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Conservation Value of Secondary Forests in Southeastern Wisconsin: A Preliminary Assessment of Plant Species Richness and Floristic Quality Danny J. Wilson and David A. Rogers Department of Biological Sciences, University of Wisconsin-Parkside Background In southeastern Wisconsin, most of the forest habitats were cleared for agriculture, infrastructure, and timber production. Small fragments of remnant forests still exist, but very few resemble their ancestral state. In the 20 th century, agricultural practices advanced throughout the U.S, thus, reducing the amount of land use practices. This resulted in the abandonment of agricultural landscapes and allowed for secondary succession to occur. Currently, much of southeastern Wisconsin’s abandoned landscapes are converting back to forests, most of which are being heavily invaded by lesser quality natives and introduced exotics. Due to the substantial transformations of these landscapes, both secondary growth and primary old growth forests and are at risk towards homogenization within their community assemblages. Main Focus The main focus of this present study was to compare the current herbaceous and woody compositions within agriculturally abandoned areas (secondary) to both historic and contemporary composition of old growth forests (primary) that occupy similar landscapes. Research Questions Are there compositional similarities in species occupancy between secondary and primary forests? Do floristic quality measures reflect species richness within secondary sites? Does distance from primary forest edge affect the floristic quality or native richness within the secondary forests? Methods Site Selection: In this study, seven secondary growth sites located within southeastern Wisconsin were selectively chosen by having immediate adjacency to at least one nearby Oak-Hickory primary growth forest. Most of the Oak-Hickory remnants and prior land-use fields were identified by the overviewing of Public Land Survey maps created in the mid-to-late 1800’s. For determining agricultural abandonment, comparison of the Bordner Survey maps from the 1930’s and current day aerial imagery were used to find areas that have converted to forests. After selecting the sites, we then plotted a multitude of waypoints distributed evenly throughout each secondary forest to be navigated to via GPS. At each location, several plots were surveyed at varying distances from primary forest edges. New coordinates at each plot center were documented upon arrival and later used to measure their distances from primary forest edges. Herbaceous Species Survey : For surveying of the herbaceous species, we placed a cross-shaped quadrat containing four 1 meter² quadrants at the center of each plot and tallied presence of each species within each quadrant. We also categorized the density of each present species in regards to the Daubenmire Cover Scale (Daubenmire 1952; Dombois & Ellenberg 1974). Woody species less than one meter in height located within each quadrant were also documented in the herbaceous survey. Shrub & Sapling Species Survey: For surveying of the shrub and sapling species, we counted all individuals present within a 1.78 meter radius from the center of each plot. Shrubs and saplings were determined as any woody plant greater than 1 meter tall, but less than 10.2 centimeters in diameter at breast height (DBH). Tree Species Survey: For the surveying of tree species, we used the point-centered quarter (PCQ) method (Cottam and Curtis, 1956) at each plot. The PCQ method divides a given sample area into four quarters, with the sample point as the center and boundary lines imagined in each cardinal direction. Within each quarter, the observer measured the distance from the plot center to the midpoint of the nearest tree and measured the diameter at breast height. Trees were defined as a mature woody plant with a minimum of 10.2 centimeters in diameter at breast height. Hemispherical Photography Hemispherical photography was used to analyze the canopy structure at the plot level and for measuring canopy cover. For photo capturing, we used a GoPro Camera mounted and balanced to a 1-meter pole placed in the center of the quadrat. These pictures were later converted to binary using ImageJ, and the black and white pixels were formulated to calculate an approximate percentage of canopy closure at each plot. 1m² Herbaceous plot 1.78m radius shrub/sapling plot PCQ method for nearest tree Fromm Bros Nieman & Co. Fox Farm, Thiensville, WI 1937 Highland Woods, Thiensville, WI 2015 Abandonment Future Directions As this project was a preliminary assessment towards understanding the dynamics of secondary forests on a small scale, the resulted analyses and comparisons have provided an incentive to continue this research but on a larger scale. If this project were to continue, by increasing the amount of secondary sites and adding adjacent old growth sites for surveying, we could see a more direct relationship towards how and why present herbaceous and woody species have colonized within the secondary sites. Also, by adding more parameters to the study, such as old growth edge size, secondary permeability, dispersal and life traits, soil quality, prior land-use, and wildlife inhabitances, these parameters could be used to build more complex models and help towards further understanding the colonization processes within secondary sites. Also, the emphasis of colonization credit could be measured in a long term approach. By revisiting the sites frequently, we could document the emergence of species that had little to no presence previously. The long-term approach would also be beneficial for understanding species dispersibility, biodiversity persistence, and changes in matrix qualities. After a certain amount of time, the status of the emerging forest communities could then be assessed for conservation worthiness, and whether or not these sites need assistance towards increasing overall richness and floristic quality. Sampling Protocol Abandoned agriculture equipment Cudahy, WI Abandoned chicken coop Thiensville, WI Abandoned chicken coop Thiensville, WI For the herb layer, secondary forest sites were found to be compositionally distinct from primary forests in either time period (Figure 1). Secondary forest herb communities were mostly dominated with White Avens (Geum canadense), Goldenrod (Solidago spp.), and Multiflora Rose (Rosa multiflora) (Table 1), all of which having low conservation coefficient values. Also, secondary sites contained little to no abundance of higher quality forest understory species, and most plot level observations within sites showed redundancy in species compositions. For the canopy layer, secondary forests sites were also dissimilar from primary forests (Figure 2). Secondary forests tree communities were dominated by Green Ash (Fraxinus pennsylvanica), Black Cherry (Prunus serotina), and Box-Elder (Acer negundo) and a near complete absence of oak (Quercus spp.) species (Table 2). With one exception, one secondary site contained a higher frequency of Black Oak (Quercus velutina), but its overall abundance between secondary sites was significantly low (<1%). Figure 1: Multi-Dimensional Scaling of herbaceous species importance values between secondary and primary forest sites Table 1: Comparison of average abundances for 10 herbaceous species. Species most abundant within secondary forests where chosen for this table. Herbaceous Species Comparisons Between Secondary and Primary Forests Figure 2: Multi-Dimensional Scaling of tree species importance values between secondary and primary forest sites Table 2: Comparison of average abundances for 10 tree species. Tree species most abundant within secondary forests were chosen for this table. Tree Species Comparisons Between Secondary and Primary Forests Site Level Variation between Native Richness and Floristic Quality in Secondary Forest Figure 3: Fit-Line Regression estimating the relationship between floristic quality and distance from primary edge Figure 4: Fit-Line Regression estimating the relationship between native richness and distance to primary edge In the analyses of species richness and floristic quality within secondary forest stands, the distance from an old growth patch was the strongest predictor while tree density, canopy composition, and canopy closure were not significant predictors. These trends may reflect the limited dispersal powers of native species which may be compensated by a colonization credit as time goes on, where the emergence and colonization of dispersal-limited species may have not yet taken place. Acknowledgements Special thanks to Alice and Scott Thomson for providing the fellowship opportunity for this research project. Thanks to Dr. David A. Rogers in assistance with this research project and several previous research opportunities. Herb Winners Herb Losers Shrub Winners Shrub Losers Tree Winners Tree Losers Acer saccharum Fraxinus pennsylvanica Quercus alba Ostrya virginiana Virburnum lentago Cornus alternifolia Cornus racemosa Viburnum opulus Geranium maculatum Geum canadense Osmorhiza claytonii Smilacina racemosa Native Winners and Losers

