18 BULLETIN 367, U. S. DEPARTMENT OF AGRICULTURE. 
Along the arroyos several grasses have taken possession, and the 
crop of feed they put on the margins of these dry watercourses is 
probably sufficient to render this broken land as productive of feed 
as the smoother areas (PI. VI, fig. 1). 
There is no doubt that the prediction made by Griffiths, that the 
mesquites and other shrubs would increase in size and number, is 
slowly coming true within the protected area (PI. VI, fig. 2, and Pl. 
VIII, fig. 1). The only retardation they have received has been from 
the occasional fires, some of which have been severe enough to com- 
pletely kill plants 10 to 12 feet high, though usually only the smaller 
bushes are killed back to the ground. 
Along with the information relative to the general character of 
the changes taking place on a protected area, some data have been 
obtained as to the rate at which these changes take place. 
The spring annuals and the six-weeks grasses occupy the bare land 
at once wherever there is sufficient rainfall. The recovery of the 
short-lived perennials was quite well advanced on this reserve after 
about three years’ complete protection, and the area covered by them 
has certainly doubled in size in seven years’ time. It has taken at 
least seven or eight years to bring about a condition favorable for 
the increase of the black grama, and this increase will doubtless con- 
tinue for another 10 years before reaching its maximum. Yet much 
of the land, where this plant normally grows, would doubtless pro- 
duce a crop of this grass where practically no forage grows now if 
it were given a period of complete rest for a few years and very 
light stocking for a number of years more. On the areas that have 
been carrying stock the recovery has been much less rapid, though 
very noticeable improvement has occurred. | 
CARRYING CAPACITY. 
The method of making quadrat measurements, established by 
Griffiths,t has been continued by the writer since he has been con- 
nected with the work. The detailed reports of these records for the 
years 1903 to 1908 and 1912 to 1914, inclusive, are on file in the 
Office of Farm Management. 
There is good reason to think that the areas now occupied by the 
crowfoot-grama and needle-grass associations, at least in that part 
of the reserve where these associations meet, has about reached its 
normal productivity under complete protection. Some further re- 
placement and substitution of species may take place, but no marked 
change in the total productivity is to be looked for. As nearly as 
the writer is able to judge, this condition has existed, on the area 
mentioned, for the past three or four years. 
1 Reported in detail in Bureau of Plant Industry Bulletin 67, p. 25 et seq. 
