الفهرس | Only 14 pages are availabe for public view |
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. |