【单选题】
Why More Fertilizer Harms PlantDiversity
The 35-year-old mystery of why fertilizers decrease biodiversity has finally been solveD、The secret They increase competition for sunlight.Adding fertilizers 1o grasslands increases the productivity of plants, but leads to a major drop in biodiversity.
The amount of nitrogen(氮) and phosphorus(磷) available to plants has doubled in the last 50 years, but the reason why this has harmed diversity has not been easy to answer. The debate has centred on whether fertilizers increase competition above or below ground-for sunlight or soil resources
To resolve the argument, Yann Hautier andAndy Hector from the University of Zurich, Switzerland built their own experimental plant community from scratch. Hautier’s team grew 32 plant communities for tour years, before transferring them to a glass house.Each community comprised four different sets of six species. Half were fertilized, the others were left unfertilizeD、 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.
After two years, the sets that were fertilized in normal light conditions showed a significant increase in productivity anti biomass, but lost around one-third of their species diversity compared to the unfertilized groups. Those that were fertilized and given additional light showed no significant loss of diversity.
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. The roots of half these plants were contained in plastic tubes, which prevented any below-ground competition: the other half were left exposeD、
Removing below, ground competition from fertilized plots had no detectable impact on the mortality (死亡率) of the seedlings (幼苗), compared to those that were exposed to full root competition, says Hautier.
"In the fertilized 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. "
Drew Purves, a computational ecologist from Microsoft ResearchCambridge is impressed with the team’s findings. "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 (补偿, 抵消) one of the most important sources of diversity loss in grasslands. \
The scientists found in the experiment thatA．the sets that were fertilized in normal light were more productive and diverse.
B．the fertilized plants with added light also lost their biodiversity.
C．below-ground competition had no significant impact on the biodiversity of plants.
D．the more fertilizer yon use the more active the plants ar
网考网参考答案：C
网考网解析：
文章的第四至七段对该项研究的结果作了介绍。第四段中捉到：两年之后，那些住正常光照条件下使用了肥料的植物组在生殖能力和个体体积上都有很大的增加，但和没有使用肥料的植物相比却失去了1/3的物种多样性，由此可排除A；第四段第二句说：那些增加了光照的使用肥料的植物却没有失去物种多样性，由此排除B；第六段中提到：和那些有着充分根部竞争的幼苗相比，减少施肥植物的地下竞争并没有对幼苗的死亡率产生明显的影响，由此可以判断C为正确选项、D项内容在文中并没有提及，故排除。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>
The 35-year-old mystery of why fertilizers decrease biodiversity has finally been solveD、The secret They increase competition for sunlight.Adding fertilizers 1o grasslands increases the productivity of plants, but leads to a major drop in biodiversity.
The amount of nitrogen(氮) and phosphorus(磷) available to plants has doubled in the last 50 years, but the reason why this has harmed diversity has not been easy to answer. The debate has centred on whether fertilizers increase competition above or below ground-for sunlight or soil resources
To resolve the argument, Yann Hautier andAndy Hector from the University of Zurich, Switzerland built their own experimental plant community from scratch. Hautier’s team grew 32 plant communities for tour years, before transferring them to a glass house.Each community comprised four different sets of six species. Half were fertilized, the others were left unfertilizeD、 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.
After two years, the sets that were fertilized in normal light conditions showed a significant increase in productivity anti biomass, but lost around one-third of their species diversity compared to the unfertilized groups. Those that were fertilized and given additional light showed no significant loss of diversity.
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. The roots of half these plants were contained in plastic tubes, which prevented any below-ground competition: the other half were left exposeD、
Removing below, ground competition from fertilized plots had no detectable impact on the mortality (死亡率) of the seedlings (幼苗), compared to those that were exposed to full root competition, says Hautier.
"In the fertilized 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. "
Drew Purves, a computational ecologist from Microsoft ResearchCambridge is impressed with the team’s findings. "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 (补偿, 抵消) one of the most important sources of diversity loss in grasslands. \
The scientists found in the experiment thatA．the sets that were fertilized in normal light were more productive and diverse.
B．the fertilized plants with added light also lost their biodiversity.
C．below-ground competition had no significant impact on the biodiversity of plants.
D．the more fertilizer yon use the more active the plants ar
网考网参考答案：C
网考网解析：
文章的第四至七段对该项研究的结果作了介绍。第四段中捉到：两年之后，那些住正常光照条件下使用了肥料的植物组在生殖能力和个体体积上都有很大的增加，但和没有使用肥料的植物相比却失去了1/3的物种多样性，由此可排除A；第四段第二句说：那些增加了光照的使用肥料的植物却没有失去物种多样性，由此排除B；第六段中提到：和那些有着充分根部竞争的幼苗相比，减少施肥植物的地下竞争并没有对幼苗的死亡率产生明显的影响，由此可以判断C为正确选项、D项内容在文中并没有提及，故排除。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>
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