The Influence of Forests on Climate

Manawatu Standard, Volume X, Issue 1471, 3 October 1885, Page 5 (Supplement)

The Influence of Forests on Climate

The commencement of a scientific j investigation of this subject was niado ! when the Bavarian ioivsb meteorolo- j gieal sutions were 'established, and when ]?nissia ? Al.»ace-ivn'raine, France, Switeriandi and Ttaly followed the example. As a general rule, it may He laid down chat m the warm seasons, as hetweenrFpviJSts and places close -a hand which are treeless, (!').. the temperatures of the earth and air are; lower in;the former ..; (2) their variations are less; (3) vtlio relative humidity is greater. After examining- observations as to evaporations Herr Weeikof state* that th» influence of forests m diminishing evaporation from water aud the soil, is so great that it cannot be accounteil for alone by the lower, temperature of the hot months, the greater .humidity, or even by the shade. An important, influence, which has hitherto been but lifcfcle appreciated, is the; .-protection'::* wfro.iiV the wind afforded by the tires, and this the writer regards as more important than all the others" together m r educing the decree of evaporation. With regard to^the iiiifluence of; forests on rain arid snowfall , there is as yet only a sin trie series,of observations supplying comparative statistics, anil extending jover-a sufficiently long period. These were taken m the neighbourhood of Nancy, and they show ■ i*n important influence of forests m increasing the rainfall. It might appear that the effect of forests on rain iii the climate .of Central ISurp'pe; m; winter would ibe small, for * th^ v the tern •; peratur^itnd humidity of the forest., and the open is 'Very little, . and the quantity of moisture m. the atmosphere is small. But the observations show, that i it is at tbia i time of the 1 year that forests get much, more rain. This' the writer attributes to the clouds being ' lower, : the - resistance which; the forest offers to ihe; movement' of the air, and to the- nipist west : wind. Forests retain rain % the under— grewths of grass,>moss, &c , much better than open ground, and let water off, superficially only' after: a heavy rainfall; ; the remainder, filters upwards slowly, and munh . of U ,i s Used tor the evaporation of the trees. ■Although love^tsi especially thick luxuriant forests, cannot exist without certain ; .•■supplies of moisture,, yet it is the same to them when the sripplies, come, for they retain what they get and use it oyer a long period. Onp example of thix is; the Lenkoran; forest oji, ; the^west coast •: of the Caspian^ where the vegetation ■is more v 1 w xuviautj than m any othci' - part of Europey yet very^little rain; Jails, ru summer, butrihe ; rainfall m, autumn and winter is great!. The water is stored- up by the forest, and is used m evaiporatipu during the heat of "the summer.^ v-Humid;ity/ y of the, atmosphere, . hoy/ever," is nob ■': icon.usterit'Avith a higfi temperature, as the Red Sea shows ; but m forests -the humidity is due to the evaporation^ of thejleavcg— -in othftr words, to a^ process by which \ heat is converted into wori, and notice i the cool Bes«. Heri Wc)cikof ; then efldeayours to ascertain the influence of forests on 'the - climatic: coriditioiis of I' llieir nefghboui'hpods m the western j»!irt of tlie Old World' between .'.the 38ili and .52nd degrees N. * latitude,' J the placeV selected being: iti allr cases m ihe open. \.Thus for 'thj? 52rid degree eight' stations are taken hetween Yalontia m Ireland on ..th.c west and Mike "Kirghiz steppes , on the 1 ' east ; fopthesofch, Guernsey on the wevt, Semipalatinßk <m / ihe eaßtr a^ 13 statioifci -and -soion for each 2 de^V of latitiide tO; ; '■ 38 . deg. A Th^i general • result of the ol)servati6hs m 5Q stations m six, different degrf'e^ of latiLiitlo is^thafc m Western Eu rope ahdf j&m. large foreste have a {Jfreai influerice oh the temperature of placed near them, anil that by their infliience the nornial increaseortVmper»»ture : as we travel ceast ward from the: Atlantic: Ocean to the interior of the continent; is; riot merely interruptedv : but they give places far removed from the coast a cdoler siimmer ihantho^e-actHally on the;sea. A striking example of this is; Bosnia, v An exanimation of the statistics shows (1) that m BDJ«ni»i the summer is 2'6beff io 4 ; 5 deg. cooler than m Herzegovina^^) even on the Island of Lissa. m the full m;- ; fluenceof the Adriatic Sen, the summer temperature is more than a degree higer;thau that of Bosnia which is ;Sepat(ited by^ lofty mountain, ranges ' fniin the sea. f ; Bosnia owes this . cbmparativelycool snnimer to its Q[feat forests, while^ flerzgpVtna v is almost disforested. To sum up-: Forests exercise an influence on climate which # dose not cease pn Jheir borders but extends overs a larger or smal ler adjacent region, according 1 to the size, kind, anil position of fiirests. Hence nVari^by affprestation {md disafforestatioh: can modify the climate around him}butit is an extreme position to hold that by afforestation the waxte places of tle.earth can He made fertile. There are plaooa, incapable of being afforeKted which, (would not give nocesyßiivy nourish men t to tr eeß, ■