الفهرس 
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Abstract
The present investigation was carried out in the north western coast zone of Egypt at zweida region(about km west Marsa Matruh) during
the period extending from spring till autumn under rain fed
condition.the objectives were to evaluate two main factors. These were:
) Plant communities as indication to the effect edaphic factors. Five
plant communities considered as the more spreading nes in the zweida
area and represent five different edaphic conditions i.e.;
a) Community of Hammada elegans (Haloxylon salicornicum
Bioss):Representative to the fine gravel clay and considered as the inner
land salty soils.It dominated by this plant species.
b) Community of Hammada –Gymnocarpos:
Representative to the bigger gravel clay. It dominated by these two plant
species.
c) Community of Hammada –Gymnocarpos –Thymelaea:-
Representative to the gravel clay but the size of gravel bigger.It
dominated by this plant community.
d) Community of Hammada- Peganum:-
Representative to the fine sand on the surface and occupy the low site of
land. It dominated by this community
e) Gymnocarpos community :-
Representative to the rocky land. It dominated by this plant community.
- season of growth:-
Two growth seasons were chosen representative to different
rainfall regimes as follow:-
a) Autumn season:
Data recorded during September. Since no rain fall was occurred.
b) Spring season:
Data recorded during April. Since higher amount of rain fall was
received. Ten list and counting quadrates were used to study the natural
vegetation in relation to the above mentioned factors i.e. plant
communities and seasons of growth.
The placement of the quadrates was chosen randomly vertically on
the vegetation gradient in land. The following measurements were
determined in order to evaluate the vegetation qualitatively and
quantitatively:
) Botanical composition:
) Plant density:
) Plant coverage (% )
) Plant frequency (%)
) The importance value
) Fresh foliage yield :-
) Dry forage yield :-
) Chemical content -
a) Crude protein (%):-
b) total carbohydrates (%):-
c) Crude fiber (%):-
d) Total ash (%):-
e) Ether extract (%):-
) Physical and chemical properties of the soil of the studied area.
The main results of the study could be summarized in the
following:
. Over the studied plant communities, in year, spring season,
significantly showed plant density /m, four times the recorded value
in Autumn season (
vs for Spring and Autumn season,
respectively).
. in year, the recorded plant density /m in Spring season
significantly reached more than six time the corresponding value in
Autumn season ( vs. for spring and Autumn seasons,
respectively).
. Over the studied seasons, similar plant density /m had expressed by
the different studied plant communities in year. On average
about
plant /m had presented by the studied plant communities.
While, in year, significantly high plant density had expressed by
both of the plant community of Hammada- Gymnocarpos and
Hammada- Gymnocarpos- Thymelaea ( and /m for the
former and the latter, respectively). Meanwhile, the least significant
plant density had presented by the community of Gymnocarpos
community (
plant / m).
. In year, It was obvious that the plant density in Autumn season
was greatly smaller than those recorded in spring season the highest
recorded value for Gymnocarpos community reach about ten times
the least recorded plant density of the same community in Autumn
season.
. Although of that this difference had considered unsignificant,
probably because of the nature of sampling error
. Percentage of plant cover in the study site was highly significantly
affected by seasons. Meanwhile, the differences among the studied
key plant Communitys had not reached the level of significance. Also,
the interaction between seasons and plant Community was un
significant, indicating that Communitys plant cover was similar
irrespective of the time of the year (season) or the rank of each
Community plant cover within each of the study seasons was sTable
. Gymnocarpos community exhibited relatively higher plant cover
among the studied key plant communities, although, it failed to reach
a significant rank. Other plant communities i.e; Hammada- Elegans,
Hammada- Gymnocarpos, Hammada- Gymnocarpos- Thymelaea,
Hammada- peganum and Gymnocarpos, expressed similar plant cover
around three percentage.
. The studied plant communities (Communitys) were significantly
similar in both years of the study. Also, the response of percentage
plant frequency to variable season plant Community interaction, was
unsignificant.
. Over the studied key plant communities, plant frequency in Autumn
season was significantly surpassing that recorded in Spring season
( and
; and for Autumn and Spring seasons
in the years of and , respectively). The magnitude of
percentage plant frequency in Autumn season significantly reached
about four times the recorded values in Spring season over all the two
years of the study.
