Does Shannon-Weaver Index Explain the Species Diversity in Home
Gardens?
Sharmila Sunwar
ABSTRACT
This paper is part of MSc thesis work on home gardens studied. The home gardens of
Durbar Gulmi (Mid-hill agro ecology) and Bharsa-Baikunthapur Rupendehi (Terai agro
ecology) were studied to examine crop species/varietal diversity in home gardens. The
study used the following techniques semi-structured interviews, direct observation and focus
group discussions to collect primary data. The diversity indices; Shannon-Weaver index
(SWI), Evenness index and Simpson’s index were employed to determine the species
richness, evenness and dominance of the species in the home gardens. Home gardens in
the Mid-hill agro ecological zone contained significantly (p=0.001) higher species diversity,
H’=4.41 (131 species) as compared to home gardens in the Terai H’= 4.25 (123 species).
Similarly, the species composition in Gulmi is more evenly distributed (J=0.906) as
compared to Terai (J=0.880). Looking at Simpson’s index it was observed that there are
more of few common species that have dominated in home gardens in the Terai (λ=0.018)
than in Mid-hills (λ=0.014). The study suggested that Evenness Index and Simpson’s Index
helped better interpretation of SWI in explaining species diversity in home gardens in the
Nepalese condition.
Key words: Species, Shannon Weaver index, Simpson’s index, Evenness index
INTRODUCTION
Home gardens are well-established land use systems within the larger farming systems in
Nepal, maintained very close to the homestead (Shrestha et al., 2002). The history of home
gardens are not well known in the Nepalese context, but previous studies from other parts of
the world define home gardens as traditional farming systems which are among the oldest
agro-ecosystems that exist throughout the world (Soemarwoto, 1987; Soemarwoto and
Conway, 1992). Species diversity that is of immediate use in the homestead is the most
prominent feature of home gardens (Soemarwoto, 1987; Hoggerbrugge and Fresco, 1993).
Many home gardens in other parts of the world have been studied and are highly
acknowledged for retaining high species diversity (Agelet et al., 2000; Eyzaguirre and
Linares, 2001; Nair, 2001 and Vogl-Lukasser et al., 2002; Trinh et.al, 2003).
In Nepal, the home gardens play a crucial role in supplying household members with a
diversity of different food crops (Rana et al., 1998; Shrestha et al., 2002). There is lack of in-
depth knowledge and information on species diversity in Nepalese home gardens. Most of
the home gardens around the world have been studied for species richness. The frequency
count of individual species is the main basis used to understand species diversity in the
home garden. However, Shannon-Weaver Index (SWI) has also been used in some of the
study of home gardens for the species diversity (Zaldivar, et al. 2002). SWI is the most
frequently used tool by many scientists for measuring the species diversity of plant
communities, birds, fungi, etc. (Brakenhielm and QingHong, 1995; Cuenca and Meneses,
1996; Parrotta et.al., 1997 and Whitford, 1997).SWI is a numerical measurement of species
and can express the diversity within the community and is generally used to compare the
diversity of the species. It is one of the simplest and most extensively used diversity indices.
The use of SWI to study the plant species richness in Nepalese home gardens is rare. Also
Evenness and Simpson’s indices are not frequently used. Therefore, the main objective of
this study is to measure the crop plant species using diversity indices in home gardens of
two different sites: Darbar Gulmi and Bharsa, Baikunthapur, Rupandehi.