HKINDKKK CRAZIXO 1 X VESTIGATIOXS IX ALASKA 



27 



ranjro observations. From i-csults tlius far obtaiiiod facts liave boon 

 brou<rht out re<rar(lin<r reproduction and recovery from injury tliat 

 liavo an important bearinjr on the i'an<re mana<rement problem. The 

 conchisions di-awn are here stated, and. thouj^h not comjjlete, are 

 indicative of what may be expected in <rrazing a lichen range. 



GROWTH ANn KEPKODUCTIOX 



The lichens are rapid in rate of reproduction or establishment 

 of new plants. Reproduction and growth take ])lacc whenever 

 favorable conditions of high moisture exist, usually in spring 

 and fall. In a wet sea.son growth may continue throughout the 

 summer, but ordinarih' the summers are dry and hot, and the 

 lichens then lose their moisture, become brittle, and stop growing, 

 (irowth may continue into the winter also in sheltered, rocky situa- 

 tions where the action of tlie sun on the frozen surface yields water 

 easily. 



'J hc average rate of growth of young plants of the sjjecies most 

 imi)()rtant as reindeer forage is about an eighth to a quarter of an 

 inch a year, and the initial growth is usually about a sixteenth to an 

 eighth of an inch. In volume — that is, number — of new plants it 

 is indicated that the lichens make rapid progress; in one measured 

 area on overgrazed range they attained about half the normal vol- 

 ume over a })eriod of five years following denudation, or four years 

 following the first appearance of new growth. Or from Id'H) to 1023 

 there is shown on this particular area a progressive annual increase 

 in volume at the rate of approximately .")0 per cent. At this rate 

 the normal stand in volume or density of cover, which in this case 

 is 40 per cent of lichen A'egetation. should be reached in another 

 two yeai's — that is, seven 3'ears following denudation. The plants 

 coming in on this area, in the order of their importance, v^ere 

 Cladonia sylvatica sylvestris, Cetraria cuculJata, CJadonia hellidi- 

 foia, C. coccifera, SphaeiophoruH coi-aUoides^ Alectoria nigricans^ 

 Cetraria isJandica, Cladonia graeiUs elongata, and C . alpestris. 



On the basis of the foregoing rates of growth and recovery, it 

 Avould usually require 7 to 10 years of protection for a lichen range to 

 come back to normal volume following initial growth; and 15 to 20 

 years to attain a normal height of 4 to 5 inches. These estimates, 

 however, are not final, more years of observation being necessary, 

 but the relative rate of recovery is apparently A'ery slow and by 

 reason of this fact, the proper management of winter range pre- 

 sents an exceptionally important problem. 



yVADKAT STUDIES 



Further results obtained on several observation quadrats 1 meter 

 square (pi. 18) tended to substantiate these estimates and pro- 

 vided additional information on the action of lichen growth under 

 partial cropping, represented artificialh^ by cutting. These quadrats, 

 established within inclosures, were on range containing a high per- 

 centage of lichen vegetation (from 70 to 90 per cent). The height 

 of the vegetation was from 3 to 4 to G inches, and occasionally 21/2 

 inches at the lowest and 10 inches at the highest. The average 

 height in all cases would be between 4 and 5 inches. 