. Over seasons, the studied plant communities, exhibited similar
percentage plant frequency amounted to about and
% in the
years of and , respectively. Exceptionally, the plant
community of Hammada- Elegans showed a percentage plant
frequency of
%. This high figure failed to reach the level of
significance. This might due to the large size of sampling error.
. Irrespective of the unsignificant effect of the interaction in both
study years, the studied key plant communities had as much
percentage plant frequency in Autumn season as twice the recorded
figures in spring season of the year and . Also, the
community of Hammada- Elegans, recorded as much five times
percentage plant frequency in Autumn season as the recorded value in
spring season of the year (
vs. for Autumn and
spring season, respectively).
. Relative density of the studied plant communities, significantly
increased in Autumn over spring season in both years of the study
( vs.
and
vs.
for Autumn and spring seasons in
and year, respectively).
. Although, the recorded relative density for each studied plant
community in Autumn season was many times the corresponding
value in spring season in both study years, that difference had
considered unsignificant. It was valuable to notice that, the
community of Hammada- Elegans, exhibited the highest relative
density of
and
during Autumn season of and
years, respectively
. Although ,the recorded relative cover for each studied plant
community in autumn season of each of and years ,
reached as much as five times in year and six times in
year the recorded relative in spring season for the community of
Hammada Elegans, Hammada – Gymnocarpos and Hammada –
Gymnocarpos -Thymelaea or four times the corresponding
figure in spring season for the Community of Hammada –Peganum
and two to three times the corresponding figures for the Community
of Gymnocarpos ,those manifested differences were considered
unsignificant .
. In year, over th studied Communitys, the relative frequency of
the studied key Communitys in Autumn season had significantly
surpassed the recorded figure for spring season ( and
%
for Autumn and spring seasons, respectively). Also, in year, the
recorded relative frequency of the studied plant Communitys in
Autumn season was significantly higher than the recorded values in
spring season (
and
% for Autumn and spring seasons,
respectively). Common speaking, the relative frequency over all the
studied plant communities in Autumn season reached significantly
about four times the recorded values in spring seasons.
. Importance value provides information could help in determining
which species from which habitat type is the most adaptive and
tolerant one to environment condition
. Through perennial species the highest value of (IV) was achieved
by Hammada elegans, Gymnocarpos decandrum and Aristida
funiculate in both two studied years . Meanwhile, Medicago
aschersoniana, and Plantago notate and Trigonella stellata Gave the
superior (IV) among annual species in the two studied years.
. In year, over plant communities, spring season produced
significantly fresh forage about double the obtained value in Autumn
season( ) and ( g/m for spring and Autumn seasons,
respectively). Similar superiority in spring season fresh range
productivity had observed in the year of , although it had
considered unsignificant ( and g/m for spring and
Autumn seasons, respectively.
Regarding plant communities fresh range productivity over seasons
of study, in year, the community of Hammada- Gymnocarpos
thymealea significantly enjoyed the fresh range productivity of
g/m. The second significant fresh range productivity rank was that of
Gymnocarpos plant community (
g/m), which was significantly
similar to the other studied plant communities.
. superior fresh range productivity was obtained from Hammada
elegans and Hammada -Gymnocarpos plant communities ( and
g / m ) respectively . while the lowest fresh range product
obtained by Gymnocarpos decandrum plant community in spring
,meanwhile in autumn the highest and lowest fresh rang yield are
achieved by Hammada - Peganum and Gymnocarpos decandrum (
and
g /m ) respectively of plant communities .
. In year, dry range productivity of spring season reached
about double that of autumn season ( vs.
g/m for the farmer
and the later, respectively). As for, the studied key plant communities
over seasons, the community of Hammada- Gymnocarpos- Thymelaea
enjoyed the highest significant dry range productivity amounted to
gm. The other key plant communities significantly exhibited
lower dry range productivity ranged between g/m for the
community of Hammada- Elegans to
g/m for the community of
Hammada- peganum with significant similarity among them.
. In year the difference between spring and Autumn season in
dry range productivity was about the same to that noticed in year,
but, it had conceded unsignificant.
. In year, the highest significant dry range productivity had
recorded by the community of Hammada- Gymnocarpos- Thymealea in
spring season (
g/m). Meanwhile, the least significant dry range
productivity had recorded by the community of Gymnocarpos in Autumn
season (
g/m). A reasonable second rank in dry range productivity
had expressed by both the community of Hammada- peganum and
Gymnocarpos in spring season. In year, a wide unsignificant
difference had recorded between the community of Hammada- Elegans in
spring season (
g/m) and the community of Gymnocarpos at
Autumn season (
g/ m ) .