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Conservation Value of Secondary Forests in Southeastern Wisconsin:

A Preliminary Assessment of Plant Species Richness and Floristic Quality

Danny J. Wilson and David A. Rogers

Department of Biological Sciences, University of Wisconsin-Parkside

Background

In southeastern Wisconsin, most of the forest habitats were cleared for agriculture, infrastructure, and timber production. Small fragments of remnant forests still exist, but very few resemble their ancestral state.

In the 20th century, agricultural practices advanced throughout the U.S, thus, reducing the amount of land use practices. This resulted in the abandonment of agricultural landscapes and allowed for secondary succession to occur.

Currently, much of southeastern Wisconsin’s abandoned landscapes are converting back to forests, most of which are being heavily invaded by lesser quality natives and introduced exotics.

Due to the substantial transformations of these landscapes, both secondary growth and primary old growth forests and are at risk towards homogenization within their community assemblages.

Main Focus

The main focus of this present study was to compare the current herbaceous and woody compositions within agriculturally abandoned areas (secondary) to both historic and contemporary composition of old growth forests (primary) that occupy similar landscapes.

Research Questions

Are there compositional similarities in species occupancy between secondary and primary forests?

Do floristic quality measures reflect species richness within secondary sites?

Does distance from primary forest edge affect the floristic quality or native richness within the secondary forests?

MethodsSite Selection:In this study, seven secondary growth sites located within southeastern Wisconsin were selectively chosen by having immediate adjacency to at least one nearby Oak-Hickory primary growth forest. Most of the Oak-Hickory remnants and prior land-use fields were identified by the overviewing of Public Land Survey maps created in the mid-to-late 1800’s. For determining agricultural abandonment, comparison of the Bordner Survey maps from the 1930’s and current day aerial imagery were used to find areas that have converted to forests. After selecting the sites, we then plotted a multitude of waypoints distributed evenly throughout each secondary forest to be navigated to via GPS. At each location, several plots were surveyed at varying distances from primary forest edges. New coordinates at each plot center were documented upon arrival and later used to measure their distances from primary forest edges.

Herbaceous Species Survey:For surveying of the herbaceous species, we placed a cross-shaped quadrat containing four 1 meter² quadrants at the center of each plot and tallied presence of each species within each quadrant. We also categorized the density of each present species in regards to the Daubenmire Cover Scale (Daubenmire 1952; Dombois & Ellenberg 1974). Woody species less than one meter in height located within each quadrant were also documented in the herbaceous survey.

Shrub & Sapling Species Survey:For surveying of the shrub and sapling species, we counted all individuals present within a 1.78 meter radius from the center of each plot. Shrubs and saplings were determined as any woody plant greater than 1 meter tall, but less than 10.2 centimeters in diameter at breast height (DBH).

