如果你使用周长，你需要做一个计算来确定树的直径：直径 = 周长除以3.14（圆周率）。

然后用树木的直径乘以它的生长因子来计算树的年龄，这是由物种决定的。公式如下：直径 X 生长因子=树龄。

• eg：让我们用红枫来计算年龄。一棵红枫的生长因子被确定为4.5，你已经确定它的直径是10英寸：10英寸直径X 4.5生长因子= 45年。

测量点应在离地面 4.5 英尺或略低于肩高处。

1英寸=2.54厘米

University of Minnesota （明尼苏达大学）, Growth Factors by Tree Species：

• Red maple，4.5
• Silver maple，3.0
• Sugar maple，5.0
• River birch，3.5
• White birch，5.0
• Shagbark hickory，7.5
• Green ash，4.0
• Black walnut，4.5
• Black cherry，5.0
• White oak，5.0
• Red oak，4.0
• Pin oak，3.0
• Linden or basswood，3.0
• American elm，4.0
• Ironwood，7.0
• Cottonwood，2.0
• Dogwood，7.0
• Redbud，7.0

How Old Is Your Tree? Variation for “How Big Is Your Tree?”

Have you ever wondered how to find out how old your tree is? In this lesson, students will estimate the age of a tree by measuring diameter and using a growth factor table.

Grade level: Middle school

Subjects: Math, social studies, language arts

Resource: How Old Is Your Tree? Student Page

Part A: Identify your tree

Find a tree you’re interested in learning about. Identify the species using a dichotomous key.

Resource: The Beginner’s Guide to Minnesota Trees has an easy-to-use dichotomous key and a basic key on the last pages.

Part B: Measure your tree and estimate tree age

1.      Measure the circumference of the trunk 4.5 feet from the ground.

2.      Calculate diameter in inches (D = C/pi)

3.      Multiply diameter by the tree’s growth factor using the chart below.

Example: A red oak has a diameter of 30 inches. Multiply the diameter (30 inches) by the growth factor for red oak in Minnesota (4.0). The estimated age is 120 years.

Chart from Purdue University, Indiana

Part C: Determine the year your tree may have sprouted.

Subtract the tree’s estimated age from the current year.

Example: Subtract 120 from 2020 (current year). The estimated sprouting year is 1900.

Optional Enrichment: Read and write about your local history.

Students may enjoy learning about what the world was like the year their tree sprouted. Provide local resources for learning about your area’s local history.

Sample elements to include in descriptive writing:

·       A current description of where the tree is growing.

·       Examples might include number and type of nearby buildings, roads, and other vegetation.

·       Age of the tree and year it may have sprouted.

·       A description of natural conditions the year the tree sprouted.

·       A description of human events the year the tree sprouted.

·       List additional significant human and natural events that happened over the tree’s lifetime.

o   Natural examples: wildfires, floods, droughts, etc.

o   Local examples: date a nearby structure or road was built, year the town was settled, year the school was built, etc.

o   National examples: year Minnesota became a state, wars, moon landing, presidential administrations, human population numbers, etc.

Resources may include:

·       Locally written history books

·       Local elders

·       Google searches about history of your town, city, neighborhood, or state

Advanced resources:

·       DNR historic air photos

·       Minnesota Historical Society

·       Minnesota Forest History Timeline

Optional Enrichment: Verify your tree’s age

To get a precise measurement, consider inviting a forester to take a core sample of the tree with an increment borer. Students can count the tree’s annual rings of growth of the core sample using a hand lens.

Student page: How Old Is Your Tree?

Name: ____________________________________________________________

1.      Identify your tree.

Go outside and find a tree that interests you. Collect a leaf and identify the tree using the shortcut guide on pages 17 and 18 of the Beginner’s Guide to Minnesota Trees. NOTE: The tree species must be one of the varieties listed in the Minnesota Trees Growth Factor Table. If the tree you measure is not listed (such as apple), find another tree that is found in the list, such as silver  maple. This website may help you: mndnr.gov/trees/native-trees.html

My tree species name: __________________________________________________

2.      Measure your tree’s circumference.

To measure circumference in inches, wrap a measuring tape around the trunk of the tree at 4.5 feet from the ground. Make sure the tape is level and straight, and not zig-zagging around the tree. The height at which you measure is important. The forestry business uses 4.5 feet as the standard height. The growth tables you will use below are based on this standard.

My tree’s circumference: ________________________________________________

3.      Convert the circumference into diameter.

Circumference measure the distance around an object. Diameter measures the width of an object. Calculate circumference using the formula: d = C/pi. Show your work.

