Austina Clark

University of Otago

Estimating species richness and comparing the species similarity using various models

It has long been realized by ecologists that it is almost impossible to get a complete census of all species within a community with limited resources. It is also difficult to compare the shared species using the finite resources, particularly with communities with large species richness and a large portion of rare species. (Colwell & Coddington 1994; Colwell et al 2004; Magurran 2004).

A total of 1200 samples (via quadrats) were collected over 4 years from 1990 to 1993 in the South Island, New Zealand. There were 10 sites involved here. The ecologist divided each site into 3 regions and then allocated three treatments randomly to these regions. These were treatment 1 (T1) where there were both rabbits and sheep on the region, treatment 2 (T2) where there were rabbits but sheep were removed, treatment 3 (T3) where both rabbits and sheep were removed. Ten quadrats were placed in each region and the ecologist collected samples from the same quadrat each year from 1990 to 1993.

The 10 sites are regrouped into three areas according to the plants growing history, A1 is the land which is covered with tall tussocks, A2 is for Hieracium and A3 is for Bare land.

Here we will apply a few methods and computer software (SPADE) is used to find the species richness in a single community. Next we use the multiple-community diversity measure to compare the similarity (Chao et al, 2008) among the areas as well as the three treatments.