2012-2013: Nature Beneath Our Feet
Mississippi Valley Field Naturalists
January 3, 2013
Death’s Bounty in the Forest
The Mississippi Valley Field Naturalists’ (MVFN) 2012-2013 public lecture series, Nature Beneath Our Feet, continues January 17 with the fourth presentation, “Coarse Meaty Debris: The Significance of Large Dead Animals in Our Forests.” You do not need to be an expert to enjoy the presentations—just possess a curiosity or appreciation for wild nature. Cottagers, hunters, fishermen, canoeists, hikers, campers, artists and seasoned field naturalists alike will find something to interest them as we explore what lives in Lanark County and how best to protect it for future generations. Refreshments are offered at each lecture.
This lecture will be presented by Dr. Paul Keddy, a biologist and writer now living in the forests of Lanark County. A professor of ecology for 30 years, he has published over 100 scholarly papers. He achieved international designation as a Highly Cited Researcher, has received awards from several scientific societies, and locally, is an MVFN-designated Champion for Nature. He has published several books used in university courses, including Wetland Ecology: Principles and Conservation. His recent lectures have included Washington, Toronto, Madrid, and Lyon. This year he will start with a lecture in Almonte, on a topic that is new and timely, the role of death in winter forests.
Within hours on a sunny morning in March, a pile of trim on a beaver pond in Lanark County (above) attracted a bald eagle (below), a coyote and 21 crows and ravens.
To prepare us for death’s bounty, Dr. Keddy will first give us a brief overview of forest restoration. There are, he says, a few simple steps which we can all take to begin to restore our native forests. He wrote about these steps in a scholarly paper back in 1996 (see www.drpaulkeddy.com) and said encouragingly, “It is entirely possible for us to restore large tracts of native forest this century, to repair the damage our species has caused. This will require, of course, time, since trees grow slowly. Hence, it is better to start sooner than later!”
This background leads naturally and ultimately to the topic of death in our forests. Large dead trees and large dead animals are vital to healthy forest ecosystems, and can be considered two indicators of restored forests. There is a natural rate of mortality and the forest floor would at one time have been strewn with both dead trees (slow to decay) and dead animals (fast to decay).
The importance of dead big trees is already rather well understood Dr. Keddy says. Scientists have known for years about the importance of dead trees, both standing and fallen. Standing dead trees, sometimes known as snags, provide important wildlife habitat. They provide holes and dens for wild species including woodpeckers, flying squirrels, tree frogs and porcupines. Some have called such trees ‘apartment buildings for nature.’ Fallen dead trees, known as ‘coarse woody debris,’ have received somewhat less attention. However, fallen dead wood is vital to forests. Fallen dead trees also provide habitat for animals, particularly reptiles and amphibians (e.g., salamanders, frogs). A piece of coarse woody debris will be teeming with more life than when it was standing alive and erect—a life after death experience! Hence, when large logs are removed from forests, many plant and animal species suffer.
But what about big, dead animals? This will be Dr. Keddy’s main focus as we know least about this aspect of forest ecology. Today this means mostly deer, but in the recent past moose, elk and caribou were also important. He adds, “But I want to make it clear from the start that this general principle applies way beyond Lanark County and beyond forests. Think of a dead elephant in South Africa, or a dead Bison in Alberta. These are not aberrations, or tragedies, but the basis of an enormous food web and a sign of a healthy ecosystem.” We can call dead animals ‘coarse meaty debris’ to emphasize similarities to coarse woody debris. They are large pieces of biological material that, left in place, will support a rich variety of other species. Their great value in energy and nutrients contributes to their far more rapid disappearance relative to dead trees. A tree may take decades to disappear, while a carcass can take only days.”
Carcasses arise out of death. It may be death from starvation in deep snow, death from old age and disease, or death from a large carnivore such as a wolf. If you visit a winter carcass, the first thing that stands out is the amount of activity around it. The snow is often beaten flat, with trails radiating out in all directions. The carcass is gone in a matter of days, with even the bones scattered in all directions.
