Impact of Humans & Environment on Forest Distribution in Southern Cape
This is a summary/introduction to Ryno Joubert’s article ‘The Impact of Humans & Environment on Forest Distribution in the Southern Cape’.
According to studies, forests are found in areas that receive annual rainfall ranging between 525 mm and 1220 mm. If you look at the southern Cape forests, it can be noted that there is no relationship between rainfall and the distribution of forests in the area. This suggests, to some people, that humans changed the area through over-exploitation. It has been suggested that much of the forested area from the Cape Peninsula to Port Elizabeth has been cleared since 1652 (arrival of European settlers), and that destruction by humans is the reason for the fragmented nature of the forests today. Many people also believe that if an area’s climate is ideal for forest growth (>500 mm annual rainfall), the whole area (coastal plateau and sea-facing mountain slopes) will be covered in forest, and that areas where human activities are currently taking place (agriculture, plantations etc.) were covered with forests originally.
The purpose of this article is to prove that the distribution of the southern Cape indigenous forests, as it is today, did not change very much since the arrival of man to the area.
Many people today believe that the whole area (From Mossel Bay to Tsitsikamma) was covered in forest, but this was in fact not the case. Small patches of forest and forest margins (edges) were destroyed over the years, but this is very minimal compared to the size of the whole area’s forests.
HISTORICAL FOREST DISTRIBUTION IN THE SOUTHERN CAPE
Palaeontological evidence suggests that forests, woodland, grassland and fynbos have occurred in mosaics over the past 10,000-20,000 years. Forests expanded during wetter periods, and shrank during drier periods. Nevertheless, fynbos, grassland, woodland and savanna have become more prominent over the last couple of thousand years due to an increasingly drier climate as they are better adapted to arid conditions and fire, which has played a major role in determining the pattern of forests. Written accounts by European travellers over the past 400 years describe a situation not very different from that found today. This does not mean that there hasn’t been forest destruction by humans. It is just that the scale at which this took place is much smaller than is generally believed.
FACTORS LIMITING FOREST DISTRIBUTION & OCCURRENCE
There are two factors that limit forest occurrence and distribution:
1. Environmental factors: The potential of an area to sustain forest growth is determined by rainfall, temperature and geology, but the actual occurrence and distribution patterns of forest in the area is determined by fire.
2. Human factors:
– Before the arrival of settlers: Groups of San hunters occasionally smoked animals out of the forests during hunts, and this could have been the cause of some forest fires in the past. The Khoi people were pastoralists and frequently burned the veld to obtain grazing for their cattle.
– Since the arrival of settlers: Grazing, exploitation, clearing, man-made fire and plantations.
SOURCE OF MISPERCEPTIONS ABOUT THE DISTRIBUTIONS OF FORESTS
Photo credit Lak van der Merwe
The occurrence and development of forests is determined by several habitat factors such as climate (of which rainfall is the main determinant), geology, fire and the sub-soil moisture regime. Yet many commentators and historians (past and present) still consider rainfall to be the determining factor, without taking other factors that restrict the development of forests into consideration. The first complete vegetation classification for South Africa, attempted by J.P.H. Acocks in 1953 (‘Veld Types of South Africa’), has probably contributed to the perception that the southern and eastern coastal belts were covered in forest around 1400AD. His book included a map with the title ‘Vegetation in AD 1400?’. Sadly only a few people notice the question mark at the end of the map title, and realise that both the book and map are based on assumptions. This assumption was, in all likelihood, based on the rainfall potential. (Stehle, 2007)
THE TRUTH ABOUT FORESTS
The true situation regarding the distribution of the forests is discussed under two subheadings:
1. Historical proof: Includes descriptions by early explorers who travelled through the Cape during the late 1700’s, historical maps, sketches and paintings.
2. Scientific proof: Includes findings of studies done in the southern Cape over recent years by various scientists that provide evidence about the occurrence and distribution of indigenous forests (past and present).
In order to read the full, detailed article, go to the following link: