16．The tree people in the Lord of the Rings-the Ents-can get around by walking．But for real trees，well，it's harder to uproot．"Because it's a sessile organism，literally，rooted into the ground，it is unable to leave and go elsewhere．"Mario Pesendorfer，a behavioral ecologist at the Cornell Lab of Ornithology．"When a tree first starts growing in a certain area，it's likely that the climatic envelope，so the temperature，humidity，soil composition and so on suits it，because it would otherwise be unable to grow from a seedling．But as it ages，these conditions may change and the area around it may no longer be suitable for its offspring．"
And if that happens？Walnuts，hazelnuts，chestnuts，oaks，pines-many rely exclusively on so-called"scatter-hoarders，"like birds，to move their hefty seeds to new locales．"Many members of the family Corvidae-the crows，jays and magpies-are scatter-hoarders，meaning they like to store food for the winter，which they then subsequently retrieve．"
Or not．And when they do forget something，a seedling has a chance to grow，sometimes a good distance away．"The Clark's nutcracker，which is found in alpine regions of western North America，is definitely the rock star among the scatter-hoarding corvids．They hide up to 100，000 seeds per year，up to 30kilometers away from the seed source，and have a very close symbiotic relationship with several pine species，most notably the whitebark pine．"
Pesendorfer and his colleagues catalogue the seed-scattering activities of the Clark's nutcracker and its cousins in a new review paper，in the journal The Condor：Ornithological Applications．They also write that，as trees outgrow their ideal habitats in the face of climate change，or battle new insects and disease，these flying ecosystem engineers could be a big help replanting trees．It's a solution，Pesendorfer says，that's good for us-getting birds to do the work is cheap and effective-and it could give vulnerable oaks and pines the option to truly"make like a tree and leave．"
56．According to the article，what makes birds help trees move from one place to another？C．
A．They want to make the environment better for survival
B．They want to change the trees into another kind
C．They want to store the nuts for winter survival
D．They are forced to help trees to survive
57．Which does the underlined word in the last paragraph mean？B．
A．growing in a better way
B．being forced to give up
C．making changes to
D．finding a mysterious way to survive
58．What is the best title of this passage？A．
A．Birds may help trees cope with climate change
B．Birds rely on nuts to survive
C．Trees help fight air pollution
D．Birds make trees in danger．
分析 本文属于说明文阅读，作者通过这篇文章主要向我们描述了许多鸟类可以帮助树木应对气候变化，让树木更好的生存下去．
解答 56．C 细节理解题．根据第二段：And if that happens？Walnuts，hazelnuts，chestnuts，oaks，pines-many rely exclusively on so-called"scatter-hoarders，"like birds，to move their hefty seeds to new locales．"Many members of the family Corvidae-the crows，jays and magpies-are scatter-hoarders，meaning they like to store food for the winter，which they then subsequently retrieve．"根据第二段的内容可知：一些鸟类会将树木笨重的果实带到别的地方．他们平时喜欢囤积食物，入冬后再拿来填饱肚子． 有些囤货，忘了，于是乎生根发芽，安居在老远 的地方．故选C项．
57．B 词义猜测题．第四段第二，三句：They also write that，as trees outgrow their ideal habitats in the face of climate change，or battle new insects and disease，these flying ecosystem engineers could be a big help replanting trees．It's a solution，根据划线后的可知如果树木理想的生长环境发生了气候变化或者病虫害，这些大自然的搬运工就会在移植的时候帮上大忙．故推知划线词表示被迫放弃的意思．故选B项．
58．A 主旨大意题．根据最后一段Pesendorfer says，that's good for us-getting birds to do the work is cheap and effective-and it could give vulnerable oaks and pines the option to truly"make like a tree and leave可知这篇文章最好的题目是鸟类可以帮助树木应对气候变化；故选A．
点评 考察学生的细节理解和推理判断能力，做细节理解题时一定要找到文章中的原句，和题干进行比较，再做出正确的选择．在做推理判断题不要以个人的主观想象代替文章的事实，要根据文章事实进行合乎逻辑的推理判断．
