THE SIERRAN MONTANE FOREST. 



213 



While no factor studies have been recorded for the Sierran montane forest, the 

 experience of foresters has enabled them to indicate the comparative relations 

 of the dominants to both water and light. Larsen and Woodbury (1916 : 7) 

 have shown the soil and water requirements of the major dominants in the 

 following, in which the order is from more exacting to less exacting. As to 

 light requirements, the dominants are ranked from the least tolerant to those 

 most tolerant of shade. 



The general relation of the dominants to the combined influence of water 

 and temperature is shown by the order in which they occur with increasing 

 altitude. The lowermost species are Pinus attenuata, P. coulteri, and Pseudo- 

 tsuga macrocarpa, followed by Pinus ponderosa, Pseudotsuga mucronata, 

 Libocedrus decurrens, P. lambertiana, Abies concolor, and P. jeffreyi. This is 

 the order of the potential succession (Clements, 1916 : 108). It corresponds 

 closely with the actual serai sequence of the dominants, when the difference 

 in the tolerance and zonal position of Libocedrus and Pinus jeffreyi is taken 

 into account. The first three species are essentially subclimax, Pinus ponde- 

 rosa is the first and most xerophytic of the true dominants in the lower half 

 or more of the forest and P. jeffreyi in the upper, and Pseudotsuga is next. 

 The remaining three differ but little, since the greater tolerance of Libocedrus 

 is offset by a smaller water requirement. 



SOCIETIES. 



Shrubs are well developed in the montane zone, but they reach their best 

 expression in open woodland and in clearings where fire has been active. 

 They disappear largely or completely in the closed forest stands, in which 

 herbaceous societies are more or less prominent. Many of the shrubs belong 

 to the same genera as the dominants of the chaparral and hence form com- 

 munities with a striking resemblance to the latter. While they ultimately 

 yield to the montane forest in undisturbed areas, recurrent fires enable them 

 to occupy the ground as a more or less permanent subclimax. The latter has 

 usually been included in the general term chaparral, but this view is ecologi- 

 cally incorrect, as Cooper (1919) has emphasized. 



Shrubs: 



Ceanothus cordulatus. 

 Ceanothus velutinus. 

 Ceanothus integerrimus. 

 Ceanothus parviflorus. 

 Ceanothus prostratus. 

 Arctostaphylus patula. 

 Arctostaphylus drupacea. 

 Castanopsis sempervirens. 



Quercus breweri. 

 Quercus sadleriana. 

 Quercus chrysolepsis vaccini- 



folia. 

 Pasania densiflora echinoides. 

 Corylus rostrata. 

 Prunus demissa. 

 Prunus emarginata. 



Castanopsis chrysophylla minor. Rhamnus californica. 



Rhamnus purshiana. 

 Holodiscus discolor. 

 Amelanchier alnifolia. 

 Symphoricarpus oreophilus. 

 Symphoricarpus mollis. 

 Ribes nevadense. 

 Rubus parviflorus. 

 Chamaebatia foliolosa. 

 Rhus diversiloba. 



