文章大意:本文是篇说明文。文章主要讲述了通过新的调查研究,得出的对全球的树木生物种类的数量估算,其中还包括一些未记录在案的树种;同时一些生物学家通过调查认为在亚马逊热带雨林里面,还有许多不知名的树种等待人们去发现,这也令这些生物学家们倍受鼓舞。
The world’s forests may hold more secrets than previously thought: a new global estimate of tree biodiversity suggests that there are about 9,200 tree species remaining undocumented. Most are likely in the tropics, according to the new research.
The new research drew on the efforts of hundreds of contributors, who have categorized trees in two huge data sets: One, the Global Forest Biodiversity Initiative, records every species found in extensively documented forest plots worldwide. The other, TREECHANGE, puts together sightings of individual species. Together they suggest there are approximately 64,100 recorded tree species on the planet — up from previous estimates of around 60,000.
The researchers reached their estimate of an additional 9,200 yet undocumented species on the basis of the number of rare ones already in the databases. Most unknown species are likely to be defined as rare, found in limited numbers in small geographical areas, says the quantitative forest ecologist Jingjing Liang. The team’s result is “a rather conservative estimate,” Liang says, “because scientists know less about the preponderance of uncommon trees in places such as the Amazon, where out-of-the-way spots could host pockets of unusual species found nowhere else.” “If we can focus the resources on those rain forests in the Amazon,” Liang adds, “then we would be able to estimate it with higher confidence.”
Silman, a conservation biologist, who was not involved in the new study agrees that the study result is likely an underestimate. His and his colleagues’ local surveys suggest there are at least 3,000 and possibly more than 6,000 unknown tree species in the Amazon basin alone. Tree species often get grouped together based on appearance, he notes, so new genetic analysis techniques will likely lead to the discovery of even more biodiversity. Sliman wonders how many species will go extinct before scientists describe them. “How many are already known to native peoples in the Amazon — or were known to peoples or cultures who have themselves been made extinct through colonization, disease, or absorption? How many “species” already have dried samples sitting in a cabinet?” he says.
Searching for the new species will inform not only conservation but the basic evolutionary science of how and why species diversify and die out, Silman says. “Just the fact that there are thousands of species of something as common as trees out there that are still left to be discovered,” he adds, “I find pretty inspirational.”
12. What is the finding of the new research?
A.About nine thousand new tree species have been identified. |
B.Thousands of tree species remain unknown to science. |
C.Maintaining tree diversity has become a global challenge. |
D.Human activities have led to the reduced number of trees. |
13. What can be learned about the research method?
A.The researchers adopted quality method to analyze data. |
B.The researchers did extensive field study in out-of-the-way spots. |
C.Inferring from the existing dada is the main research method. |
D.Doing surveys and interviews is the main research method. |
14. What does the underlined word “
preponderance” in paragraph 3 probably mean?
A.majority | B.evolution | C.cultivation | D.capability |
15. According to Silman, one of the reasons for the underestimate of the tree species may be that ________.
A.genetic analysis technique failed to produce accurate information |
B.trees of similar sizes in the Amazon basin are grouped together |
C.too many rare trees were made into dried samples before being documented |
D.the local peoples or the local cultures are not fully aware of the tree species. |