Large birds of prey such as Golden Eagles and Bald Eagles may arrive first. Smaller scavengers such as Crows and Ravens feed among the eagles. Turkey Vultures also come early. Many mammals including fishers, minks, and other weasels come to enjoy.
What is more surprising, perhaps, is the number of smaller birds that are attracted to carcasses, such as woodpeckers, nuthatches, and chickadees. Keddy says, “Think of all the birds that visit a feeder to eat suet. A suet feeder is really a small carcass for wild birds. It replaces a food source they used to find whenever wolves or cougars killed a moose or deer.”
Even the bones are soon dispersed. Bones contain phosphorus, a vital nutrient for producing more bones in living animals. Many kinds of small mammals arrive to gnaw on the bones.
Winter carcasses are vital to the survival of many animals. Summer carcasses have their own story, since many kinds of summer birds and insects participate in the feast. There may, or may not, be time for Dr. Keddy to talk about burying beetles, but the topic of carcasses is a good place to begin a long cold winter. Perhaps Sam McGee already knew this story.
Discover which species visit a winter carcass feeding station in Keddy’s forest and what may feed on you if you succumb to the cold while snowshoeing. Tell us about animals you have seen feeding on winter carcasses. Let’s start the conversation about how we get more large carcasses back in our forests. Dr. Keddy’s lecture “Coarse Meaty Debris: The Significance of Large Dead Animals in Our Forests” will be held at 7:30 pm on Thurs. Jan. 17, 2013, Almonte United Church, 106 Elgin St., Almonte. All are welcome ($5 fee for non-members). For further information please contact MVFN’s Program Chair Cathy Keddy at 613-257-3089.
Opening a can of worms - Lecture report written by Linda Mosquin
As a gardener I have dug up many earthworms in our flower and vegetable gardens and have long considered the earthworm to be a friend, always marveling at its ability to break up, aerate and improve the soil. Or, as our Mississippi Valley Field Naturalist’s speaker Dr. Paul Gray of the Ontario Ministry of Natural Resources(OMNR) more largely described them, as “. . . ecological engineers famous for their ability to ingest and integrate soils through different layers, for their contribution to agricultural productivity, for their role as food for wildlife and for use by anglers as fish bait.” Many animals eat earthworms…. think crows, gulls, skunks, flickers, robins and others. In Ontario the business of exporting worms to the United States is valued at 110 million dollars a year and involves a migrant work force picking worms at night. And with agricultural fields and pastures in Ontario using more than 5 million hectares of soil, the earthworm would appear to be a seemingly benevolent creature.
Indeed, the lowly earthworm helps the economy, but as Ontario Ministry of Natural Resources (OMNR) Paul Gray recently told an MVFN audience, the evolving earthworm story in North America is much more complex. He is co-author of the 2012 report: Implications of a Potential Range Expansion of Invasive Earthworms in Ontario’s Forested Ecosystems.
Indeed, the earthworm helps the economy, but as our speaker pointed out, with warmer climate change due to humans burning fossil fuels, the evolving earthworm story in Canada/North America is more complex and darker. Native Ontario earthworms, where they existed, are believed to have been eradicated with the Wisconsin glaciers 10,000 years ago and southern native species did not manage to re-colonize this area. Thus our forests developed in the absence of earthworms until they arrived with soils (for ballast) and plants brought here by European settlers. So at present 17 European non-natives and two North American (non-native to Ontario) earthworm species thrive in the province. Some of these earthworms are invasive and with our warming climate it is becoming more apparent that there is a potential for range expansion of these worms in Ontario’s forested ecosystems. Already much damage has been done to the forest habitat around the Great Lakes.
Gray presented a number of detailed charts depicting the warming trend for climate change in Ontario. The International Panel on Climate Change models show the warmest trends of between 9-10 degrees, in the northern latitudes, and 4-5 degrees in our area by the end of the century. Earthworms can be killed by freezing but they have developed systems to avoid this happening. As climate warms they will continue to move forward into our northern forests.
