded (mean of 3 leaves per bud. The total surface of the leaf and the leaf blade is visible.)

Full leaf unfolding was observed (average) on first of April for Lime, on 26th of March for Birch and on 7th of April for Beech.
 
BBCH: 13

For more results see www.phaenonet.ch

In Croatia it is sunny so the birch and hazelnut are still green