The Amphibians and Reptiles of Sinaloa, Mexico - Smithsonian ...

52 UNIVERSITY OF KANSAS PUBLS., MUS. NAT. HIST.
areas from 300 to 1000 meters; oak forest from 900 to 1500 meters;
and, pine forest at elevations from about 1500 to 2750 meters. Much
of the information presented on the Rio Mayo vegetation has been
assimilated into the description of the vegetation of the northern
and central sections of the state.
Two important papers by Gentry on the vegetation of two mountains
in Sinaloa appeared in 1946. One dealt with the flora of
Sierra Tacuichamona, an isolated peak in the central part of the
state (Gentry, 1946a). The other pertained to the vegetation of
Sierra Surotato in the northern highlands (Gentry, 1946b). General
works {e. g., Leopold, 1950) include Sinaloa in their coverage, but
without specific details. Other than the papers by Shreve and
Gentry, there are no detailed treatments of the flora of the state
available at this time.
Because of the paucity of information pertaining to the vegetation
of Sinaloa, we were faced with several problems in our attempt to
present a vegetational classification that would be useful in interpreting
the distributional patterns of the fauna and still meet the
demands of most plant geographers by presenting a classification
of the vegetation by type, rather than a classification of animal
habitat based on vegetation, as proposed by Duellman (1965:640).
Difficulty was encountered in those areas where the natural vegetation
had been cleared and the land currently is being used for agricultural
purposes. Agricultural development has been favored by
the availability of hydroelectric power, and water resources made
usable by the recent construction of dams on the Rio Fuerte and
on the Rio Culiacan. As a result, large areas are under cultivation
from Los Mochis south to Guasave, and extensive tracts are being
cleared north and west of Culiacan, The floodplains of the northern
rivers are mostly devoted to vast fields of sugar, cotton, garbanzos,
tomatoes, and corn. In the agricultural areas the native vegetation
has been almost completely destroyed, and it is nearly impossible
to detect any changes in the physiognomy or composition of the
natural vegetation, if such changes did exist
A system of vegetation classification proposed by Holdridge
(1947:367-368) is utilized in this study. Holdridge contended that
a plant formation of a particular area is a reflection of the interaction
between mean annual precipitation and mean annual biotemperature
with respect to the amount of evaporation and transpiration.
With the aid of the chart presented by Holdridge
(1964:18), Sinaloa can be conveniently divided into five bioclimates.