Earthworms are classified into three ecological groups, namely: endogeic, these are rich soil feeders, topsoil dwellers, have no pigmentation, make horizontal burrows, and are small (approx.7.5-12.5 cm). Epigeic earthworms are top-litter feeders and dwellers; they are pigmented, make no burrows and are the smallest (at 7.5cm). Anecic earthworms are larger (12.5-20 cm) earthworms which are litter and soil feeders and dwellers, dorsally pigmented, and make extensive permanent vertical burrows.
Given the different strata of the soil the different earthworms groups reside in and their burrowing habits, it is no surprise that the impact on forests from earthworms is greatest when all three kinds of earthworms are present. As they move into a forest one can see the edge of the healthy, rich, thick horizon zone meeting the edge of the ‘denuded’ soil caused by earthworms eating up much of the available organic material. Organic layers are lost, protozoa are eaten, micro-arthropod eggs are damaged and micro-fauna are preyed upon. Plant communities are weakened and often destroyed. Invasive earthworms do most damage to hardwood forests, such as those consisting of maple, basswood, red oak, poplar, or birch species. So a forest that once had a lush understory ends with a single species of native herb and essentially no tree seedlings. Over time (spreading 5 to ten meters a year) earthworms change the forest soils from a fungal to a bacterial dominated system which hastens the conversion of leaf litter to mineral compounds, starving the plants of organic nutrients. This change in soil eliminates seedlings, ferns, and wildflowers. There is evidence emerging that changes caused by alien earthworms can even eventually affect small mammal, bird and amphibian populations and increase the impacts of herbivores like white-tailed deer. Invasive plants such as buckthorn and mustard garlic can establish a roothold in a diminished ecosystem. These species reduce and destroy habitat for native species and are a serious threat to biodiversity and the health of our forests. Once established, earthworms are virtually impossible to eradicate.
Much of Paul Gray’s presentation on earthworms is based on American information since most of the research has been done there, although one of the best known books on earthworms, “The Earthworms (Lumbricidae and Sparganophilidae) of Ontario” (1977) was written by a Canadian, John W. Reynolds.
Gray described the findings from a multi-species invasion of earthworms at a site in Timmons he worked on in 2011. Nineteen species were identified at this site. Along with other researchers, he has developed a ranking system for the risk posed by these species as a preliminary ‘Invasion Index’ for earthworms in Ontario. Categories included in the ranking system are abundance, distribution, reproduction, transportability as bait, most northerly isotherm (temperature) and pH tolerance. Earthworms like a neutral pH but can exist in a wide range of acidic soil. As the soil becomes less acidic they will find it easier to establish themselves. The species were ranked low, medium or high for invasion potential. The full details of their findings are contained in the OMNR report released in 2012: “Implications of a Potential Range Expansion of Invasive Earthworms in Ontario’s Forested Ecosystems: A Preliminary Vulnerability Analysis” which Gray co-authored with others and which was released in 2012. The speaker had copies of this excellent report at the lecture and it is also available online at the OMNR website http://www.mnr.gov.on.ca/en/Business/ClimateChange/Publication/STDPROD_092882.html.
How do earthworms travel into forested areas in Ontario? With human help of course! Fishermen dumping bait near forested areas, gardeners moving compost, road building, or ATV tire-treads or truck tire-treads which have adult worms and cocoons (egg cases), could all start an earthworm invasion into forested areas. There are some simple things you can do to prevent their further spread. For example, people should take unused fishing bait home and freeze the container for at least a week before discarding the contents, avoid dumping compost anywhere except in your own garden, and wash ATV or other soil-holding vehicle tires before transporting the vehicle. In Minnesota, where extensive research on earthworms has been done it is illegal to dump worm bait.