Tree Species Survey:For the surveying of tree species, we used the point-centered quarter (PCQ) method (Cottam and Curtis, 1956) at each plot. The PCQ method divides a given sample area into four quarters, with the sample point as the center and boundary lines imagined in each cardinal direction. Within each quarter, the observer measured the distance from the plot center to the midpoint of the nearest tree and measured the diameter at breast height. Trees were defined as a mature woody plant with a minimum of 10.2 centimeters in diameter at breast height.

Hemispherical PhotographyHemispherical photography was used to analyze the canopy structure at the plot level and for measuring canopy cover. For photo capturing, we used a GoPro Camera mounted and balanced to a 1-meter pole placed in the center of the quadrat. These pictures were later converted to binary using ImageJ, and the black and white pixels were formulated to calculate an approximate percentage of canopy closure at each plot.

• 1m² Herbaceous plot

• 1.78m radius shrub/sapling plot

• PCQ method for nearest tree

Fromm Bros Nieman & Co. Fox Farm, Thiensville, WI1937

Highland Woods, Thiensville, WI2015

Abandonment

Future DirectionsAs this project was a preliminary assessment towards understanding the dynamics of

secondary forests on a small scale, the resulted analyses and comparisons have provided

an incentive to continue this research but on a larger scale. If this project were to

continue, by increasing the amount of secondary sites and adding adjacent old growth

sites for surveying, we could see a more direct relationship towards how and why present

herbaceous and woody species have colonized within the secondary sites. Also, by adding

more parameters to the study, such as old growth edge size, secondary permeability,

dispersal and life traits, soil quality, prior land-use, and wildlife inhabitances, these

parameters could be used to build more complex models and help towards further

understanding the colonization processes within secondary sites.

Also, the emphasis of colonization credit could be measured in a long term approach. By

revisiting the sites frequently, we could document the emergence of species that had

little to no presence previously. The long-term approach would also be beneficial for

understanding species dispersibility, biodiversity persistence, and changes in matrix

qualities. After a certain amount of time, the status of the emerging forest communities

could then be assessed for conservation worthiness, and whether or not these sites need

assistance towards increasing overall richness and floristic quality.

Sampling Protocol

Abandoned agriculture equipment Cudahy, WI

Abandoned chicken coopThiensville, WI

Abandoned chicken coopThiensville, WI

For the herb layer, secondary forest sites were found to be compositionally distinct from primary forests in either time period (Figure 1). Secondary forest herb communities were mostly dominated with White Avens (Geum canadense), Goldenrod (Solidago spp.), and Multiflora Rose (Rosa multiflora) (Table 1), all of which having low conservation coefficient values. Also, secondary sites contained little to no abundance of higher quality forest understory species, and most plot level observations within sites showed redundancy in species compositions.

For the canopy layer, secondary forests sites were also dissimilar from primary forests (Figure 2). Secondary forests tree communities were dominated by Green Ash (Fraxinus pennsylvanica), Black Cherry (Prunus serotina), and Box-Elder (Acer negundo) and a near complete absence of oak (Quercus spp.) species (Table 2). With one exception, one secondary site contained a higher frequency of Black Oak (Quercus velutina), but its overall abundance between secondary sites was significantly low (<1%).

Figure 1: Multi-Dimensional Scaling of herbaceous species importance values between secondary and primary forest sites

Table 1: Comparison of average abundances for 10 herbaceous species. Species most abundant within secondary forests where chosen for this table.

Herbaceous Species Comparisons Between Secondary and Primary Forests

Figure 2: Multi-Dimensional Scaling of tree species importance values between secondary and primary forest sites

Table 2: Comparison of average abundances for 10 tree species. Tree species most abundant within secondary forests were chosen for this table.

Tree Species Comparisons Between Secondary and Primary Forests

Site Level Variation between Native Richness and Floristic Quality in Secondary Forest

Figure 3: Fit-Line Regression estimating the relationship between floristic quality and distance from primary edge

Figure 4: Fit-Line Regression estimating the relationship between native richness and distance to primary edge

In the analyses of species richness and floristic quality within secondary forest stands, the distance from an old growth patch was the strongest predictor while tree density, canopy composition, and canopy closure were not significant predictors. These trends may reflect the limited dispersal powers of native species which may be compensated by a colonization credit as time goes on, where the emergence and colonization of dispersal-limited species may have not yet taken place.

Acknowledgements

Special thanks to Alice and Scott Thomson for providing the fellowship opportunity for this research project.

Thanks to Dr. David A. Rogers in assistance with this research project and several previous research opportunities.

Herb Winners Herb Losers

Shrub Winners Shrub Losers

Tree Winners Tree Losers

Acer saccharum Fraxinus pennsylvanica Quercus alba Ostrya virginiana

Virburnum lentago Cornus alternifoliaCornus racemosaViburnum opulus

Geranium maculatumGeum canadenseOsmorhiza claytoniiSmilacina racemosa

Native Winners and Losers