Take ac­tion now on spring frost dam­age

This year’s late spring frosts could sub­stan­tially re­duce the value of your plan­ta­tion un­less re­me­dial steps are taken to re­vive damaged trees

Irish Independent - Farming - - FORESTRY -

It may sound a bit daft talk­ing about frost in Au­gust but bear with me, there’s a good rea­son why. The late spring frosts in the mid­dle of May caused sub­stan­tial dam­age to trees around the coun­try. Both broadleaf and conifer trees have been af­fected. A lot of this dam­age can be at­trib­uted to the mild win­ter and the warm weather we had in March, April and May.

Trees flushed ear­lier than usual, and this has in­flu­enced the sever­ity of the dam­age caused by the spring frost. What was also un­usual was the height of the trees af­fected. Frost will reg­u­larly dam­age trees up to two me­tres in height, but this spring trees as tall as five me­tres were in­jured.

It is thought that the buds, nee­dles and leaves of young trees were coated in mois­ture which froze and the sub­se­quent thaw­ing was too rapid. The mois­ture or ice on the shoots formed a film around the fo­liage. This may have acted as a mag­ni­fy­ing glass in­creas­ing the sun-scorch dam­age on the sen­si­tive young leaves.

The ta­ble out­lines the sen­si­tiv­ity of some broadleave­s and conifers to late spring frosts.

Young forests

Frost can kill young trees, par­tic­u­larly those grow­ing in frost pock­ets such as low-ly­ing ar­eas, val­ley bot­toms or lower down hill­sides. In most in­stances, the young trees will sur­vive. Se­verely damaged trees may be alive, but their qual­ity is com­pro­mised.

Dam­age to the side shoots is not as se­ri­ous as dam­age to the leading shoot. If the leading shoot is damaged, then that tree will fork from that point on. These trees will need to be shaped in order to pro­duce a qual­ity tree. Fail­ure to do so will re­sult in low-value pulp­wood.

I dis­cussed how to do this a few months ago.

For af­foresta­tion grant pur­poses, at least 90pc of your trees must be free from com­pet­ing veg­e­ta­tion, free-grow­ing and spread evenly over the site at year four. In frost-damaged plan­ta­tions, the pro­por­tion of trees with dam­age to the leading shoot should not ex­ceed 30pc.

If you no­tice any frost dam­age, con­tact your forestry con­sul­tant, walk the for­est to­gether and dis­cuss how to rec­tify the dam­age.

Older forests

Leading shoots that have been killed off by frost will re­sult in forked lead­ers, crooked stems and loss in height growth. This re­duces tree

TOL­ER­ANT

SUS­CEP­TI­BLE

Birch

Hazel Horn­beam Lime Nor­way maple Scots pine Wil­low Alder Hawthorn Nor­way spruce Sycamore Beech Dou­glas fir Oak

Sitka spruce Span­ish chest­nut Wal­nut Western hem­lock qual­ity con­sid­er­ably.

If you have a broadleaf wood­land, you should con­tinue to shape and high-prune your trees, even if you have to use ex­tend­able poles.

In a conifer plan­ta­tion, check if dam­age has been done to the leading shoots. Don’t worry about dam­age to the side shoots. If a plan­ta­tion has been se­verely damaged and many leading shoots are dead, the po­ten­tial loss in qual­ity could even­tu­ally be sig­nif­i­cant.

Man­age­ment op­tions are lim­ited and time-con­sum­ing. If the trees are not too tall, with ex­tend­able lop­pers you can re­move one of the forked lead­ers. After that, ac­cess becomes re­ally dif­fi­cult.

If many trees are damaged, con­cen­trate your ef­forts on the best 500 dom­i­nant trees evenly spread out.

The drop in rev­enue due to frost dam­age in first and second thin­nings is not that sub­stan­tial. Most tim­ber in such thin­nings will be sold as pulp­wood or maybe some pal­let­wood. For pulp­wood es­pe­cially, qual­ity is not im­por­tant.

How­ever, the fi­nan­cial loss at clear­fell is a dif­fer­ent mat­ter. Some of the fi­nal-crop trees may be down­graded from the most valu­able sawlog cat­e­gory to the less valu­able pal­let­wood or even pulp­wood cat­e­gories.

Have a look at the panel opposite for a guide on how to es­ti­mate the num­ber of damaged trees.

So it is im­por­tant to go for a walk through your for­est now to see if any of your trees were damaged by frost a few months ago. By do­ing noth­ing now, you may well no­tice the dif­fer­ence in your pocket in many years to come.

Steven Meyen is a Tea­gasc forestry ad­vi­sor email: steven.meyen@tea­gasc.ie Dam­age lim­i­ta­tion:

This year’s warm weather in March fol­lowed by late spring frosts caused some se­vere dam­age (left) to some young Sitka spruce trees and also af­fected broadleave­s such as oak (be­low)

The drop in rev­enue due to frost dam­age in first and second thin­nings is not that sub­stan­tial, but the fi­nan­cial loss at clear­fell is a dif­fer­ent mat­ter

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