More research in Ontario on managing invasive earthworms, especially with our warming climate, would be useful. Regulation and education could help prevent alien earthworms from invading Ontario forests. Another route to scientific research that is very much supported by Gray is citizen science. He would be happy to help organize training and seek support for citizen groups that would like to become involved in collecting data about invasive earthworms. If you are interested in starting or joining such a group consider contacting Dr. Gray at To help citizens become informed on earthworms there are various sites on the internet which offer additional information such as http://www.naturewatch.ca/english/wormwatch/ and http://www.nrri.umn.edu/worms/default.htm
Paul Gray (right) of the Applied Research and Development Branch, OMNR, in lively discussion with MVFN President Ken Allison (left) and member Neil Carleton after his presentation on earthworms. Photo Pauline Donaldson
‘Ground beetles’, a spectacular insect group, featured at MVFN natural history talk
Report of October 2012 MVFN Lecture
by Joel Byrne
About 350,000 species of beetles occupy this planet. They are found in nearly every terrestrial habitat and many watery ones, pole to pole. There are more named species of beetles than there are named species of any other group. When I saw the title of Dr. Henri Goulet’s presentation to the Mississippi Valley Field Naturalists: My Favourite Insect Group – Ground Beetles (Carabidae), I thought of a quote attributed to J.B.S. Haldane, a distinguished British biologist, who, when asked what he had learned about the ‘creator’ from looking at nature, replied that the creator “. . . has an inordinate fondness for beetles,” referring to the enormous abundance of beetle species. Henri Goulet, MVFN’s second speaker, in the lecture series Nature Beneath Our Feet, is a research scientist emeritus with Agriculture and Agri-Food Canada, and he also has a fondness for beetles—ground beetles. Why, out of 160 families of beetles would he choose to study ground beetles? The answer was found in his talk, as he shared some of his fond memories in a lifetime of adventures tracking down his favourite group of animals.
Henri (he is a friend) opened his talk by posing some basic questions: what is a beetle, what is a ground beetle? A series of photos outstanding for their clarity, detail, and colour followed, displaying anatomical features of beetles that distinguish them from other insect Orders. One could clearly see that the beetles have no tail-like structure and that their wing covers do not overlap. It is these wing covers or elytra which give rise to the name of the Order of insects to which beetles belong, i.e. Coleoptera, meaning ‘sheath wings’ in Greek. In this Order is a suborder, Adephaga, meaning ‘voracious.’ And in this voracious group is the ground beetle family, Carabidae, our speaker’s favourite.
Carabid beetles number some 1700 species strong in North America; 250 species around Ottawa. The carabids have long antennae, large jaws, and long legs. Some are very fast, among the fastest animals in the world, for their size. Combine their murderous mandibles with their long speedy legs and you have a formidable predator. Even their larvae are usually big-jawed, active insect predators. All this is bad for their prey, often invertebrates, and good for us since a lot of invertebrates we consider farm and garden pests, aphids, slugs and caterpillars, are consumed. If any invertebrate wishes to avoid being devoured by a ground beetle in Canada, they should retire to a cave, since this is one of the few habitats ground beetles don’t inhabit, we learned.
Then came the big question, posed by Henri—Why do I find ground beetles fascinating? Henri’s fascination and fondness for ground beetles goes back to his childhood days in winters when he dug down in snow, then into and under the leaves where he found many of his pals stiff with cold, and warmed them up. But what got Henri interested initially in studying ground beetles was seeing species with dark metallic reflections.
There are many other reasons ground beetles became so fascinating to Henri. Unlike butterflies and dragonflies which quickly fly away, adult ground beetles are easy to pick up under debris or under the soil surface. The adults are quite easily seen, ranging in size from 1.5 mm to 30 mm, most being 5-10 mm in size. Adults live at least one season and of course, can be found even under snow. Adults come in a great variety of shapes. Many shiny black ground beetles have a ‘typical’ shape, athletic, but some are anything but typical. The ‘snail eater’ is a case in point having ‘strikingly elongated mouth parts’ the better to lunch on the inside of a snail’s shell. There are round sand beetles that look like pills. Bombardier beetles are much wider aft than most, perhaps to house a sort of two-chambered gun at the end of their abdomen where they mix hot chemical ‘bullets’ and ‘fire’ them with an audible pop at anything that threatens them. Many in the Adephaga suborder are ‘accomplished stinkers’, thus avoiding predation.
