48 



University of California Publications in Botany [VOL. 9 



ZONE INDICATORS FOR THE ARCTIC-ALPINE LIFE-ZONE 



Athyrium alpestre 



Agropyron Scribnerii 



Trisetum Congdoni? 



Poa Pringlei var. Hanseni 



Festuca ovina var. brachyphylla 



Carex Breweri 



Carex nova 



Luzula spicata var. nova 



Juncus Parryi 



Salix tenera 



Eriogonum Kingii 



Oxyria digyna 



Polygonum shastense 



Silene Watsonii 



Aquilegia pubescens 



Ranunculus oxynotus? 



Draba oligosperma 



Draba glacialis 



Draba Lemmonii 



Draba Breweri 



Arabis Lemmonii 



Sedum integrifolium 



Ivesia lycopodioides 



Ivesia pygmaea 



Ivesia Muirii 



Lupinus danaus 



Astragalus tegetarius 



Epilobium anagallidifolium 



Podistera nevadensis 



Primula suffrutescens 



Phlox caespitosa var. muscoides 



Polemonium eximium 



Polemonium pulcherrimum var. parvi- 



folium 



Pentstemon Menziesii var. Davidsonii 

 Hulsea algida 

 Erigeron nevadensis? 

 Erigeron ursinus 



Erigeron compositus var. trifidus 

 Raillardella argentea 

 Antennaria medial 

 Crepis nana* 



ZONAL LIMITS JN THE SIERRA NEVADA 



The scheme of life-zones depends upon effective temperatures dur- 

 ing the vegetative season and the rule holds that temperature decreases 

 with altitude. Hence in mountainous regions like the Sierra, having 

 some elevations rising to or above snow-line, the sequence of zones will 

 be in general altitudinal, the arctic-alpine zone including the summit 

 region. But it by no means follows that, at a given altitude in the 

 Sierra on the same cross-section, one may find the same life-zone. 

 The data presented in the section on the climatology of the Sierra and 

 especially that portion dealing with the local climates of five r^pre- 

 sentative high mountain stations, show that two stations (Fordyce and 

 Bridgeport) may have the same altitude yet their geographic position 

 gives to the one a climate quite unlike that of the other. Fordyce has 



* Hall and Grinnell^i have recently published lists of zone indicators for all 

 life-zones and including the entire state. Through the courtesy of Dr. Hall I was 

 enabled to compare their lists for the boreal zones with my own before the publi- 

 cation of their paper. There are some differences in the two lists but it has seemed 

 best to publish the lists given here as originally prepared for the Sierra Nevada 

 only and let field comparison determine what correction should be made. It should 

 be said, too, that Hall and Grinnell's lists are prepared from a somewhat different 

 viewpoint than that adopted in this report. In their paper, plants have been 

 chosen as zone indicators which are believed to occur outside the assigned zone 

 very rarely or not at all, while in the lists appearing above frequency (dominance) 

 has been taken as the basis for zonal assignment. 



