Question

Biodiversity affects the healthy functioning of ecosystems. Using Tilman and his colleague’s field experiment results, explain how they concluded that the redundancy hypothesis best supported their findings.

Answer 1

Tilman and his collegues tested the redundancy hypothesis by adding nitrogen to an undisturbed ecosystem. The samples were taken from the plot for a period of over 20 years. Some of these plots were control where no nitrogen fertilizer was added, while some received additional nitrogen.

The results indicated that the plots where high levels of nitrogen was added showed a decrease in biodiversity over time as compared to the control plots. The additional nitrogne resulted in the proliferation of quack grass which dominated the other species.

This decline in the biodiversity of the experimental plots amde them susceptible to conditions like drought, because the more the number of species in an area, the more are the chances that some will be drough-resistant.

The crashing/death of the plant populations of the different species results in more nitrogen release into the soil which then leaks into the surface runoff and ground water affecting the qaulity of water resources.

Thus, he concluded that more the number of species, the more stable, resilient, and productive an ecosystem will be.