Henri then showed us phenomenal photos of what, I believe, fascinated us all the most— their great variety of colours. The wing-cover slides alone, entitled Elytral Sculpture, were worth the price of admission. “Our perception is very much affected by what we are.” We are humans and most of us are more interested in butterflies than a lot of black beetles because as humans we are attracted to colours. So when the first slide of elytral sculpture popped onto the screen there was a collective sigh. Mind-bogglingly beautiful metallic greens, bronzes, purples and blue blacks, more emerald greens. Also turquoise wing covers trimmed with copper called ‘the best’ in Canada, Carabus vietinghoffi, from the land of small willows. It was as if a sculptor and a jewelry designer had collaborated in crafting them.
As if an expert sculptor and jeweler had collaborated to craft it! A Carabus vietinghoffi, from the ‘land of small willows,’ with its turquoise wing covers trimmed with copper. This is the ground beetle Henri considered ‘the best’ in Canada. Photo Henri Goulet.
There followed a series of photos of completely-assembled, i.e. entire specimens of ground beetles, starting with solely black species, then switching to beetles ranging from pale to dark single-coloured, to two-coloured species, and then three-coloured species. Then came the ones with dark metallic reflections, the ones that initially interested Henri, then ones with bright metallic reflections (my favourites), and then species with two and three hues of metallic reflections, and finally species with metallic hue and pigment colours. At which point Henri said, “So I hope I’ve exposed you to a lot of colours.” We were mesmerized, colour-saturated!
This ground beetle, Elaphrus clairvillei, inhabits only marshy meadows and swampy places. Dr. Goulet is an excellent photographer and here, as in many photographs, he has captured the stunning beauty of the beetle. Photo courtesy Henri Goulet.
The balance of the talk was devoted to many other special features of ground beetles which could have been a talk in itself. Most ground beetles hide in the day. Look for them under logs and rocks, and in stumps. Ground beetles are found on all land habitats except in water (one species stays under rocks submerged by tides). Most species are potentially excellent bio-indicators because their habitat requirement varies from quite narrow to extremely narrow. For example Elaphrus clairvillei inhabits marshy meadows and swampy places, but will not live in bogs as they are too acidic. Some adult ground beetles are very long-lived, 2-7 years. Most ground beetles are finicky about where they live but not fussy about what they eat. A good example, ‘caterpillar hunters’ (Calasoma sycophanta), are forest ground beetles which emerge in the spring, look around for their prey and venture out and stay out if their prey is present, otherwise they return to the ground. Among ground beetles there are predators, scavengers, and herbivores (many are ‘weed-seed’ eaters), and even parasites (the very colourful leaf beetle parasites for example)—a very wide range of modes of life indeed.
A huge fan of the ‘ground’ beetles, Dr. Henri Goulet (centre), fields questions after his talk at the Almonte United Church, while others examine some of the many species specimens provided by the speaker for display. Photo Pauline Donaldson
The talk wound down with a lively question and answer period, while in the background the slide show continued. There was an initial burst of oohs! and ahs! as very colourful beetles seemed to dash across the screen: fabulous close-ups of live tiger beetles on the hunt. What a spectacular way to end the show!
A word about Henri Goulet’s photographs— superb! His photos, taken with meticulous care, will long be remembered by those who set aside a few hours of a fall evening to learn and be entertained by the learning. What I came away with was the impression of incredible beauty in the colours and design of the host of ground beetles, each species with its own variation on the general plan.
I enjoyed the lecture so much I saw it twice!
Resources: reference books on ground beetles are Common Ground Beetles (1987) by Trevor G. Forsyth and An Illustrated Identification Guide to Adults and Larvae of Northeastern North America Ground Beetles (2010) by Yves Bousquet.
Mississippi Valley Field Naturalists
October 24, 2012
The Lowly Worm
The Mississippi Valley Field Naturalists’ (MVFN) 2012-2013 public lecture series, Nature Beneath Our Feet, continues November 15 with the third presentation, “Earthworms: Whose Friends are They?” You do not need to be an expert to enjoy the presentations—just possess a curiosity or appreciation for wild nature. Cottagers, hunters, fishermen, canoeists, hikers, campers, artists and seasoned field naturalists alike will find something to interest them as we explore what lives in Lanark County and how best to protect it for future generations. Refreshments are offered at each lecture.
