Table 4 Summary of similarities and differences between the two study areas

Terrain

Moderately steep

Low elevation mountains

Geology

Cretaceous and Tertiary rocks, mudstones, sandstones, argillites

Jurassic and Cretaceous sedimentary rocks, marls

Climate

Rainfall 1000 – 2500 mm

Mountainous with Mediterranean influences

Susceptible to cyclones

Mean annual rainfall 850–1000 mm

Convective storms in headwaters

Historical deforestation - when

Some pre-1800’s most late 1800’s and early 1900’s

Neolithic period

15^th and 19^th centuries human-induced erosion

Historical deforestation - why

Some vegetation clearance by Maori pre-1850

Climate change and agriculture expansion

Widespread vegetation clearance by early Europeans 1880’s

Industrial demand for wood

Recognition of “problem”

Early warnings 1920’s

Early 19^th century

Big floods 1938-1947

Late 19^th century hillslope erosion, head water channels aggrading

Policy intervention

Soil Conservation and Rivers Control Act 1941

Reforestation in mountains 1860 – Restauration des terrains en Montagne Act (RTM)

Catchment Board 1944

Other laws to control erosion 1864, 1882

Demise of New Zealand Forest Service 1987

Erosion control programme lasted 50 years up to First World War

East Coast Forestry Project 1993

Revegetation

New Zealand Forest Service plantings 1960’s

Species used - Pinus ngira J.F.Arnold

Species used - Pinus radiata

Protection forests 120 - 140 year old trees

Protection/production forests

30 year old trees before harvesting

Landscape response

Observations of hillslope processes slowing 1980’s - 1990’s

Decrease in sediment yield

Headwater channel responses 1990’s

River incision

Main channel responses not observed but constant

Reduced flows in some rivers

Channel interventions

Raising stop banks

Dams

Gravel extraction