Lawn, Meadow or Wetland? Evaluating Plans for a City Park

Use seasonal survey data, criteria and constraints to judge competing designs.

Answer Key

Pollinators through the seasons

Read the passage and study Table 1. Then answer the questions.

Four Plans for Linden Park

1Linden Park is a city park with an 8,000 m² lawn that slopes down to Mill Creek. After heavy rain, water runs across the mowed grass and into the creek, carrying soil and lawn fertilizer with it. Healthy ecosystems provide services that people depend on, such as soaking up rain, keeping water clean and pollinating plants. The city's parks board wants to replace part of the lawn to support more kinds of living things and to protect the creek, so it asked a seventh-grade class at Eastgate Middle School to help compare four plans.

2Plan A adds large beds of annual flowers, which are planted each spring and bloom mostly in midsummer, and keeps the rest as lawn. Plan B turns much of the lawn into a meadow of native wildflowers and grasses that bloom at different times from April to October, with a 10 m wide strip of native shrubs along the creek. Plan C plants a row of shade trees along the creek and keeps the rest as lawn. Plan D digs a wetland pond with a wooden boardwalk.

3The board set three constraints. A plan must cost no more than $25,000 to install and no more than $6,000 a year to maintain, and it must leave at least 3,000 m² of open lawn for a youth soccer field. The board's criteria are more kinds of pollinators and birds, more rain soaked into the ground and a cleaner creek.

4The class first studied small examples of each kind of planting that already grow in the park or nearby. They marked a 10 m by 10 m plot in each one and, on one sunny morning in each season, counted how many different pollinator species, such as bees, butterflies and hover flies, visited the plot in 30 minutes (Table 1). There was no wetland nearby, so Plan D has no plot. The city's engineer then estimated the costs of each plan, how much of the rain falling on the area would soak in, and how much open lawn would be left (Table 2 in Section 2).

Table 1. Pollinator species seen in 30 minutes
Season	Lawn	Annual flower bed	Native meadow	Tree row
Spring	2	2	6	4
Summer	3	9	14	5
Fall	1	3	9	3

In summer, how many more pollinator species visited the native meadow plot than the lawn plot? 11 species

Which pattern in Table 1 best supports the claim that a meadow helps pollinators through the whole growing season?

A. The lawn plot had fewer species in fall than in spring.
B. The meadow plot led the other plots in spring, summer and fall.
C. The tree row plot had 5 species in summer and 3 in fall.
D. The flower bed plot jumped from 2 to 9 species in summer.

Why did the native meadow plot have more pollinator species in spring and fall than the annual flower bed?

A. Its plants bloom at different times, so it has flowers open in more seasons.
B. The flower bed was surveyed on rainy mornings, when few insects fly.
C. Pollinators prefer tall grass to flowers in the cooler months.
D. The flower bed plot was smaller, so it had room for fewer insects.

Circle the three measurements that tell how well a plan supports biodiversity or an ecosystem service.

Number of pollinator speciesInstall costPercent of rain soaked into the groundMonths needed to finish buildingAmount of soil washing into the creekYearly upkeep cost

Comparing the plans

Use Table 2 and the constraints in paragraph 3.

Table 2. The engineer's estimates
Plan	Install cost ($)	Yearly upkeep ($)	Rain soaked in (%)	Open lawn left (m²)
Lawn as it is now	0	7,000	30	8,000
A: Flower beds	12,000	9,000	35	7,000
B: Meadow and shrubs	20,000	3,000	80	3,000
C: Tree row	15,000	5,000	50	6,500
D: Wetland pond	40,000	4,000	90	4,000

Sort each plan by whether it meets the board's three constraints.

Plan A: Flower bedsPlan B: Meadow and shrubsPlan C: Tree rowPlan D: Wetland pond

Meets all three constraints	Breaks a constraint
Plan B: Meadow and shrubs Plan C: Tree row	Plan A: Flower beds Plan D: Wetland pond

What is the total cost of Plan B for the first 5 years (install cost plus 5 years of upkeep)? $35000

How much less open lawn does Plan B leave than Plan C? 3500 m²

Of the plans that meet the constraints, which one does best on both the pollinator criterion and the rain criterion?

A. Plan C
B. Plan A
C. Plan D
D. Plan B

A neighbor says Plan A is the best choice because it adds the most colorful flowers. Which evidence best answers the neighbor?

A. Plan A soaks up the most rain, so it would do the most for the creek.
B. Plan A's flowers are not native, so bees and butterflies avoid them in summer.
C. Its beds drew few pollinators in spring and fall, and its upkeep is too high.
D. Plan A costs more to install than Plan B, so it breaks the budget.

10.

Which plan should the parks board choose? Make a claim, use evidence from both tables and the constraints, and explain your reasoning. Name one trade-off of your choice.

The board should choose Plan B. It meets every constraint: it costs $20,000 to install (under $25,000), $3,000 a year to maintain (under $6,000) and leaves 3,000 m² of open lawn, just enough for the soccer field. It does best on the criteria: the meadow plot had the most pollinator species in every season (6, 14 and 9), and Plan B soaks in 80% of the rain, so less water would carry soil and fertilizer into Mill Creek. Plan A breaks the upkeep limit and Plan D breaks the budget, and Plan C soaks in only 50% and drew fewer pollinators. The trade-off is that Plan B leaves 3,500 m² less open lawn than Plan C, so there is less space for picnics and play.