This lecture will be presented by Paul Gray from the Applied Research and Development Branch, Ontario Ministry of Natural Resources, Peterborough. He is an author of the recent publication Implications of a Potential Range Expansion of Invasive Earthworms in Ontario’s Forested Ecosystems: A Preliminary Vulnerability Analysis.
Earthworms and beavers have more in common than you may realize. Both are described as “ecosystem engineers” because of their abilities to make significant changes in our environment. The underground burrowing systems that worms create increase the amount of water and air that reaches plant roots and other soil organisms. Also, earthworms mix the plant litter and organic matter into the soil, increasing the speed at which they decay and release nutrients. No wonder gardeners love them!
The last glaciation eradicated native earthworms from Ontario. Our forests developed in the absence of earthworms until they arrived with soils (for ballast) and plants brought here by European settlers. Since then both adults and cocoons (egg cases) have continued to be spread through dumping of unused fish bait, transport of compost, mulch, and top soil, movement of landscape plants with soil around their roots, dispersal from tire treads, and road building that involves bringing in soil from elsewhere. At present, 17 non-native European and two North American (non-native to Ontario) earthworm species survive in the province.
Beyond the garden, in native forest ecosystems, earthworms are very bad news. They significantly alter forest soil structure and chemistry, reduce nutrient availability, and decrease the diversity of understory vegetation, soil fauna, and belowground fungal communities. That is, they reduce and destroy habitat for native species.
There is also evidence that changes caused by earthworms lead to a cascade of other changes in the forest that affect populations of small mammals, birds and amphibians, exacerbate the impacts of herbivores such as white-tailed deer and facilitate invasions of other exotic species such as slugs, European buckthorn, and garlic mustard. Thus earthworms pose a serious threat to the biodiversity and long term stability of our forests. With a warming climate, the potential for some earthworm species to expand their distribution or expand populations already established in forested ecosystems will increase, likely resulting in further significant ecological changes and socioeconomic impacts.
Because earthworms are spread mainly by human activities, there are some simple things you can do to prevent their further spread—take unused fishing bait home with you and freeze the container for at least a week before discarding the contents, freeze (as previously) compost before using it, wash ATV or other soil-holding vehicle tires before transporting the vehicle, join the Great Lakes Wormwatch citizen science effort (http://www.naturewatch.ca/english/wormwatch).
Interested in forest conservation? Get “the dirt” on earthworms at Paul Gray’s lecture “Earthworms—Whose Friends Are They?” and spread the word to your friends and neighbours. This MVFN presentation will be held at 7:30 p.m on Thurs. Nov. 15, 2012, Almonte United Church, 106 Elgin St., Almonte. All are welcome ($5 fee for non-members). For further information please contact MVFN’s Program Chair Cathy Keddy at 613-257-3089.
Soil fundamentals talk a natural start to MVFN’s Nature Beneath our Feet lecture series
Lecture report of September 2012 MVFN lecture – written by Pauline Donaldson
As students returned to school in September, the Mississippi Valley Field Naturalists (MVFN) natural history lectures resumed at the Almonte United Church social hall ‘classroom.’ You do not need to be an expert to enjoy these talks, just a curiosity and fascination for our natural world. And, in the case of the soil presentation which set the groundwork, so-to-speak, for the series “Nature Beneath our Feet”, some soil vocabulary would also have been useful. Guest speaker for “Lanark County Soil FUNdamentals” was soil scientist David Kroetsch, a botanist and ecologist with the Canadian Soil Information Service. Kroetsch was involved in soil survey ‘upgrade’ work in Mississippi Mills in 2000 and participates in environmental education programs such as the Lanark County Stewardship Council’s Envirothon for youth.
As Kroetsch began his MVFN presentation on soils, it was evident that many of us, with the possible exception of farmers and soil scientists in the audience, would be learning a new vocabulary– unfamiliar words such as ‘gleysols’ (soils that are greenish-blue-gray due to a predominance of a reduced vs. oxidized iron, caused by wet conditions) or ‘catena’ (from Latin for chain and referring to a group of related soil types with similar ‘parent’ material but different drainage). On the other hand, familiar words such as ‘horizon’ took on additional new meanings with reference to soil.
