Tom's Blog

Thursday, February 4, 2016

An urban relic of the presettlement bur oak savanna

Mineral Point Road, from Gammon Road west to the Beltline, travels through one of the most heavily commercial areas in Madison. Which is why it is so startling to see, at the corner of High Point Road, a large grove of bur oaks. I have been intrigued by this grove for many years and have now found time to look into their origin.
 
Photo looking across High Point Road toward Mineral Point Road.
There are about a dozen large bur oaks here.

Realizing that such a grove hinted at oak savanna, I accessed the original surveyor's records for this area. Sure enough, this is a classic bur oak savanna, as the surveyor’s notes indicate.


Public Land Survey, Interior field notes, Dec. 1834, Orson Lyon surveyor
T7N R8E
North between Sections 22 and 23
Bur oak 9 inches diameter
40.00 Set quarter section post between White Oak 30 N69W42 and Bur oak 14 S14W65
40 91 Bur oak 12 inches diameter
70 70 Bur oak 12 inches diameter
80 00 Set post corner to Sections 14 15 22 23 bearings
Bur Oak 14 S83 E33
Ditto N 57 W 52
Land rolling & 1st rate Timber
Bur & White Oak
Undergrowth Oak & grass
The statement mentioning “grass” in the undergrowth shows that this was a fairly open savanna, since prairie grass does not compete under too much shade.



Surveyor's original plat map of the Town of Middleton, showing the location of the bur oak grove (red rectangle added).
The extensive prairies are shown by the surveyor's sketches.
Note also the Blue Mounds/Portage (Fort Winnebago) trail around the west end of Lake Mendota

 [This area, T7N R8E, is now known as the Town of Middleton]

By 1937, when the first air photos become available, most of the land around the bur oak grove had been turned to cultivation. (See air photo)


Air photo of Section 23. Mineral Point Road is the horizontal white line across the lower part of the photo.
The bur oak grove is clearly visible.





Note in the surveyor's plat map that farther west there are areas that were mostly prairie. The high plain west of where the Beltline runs today was a large prairie, almost 3,000 acres in extent. Using current landmarks, this prairie encompassed: UW West Ag Expt Station; Junction Road overpass; Pleasant View Road; Elderberry Road; Pioneer Road; West Middleton Church; West Middleton School; Kwik Trip; Tumbledown Golf Course; Point Road; Valley View Road; Sugar Maple Lane; and Point Six Movie Theater.

Airport Road now runs through what was once the large prairie shown at the north end of the map.

There is also other large prairies in the adjacent Town of Cross Plains, extending east, north, and south from Pine Bluff junction.

The surveyor’s plat map also shows a trail from Blue Mounds to Portage that goes across the middle of the Town and around the west end of Lake Mendota (called 4th Lake on the map). This trail later became a local branch of the famed Military Road that ran between Galena, Illinois and Green Bay.

What happened to all this prairie and savanna?

By 1890, (the oldest plat map I looked at) the whole of Middleton Township was agricultural. There was an East Middleton P.O. at the junction of Mineral Point Road and County M (now called Junction Road) and a West Middleton P.O. at the corner of Pioneer Road and Mineral Point Road. There was no indication in the 1890 plat map of the presence of prairie.

In my early days in Madison (1971-1972) the area around Mineral Point Road and the Beltline was still completely open, except for a small American Exchange Bank and Big Sky Drive-in Theatre. West Towne Shopping Mall, at the corner of Mineral Point and Gammon Road, opening on 100 acres in 1970, was the first step on the road to perdition! (In a 1970 air photo in the Wisconsin Historical Society archives, the land around West Towne was still completely rural.)


This brief history is instructive. It shows how easy prairies are to destroy. Savannas are also destroyable, but with more difficulty. Especially in the early days of settlement, when only horse-drawn equipment was available, trees were harder to eliminate. But by the 1970s, anything was possible.

The small bur oak relic at Mineral Point/High Point provides us a tiny glimpse of what this area once looked like!

Sunday, January 24, 2016

Prairie dropseed (Sporobolus heterolepis), an interesting species of high conservation status

There are only a few prairie species in our area with a Coefficient of Conservatism of 10. One of these is prairie dropseed, (Sporobolus heterolepis), an important grass species which is much more prevalent farther west. According to the Atlas of Wisconsin Prairie plants by Cochrane and Iltis, prairie dropseed is an indicator of unplowed and relictual prairies, especially in dry-mesic and mesic sites.

