Ecological Essay
Consistent effects of productivity and disturbance on diversity between landscapes
By Jonathan Tonkin and Russell Death
INTRODUCTION
Nowadays, ecologists are trying to formulate various models to explain diversity patterns because there are lots of factors that can influence diversity but there is a little progress pertaining to this concern. In terms of lotic systems’ diversity, there has been a minute support for any of the major diversity models. Consequently, it was found that productivity combined with disturbance has a big impact on diversity of the communities within the stream benthic region. Along with this discovery, there is a small harmony on how these respond to diversity. Most of the models were developed on inactive organisms such as corals, which is way too different with the lotic system wherein it is dominated by moving organisms. Disturbance usually demands groupings in lotic habitats but nevertheless flooding are the most widespread means of disturbance. Death proposed that the main effect of disturbance on diversity in New Zealand streams was to limit primary productivity. It means that productivity will set the standards of higher diversity while disturbance renews the colonization process of streams invertebrates. This proposal also foresees the increase of diversity in a log linear manner along with increasing productivity and decline linearly with increasing disturbance. Tonkin also builds this model to suggest quadratic decline in diversity with increasing disturbance and found a stronger dependence on productivity and disturbance in open as opposed to closed canopy systems. Subsequently, Tonkin and Death investigate whether the effects of productivity and disturbance on diversity differs between pristine and non-pristine agricultural region and assess the fit of three different productivity-disturbance models in these systems by sampling 16 streams on multiple occasions in the North Island of New Zealand. To do this they analyze
By Jonathan Tonkin and Russell Death
INTRODUCTION
Nowadays, ecologists are trying to formulate various models to explain diversity patterns because there are lots of factors that can influence diversity but there is a little progress pertaining to this concern. In terms of lotic systems’ diversity, there has been a minute support for any of the major diversity models. Consequently, it was found that productivity combined with disturbance has a big impact on diversity of the communities within the stream benthic region. Along with this discovery, there is a small harmony on how these respond to diversity. Most of the models were developed on inactive organisms such as corals, which is way too different with the lotic system wherein it is dominated by moving organisms. Disturbance usually demands groupings in lotic habitats but nevertheless flooding are the most widespread means of disturbance. Death proposed that the main effect of disturbance on diversity in New Zealand streams was to limit primary productivity. It means that productivity will set the standards of higher diversity while disturbance renews the colonization process of streams invertebrates. This proposal also foresees the increase of diversity in a log linear manner along with increasing productivity and decline linearly with increasing disturbance. Tonkin also builds this model to suggest quadratic decline in diversity with increasing disturbance and found a stronger dependence on productivity and disturbance in open as opposed to closed canopy systems. Subsequently, Tonkin and Death investigate whether the effects of productivity and disturbance on diversity differs between pristine and non-pristine agricultural region and assess the fit of three different productivity-disturbance models in these systems by sampling 16 streams on multiple occasions in the North Island of New Zealand. To do this they analyze