We were all familiar with the word soil, but what is soil really? Kroetsch explained that from early on soil was recognized appropriately as a natural living ‘thing’, understood to be different from bedrock, and formed by complex processes. “It is the unconsolidated material on the surface of earth, comprised of minerals, organics, water and air and which supports plants whose roots grow into it”. In the 1930’s answering the question, how does soil form? Hans Jenny, the ‘father of soil genesis,’ developed fundamental soil science principles and some terminology still used today. Soil is formed over time and five main factors determine the end product: the parent material, the living organisms present, the climate, the topography (surface shape of the land), and time itself.
Soils sharing the same parent material are related. The material might be unsorted glacial material or till, organic deposits from plants such as in swamps, lake deposited material as in lacustrine soils, or other parent material. Secondly, living organisms of many types are present and play a critical role. These include bacteria such as nitrogen fixers critical for the nitrogen cycle. Fungi could include the mycorrhizae, a group of fungi that form essential symbiotic relationships with the roots of plants and trees. Microfauna are also there, i.e. tiny animals such as nematodes and the fascinating tardigrades, among others. A little larger, the mesofauna include mites, springtails etc., and finally, there are macrofauna such as slugs, snails, insects, earthworms, beetles and larvae which feed on other soil organisms and decaying matter. The third factor, climate, further ‘molds’ soil through cycles of freeze thaw, drying, and precipitation, and may alter soil pH (acid or base). The pH of soil in turn affects its overall chemistry, for example high acidity can cause calcium carbonate to be leached from clay soils making them more mobile. Fourthly, topography, or the shape of the land where the soil is, can affect the soil, i.e. whether or not it is on a slope or in a depression determines whether moisture will accumulate or drain away. Precipitation, moisture and drainage interact. Heavy precipitation and drainage can result in a lot of things being selectively removed from the soil, critically changing it, such as when ‘Leda’ clay suddenly starts to flow, compromising human built structures. A single soil type becomes a catena, depending on the slope of land and how well drained it is. For example the Almonte catena has subtype ‘Almonte’ on good drainage and ‘Snedden’ on imperfect drainage. The fifth factor is time.
Over time the ‘horizonation’ of the parent material occurs, things are added and changed over 10, 000 years. Soil horizons are all the distinct layers in soil, of different thickness, colour and texture which you see when you dig a large deep hole. A summary of the horizons present in the soil is a ‘soil profile’. Most soils have at least 3 or 4 horizons: a surface ‘O’ layer which is the organic layer. This layer is very thick in forests, or at least it should be. Often there is an ‘A’, ‘B’ and finally a ‘C’ layer which may be the ‘parent’ rock material.
Looking at the big picture, Kroetsch explained that on a landscape level, forces of climate and the glaciers retreating created broad distinctive zones of soil and vegetation. For example, in much of Lanark County receding glaciers scraped surface material off ancient Precambrian bedrock leaving hard bare rocky ground. In other parts of the county productive lacustrine soils such as the Almonte soils were deposited from the Champlain Sea which filled part of Lanark County after the glaciers receded. To map distribution of soil types across the country, soil surveys are done by Agriculture and Agri-Food Canada using protocols described online at http://sis.agr.gc.ca/cansis/taxa/cssc3/intro.html; the first in Canada was done in1914 by A. J. Galbraith. The Canadian soil classification system is hierarchical, similar but not identical to one used in the U.S. Examples of Canadian soil types classified are chryosoils (frozen soils), podzolic soils (generally acid soils on the Canadian Shield), chernozyn (associated with grasslands) and gleysols (poorly drained but productive for agriculture when used with tile drainage, such as in the heavily farmed regions of Southern Ontario). Modern soil survey work, Kroetsch explained, involves site descriptions with GPS, and including elevation, slope, aspect and length of the slope, soil profiles and photographs. Vegetation, land use, stoniness, rockiness, and seepage/water table depth are recorded. The information gathered and interpreted is used by farmers and by municipalities for land use decisions.
