Research Results - (PDF, 101 mb) - USAID

arley supplement, and suggests that it would
be worth exploring the availability of cheaper
equivalent feeds.
Dietary Intake on Alfa Grass Vegetation
The grazing study to determine intake,
diet composition, and diet quality of small
ruminants utilizing Stipa tenacissima(alfa grass)
vegetation at El Faijah, as described in last year's
annual report, was repeated again in 1990. Due
to normal variability in animal grazing behavior
and high annual variability in type and quantity
of forage available on semi-arid rangelands, it is
scientifically prudent to conduct range grazing
trials for at least two, preferably three, years.
[Some journals will not accept papers for publication
based on only one year of grazing trial
data.] The data collected from this study in
1990, however, appear at the initial analysis to
be anomalous, especially with regard to the
proportion of alfa grass in the diet at different
seasons of the year. The computer data records
need to be verified with the raw data sheets, and
the data analysis or field data collection procedures
need to be checked, before any of the
results can be reported.
Response of Two Stipa species to Defoliation
Data analysis was finally completed by
Brahim El Bare (studying under Omar Berkat)
on a study to evaluate the responses of two Stipa
species to different defoliation regimes, S.
tenacissima(alfa grass), a coarse and relatively
unpalatable grass dominating much of the semiarid
steppe, and S.barbata,a palatable forage
species in the alfa grass community. The experiment
was a factorial design of four clipping
intensities (clipped at the leaf ligule, 50% of the
blade, 25 %of the leaf blade, and a control) and
four clipping frequencies (interals of one, two,
four, and six weeks beween defoliations). This
was a pot trial conducted over a three-month
period in the winter of 1988-89 with transplants
from the Plaine de l'Aarid experimental area
near Midelt; the pots were not irrigated during
the experiment.
The results showed that S.barbatahas
more tolerance of defoliation than S. tenacissima,
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due to a greater ability to replace leaf tissue
removed. Rate of leaf elongation for S. barbata
was two to three times higher than for the alfa
grass, and the former species was able to retain
more of its leaves. S. barbata'stolerance of
defoliation extended to the most severe treatment.
As might be expected, the harvested
phytomass decreased with increasing frequency
and intensity of defoliation, but cumulative
phytomass increased with more frequent clipping,
though not with more intensive leaf
removal.
Community Dynamics and Regeneration of
Alfa Grass
Although alfa grass may not appear to
be a very desirable rangeland species in North
Africa, given its low value as livestock forage
and preemption of soil resources, it plays an
important ecological role of stabilizing areas
that it dominates against site degradation. At
places in the semi-arid zone of Morocco where
the alfa grass has been removed by repeated
burning or long-term heavy grazing, harvested
for fuel, or cleared for cultivation, the soil is
highly vulnerable to erosion. One cannot rely
on other desirable perennials, such as Artemisia
species, to fill the niche vacated by a diminishing
alfa grass population. Therefore, rather than
looking for a substitute for alfa grass on semiarid
rangeland, a more rational strategy may be
to enhance the productivity of more palatable
species associated with the alfa grass and manage
the range to preserve the integrity of alfa
grass dominance. We know from observation
that successful establishment of alfa grass from
seedlings is a rare occurrence, and the species is
a poor colonizer of new sites. Thus it is important
to know the ecological factors that favor
viable seed production and seedling survival of
Stipa tenacissima,and to understand the germination
characteristics of the species.
An ongoing study to improve our understanding
of the regeneration of Stipa tenacissima
was continued in 1989-90 at the Plaine de
l'Aarid research station. Seedling emergence
and establishment are being followed in fifty
1m 2 permanent plots arranged along five
transects (10 quadrats per transect) in an alfa