Fundamental question
How is a naturally functioning riparian forest best reestablished?
Hypotheses
- #1: Survivability and growth of riparian trees depends on reforestation method and treatment plan.
- Null hypothesis #1: There is no difference in survivability or growth of riparian trees because of reforestation method or treatment plan.
- #2: The number and diversity of naturally recruiting riparian tree species is a function of reforestation method and treatment plan.
- Null hypothesis #2: There is no difference in the number or diversity of naturally recruiting riparian tree species because of reforestation method or treatment plan.
- #3: The number and diversity of invasive exotic species is a function of reforestation method and treatment plan.
- Null hypothesis #3: There is no difference in the number or diversity of invasive exotic species because of reforestation method or treatment plan.
- #4: The survivability of riparian trees is dependent on floodplain hydrology relative to the species' wetland indicator status.
- Null hypothesis #4: There is no difference in the survivability of riparian trees because of floodplain hydrology.
Experimental design
There are currently three commonly used methods for floodplain or bottomland restoration in the Midwest. Each method will be utilized in two 1 acre plots and compared to unplanted control plots. In each section (N and S), 4 - 1 acre plots will be planted as follows:
Control plots
- Zero trees
- Pretreatment - mow and spot herbicide
Containerized plants
- 310 trees
- 3 gallon containers
- Planted in 12 foot grid
- Pretreatment - mow and spot herbicide
Bare root, random seedlings
- 400 bare root seedlings
- Cut turf in random pattern, plant 12' along path
- Pretreatment - mow and spot herbicide
Bare root, row seedlings
- 400 bare root seedlings
- Cut turf in rows, plant 12' along row
- Weed inhibitor mat around trees
- Native wild rye grass between rows to control competition
- Pretreatment - mow and spot herbicide
Design considerations
- Each treatment method will be planted in both the northern and southern section.
- Treatment plots will be randomly placed in each section.
- Trees will be randomly placed within each treatment plot.
- Equal numbers of trees and an equal distribution of tree species will be planted in each treatment plot.
- The tree species included in the restoration experiment will include 12 native riparian tree species available (see Table 1) and utilize regional ecotypes wherever possible.
Selection of tree species planted
The tree species to be utilized in the experiment are based on the Inclusive Riparian Tree list recommended to the White River Advisory Board (see Table 2) but further modified for:
- geographic range to include only those species that occur on the Tipton Till Plain;
- wetland indicator status to include only those species with FAC or wetter status;
- and excluding extremely rare or habitat restricted species (ie. rock elm and blue ash).
American elm was formerly an important canopy species on many Indiana floodplains. Dutch elm disease now usually kills this tree before it gets to canopy height. We have excluded it from our planting list.
