Rit Landbúnaðardeildar : B-flokkur - 01.06.1957, Blaðsíða 33

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Summary.
An Ecological Survey of Gnúpverjaafréttur, Iceland.
Gnúpverjaafréttur is a strip of land west of Thjórsá river in South Iceland, ex-
tending north-east from the border of the farming district towards the interior
the country. This land is used as a common grazing for sheep in summer. It was
surveyed in 1955; the field work was carried out with the aid of aerial photographs.
The present report briefly describes the geology of Gnúpverjaafréttur and out-
lines its soil and climatic conditions (chapters 2, 3 and 4).
Each of the major ecological units, or plant associations, found in this area
are described (chapter 5). On the accompanying maps are indicated, with the aid
of four colours, the four major land types of the area: (1) mineral soils, (2) bogs,
(3) moss or Grimmia heath and (4) sandy, gravelly or rocky areas without any
vegetative cover. Within each land type with vegetative cover, the existing major
plant associations are defined and given special symbols, the key of which is printed
on the maps.
The number of the plant associations, or mapping units, is as follows: 11 plant
associations of mineral soils, 9 plant associations of bogs, and 4 moss heath as-
sociations.
The purpose of the present survey primarily is:
1) To get a fairly accurate picture of the present vegetative status of the range
land area in question, that could serve as a check, if one wishes to measure
changes in vegetative cover, that may take place in the course of time.
2) To obtain a primary basis, on which estimates of carrying capacity could rest.
In order to make such estimates, the carrying capacity of each particular plant
association would have to be determined. Such studies, however, are outside
the scope of the present work. In table 2 the total area of each plant association
is listed.
A few analysis showing protein, phosphorus, calcium, and potassium contents
of various range plants, collected at different stages of maturity, are listed in tables
4 and 5. The value of such analytical data for the estimation of nutritional value of
the plants in question, however, may be limited.
Chapters 7 to 9 deal with the nutritive or grazing value of single plant species
and plant associations. A few supplementary studies that are required in order to
make full use of the accompanying maps are mentioned.
In the last chapter a qualitative comparison between the vegetative status of
the range area in question in the summers 1940 and 1955 is made by Mr. Steindór
Steindórsson, who visited Gnúpverjaafréttur during both these summers.
Heimildarrit.
Bergþórsson, Páll (1956). Fræðslurit Búnaðarfélags fslands nr. 21: Hvernig er
veðrið?
Jóhannesson, Björn (1956). Rit Landbúnaðardeildar, B-flokkur, nr. 8.
Kjartansson, Guömundur (1943). Árnesinga saga I, bls. 161—162. Reykjavík.
Mölholm Hansen, H. (1930). Studies on the Vegetation of Iceland. Copenhagen.
Pjeturss, Helgi (1910). Island. Handb. d. reg. Geol., Bd. IV.
Steindórsson, Steindór (1945). Studies on the Vegetation of the Central Highland
of Iceland I. The Botany of Iceland. Copenhagen.
Steindórsson, Steindór (1952). Studies on the Vegetation of the Central Highland
of Iceland II. Handrit.
Vigerust, Yngvar (1949). Árbok for Beitebruk i Norge 1946—47, Bind XVIII.
Vik, Einar (1953). Norslc Fjellbeite, Bind VIII.