Permaculture Designers Manual

 

CHAPTER 10 –

THE HUMID TROPICS  IN PERMACULTURE

Section 10.7 –

Integrated Land Management in Permaculture

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The Maori marae or Hawaiian ohana were geomorphic and sociological units in which land and people were integrated for sustenance.

They may have evolved out of early errors of over-clearing, excessive burning and the extinction of useful animals before reaching equilibrium.

We can only hope that the modern world also has time to take stock and come to its senses, but that will rely on determined change by many thousands of us within society.

Presuming a hill-to-shore profile (often a volcanic cone profile, Figure 10.28), the stable tropical landscape may require some or all of these features:

PROTECTED SKYLINE AND HILL FORESTS

These not only protect soils and waters, but both mine and release plant nutrients from the upper (sometimes steep) slopes.

They can be used as a limited forage resource and mulch provision, but should have iron-clad protection.

Their clearing brings compound catastrophes ranging from landslide to loss of nutrient in water and crop, desertification and consequent severe social disruption.

At the base of these forests, as the slope eases to 15° or less, water can be diverted or harvested to replenish groundwater and irrigate terraces and crops.

 

MIDSLOPE OR KEYPOINT

A diversion of stream water here will lead water out to ridges for terrace crop and village use.

Thus, cropping commences below this critical point. Human occupation and complex cultivated forests and gardens can now be established down slope.

The stable plateau, the hill rising above the valley and bench sites above the reach of flood and sheltered from hurricane and tsunami are prime cluster settlement (village) sites, with some scattered housing higher on ridges and the forest edge.

LOW SLOPES

(2°-15° slope) are well suited to earth-shaping as terrace and paddy, with limited grazing and innovative forestry.

These are the sustainable agricultural areas, where attention to sub-contoured agriculture, windbreak and access will help divert run-off and water to crops.

 

COASTAL FLATS AND VALLEY FLOORS

Rich and often deep humus soils can accumulate on valley floors.

Greywater and processed manures from settlement and livestock add to fertility, where extensive aqua-cultures or rich forest/orchard crop can be developed.

SHORELINES

Preserved for 100m (330 feet) or so inland for essential windbreak, shore stability and cloud generation over land.

Selected quiet harbors and refuges accept fishing settlements based on sea resources.

Shorelines with 15-20 year tsunami history need sacrificial palms (Casaurina) barriers to reduce storm damage.

There may be lightly-built and temporary shore housing, which is used only when working the coast, with more substantial homes and sheltered gardens safely inland or behind earth embankment.

If shallows or a coral-based lagoon / reef system stretches offshore, the following categories of use also apply.

 

LAGOON AND ESTUARY SEA IMPOUNDMENTS

Ancient and yet innovative sea-walls (usually of semi-permeable coral blocks with entries, flood-tide gates and a series of inner pens) are an excellent use of the shallows.

Restricted mangrove plantations help stabilize the banks and provide sea mulch while catching any silt that washes down from above.

These warm-water lagoons are rich in algae and are good sites for cultivated seaweed.

They also impound and fatten mullet and mangrove fish, oysters and eels, shellfish and prawns.

In the sea lagoons, mobile phosphates are fixed in plants and mud in a few days and are then available for growth.

Such rich estuaries are invaluable as managed mari-cultures.

 

MARINE CONSTRUCTS

Artificial reef systems of tires (on sand), coral blocks and boxes of palm trunks greatly enlarge the habitat for sedentary fish and lobsters; within a year, these constructs are consolidated or cemented by corals.

Weak electrolysis on metal mesh creates an artificial but permanent coralline deposit more rapidly. In extensive sandy shallows, log barriers full of sand and stabilized with mangroves provide shore barriers, lagoon walls, and “edge” in the sea.

It is as well to have an integrated concept of appropriate land use in mind for both broad policy planning and future land redistribution.

There are slow moves in present government circles to institute some sanity into life and landscape as (like agriculture) government must change towards an environmentally sound policy.