According to the USFS fire effects database, prairie dropseed grows in mesic prairies, well-drained moraines, rock outcrops, glades, open savannas, barrens, lightly grazed pastures, and along railroad and highway rights-of-way. It is considered a climax species that is codominant with little bluestem, big bluestem, and Indian grass.

It is a deep-rooted, long-lived, and drought-tolerant perennial which does well as a ground cover for hot and dry sites. According to Weaver's work in Nebraska, even relatively small dropseed colonies may have roots extending as deep as 4-5 feet into the soil. It is a classic "bunch" grass, and each bunch can remain in place for many years.

Prairie dropseed benefits greatly from fire. According to the USFS fire effects database, fire promotes flowering and seed set. In a Wisconsin study, fire increased flower production by 25 times, vegetative cover by 30 times, and the average plant height by 4 inches.

As befitting a C4 (warm-season) plant, prairie dropseed is only found in open sunlight or at the edge of savannas where full sunlight is still available.

At Pleasant Valley Conservancy there are nine locations where prairie dropseed was remnant, and in addition we have been successful in establishing it from transplants raised from seeds collected on site. In the table below, the original remnant populations were in Unit 1, 2, 3, 3A, 4, 6, 7, 9, and 10. It was planted and is thriving in the Cabin, Pocket, Ridge, and Toby's Prairies, the East Basin Prairie, and Unit 11A savanna. Its presence in the Circle and Triangle might have been either from remnant or planted sources. Left out of this table are the several plants present among the rocks on the East Overlook. Photos of some of these populations are shown below.

Cabin prairie
Circle
east basin
Pocket Prairie
ridge prairie
Toby's Prairie
triangle
Unit 1
Unit 10
unit 11A
Unit 2
Unit 3
unit 3A
Unit 4
Unit 5
Unit 6
Unit 7
Unit 9




Long-term dropseed population in the upper part of Unit 1, surrounded by little bluestem.
After the first burn in 1997, this population flourished, with extensive seed set.
The seed collected here was used to establish populations in the planted prairies and open savannas




A second remnant population in the lower part of Unit 1, visible from the Quarry trail.



Dropseed establishes well in rocky areas.
This remnant plant has been thriving for a number of years at the lower end of Unit 10 savanna.


There are 8 or 10 dropseed plants growing as remnants among the rocks on the Rocky Overlook (Unit 6).
These plants are best seen in the late fall of the year when their distinct brown color stands out.




In early fall, when the prairie grasses are starting to turn, dropseed can be easily spotted
because it retains its bright green color longer.
This plant in Unit 10 savanna is growing among the dolomite rocks.


Strangely, prairie dropseed is also used extensively in residential and commercial landscape plantings, and for roadside revegetation. In many of the landscape plantings, specially selected "cultivars" are used, such as Tara, Chanticleer, or Winter. Presumably these cultivars have been selected from desirable-looking plants found in natural settings.The photo below shows a typical situation.




In the Madison area, dropseed can often be found growing in special beds near commercial banks, shopping centers, or dividers within parking lots. Some of these populations may even set seed!

Friday, January 22, 2016

Floristic Quality Assessment at Pleasant Valley Conservancy Based on 13 years of Data

The Floristic Quality Index (FQI) has become a widely used measurement of natural areas quality. This standardized tool was developed by Floyd Swink and Gerould Wilhelm at the Morton Arboretum, and is explained in detail in their book: “Plants of the Chicago Region”, published by the Indiana Academy of Sciences. FQI is not a stand-alone value, but is  used together with other assessments to evaluate the quality of a site.

Measuring the FQI begins with an assemblage of a complete species list for the site. Each species is assigned a unique Coefficient of Conservatism (a number from 0 to 10), which expresses the probability that this plant species is likely to occur in landscapes relatively unaltered from those of pre-settlement times. Plant species with high C values are relatively specialized in their requirements, and are thus found in more restricted habitats.

C values are assigned to species on a state-wide basis, and the C values for Wisconsin plants can be found in an extensive publication edited by Thomas Bernthal issued by the Department of Natural Resources.

FQI is calculated by multiplying the mean C value for a site by the square root of the number of species at that site. (As far as I can determine, Swink and Wilhelm have not explained the basis for this formula. Why, for instance, square root of number of species?)