The last complete soil survey of Lanark County was done in 1961and the original report and soil maps from then are posted at http://sis.agr.gc.ca/cansis/publications/surveys/on/on40/index.html. One can review or download 2 large maps (each one is in two pieces, a north and south section), the ‘Soil Map of Lanark County’ which maps in detail the soil and soil composite types found across Lanark County, and the ‘Soil Capability Map of Lanark county’ which shows the corresponding ‘soil capability’. This is the capability with respect to agronomic usefulness ranging from Class 1 to Class 7. For municipal purposes Class 1-3, which are good agricultural lands, are ‘protected’ in all official plans, Class 4 is marginal for cultivated field crops, Class 5 for permanent hay pastures, and Class 6 and 7 is classified as having no agricultural use. Keep in mind though that the groupings do not consider, for purposes of agronomic capability classification, that the land may be well-suited to production of trees, wild berries and other plants not requiring cultivation.
Those attending the Kroetsch lecture will hopefully have a firmer grasp of concepts to interpret soil survey maps. However, to better understand the soils and ecosystems of the area it helps to have a ‘big picture image’ of the underlying geology of Lanark County. Local ecologist Paul Keddy’s book Earth, Water, Fire: An Ecological Profile of Lanark County is a very useful resource in this regard and helps put into perspective how the geology affects the soil type or lack of soil and the natural environment. Maps in the Keddy book show margins of geological formations such as old Precambrian rock or land over newer sandstone or limestone plains, and areas formerly covered by the ancient Champlain Sea, as well as locations of the many areas of natural and scientific interest in the county. For example, the Burnt Lands Alvar, a unique area of very shallow soil over limestone pavement, or Wolf Grove where the Canadian Shield juts up presenting an obstacle to road building and farming alike. Lands such as that, on the very old Precambrian rock, include much of Lanark County, particularly in north and west. Hard granite rock predominates and there you find extensive areas of rocky soil composites with shallow, acidic soil or bare rocky ground. These are seen on the 1961 soil maps as the extensive beige areas which are ‘Monteagle sandy loam-Rock’ (indicated as 237,700 acres worth in the report) and extensive dark brown areas of Tweed sandy loam-Rock complex (some 124,000 acres), both with Class 7 capability. Such land though has much value for wildlife habitat and leisure. Very mucky wet areas which do not drain may be too wet for agriculture but these swamps and bogs are very productive and are classed as significant wetlands. On the other hand areas south and west in Lanark County are on newer Paleozoic bedrock of limestone or sandstone with deeper more alkaline soil originating from lacustrine deposits, and there you find more productive agricultural soils such as Appleton, Lanark , Snedden or Grenville loam or silt loam on the map.
Having returned to survey some areas, of Mississippi Mills in 2000, Kroetsch noted that the nature of soils has remained relatively the same with some exceptions. Human activities cause changes in classification on a small spatial scale due to over-agriculture, drainage of wetlands, addition of fertilizers, and atmospheric pollution. So they are considering adding a 12th soil type to be called anthroposoils. Generally, Kroetsch says, soil surveys have a half-life of only 25 years. Change will always occur, but at different rates. When forests were logged early last century soil became vulnerable to erosion. A more recent problem is earthworms. A typical forest will have a very thick ‘O’ horizon over a thin ‘A’ horizon. When non-native earthworms invade a forest they can very quickly consume the organic layer while at the same time depositing a thick ‘A’ horizon comprised of their castings. The absence of the ‘O’ layer is detrimental and the new ‘A’ horizon is too dense, leading to poor water infiltration and more erosion which is not good for the forest. We will hear more about earthworms at our November lecture as MVFN’s Nature Beneath our Feet series continues.
Following the Lanark County Soil FUNdamentals talk there was an opportunity to socialize, enjoy refreshments or discuss soil profile samples and other items displayed by speaker, David Kroetsch of the Canadian Soil Information Service. Photo by Pauline Donaldson