Download Free Apps & Games @ PHONEKY.com
Download Free Apps & Games @ PHONEKY.com
Subject: Fertiliser harms
Replies: 13 Views: 912
dk_bhat 5.05.09 - 06:59am
Why more fertiliser harms plant diversity *
dk_bhat 5.05.09 - 07:00am
The 35-year-old mystery of why fertilisers decrease biodiversity has finally been solved. The secret? They increase competition for sunlight.
*
dk_bhat 5.05.09 - 07:00am
Adding fertilisers to grasslands increases the productivity of plants, but leads to a major drop in biodiversity. *
dk_bhat 5.05.09 - 07:00am
The amount of nitrogen and phosphorus available to plants has doubled in the last 50 years, but the reason why this has harmed diversity has not been easy to answer. *
dk_bhat 5.05.09 - 07:00am
The debate has centred on whether fertilisers increase competition above or below ground for sunlight or soil resources? *
dk_bhat 5.05.09 - 07:01am
To resolve the argument, Yann Hautier and Andy Hector from the University of Zurich, Switzerland built their own experimental plant community from scratch. *
dk_bhat 5.05.09 - 07:01am
Hautier's team grew 32 plant communities for four years, before transferring them to a glass house.
*
dk_bhat 5.05.09 - 07:02am
Each community comprised four different sets of six species. Half were fertilised, the others were left unfertilised. Half of each of these sets had light added, using a system of three fluorescent tubes that were raised as the canopy grew, while the other half were left to grow in normal light conditions *
dk_bhat 5.05.09 - 07:02am
After two years, the sets that were fertilised in normal light conditions showed a significant increase in productivity and biomass, but lost around one-third of their species diversity compared to the unfertilised groups. Those that were fertilised and given additional light showed no significant loss of diversity.
*
dk_bhat 5.05.09 - 07:02am
To uncover whether underground competition for root space had any influence on biodiversity, the team added two new species of plant at the beginning of the second year *
dk_bhat 5.05.09 - 07:02am
The roots of half these plants were contained in plastic tubes, which prevented any below-ground competition: the other half were left exposed.
*
dk_bhat 5.05.09 - 07:02am
Removing below-ground competition from fertilised plots had no detectable impact on the mortality of the seedlings, compared to those that were exposed to full root competition, says Hautier *
dk_bhat 5.05.09 - 07:02am
In the fertilised groups without additional light, there was no difference with or without the root-tube they died both ways. Even if we remove competition below ground, these plants are unable to grow.
*
dk_bhat 5.05.09 - 07:03am
This is a rare example of a simple experiment providing an unambiguous answer to an important ecological question. If these results are general to temperate grasslands which seems likely then we can start to develop more targeted policies to offset one of the most important sources of diversity loss in grasslands. *
