Shelter 71 



management of grouse range must take cognizance of these prin- 

 ciples. 



PLANT SUCCESSION CHANGES COVER TYPES 



Grouse range is an unstable, ever-changing complex. The plants 

 change with the years, and as they mature, particularly the tree spe- 

 cies, the character of the cover types gradually changes. Not only do 

 the plants grow, and thereby alter the physical nature of the cover, 

 some of them die and are replaced by new plants, often different 

 species. Thus the composition of species in a cover type changes 

 too. This phenomenon of plant succession follows definite laws. 

 Grouse management must be based largely on these laws. 



In order to understand the character of plant succession as it 

 affects grouse habitat, let us consider the history of an abandoned 

 farm field next to a woodland. To be specific, let it be a timothy 

 meadow which has about run out due to lack of fertilizer and loss 

 of topsoil by erosion. Many annual and perennial weeds have al- 

 ready replaced a part of the timothy at the time of abandonment. 

 Upon going wild these weeds gradually displace most of the timo- 

 thy and the field is taken over by goldenrod, daisies, deWl's paint- 

 brush, poverty grass, wild carrot, and associated plants. If the field 

 had been recently ploughed before abandoimient the weeds would 

 be primarily annuals for a time, such as ragweed, foxtail, and smart- 

 weed, which would then be succeeded by the perennials. 



The decline in fertility may continue for a time after abandon- 

 ment and portions of the field may be so poor as to be barren of 

 vegetation, or merely support mosses. But sooner or later the first 

 woody pioneers begin to take hold— often dewberries and blackber- 

 ries at first, or sometimes sweet fern, or plants like quaking aspen or 

 fire cherry. Up to the time these woody plants attain some size and a 

 fair density, the cover is essentially of one type so far as the grouse 

 is concerned— open land. But as the brushy type takes over, the area 

 becomes overgrown land, with an entirely different prospect for 

 grouse. 



The changes that take place during the overgrown stage depend 

 upon the species that are initially established and, as in all stages of 

 succession, upon the distribution of mature seeding plants in the 

 vicinity ( see Plate 17 ) . Generally the composition gradually changes 



