362 FOREST INDICATORS. 



The moss {Mnium sp.) was found only in cool, moist, and shaded situations, 

 thereby indicating unusually favorable site conditions. The monkey flower 

 {Mimulus langsdorfii) was the only plant which was confined to the proximity 

 of water, indicating excessive soil moisture conditions. 



" Practically all of the species listed a.s occurring entirely on Site II, which 

 do not overlap on other sites, were found in hot, dry, and unshaded situations 

 and might be regarded tentatively as indicators of poor western yellow-pine 

 sites in the San Mateo Mountains. The mesophytes listed as possible Site I 

 indidators were not found on poorer sites in this locality. However, it may be 

 true that further detailed studies in the San Mateo Mountains might require 

 a different listing of the vegetation than that here given. A number of the 

 species listed as occurring on only one site are, to the writer's personal knowl- 

 edge, known to occur on different sites in other parts of the Southwest. The 

 vegetation on Site II was comparatively sparse and more open than on Site I 

 where it was also more luxuriant and vigorous. Those species which were 

 found to overlap on both sites normally made their optimum development on 

 Site I. Approximately twice as many species were found on Site I as on Site 

 II." 



Afforestation indicators. As already stated, the indicators of the pos- 

 sibility of forest production in grassland and scrub climaxes are either such 

 extra-regional communities of trees as are found in savannah or in the fring- 

 ing woods of river valleys, or such grasses and shrubs as indicate an approach 

 to the water requirements of trees. As a matter of fact, practical afforesta- 

 tion has been confined chiefly to the sandhill regions of Nebraska and Kansas, 

 in the first of which all four of these indicators have been present in some degree. 

 Indeed, the success of planting in Nebraska and its failure in Kansas are related 

 to the fact that these indicators were present in the one State and largely 

 lacking in the other. While it is clear that no sharp line can be drawn be- 

 tween reforestation and afforestation, the latter is regarded as having to do only 

 with those climaxes, grassland and scrub, in which trees occur at the margins 

 or in valleys. While pine savannah and valley woodland were doubtless more 

 extensive in the sandhills of Nebraska during the wet phases of some of the 

 major climatic cycles of the present geological period, it is practically certain 

 that this region has belonged to the grassland formation since the Miocene 

 at least (plate 92). 



Bessey (1887, 1895) was the first to point out the evidence which indicated 

 that the sandhills of Nebraska could be forested, or reforested as he regarded it. 

 This evidence consisted wholly of valley and canyon reUcts of woodland, 

 chiefly yellow pine. It was summarized as follows : 



"There are many isolated canyons which contain trees; there are western 

 as well as ea.stem trees and shrubs in these canyons; the yellow pine of the 

 Rocky Mountains now grows with other trees upon the hills of Pine Ridge 

 from the Wyoming hne in Sioux County to the Dakota line in Sheridan County ; 

 the yellow pine is now to be found in the canyons of the Niobrara River and 

 its tributaries as far east as the border of Holt County ; it extended eastward 

 along the North Platte River and Lodge Pole Creek to Deuel County until the 

 pioneers destroyed it, forty or fifty years ago ; it grew in considerable quanti- 

 ties in at least one station on the Republican River until destroyed by the 

 early settlers; in the Loup Valley there are yellow pines on the South, Middle, 

 and North Loup Rivers; logs and fragments of pine trees occur here and there 

 in the sandhills." 



