Vol. 1(2) SEP 2011 - SAVAP International

Academic Research International
ISSN: 2223-9553
Volume 1, Issue 2, September 2011
degradation shows first an increase then later a decrease when plotted against some other
independent variable.
Patel et al (1995) studied smallholder wood production and population pressure in the central
section of the Murang district in Kenya , in the highlands north of Nairobi . Wood trees are
grown here in woodlots, on land borders, or (intercropping) in fields of maize and beans
(maize and beans are the stable food crops, but vegetables and non-food cash crops are also
grown). Both wood trees and fruit trees are used for erosion control on steep slopes.
In this district there had been considerable environmental degradation: Soil erosion has long
been recognised to be a serious problem, being caused by a combination of factors - high
rainfall, steep slopes and intensive cultivation. At the same time, population pressure has led
to farm size reduction through inheritance.
The research method involved modelling simulations based on data collected in five rounds
of surveys in 1991/92 of 115 randomly selected households. In this work, number of trees is
the dependent variable. The independent variables used were land area, fruit trees (which
might be a proxy for the amount of highly sloped land), labour and expenditure per capita
(the latter was a proxy for income).
The elasticities associated with each independent variable were:
Land: 0.36; Fruit trees: 0.19; Labour: 0.4; Expenditure per capita: 0.24.
While the expenditure variable was important in size (as measured by its elasticity), it was
not significant, but the other variables were significant.
As far as the land variable is concerned, households with greater land area are likely to have
more trees. However, the elasticity of the expected value of the number of trees grown with
respect to land is less than one, indicating that households with less land grow more trees per
acre, if the other variables are held constant. The elasticity further implies, say the authors
that if the other variables are held constant the number of trees per acre will increase as land
is subdivided - the predominant form of land transaction.
However, the other variables are not constant as land is divided. Further investigation by the
authors nevertheless suggested that with decrease in parcel size, while the expected number
of trees per household falls, the expected number of trees per acre rises. Indeed, the authors
say they expect to see an increase in total tree cover as farm size decreases even to one-fourth
of its present level. They conclude that the results are analogous to the EKC where
environmental degradation is shown to worsen, then improve, as per capita incomes improve.
And their more general conclusion was:
“The existence of a persistent fuelwood 'gap', and the notion that population pressure will
lead to declining tree cover, are not supported by the analysis. A simulation model indicates
that as land continues to be subdivided tree cover may actually rise, a result consistent with
other evidence of an 'environmental Kuznets curve'”.
However, the authors caution against being too optimistic about eventual environmental
consequences. They say “there still exist at least three potential market failures that would
give rise to suboptimal tree stocks in East Africa”.
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