BOTTLE REFORESTATION – Part 1 (Willem Van Cotthem)

BOTTLE REFORESTATION – a new method to combat desertification

PART 1 : From cutting to young tree

All over the world tree nurseries use plastic bags (mostly black ones) to grow tree seedlings.  Generally speaking, these seedlings are taken to the plantation site in their plastic bags, where the bags are cut open and the root ball is positioned in the planting pit. During that rough handling, the root ball is usually broken and the roots damaged, causing a lot of difficulties to get the seedlings growing due to transplant shock.

It is well known that many people, after tree planting in the field, do not take care of those useless pieces of plastic bags, which are then left (littered) at the planting site.  That is one of the reasons why one can find plastic nursery bags almost everywhere at plantation sites, polluting the environment (trees are blooming with colored bags).

Considering the heavy pollution load of plastic bags on the environment, and considering that billions of plastic bags are used every year at the global level, we have been looking for a more efficient and cheap alternative.

Experiments with plastic bottles showed that this can be an interesting solution to:

(a)   Reduce the damage to the root system at planting time.

(b)  Reduce the volume of irrigation water needed to keep the seedlings alive (higher water use efficiency WUE) before and after transplantation.

(c)   Enhance biomass production in a shorter period (stronger seedlings).

(d)  Enhance survival rate of the tree seedlings.

(e)   Enable reforestation at the most hostile locations.

(f)    Avoid pollution of the earth’s surface with plastic nursery bags.

Tree seedlings grown in bottles can very easily be transported to the plantation site without significant damage to the plants and their root system.  This makes this method very interesting for large-scale afforestation or reforestation programmes.  Therefore the method is called “bottle reforestation” or “bottle afforestation”.

Different variants of growing tree seedlings in bottles can be used.  The first will be described below, others will follow.

Growing seedlings in plastic bottles – Variant 1

The simplest method is illustrated in a few steps:

2010 – Fruit juice bottle 15 cm (6 inchs) high

2010 – Two perforations 2,5 cm (1 inch) above the bottom let a possible surplus of irrigation water run out of the bottle (to avoid acidification of the potting soil inside and to avoid asphyxiation of the roots)

2010 – Willow tree (Salix matsudana) cuttings, rooting in water for 1-2 weeks

2010 – Rooted willow cutting planted in plastic bottle filled with potting soil. Only a minimal quantity of water is needed to keep the potting soil moistened for a very long period (almost no evaporation).

2010 – Soon after planting the cutting in the bottle new shoots are formed and many new roots are growing towards the bottom of the bottle.

2010 – In less than 1 month a young willow is developed, ready to be planted.

Published by

Willem Van Cotthem

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