OG Test 1 - Reading 5

Questions 1-11 are based on the following passage.

This passage is excerpted from Joseph Mascaro, Gregory P Asner, Stuart Davies, Alex Dehgan, and Sassan Saatchi, “These Are the Days of Lasers in the Jungle,” ©2014 by Joseph Mascaro, et al.
Just as the Moon`s history was disrobed by laser ranging
50 years ago, Earth`s tropical forests are giving up their
secrets to the light. Airborne light detection and ranging-
Linecalled LiDAR-has over the last ten years become a key
5tool that ecologists use to understand physical variation in
tropical forests across space and time. Like an MRI of the
human brain, LiDAR probes the intricate three-
dimensional architecture of the forest canopy, unveiling
carbon that forests keep out of the atmosphere, and also
10the mounting threats to that carbon storehouse: drought,
fire, clandestine logging and brash gold-mining operations.
Even the quintessential natural disturbance of the sun-
filled light gap-long thought to enhance the incredibly
high species diversity of tropical forests-has been
15deconstructed by laser technology.
Laser ranging in tropical forests is such a game-changing
technology that science results can scarcely get through
peer-review before they are dwarfed by still larger-scale
studies. In a decade, laser power on commercial-grade
20LiDARs has skyrocketed and costs have plummeted. These
improvements in LiDAR technology allow airplanes to fly
faster, higher and farther, covering more forest area in a
single day than every ground-based survey that has ever
been collected in the history of tropical ecology. To
25estimate the amount of carbon stored in a 50-hectare
tropical forest monitoring plot on the ground-the largest
field plot in the world-takes a team of 12 people about
eight months: a slog of rain and mud and snakes with tape
measures and data log books. Today`s airborne LiDARs
30can get you to within about 10% of the same carbon
estimate in eight seconds.
It is this staggering contrast in scale between LiDAR
and fieldwork that led us here: Before this decade is out, we
could directly assess the carbon stock of every single square
35hectare of tropical forest on Earth. We could do it just as
well as if we were standing there in the flesh with tape
measures in hand. And we could do it for far less than what
we have already spent to offset carbon emissions from
forests. . . .
40It is easy in principle, though logistically nightmarish, to
measure carbon in tropical forests. A strict constructionist
would cut, dry and weigh the biomass of the world`s
forests. But this is a self-defeating enterprise. As a result, it
is likely that no one has measured carbon over a single
45hectare of tropical forest, even with the most detailed field
surveys. For a century ecologists and foresters have relied
on allometric1 estimation in lieu of carbon measurements
to translate field surveys of tree diameters, heights and
wood densities into whole-forest carbon estimates. Given a
50volume with known dimensions and density, one would
estimate its mass in a similar fashion.
As the new kid on the block, LiDAR has been tacked
onto the back end-initially thought of as kind of large-
scale helper to field surveys. Carbon estimates from the
55field have been treated as something inherently closer to
the real thing than measurements made by LiDAR-
ground "Truth" with a capital "T". This is perhaps
understandable historically, but vis-à-vis actual carbon,
there is no such thing as ground truth: both field and
60LiDAR efforts rely on allometry to convert measurements
into carbon estimates. Prior to using these measurements
for carbon estimation, they exist as standardized, spatially
explicit, archivable and verifiable data-the needed
substrate for a REDD2-type accounting program.
65Due to the constancy of the underlying measurements,
both field and LiDAR data could provide the needed
information if they covered every hectare on Earth. But, in
the case of field surveys, this is impossible. The surveys
that do exist measure a tiny amount of actual forest, and
70so what might be verified is widely spaced. And to avoid
fraud and protect landowners, many governments keep
their plot locations secret. Satellite LiDAR data remain
sparse, providing only extrapolated, coarse-resolution
carbon estimates with very high uncertainties, and there is
75no prospect of wall-to-wall coverage in the near future. By
2020, airborne LiDAR could give us a direct measurement
of 3-D forest structure for every hectare in the tropics: a
standardized database from which to build a carbon

Question 1

The authors' central claim in the passage is that

  • A LiDAR`s opponents have prevented the technology from advancing to a point where it might be scientifically useful, favoring traditional methods.

