Blue Ash is an interesting tree. When wounded, it oozes sap that turns blue when exposed to air (you can make a dye out of it), the twigs are square-shaped & it has a sweet tooth. That is, it exclusively grows on soils that are “sweet” or limy. Most common in limestone areas, it also is found in areas where calcium carbonate crust is leached within the upper 36″ of soil. Calcium leached deeper than this & higher soil acidity will see Blue Ash disappear in native woodlands. It is this limy soil that gives rise to a unique type of woodland in Indiana made up of trees that have “sweet tooths”. These species include Chinkapin Oak, Blue Ash, Black Maple, Butternut, Ohio Buckeye, Shumard Oak, Honeylocust & Eastern Redcedar. In fact, this exclusive type of woodland is found in several areas of the state with Blue Ash making a substantial part of the forest.
It feels most at home & most common in savanna environment, though & on uplands that are rocky, very limy & well-drained. It is not as common or nearly as widespread as Green & White Ash in the state.
Its silvery bark is attractive & is noticeable as it mixes with its frequent partner with its silvery bark: Chinkapin Oak. The bark, ridged & a bit flaky, unlike the typical diamond-shaped furrows associated with most other ash species.
Consideration should be given to this drought-tolerant & low-fire tolerant tree. It tolerates very alkaline environments & holds up well in cities. I have seen offered at a nursery in Terre Haute, Indiana, but not in Lafayette or West Lafayette.
Unfortunately, trees may be doomed by the ever-expanding Emerald Ash Borer, which has halted all ash species planting in many cities anyway.
LIMESTONE HILLS OF SOUTHERN INDIANA
In the limestone hill country of southern Indiana, ridgetops are dominated by Chinkapin Oak & hickories (with White & Black Oak) with mixed Blue Ash & Eastern Redcedar on cliffs. Some limestone glades have Post, Blackjack, Black Oak with some Chinkapin Oak & Blue Ash with Eastern Redcedar. If Chestnut Oak covers the sandstone, siltstone knobs & hills of southern Indiana, then Chinkapin Oak/Blue Ash is frequent on the limestone tops.
On lower slopes comes Tuliptree, White Ash, American Beech & Sugar Maple. Coves harbor Black Walnut, American Basswood, Sugar Maple, American Beech & Northern Red Oak.
Low limestone woods have lots of Ohio Buckeye, Butternut, American Sycamore & Honeylocust.
KARST PLAIN OF SOUTHERN INDIANA
Blue Ash-Chinkapin Oak barrens/savanna mixed with Black Oak & several crab & haw species in the barrens area of southeastern Indiana where large expanses of treeless grassland occurred. Post Oak also occurred. The region, pretty flat, & fertile with soils rich in lime & phosphorus, had nearly all drainage underground with caves. So, very few, if any natural fire breaks existed at settlement.
It appears that Blue Ash/Chinkapin Oak savanna/barrens tended to occur the most on the edge of the more open & scrubby barrens & prairies, that is they required bit less fire frequency to maintain themselves. In the heart of such savanna, Black maple would occur around more protected limestone sinkholes & wetter areas where underground streams suddenly surfaced.
BLUEGRASS UPLANDS OF SOUTHEASTERN INDIANA
Here, Blue Ash is found in two eco-types. One, the mesophytic limestone forests in rolling uplands & ravines & around streams with White Basswood, Yellow & Ohio Buckeye, Tuliptree, Chinkapin Oak, American Sycamore, Eastern Redcedar, American Beech & Black Maple.
In the less-sloping areas, there was some Bur Oak-Chinkapin Oak-Blue Ash savanna at European settlement. This is a northern extension of the great Blue Ash-Chinkapin-Bur Oak savanna of the Kentucky Bluegrass region. Usually with a grassy understory with prairie wildflowers, the environ needed low fires to maintain itself in flatter, stream-less areas.
