As biodiversity increases in an ecosystem,its stability $...$

Is it possible that productivity and diversity of a natural community remain constant over a time period of,say $100$ years?

Outdoor plot experiments were conducted by

Which of the following characteristics are seen in a stable community?
$i$. It is strong enough to withstand environmental disturbance and recovers quickly.
$ii$. It is resistant to invasive species.
$iii$. It exhibits constant change in biomass production over a period of time.
$iv$. It has more species diversity.

Assertion: Communities that comprise of more species tend to be more stable.
Reason: $A$ higher number of species results in less animal variation in total biomass.

Who conducted long-term ecosystem experiments using outdoor plots?