  • B Fieldwork and LiDAR are best used in combination when mapping carbon in tropical forests, in order to avoid human error while maintaining accuracy.

  • C LiDAR is as important a technology as MRI scanning or the scientific study of the moon with lasers.

  • D LiDAR technology is faster, cheaper, and nearly as accurate as traditional field methods for measuring the carbon biomass on Earth.

Question 2

In the first paragraph, the words "disrobed," "unveiling" and "deconstructed" primarily serve to

  • A highlight the negative connotations that laser technology currently has.

  • B emphasize the extensive reach of laser technology.

  • C demonstrate the inherently unknowable characteristics of objects, even with laser technology.

  • D implicitly compare lasers to other forms of technology.

Question 3

The authors imply that the main benefit of using LiDAR, as opposed to fieldwork, for measuring carbon in tropical forests is the

  • A scale and rapidity with which LiDAR can be used.

  • B expense of hiring scientists to carry out fieldwork.

  • C rapid changes and improvements in LiDAR technology.

  • D precision of LiDAR, which eliminates human error.

Question 4

Which choice provides the best evidence for the answer to the previous question?

  • A lines 19–20 ("In . . . plummeted")

  • B lines 20–22 ("These . . . farther")

  • C lines 33–35 ("Before . . . Earth")

  • D lines 35–37 ("We could . . . hand")

Question 5

As used in line 48, "translate" most nearly means

  • A convert.

  • B move.

  • C transform.

  • D express.

Question 6

The authors use the phrase "ground "Truth" with a capital "T"" (line 57) in order to

  • A argue that field measurements should be given up in order to focus exclusively on LiDAR measurements.

  • B illustrate the impossibility of ever gaining accurate and usable measurements from either fieldwork or LiDAR.

  • C defend the idea that LiDAR measurements are inherently more accurate than measurements obtained via fieldwork.

  • D note the excessive faith scientists have put in the accuracy of field-survey estimates.

Question 7

The authors imply that the response of various officials to attempts to measure their countries` carbon stock through field surveys has been

  • A unhelpful, because they fear that jobs for their countries` scientists will be lost.

  • B helpful, because their countries have invested significantly in technology to allow studies to expand.

  • C helpful, because their countries stand to benefit from universal carbon data that the studies will uncover.

  • D unhelpful, because they do not make their countries` land holdings readily available for study.

Question 8

Which choice provides the best evidence for the answer to the previous question?

  • A lines 65–67 ("Due . . . Earth")

  • B lines 68–70 ("The surveys . . . spaced")

  • C lines 70–72 ("And . . . secret")

  • D lines 72–75 ("Satellite . . . future")

Question 9

The data in the graph support the authors' point in paragraph five (lines 52–64) about the uses of LiDAR by

  • A providing an example of the use of information from LiDAR in conjunction with traditional field-based estimates.

  • B comparing data gathered by LiDAR technology from three separate forest sites.

  • C showing LiDAR`s superior accuracy compared to data gathered through fieldwork, even though the graph uses estimated figures.

  • D presenting an example of the use of LiDAR in a tropical forest, which until this study was purely hypothetical.

Question 10

It can reasonably be inferred from the graph that

  • A for the same mean canopy height (above $$25 MCH^2$$).tropical forests have more carbon biomass than temperate forests.

  • B there is an inverse relationship between mean canopy vertical height and aboveground carbon biomass.

  • C at a mean canopy height of 625 MCH2, all three types of forests depicted will have approximately the same aboveground carbon biomass.

  • D on average, the new tropical forest has less aboveground carbon biomass at a given canopy height than the boreal-temperate forest depicted.

Question 11

The information from the graph best supports the claim that the carbon biomass of the three forests depicted is most disparate at

  • A $$25 MCH^2$$

  • B $$225 MCH^2$$

  • C $$400 MCH^2$$

  • D $$900 MCH^2$$


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