. in season, Hammada- Gymnocarpos- Thymelaea
communitypresed significantly the highest ash productivity (
g/m).
While, the other studied plant communities produced significantly
similar ash productivity ranged between g / m for Hammada-
Elegans community to g/m for Gymno carpos community. Also, in
season, the least ash productivity had produced by both of
Hammada- Elegans community ( g/m) or Hammada- Gymnocarpos
community ( g/m). Meanwhile, the highest significant ash
productivity was presented by Gymnocarpos community ( g / m).
The second significant ranke was occupied by both of Hammada-
Gymnocarpos- Thymelaea cmmunity ( g / m) and Hammadapeganum
community ( g/m).
. In season, the highest significant ash productivity was
exhibited by either Gymnocarpos community in Autumn ( g/m) or
spring ( g/m) season or Hammada- Gymnocarpos
Thymelaeacommunity in atumn season (
g/m) or Hammadapegoanum
community in Autumn season ( g/m).
. Over the studied key plant communities, spring season of
year, significantly (p ) out yielded Autumn season in
carbohydrates /m ( and
g/m for spring and Autumn seasons,
respectively). Similar carbohydrates productivity trend had observed in
season, although, had not reached the level of significance.
. Over seasons, Hammada- Gymnocarpos- Thymelaeaplant
community, had significantly surpassed all the studied key Community
in carbohydrates productivity in year. The magnitude of
carbohydrates productivity of that superior plant community reached
g/m. Meanwhile, the other plant Communities produced
significantly less carbohydrates of about g/ m. Also, distinguished
variations among the studied key plant communities had obtained in
season, although had not reached the level of significance
. In year, significant superiority of spring over Autumn season
in fiber productivity had recorded. The magnitude of spring fiber
productivity amounted to times that of Autumn season. In
year, although, spring fiber productivity was
times that of Autumn
season, it had not reached the level of significance.
. Over range productivity seasons in year the community of
Hammada- Gymnocarpos- Thymelaea gavehighest significant fiber
productivity of g/m. Meanwhile, the other studied key plant
communities produced significantly less fiber per square meter
amounted to about
g/m on average. In season, wide
difference in fiber productivity between Hammada- Elegans community
from one side ( g/m) and the other studied key plant communities
( g/m on average)
. In year, over the studied plant communities, spring
vegetations significantly yielded about two folds protein of that
produced from autumn season ( vs. g/m for spring and autumn
seasons respectively). In the meantime, the superiority of spring protein
productivity in year was unsignificant. Also, plant communities,
produced significantly similar protein from unit area reached about
and g/m in each of and years, respectively.
. Except for, the effect of seasons in year, the effects of
seasons, plant Communitys and the interaction between seasons and
plant Communitys had not reached the significance level in any of the
study years.
. Except for, the effect of seasons in year, the effects of
seasons, plant Communitys and the interaction between seasons and
plant Communitys had not reached the significance level in any of the
study years
. The analysis of variance for fat productivity of the studied plant
Communitys in Zweida region (North western coast of Egypt) during the
years of and . Season effect was highly significant (p )
in year. While that effect failed to reach the significance level in
year. In the mean time, differences among the studied plant
communities found significant (p ) only in year. The
interaction between seasons and plant communities was unsignificant of
both the study years .
. Although, Hammada- Gymnocarpos- Thymelaeaplant community
and Hammada- Elegans plant community had shown a noticeable
superiority in fat production during spring season of each of and
years, respectively. That level of production failed to express
significance.
. -T.D.N. Productivity had significantly (p ) varied with
season of estimation in year, but, not in year. Also, the
studied key plant Community produced significantly (p ) different
total digestible nutrients in year, only. The interaction between
season and plant Community had not reached the level of significance in
any of the study years.
. The effect of season plant Community interaction on total
digestible nutrients productivity (g/m) had shown in Table (
). In
study years, the rank occupied by each plant community in each season
was nearly constant. The difference in magnitude of Table digestible
nutrients productivity from spring to Autumn season was relatively
smaller than sampling error. This situation might be responsible for
unsignificant interaction. In year, the rank of the tested plant
communities varied with season, but, not to the level that make
asignificant difference because of the relatively similar productivity
magnitude, in most cases.