Biology of Dryland Plants
Mandujano, Maria .
Demography of dryland plants.
Size-stage classified population matrix
models have been used to describe the structure and dynamics of
desert plants and to explore how spatial and temporal environmental
heterogeneity influence population dynamics. Matrix models provided
complementary information on population dynamics and the life history,
and even though
the potential of these models has been demonstrated, demographic
studies of desert plants are scarce. Summarizing the
available information, the finite rate of population growth (l)
varied among species, but generally yielded l
micro endemic rare species are an exception were l
Dominant elements or invasive species under some particular rainy years
shown l > 1,
and shrub species
fluctuate among years or sites from low l < 1
to huge population rates of increase (l ca.
Reproductive value increased monotonically with plant size with few
exceptions, but dominant landform species produced orders of magnitude
more offspring than rare species. Prospective analyses showed that
sensitivity values were highest for sexual recruitment in all
populations, suggesting environmental bottlenecks in these transitions.
Absence of recruitment in succulent species is the most common pattern
reported whereas woody species show low, but constant recruitment.
Elasticities summed over size-classes or demographic processes differed
widely between years, habitats and species. In general stasis show the
highest elasticities and sexual recruitment the lowest. However
plotting elasticities of different species in GLF demographic triangle
indicate that species with clonal propagation shifted upwards in the
triangle (increase growth with respect to survival). Matrix models
aptly summarize the striking
spatial and temporal differences found in the structure, population
dynamics and life history traits of desert plants. With sufficient
demographic data, these
models can be used in decision making to preserve threatened species,
fix carrying capacities and to assess the effects of different factors
(e.g. interactions) on population dynamics.
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1 - Universidad Nacional Autonoma de Mexico, Instituto de Ecologia, Ciudad Universitaria, A.P. 70-275, Mexico, D.F., 04510, Mexico
arid and semi-arid environments
matrix population models.
Presentation Type: Symposium or Colloquium Presentation
Location: Salon K - Austin Grand Ballroom/Hilton
Date: Wednesday, August 17th, 2005
Time: 3:30 PM