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2) A high percentage of soil nutrients is not readily
available to plants, particulwly in the mt , acid,
leached crganic soils of the Lake District, either
because, nutrion Es are in resistant or~anic mztter 'in
peat, or in soil horizons below the rooting zone, of
herbage species. Perhaps t h rzte ~ of removal of
nutrients in sheep ought t o be related to tho rate
at which nutrients can be supplied to herbage plats
from the rooting zone rather than to the total soil
nutrient pool.
Although Rams &kdelch (1969) gathered
a vast amount of data on the sheep arid vegetation at Moor
House they mere forced to state that .,..I1
as little is
known about other factors such as uptake of nutrienks by -
roots at hbor House, it is at praaent inpossible to
de-terruine whether individuu swards or vegetation types
are declinir,~ in their stock of minerals and nutrientsn,
3) Although levels of removal are currently low in relatio&to
nut liont a in precipitation, this fact doea fiat necessarily apply
during the psst few hundrod 9 ers.
In this period not mly
is the record of sheep densities inoomplat& but also data
on nutrient inputs are 1mlcing.
Composition of precipi-
tation is known tc v~ry with the because of factors suoh
aa changes in air pollution and d nd direction,
We 'canncb
therefore assess accurately the imporbance of removal of
nutrients by animal a in the past.
Effects of agficultuml vehicles
Damage to soil and vegetation by wheeled and tracked ~ehiclea may be
conaidexlable on and around well-used tracks especially where the soil
is wet. The effects include many of those already mentioned in
association with trampling by animls,