I. General introduction to the field of research

1. Geographic data

New Caledonia is located between the 19° and 23° of Southern Latitude and the  164° and 167° of Eastern Longitude.
Habitat: SE of the Grande Terre; Plaine des Lacs, map no. 4837, Série orange of the Institut Géographique National.
Area: Chutes de la Madeleine.

2. Climate

The climate is tropical oceanic.
Annual precipitations range from less than 1000 mm for the western coastal areas up to 4000 mm for the mountain range of Mt. Panié in the north, the Massif de Kouakoué and the Mt. Humboldt in the south.
The amount of precipitations for Plaine des Lacs range from 2000 mm to 3000 mm.
Due to the oceanic situation the average temperature is well-balanced. At Nouméa it ranges from 22° to 24° C.


3. Soil

Predominating are magnesium iron silicates and their weathering products, recognizable by their intensive russet colour.
Layers of this soil called serpentine often reach great thickness or can be found in all types of transition to bare rock.
This soil and the intensely tinging dust characterize one third of the island and the landscape of the Plaine des Lacs.
The ultra alkaline-rocks or peridotites, with a content of silicate less than 45%, are characterized by calcium deficiency and dependently by lack of phosporus, aluminium and alcaline earth metals (especially potassium).
In contrast, they are rich in iron and magnesium and partially the content of heavy metals like chromium, nickel, cobalt and manganese is high, conditions that surely affected the evolution of the flora.
Since 1875 until now the mining of nickel continues, the most important raw material.
Therefore the consequences for nature that are to be expected are grave.
Prospection and road construction might rapidly destroy the lightly spread out vegetation and the thin humus layer so that  intense and irreparable erosion will occur.