Snails and butterfly orchids at Greenfield

I went to Greenfield in the Chilterns yesterday.  The greater butterfly orchids are now emerging and recognisable, but they have suffered significantly from snail attack over the last month.   In some cases the entire growing tip has been eaten off.

The effect of snail damage can be summarised as follows. There were 92 numbered plants in what we term the study section last year, and I added a further 4 yesterday, bringing the total up to 96.  Of these:

Nothing above ground     28  (maybe at least partly due to snails)

Chewed but plant visible  15

Recognisable leaves        53

 of which 3 leaves             2

              2 leaves           29

              1 leaf               22

      

Of those with recognisable leaves 24 out of the 53 had suffered some snail damage.    The landowner put slug pellets down after my visit to try to curtail further damage.   This is one of the snails found in the laef litter

The snail damage has been much more severe than last year, probably because the spring has been mild and reasonably damp, whereas last year March and April were colder than normal, but then I do not know much about snail ecology, which for anyone studying orchid populations seems increasingly important.

In the north enclosure, where there were 258 plants last year including juveniles, I put bamboo stakes by the emerging plants, and removed by hand as much of the Dog's mercury as possible around the emerging plants so they do not get overwhelmed as happened last year.   I did not make a count but there were around 150 stakes.  Because only a few of the plants are numbered it will be impossible to pick up on losses from snails but I am sure the worst impact is in the south where the leaf litter is deeper, because there are two large beech trees overhanging the area.    

On a slightly better note, the orchids are spreading beyond the two enclosures, and I counted 40 plants in an area over which I put the brush cutter a month ago.

Next year we might consider taking off some of the leaf litter, but it may be beneficial to the germination and development of new plants.   I don't know!