ON THE WATER RELATION IN LIMESTONE AND DIABASE VEGETATION IN THE LEEWARD ISLANDS OF THE NETHERLANDS ANTILLES

Abstract

In a same macroclimate on the islands of the Leeward Group of the Netherlands Antilles two types of vegetation are chiefly found. A vegetation pertaining to the dry evergreen formation series on limestone and a vegetation on diabase belonging to the seasonal formation series. Study was made of the water relation at the end of the rainy season during which transpiration, water deficit, suction pressure and soil water were investigated. From the course of transpiration curves it was concluded that water relations in diabase soil are more sever than those in the limestone. Water deficit in plants, growing on diabase appears to be much higher than those of limestone. Suction pressure divergates strongly in both cases. In the upper soil layers the amount of water that can be taken up by plants is small both in limestone and diabase. In deeper layers of the limestone soil there is more water than in diabase of the same level. Vegetation on diabase is determined by a sufficient amount of water in the soil during the rain season and a great drought during the other months. On the other hand in limestone the amount of water in the soil is larger during a longer period. Because of the higher suction pressure of this soil only plants developing a higher suction pressure can occur.