快猫短视频

DIVERSE ecosystems are far more productive than monocultures, according to a
new study. In a seven-year experiment, David Tilman, an ecologist at the
University of Minnesota in St Paul, found that plots of grassland planted with
16 species produced 2.7 times as much biomass as plots planted with a single
species.

Tilman鈥檚 work has been controversial. In 1996 he pointed to the link between
diversity and productivity. But critics dismissed the results from these earlier
experiments, saying that they could have been caused by faulty experimental
design. They argued that the apparent productivity of the diverse plots could be
because they were planted with species that on average grew faster than those
that had been planted with just one species (快猫短视频, 15 August
1998, p 30).

In his latest paper Tilman refutes these criticisms. He planted 168 plots,
each measuring 9 metres square, with between 1 and 16 different grassland
perennials. He says that the superior performance of the diverse plots cannot be
explained by a few extremely productive species. 鈥淭hese results lay to rest a
variety of concerns,鈥� Tilman says. However, he adds that it鈥檚 still not clear
how the findings will scale up to real-world ecosystems.

Michael Huston, an ecologist at Oak Ridge National Laboratory in Tennessee,
remains unconvinced by Tilman鈥檚 work: 鈥淚 don鈥檛 think it鈥檚 settled anything.鈥� He
says the findings may be a result of nitrogen-fixing legumes in the
high-diversity plots, which are known to promote the growth of grasses.