Tropical Gardening: Colombia’s drylands expanding

By NORMAN BEZONA Professor emeritus, University of Hawaii College of Tropical Agriculture and Human Resources | Sunday, September 15, 2019

Desertification is nothing new to the world, but global warming combined with human activities is accelerating this phenomenon.

The old saying “rain follows the forest and desert follows man” is rather depressing, but it doesn’t have to be if we understand how deserts are created and how we can reverse the process.

It is difficult to do much about another country, but we can learn from mistakes made in other places to make sure we don’t repeat them. Luckily, we live on a relatively big island. Our population is small and we have a sense of aloha aina, so let us focus on our own gardens.

A garden planted with no thought given to dry spells will do well in rainy periods but deteriorates without irrigation in dry periods, even in East Hawaii.

Fortunately, many garden plants in Hawaii are fairly hardy when it comes to short water supply, so we have a long list to call upon. It’s important to vegetate these areas so that our islands don’t look like Death Valley in years to come.

There are two factors that make these plants able to survive moisture stress.

First, some plants are notably resistant to drought. This quality is centered largely in the cellular structure and has a bearing on the economy with which the plant functions.

Some plants have the ability to carry through extended dry periods because of a happy faculty of closing the pores of the leaf against transpiration, or turn the leaf back or edge-on to the sun. Others root deeply to tap and have available for dry periods any accumulated moisture of sub soil. Our native Acacia koa is an example.

The garden environment is the other critical factor.


Author: Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.