Structural and functional attributes of the plant community in a non-saline depression of north-western Egypt

Abstract

Sub-samples of organs in the different life forms of the community were used to evaluate the contents of organic components and mineral nutrients. These were then integrated to provide the general functional attributes and structural features of the community. The study indicates that the bulk of biomass is from the woody life forms. The calculated net primary productivity reflects a low growth rate (on a ground area basis), although the relative growth rate (on a shoot biomass basis) is rather high. The production of organic components and uptake of nutrients are related to growth and phenological activities, with a general increase towards the peak of vegetative activity, especially for total non-structural carbohydrates and crude protein contents. Variations in the protein to carbohydrate ratio indicate that the community is operating on the basis of conserving and storing carbohydrates while minimising losses of complex organic compounds and meagre nutrients through litter fall, although differences do occur among the life forms. The maintenance respiration is estimated at about three-fold the calculated annual net primary photosynthate fixed by the community. It is concluded that the plant community is capable of both physiological reactions under favourable environmental conditions, and survival tactics to withstand harsh conditions, thus displaying a relative stability in its ecological performance.