/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 40 Determining tree biomass It is e... [FREE SOLUTION] | 91Ó°ÊÓ

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Determining tree biomass It is easy to measure the "diameter at breast height" of a tree. It's hard to measure the total "aboveground biomass" of a tree, because to do this you must cut and weigh the tree. The biomass is important for studies of ecology, so ecologists commonly estimate it using a power model. Combining data on 378 trees in tropical rain forests gives this relationship between biomass \(y\) measured in kilograms and diameter \(x\) measured in centimeters: \(^{20}\) $$ \widehat{\ln y}=-2.00+2.42 \ln x $$ Use this model to estimate the biomass of a tropical tree 30 centimeters in diameter. Show your work.

Short Answer

Expert verified
The estimated biomass of the tree is approximately 101.27 kg.

Step by step solution

01

Substitute Given Diameter into the Model

Substitute the provided diameter of the tree, which is 30 cm, into the given power model equation. The equation provided is \( \widehat{\ln y} = -2.00 + 2.42 \ln x \). Here, \( x = 30 \). So, we substitute this into the equation.
02

Calculate the Natural Logarithm of the Diameter

Find \( \ln 30 \) using a calculator or natural logarithm tables. This will be used to determine \( \widehat{\ln y} \).
03

Compute the Estimate of ln(y)

Substitute the value of \( \ln 30 \) into the equation to find \( \widehat{\ln y} \):\[ \widehat{\ln y} = -2.00 + 2.42 \ln 30 \]
04

Solve for y by Exponentiating

To find the estimated biomass \( y \), exponentiate both sides of the equation from step 3: \[ y = e^{\widehat{\ln y}} \] This will convert the estimated natural logarithm of the biomass back to biomass in kilograms.
05

Calculate the Final Estimated Biomass

Compute the value of \( y \) using the exponential function on a calculator. This will give you the estimated biomass of the tropical tree with a diameter of 30 cm.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Power Model
In the context of ecological studies, a power model is often used to establish relationships between variables. It typically takes the form \( y = a \, x^b \), where \( y \) is the dependent variable, \( x \) is the independent variable, and \( a \) and \( b \) are constants derived from data. The power model is particularly useful for estimating quantities that are difficult to measure directly, such as tree biomass. This model can represent how tree diameter, a easily measurable trait, scales with more challenging to measure traits like biomass. In our exercise, the model used is a variation that involves natural logarithms, yet it essentially serves the same purpose by bridging diameters and biomass values in an empirical manner.

This statistical approach helps ecologists make informed decisions about ecosystem health and carbon storage potential without performing invasive measurements. By using a power model, they can efficiently gather large datasets from non-destructive methods, contributing to sustainable management of tropical rain forests.
Ecological Studies
Ecological studies focus on understanding the relationships between living organisms, including trees, and their environments. These studies are crucial for conserving biodiversity and managing natural resources effectively. Biomass estimation plays a key role here because biomass reflects the amount of carbon stored in an ecosystem, which has implications on global carbon cycles and climate change.

Researchers in ecological studies often leverage mathematical models, such as the power model, to draw insights into how ecosystems function under different conditions. By estimating the biomass of trees, ecologists can infer patterns about the health of forests, the availability of resources, and the potential impacts of environmental changes. Additionally, these studies help guide policy decisions towards preserving tropical rain forests—a biodiversity hotspot that serves as a major carbon sink.
Natural Logarithm
The natural logarithm, denoted as \( \ln \), is a fundamental mathematical concept often used in modeling real-world phenomena. It is the logarithm to the base \( e \), where \( e \) is approximately equal to 2.71828, a mathematical constant.

In the biomass estimation problem, the natural logarithm is used to transform nonlinear relationships into linear ones. This transformation simplifies computations and allows the power model equation to be expressed as a linear equation, making it easier to derive coefficients through statistical techniques such as linear regression.
  • The natural logarithm can be calculated using scientific calculators or log tables.
  • Manipulating equations with \( \ln \) involves applying properties such as \( \ln(a \cdot b) = \ln a + \ln b \) and \( e^{\ln a} = a \).
These properties are utilized in estimating the tree's biomass, converting the logarithmic predictions back into a readable scale for practical interpretation.
Tropical Rain Forest
Tropical rain forests are dense, biologically diverse regions located near the equator. They maintain a warm climate with high humidity and substantial annual rainfall, creating a unique environment that is home to many plant and animal species. These ecosystems play a critical role in global ecology due to their high productivity and vast carbon storage capability.

Studying tree biomass in tropical rain forests is particularly significant, as these forests act as major carbon sinks, helping to mitigate the effects of climate change. By estimating the biomass of individual trees, ecologists can assess the overall carbon sequestration potential of these forests.
  • Tropical rain forests are essential for maintaining global biodiversity.
  • They provide habitat for countless species, some of which are not found anywhere else.
  • These forests support various human communities and economies through resources such as timber and medicinal plants.
Establishing precise biomass estimates helps inform conservation strategies to protect these critical ecosystems in the face of deforestation and climate challenges.

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Most popular questions from this chapter

Killing bacteria Expose marine bacteria to X-rays for time periods from 1 to 15 minutes. Here are the number of surviving bacteria (in hundreds) on a culture plate after each exposure time: \(^{21}\) $$ \begin{array}{cccc} \hline \text { Time } t & \text { Count } y & \text { Time } t & \text { Count } y \\ 1 & 355 & 9 & 56 \\ 2 & 211 & 10 & 38 \\ 3 & 197 & 11 & 36 \\ 4 & 166 & 12 & 32 \\ 5 & 142 & 13 & 21 \\ 6 & 106 & 14 & 19 \\ 7 & 104 & 15 & 15 \\ 8 & 60 & & \\ \hline \end{array} $$ (a) Make a reasonably accurate scatterplot of the data by hand, using time as the explanatory variable. Describe what you see. (b) A scatterplot of the natural logarithm of the number of surviving bacteria versus time is shown below. Based on this graph, explain why it would be reasonable to use an exponential model to describe the relationship between count of bacteria and time. (c) Minitab output from a linear regression analysis on the transformed data is shown below. $$ \begin{aligned} &\begin{array}{lllll} \text { Predictor } & \text { Coef } & \text { SE Coef } & \text { T } & \text { P } \\ \text { Constant } & 5.97316 & 0.05978 & 99.92 & 0.000 \\ \text { Time } & -0.218425 & 0.006575 & -33.22 & 0.000 \end{array}\\\ &\begin{array}{lll} S=0.110016 & R-S q=98.8 \frac{8}{6} & R-S q(a d j)=98.7 \% \end{array} \end{aligned} $$ Give the equation of the least-squares regression line. Be sure to define any variables you use. (d) Use your model to predict the number of surviving bacteria after 17 minutes. Show your work.

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