LIMESTONE CANYONS OF ENTRENCHED AREA OF NORTH-CENTRAL INDIANA (& SOUTHEASTERN INDIANA)
Blue Ash reaches its greatest occurrence in this region of Indiana where it is found in forested ravines & slopes with Chinkapin Oak, Black Maple, Ohio Buckeye, American Sycamore, Butternut, Black Walnut, Eastern Redcedar, American Beech & Tuliptree. It grows most commonly in the sweet soil where chunks of limestone protrude from the ravines. On limestone cliffs, it is frequent with Eastern Redcedar & American Sycamore.
In southeastern Indiana where streams have eroded through the acidic Illinoian Till Plain (with all of its clayey, sticky, acid soils made up of flatwoods), limestone may be exponsed in these cut canyons. There, pockets of limestone-loving Blue Ash, Chinkapin Oak, Eastern Redcedar, Ohio Buckeye & American Sycamore can be found.
TIPTON TILL PLAIN
Blue Ash occurs in this region around gravelly eskers & kames of calcareous gravels & sands (ground limestone) & till plain over limestone & calcium carbonates leaches within upper 36″ of the soil. This occurs in young deposits of Wisconsinan glacial till where calcium has been leached the least in the soil.
At European settlement, great forests of Ohio Buckeye, Blue Ash & other species (especially Beech & Black/Sugar Maple) made up large expanses of the Tipton Till Plain in central & eastern Indiana.
It appears areas of park-like Bur Oak-Blue Ash-Chinkapin Oak-Black Maple savanna existed when European settlers arrived in parts of central & eastern Indiana near prairie pockets & even away from them. This savanna/forest time in limy areas was probably barrens/prairie in the past, as Black Maple, Bur Oak, etc. in this area seems to indicate a woodland of Beech/Maple cut off from original forests & evolving into a woodland commonly found in bottom areas in Iowa & Nebraska & in old prairie areas over limestone in Ontario, Ohio & Michigan.
This calcareous till (where Blue Ash is common) may have it origins in glaciers scrapping off limestone uplands in Ontario & depositing this till at the end of the Wisconsinan glacial period.
I have found Ohio Buckeye, Black Maple, Chinkapin Oak, Blue Ash, American Basswood woodland behind the Colony Pines subdivision in West Lafayette by a creek. Ohio Buckeye was abundant in this woods.
“YOUNG” CALCAREOUS LOESS UPLANDS WITH SUFFICIENT LOESS KINDCHEN
In the deepest, youngest wind-blown silt deposits off the Wabash River valley in southwestern Indiana, there are some scattered populations of Blue Ash, where it is usually with Chinkapin Oak. Such sites usually have considerable loess kindchen (hardened calcium deposits in the soil or floury loess). The calcareous loess is often yellowish to buff-brown in color & very fertile. Native Americans used loess kindchen for dolls & Europeans in their homelands used loess kindchen for the same thing. Some of the “kindchen” is even hollow inside & rattles, so some of them were used as rattle toys. The term “loess” is German for “loose”, as floury loess is very easily eroded by wind & water. “Kindchen” means “young child” or “kiddy” in German. This refers to the using of kindchen found in the loess deposits of the North European Plain to make dolls for kids.
I found some native, old-growth Blue Ash-Chinkapin Oak woodland in Knox & Vigo counties in this environment. At Terre Haute, on rolling, young calcareous loess, I found Blue Ash with Bur Oak, Chinkapin Oak, White Oak, a rare White-Chinkapin Oak hybrid called “Deam Oak”. Another similar woodland on young, rich limy loess was made up of Bur, Chinkapin, Shumard Oak, Blue Ash, American Basswood, American Beech & Black Maple.
In Knox County, I found several large specimens with Chinkapin Oak, White Oak, Tuliptree, American Beech & Sugar Maple on deep, deep loess deposits on the east side of Vincennes.
I know of a few trees in Gibson County on steep loess slopes northwest of Patoka & a few on deep loess deposits in Sullivan County.