#2 Introduction to wetland management

Passive wetland management

minimal human intervention, allow natural ecological process to take place

Active wetland management

ongoing direct intervention by humans into ecological processes

• Tend to show up more in wetlands*

What are two advantages of passive management?

• Low cost/ lower time investment

• Allows natural processes and succession to occur

What are two advantages of active management?

• Can target specific ecological outcomes

• Can prevent undesirable states (e.g., invasive species dominance)

Why is active management especially common in wetlands compared to other ecosystems?

Wetlands are characterized by high variability and instability, which do not align well with passive management

• wetlands can easily become dominated by a single species → requires active manipulation

How has removing natural hydrological variability influenced the need for active management?

water control → reduces natural disturbances such as floods and droughts

• no disturbance→ less diverse, competitive species-dominated states

• requiring managers to artificially create disturbances to maintain biodiversity

Intermediate Disturbance Hypothesis

biodiversity is highest at moderate levels of disturbance

• frequent or intense enough to prevent competitive exclusion, but not so extreme that only a few tolerant species survive

What is one example of a wetland disturbance and explain its ecological role?

Flooding

• breaks up vegetation, redistributes nutrients, and creates new habitat patches

• increasing niche availability and promoting biodiversity

What happens in wetlands with very low disturbance levels?

Competitive dominant species take over

• reduces biodiversity and leads to homogeneous vegetation

What characterizes a high-disturbance wetland system?

Only a few disturbance-tolerant or fast-colonizing (ruderal) species can persist

• Late-successional species cannot establish

Why are early- and mid-successional wetlands often the most productive?

They contain a dynamic mix of species, high nutrient cycling, and abundant niche space created by moderate disturbances

Why do many wetlands have legal or regulatory mandates for active management?

Certain functions may not be maximized through natural succession.

• Regulations may require maintaining specific habitat types or ecosystem services

• (e.g. waterfowl habitat, flood control, or nutrient retention)

What are some common active management techniques in wetlands? (first 3)

• Water control

• Adding infrastructure-> roads/ paths to walk/ pumps

• Structures to add enrichment for wildlife

What are some common active management techniques in wetlands? (last 3)

• Vegetation control

• Remove invasives, promote “target” species

• Simulated disturbances

What are three common hydrological management strategies in wetlands?

• Levees and dikes

• Water control structures

• Manipulation of hydroperiod/hydropattern (timing, depth, and distribution of water)

What are 3 types of vegetation control?

• Mechanical removal

• Herbicides 

• Planting (restore community)

Why is vegetation control used in wetlands?

used to reduce invasives, control overdominant species (e.g., cattails), and promote desired plant communities

What are some examples of simulated disturbances?

• Disking (tiller-> grinds up and mix veg with soil), stomping, mowing, rollers (crush things), choppers

• Burning

Why is burning, as a way to simulate disturbances, a good method to use in wetlands?

Cycle nutrients and simulate historic disturbances

Why is modern wetland management often compared to agriculture?

Because it uses intensive manipulations to “cultivate” desirable plant communities and support wildlife—similar to farming practices

• (water control, vegetation management, soil disturbance)

What role did market hunting play in shaping early U.S. wetland management?

• Market hunting depleted waterfowl populations, prompting the Migratory Bird Treaty Act (1917) and federal refuge creation

• → enabled later wetland conservation and management efforts

How did the Migratory Bird Treaty Act and Duck Stamp revenues influence wetland management?

They provided consistent funding for the National Wildlife Refuge System, enabling large-scale wetland conservation and management projects

How did biologists examining duck diets influence management?

Understanding duck food requirements led to intensive manipulations to produce high-quality forage for migrating waterfowl

• (e.g., moist-soil management)

North American Waterfowl Management Plan (NAWMP)

a multinational strategy to conserve waterfowl and their wetland habitats

• coordinates conservation across the U.S., Canada, and Mexico

How have NAWMP goals evolved since 1986?

Initially focused mainly on ducks, now includes shorebirds, other wetland species, and broader habitat conservation

Describe wetland management in the Prairie Pothole Region under NAWMP

• Management is largely passive

  • individual wetlands receive minimal manipulation.

• Conservation efforts focus on protecting the surrounding landscape matrix

What type of wetland management is common in California’s Central Valley under NAWMP?

Moist-soil management and intensive seasonal hydrology control

• often involving water level manipulation and vegetation management

What is green-tree reservoir management under NAWMP, and where is it primarily used?

controlled flooding of hardwood forests during winter to provide habitat for waterfowl

• requiring precise hydrologic and vegetation management

• Used in the Southern Bottomland Hardwood region

What wetland type characterizes much of the Central U.S. and is included in NAWMP priority areas?

Playa wetlands

• shallow, circular, ephemeral basins important for migratory birds