Since 2002 I have been keeping detailed records of plant species at Pleasant Valley Conservancy. This year Amanda brought together all data from 2002 through 2015 (13  years), sorted them by management unit, and then applied the C values and made the FQI calculation for each unit. The table below provides the data, sorted by FQI (highest on top). Also given in the table is the acreage and total number of species for each unit, and a brief description of its ecological character. The location of each unit can be found in the Management Map found at this link.

The single highest FQI was in Unit 6, an outstanding hill prairie/savanna. This unit is a large remnant with a bur oak savanna above and in the gullies and dry mesic prairie on the lower slopes. Before restoration had begun this unit, although fairly degraded, had a well developed tallgrass prairie flora with a big bluestem remnant at the top under the rocks and little bluestem on the lower slope, and two moderately sized Indian grass patches.

Also, high FQI values were found in Unit 11A, Unit 10, and Unit 12A, all of which are well-restored oak savannas.

Other units with high FQI values were three of the older and larger planted prairies (Toby’s, Valley, Pocket) and four of the larger savanna areas (Units 5, 8, and 12B.

Other high FQI values were found in the larger units (not surprising, because the larger units in general had more species).


The rest of the data for units at PVC, all with FQI values over 30, are given in the table below.
Name
FQI
Acreage
Total species
Present status

Unit 6
63
4.48
153
Upper (Bur oak savanna) Lower (Prairie remnant)
Unit 11A
61
5.17
119
Prairie remnant and bur oak savana
Toby's Prairie
61
3.63
126
Dry-mesic prairie (partially remnant; mostly planted)
Unit 10
60
2.9
136
Bur oak savanna
Unit 12A
59
5.95
138
White oak savanna
Valley Prairie
58
3.85
130
Dry, mesic, and wet-mesic prairie (planted)
Pocket Prairie
57
4.5
104
Dry, mesic, and wet-mesic prairie (planted)
Unit 7
56
1.58
117
Upper (Bur oak savanna) Lower (Prairie remnant)
Unit 3
56
1.03
105
Prairie remnant
Crane Prairie
55
2.6
130
Dry, dry-mesic, and mesic prairie (planted)
Unit 8
54
1.3
102
Bur oak savanna
Unit 12B
54
0.98
114
White oak savanna
Unit 5
52.5
1.61
105
Bur oak savanna
Unit 2
52
1.6
89
Prairie remnant
East Basin
51.5
4.4
100
Dry-mesic, mesic, and wet-mesic prairie (planted)
Ridge Prairie
51
1.67
100
Dry-mesic prairie (planted)
Unit 23
51
0.38
93
Bur oak savanna
Unit 19C
48
1.13
71
Black/bur oak savanna
Unit 21
47
3.38
75
White oak woodland
Triangle
47
0.55
81
Hill's oak savanna
Unit 20 combined
46
3.35
86
Woods and prairie mix
Barn
46
0.48
87
Wet mesic prairie (planted)
Unit 9
45
1.82
82
Bur oak savanna
Cabin Prairie
45
0.54
83
Mesic prairie (planted)
Unit 1
44
1.18
61
Prairie remnant
Unit 11D
43
4
74
White oak savanna
Unit 4
41
0.32
48
Prairie remnant
Unit 19A
40.8
0.33
69
Bur oak savanna
Unit 19B
38
1.64
51
Bur oak savanna
Unit 19D
35
1.05
30
Bur oak/black oak savanna
Unit 19E
34
1.47
37
White oak savana


Amanda also made the FQI calculations for Pleasant Valley Conservancy has a whole. There were 335 total species, the average C value was 5.1, and the FQI for the whole Conservancy was 93.21. (This number is much higher than that of any single unit, reflecting the importance of species number in the FQI calculation.)

Another interesting analysis is that of the various planted prairies at PVC. The table below shows, not surprisingly, that the older planted prairies have higher FQIs than the younger ones.

Name
FQI
Size (acres)
Year planted
Age in 2016
Toby’s
61
3.63
1998
18
Pocket Prairie
57
4.5
1999
17
Valley Prairie
58
3.85
2002
14
Barn Prairie
46
0.48
2002
14
Cabin Prairie
45
0.54
2002
14
Crane Prairie
55
2.6
2005
11
Ridge Prairie
51
1.67
2005
11
East Basin
51.5
4.4
2009
7