AU­TUMN LEAVES

Nottingham Post - - WILD LIFE -

AT this time of the year the nat­u­ral en­vi­ron­ment re­ally “shows its colours” as de­cid­u­ous trees pre­pare for the com­ing colder months by shed­ding their leaves as they are sus­cep­ti­ble to be­ing dam­aged dur­ing the very cold and wet weather of win­ter.

Dur­ing the spring and sum­mer months the leaves are crit­i­cal for the pro­duc­tion of the nu­tri­ents that are nec­es­sary for the tree’s growth and sur­vival. The leaves use a process known as pho­to­syn­the­sis whereby the sim­ple mol­e­cules of wa­ter and car­bon diox­ide re­act to form glu­cose and oxy­gen. The wa­ter is taken up from the ground by the trees’ roots and the car­bon diox­ide is ab­sorbed from air via tiny holes in the leaves known as stom­ata.

Light en­ergy is re­quired to drive this chem­i­cal re­ac­tion and en­ergy from sun­light is ab­sorbed by the green pig­ment in the leaf known as chloro­phyll. The glu­cose is then fur­ther “biosyn­the­sised” us­ing oxy­gen in a process known as “res­pi­ra­tion” to pro­duce the nu­tri­ents that the tree needs to live and grow.

Leaves tend to be pre­dom­i­nantly green due to the green chloro­phyll, be­ing the dom­i­nant leaf pig­ment, mask­ing other pig­ments in the leaves which range from yel­low to pur­ple. Dur­ing au­tumn the changes in day­light length and tem­per­a­ture are de­tected by the trees and they start to shut down the pho­to­syn­the­sis process in the leaves.

Valu­able nu­tri­ents in the leaves, which are mainly sug­ars, are re­ab­sorbed by the tree and stored in the roots for later use. In prepa­ra­tion for leaf shed­ding the tree even­tu­ally cuts off the trans­port of these sug­ars back to the tree. The green chloro­phyll is one of the first mol­e­cules to be bro­ken down with the green colour less­en­ing mak­ing the colours of the other pig­ments more prom­i­nent.

Any re­main­ing sug­ars in the leaf are even­tu­ally con­verted to an­tho­cyanins pro­duc­ing other red, pur­ple and pink pig­ments. Even­tu­ally the leaves fall from the tree and a pro­tec­tive layer of cells grows over the ex­posed area to pre­vent dam­age to the tree.

A bal­ance be­tween weather con­di­tions and the un­der­ly­ing chem­i­cal pro­cesses in the leaves can have a dra­matic im­pact on the depth and colour range of au­tumn leaves. On bright sunny days pho­to­syn­the­sis can still oc­cur in the leaves due to re­main­ing chloro­phyll which then in­creases the con­cen­tra­tion of sug­ars within the leaves re­sult­ing in more even­tual pro­duc­tion of the red­der an­tho­cyanin based pig­ments.

Dry weather also in­creases the sugar con­cen­tra­tion within the leaves giv­ing a red­der colour. Cold nights can de­stroy the chloro­phyll with the leaves fading to yel­low. A com­bi­na­tion of cold nights, dry weather and sunny days can re­sult in the great­est colour range and in­ten­sity of au­tumn leaf colours.

As the nat­u­ral world pre­pares for win­ter, au­tumn is a great time to visit one of the Trust’s re­serves. If you visit one of our wooded re­serves, such as Bunny Old Wood in Rush­cliffe, Dukes Wood Na­ture Re­serve near Eakring and Ea­ton and Gam­ston Woods near Ret­ford you may be rewarded with some re­ally spec­tac­u­lar au­tumn colours.

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.