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harmless and it is the subsequent logging operations
~ i c h increase sail erosion and strer:n turbidity (~rness,
1967; Packer, 1967). Likens et al., (1970) studied
effects of clear-felling an am. of a e d har&mods ~12th
sms pine and fir in north-east USA. Their eqerimental
area had a continental type of climate but in sane respeots
resembled parts of tho Lake District . Altitude ranged
f'rm 229-1 006 m, rainfiill was about ? 23 cm cnd the soil
was acid podzolic glacial till overlying acid metafnarphic
rock. The =in results wem as follows :
I , hual run-off of wzter increased by 39% in the first yea
and 2% in the second year afiw clearfelling over the
values expected if the forest had not been cuk.
Particulate matter in streamv'ratcr incr~zsed from about
25 kg to 100 kg ha-', with an increase in inorganic
particulate matter from about a half t o t hree-quarters
of tho total.
Concentrations of a11 rn j or ions, except ammonium, sulphat e
and bicarbonate, ftl the stremwater increased five months
nrter deforestation, Nitrate shm ed a 41 -fold and 56-fold
horease in the first 2nd second years rcspctively afier
clear-felling.
4. The incroase ii cat ions was explained by a change in the
nitrogen cycle jn the forest system, In the un3isturbd
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system, any nitmte produced during decomposition of plant
rewins was conserved by uptake by plerrt s but *en the
vegetation tvss removed, nitrate plus associated cations were
readily washed out of the aoil.
Wdrogen ions replace& the
cations in bErth the deomposhg organic natte~ and on
inorganic material 3.