My tree’s diameter: _________________________________________________

Go to next page!

4.      Use the growth table to estimate the age of your tree. Multiply diameter by the correct growth factor listed in the table below. Show your work:

My tree’s estimated age ________________________________

Minnesota Trees Growth Factor Table

5.   5, Find the year your tree sprouted. Subtract the estimated age of your tree from the current year.

My tree sprouted in ___________________________________(year)

https://felling.uk/calculator/tree-growth

Tree Growth Rate Calculator UK

1. Select Tree Type
Choose the correct tree type from the dropdown menu. This is important because different trees grow at different rates.

2. Enter Current Height
Measure the tree’s current height in metres and input it into the calculator. Our tree height calculator can help with this measurement.

3. Enter Tree Age
Input the tree’s age in years. Our tree age calculator can assist you if you’re unsure of the age.

4. Choose Soil Type
Select the soil type from the options: loamy, sandy, clay, silty, peaty, or chalky. The type of soil affects how well a tree can grow.

5. Select Soil Quality
Assess the soil quality and choose from poor, average, or good. Soil quality impacts the tree’s ability to absorb nutrients.

6. Select Sun Exposure
Choose the level of sun exposure: full sun, partial shade, or full shade. Sun exposure influences the tree’s growth rate.

7. Calculate Growth Rate
Click the “Calculate Growth Rate” button to see the result.

https://github.com/bmaillou/NYCTreeGrowth

Analysis of NYC Tree Census data to determine growth rates. This site will provide the data and python scripts used in the analysis to calculate tree growth rates. Below I list each script and the data sets used. The ARCgis methods to add data are not provided as they were performed in ARCgis however the data is included. All input and output files are noted. An older version of Python is used in srcipt 6 such that it worked with basemap.

1. 1-Combine NYC raw data into one Database: This script takes the NYC 2005 and NYC 2015 Tree census data and combines them into one data base aligned by postal code, address, species. It then exports the combined file to excel.
   1. Input files
      1. 2005_Street_Tree_Census.csv
      2. 2015_Street_Tree_Census_-_Tree_Data.csv
   2. Output Files
      1. PaperVersionUncleaned_05_15_combined.xlsx
   3. Output figures
      1. None
   4. Output Data
      1. None
2. 2-Clean_all_growth_data: This takes the combined database and then cleans the data. It does some basic descriptive statistics and exports the cleaned database for further analysis.
   1. Input files
      1. PaperVersionUncleaned_05_15_combined.xlsx
   2. Output Files
      1. Cleaned_NYC_Growth.xlsx
   3. Output Figures
      1. Multiple but none used in Paper
   4. Output Data
      1. Summary of basic tree growth used in results
      2. Data for Table 2
3. 3-Figure1_and_2_Growth_Plots: This uses the cleaned and uncleaned NYC growth databases for ground truthing and temrporal validation and presenting the firts figures.
   1. Input files
      1. PaperVersionUncleaned_05_15_combined.xlsx (FIX THIS)
      2. Cleaned_NYC_Growth.xlsx
      3. NYC Trees_V2 – latest.xlsx. (Ground Truthed data)
      4. TemporalValidationData.xlsx
   2. Output Files
      1. None
   3. Output Figures
      1. Figure 1
      2. Figure 2
   4. Output Data
      1. Summary of ground truthed data
      2. Summary of Temporal Validation data
4. ARCgis scripts are performed offline to add more data to the NYC growth database for comparisons
   1. Input files
      1. Cleaned_NYC_Growth.xlsx
   2. Output Files
      1. tree_census_join_20210613.xlsx
   3. Output Figures
      1. None
   4. Output Data
      1. None
5. 5-Forest_Plot_statistics: Uses the cleaned NYC growth database with the additional data to do the statistical analyses. It outputs the fitted data for the maps.
   1. Input files
      1. tree_census_join_20210613.xlsx
   2. Output Files
      1. fitted_growth_rates.xlsx
   3. Output Figures
      1. Figure 4
      2. Figure 5
      3. Figure 6
   4. Output Data
      1. Summary Statistics
6. 6-for-paper-Take-NYC-growth-Data-Make-maps-ACS.ipynb: Creates the maps
   1. Input files
      1. fitted_growth_rates.xlsx
   2. Output Files
      1. none
   3. Output Figures
      1. Figure 3
      2. Figure 7
      3. Figure 8
   4. Output Data
      1. none