Diversity, Redundancy, and Resilience

Grasslands face a long list of challenges.  In many regions, habitat loss and fragmentation top that list, leaving prairies to struggle for survival as tiny isolated patches of habitat.  In addition, invasive plants and animals keep finding new footholds within both fragmented and unfragmented prairies.  Many of those invaders are aided by nutrient pollution – increasing levels of nitrogen, for example, which help species like reed canarygrass and smooth brome monopolize formerly diverse plant communities.  Most of all, the climate continues to flail crazily about, ratcheting up the temperature and tossing out more and more extreme weather events.

How can grasslands possibly survive all of that?

I’m actually pretty optimistic about the future of prairies.  Prairies are inherently resilient, and if we do our jobs as land managers and supporters of conservation, we can help ensure their continued resilience and survival.  Resilience in prairies and other ecosystems is the capacity to absorb and adapt to whatever challenges are thrown at them, while sustaining their essential functions and processes.  That resilience is built largely upon two pillars: biological diversity and the size/connectivity of the habitats that biological diversity depends upon.

Plant diversity is a key component of ecological resilience, along with the other biological diversity associated with it.  Taberville Prairie, Missouri.

We’ve severely compromised the “habitat size/connectivity” pillar in many regions of North America, but even in little prairie fragments, there is an incredible diversity of organisms, providing the countless services needed to sustain life and productivity.  In a healthy and diverse prairie, not only are all the bases covered, there is considerable redundancy built in to the system because of the number of different species present.  If one plant, animal, or microbe is unable to do its job because of drought, fire, predation or disease, another can step up and fill the role. Diversity provides redundancy, and redundancy helps ensure that prairie systems stay healthy and productive, regardless of circumstances.

It’s not hard to find examples of this kind of built-in redundancy in prairies.  In fact, you can find it within some very recognizable groups of species.  Let’s start with sunflowers.

While most people know what a sunflower looks like, you might not realize how many different kinds there are.  Here in Nebraska, we have at least nine different sunflower species, plus a lot of other flower species that look and act much like sunflowers.  Two of our official sunflowers are annuals, often classified as weeds because of their ability to quickly colonize areas of bare or disturbed soil.  The other seven species are long-lived perennials, each with its own set of preferred habitat conditions.

Plains sunflower, an annual, is a rapid colonizer of exposed in sandy prairies around Nebraska. The Nature Conservancy’s Niobrara Valley Preserve.

All sunflowers are tremendously important providers of food and shelter to wildlife and invertebrates.  There’s a reason sunflower seeds are so prevalent in bird feeders – they pack an enormous amount of nutrition into a little package.  Because of that, a wide array of both vertebrate and invertebrate animals feed eagerly on sunflower seeds when they can find them.  Sunflowers also produce an abundance of pollen and nectar, and make it very accessible to pollinators and many other creatures by laying it out on a big open platter.  It’s rare to find a sunflower in full bloom that doesn’t have at least one little creature feeding on its nectar, pollen, or both.  Grazing animals can get a lot from sunflowers as well; the forage quality of sunflowers is very high, especially before they bloom.

During or after droughts, intensive grazing bouts, fires or other events that leave bare soil exposed, annual sunflowers thrive, and they can provide abundant resources at a time when many other plant species can’t.  We see this often in the Nebraska Sandhills, where plains sunflower (Helianthus petiolaris) turns the hills yellow during the summer after a spring fire or the year after a big drought.  Plains sunflower isn’t the only plant that flourishes under those conditions, but its presence in plant communities is a great example of the kind of built in redundancy that helps ensure there are plants for animals to eat, even when many normally-abundant prairie plants are scarce or weakened.

Nebraska’s perennial sunflowers span a wide range of habitats, from wet to dry and sunny to shady.  You can find a sunflower in just about any habitat type in Nebraska.  That’s another great example of built-in redundancy, and a reason for optimism about the future.  As climate change alters the growing conditions across much of Nebraska, it seems unlikely that any habitat will change so dramatically that it will become devoid of sunflowers.  Instead we’ll probably see changes in the relative abundance of each species from place to place.  In addition, remember that what we call a sunflower is a fairly arbitrary categorization; there are lots of other wildflowers that provide very similar resources/services, including plants like rosinweed (Silphium integrifolium), false sunflower (Heliopsis helianthoides), sneezeweed (Helenium autumnale), and many more.  Those sunflowerish plants also span a wide range of habitat preferences and growth strategies, making it likely that some of them will be blooming abundantly every year, no matter what drought, fire, or grazing conditions are thrown at them.

An illustration of the general habitat preferences of several perennial sunflowers found in Nebraska.  The variety among habitats used by these species makes it likely that some kind of perennial sunflower will persist in most locations, regardless of how climate and disturbance patterns change over time.

Milkweeds are another group of organisms that demonstrate the diversity and redundancy in prairie ecosystems.  There are 17 milkweed species here in Nebraska, along with several other related species (like dogbane) that produce the same kind of sticky white latex.  While that latex is toxic to most creatures, a number of invertebrates have figured out how to feed on milkweed plants without suffering harmful effects.  Many have actually turned the toxin into an advantage by ingesting the substance and making themselves toxic to potential predators.  The most famous of these critters, of course, is the monarch butterfly, which uses milkweeds as larval hosts.

A selection of milkweed species found in Nebraska, demonstrating the variety in flower colors and shapes among the group.

When you picture a monarch caterpillar on a milkweed plant, you probably envision a tall plant with a big pink flower.  In reality, monarchs can use many (maybe all?) milkweed species as larval hosts.  Because each species of milkweed has its own unique set of preferred habitat and growing conditions, the diversity of milkweed species in Nebraska should help monarchs find a place to lay eggs regardless of weather, disease outbreaks, or other events.

The spring of 2017 provided a compelling example of this.  In most years, monarchs overwintering in Mexico fly into the southern United States and lay eggs on milkweed plants there.  The subsequent generation than flies northward into Nebraska and other  nearby states.  For some reason, many monarchs broke from that pattern in 2017, and arrived in Nebraska much earlier than normal.  This caused a great deal of concern because the milkweed most commonly used for egg laying – common milkweed (Asclepias syriaca) wasn’t up yet, and just as it started emerging, a freeze knocked it back down.  Fortunately, common milkweed wasn’t the only option available to monarchs.  Whorled milkweed (Asclepias verticillata) is also fairly common, starts growing earlier in the year than common milkweed, and is more resistant to cold weather.  Monarchs seemed happy to lay their eggs on the skinny leaves of whorled milkweed, and those of us worried about monarchs breathed a sigh of relief.  Once again, diversity created redundancy, and monarchs found habitat for their babies, even though they arrived well ahead of schedule.

A monarch egg and caterpillar on whorled milkweed earlier this spring (April 27, 2017) in Nebraska.

A broader example of redundancy and resilience in prairies includes the interdependence between bees and plants.  If you’ve followed this blog for long, you’re surely aware that there are thousands of bee species in North America, and potentially 80-100 or more species in a single prairie.  Most of those bees can feed on the pollen and nectar from many kinds of wildflowers, though some are restricted by their size or tongue length from accessing certain species. Because most plants only bloom for a few weeks, and most bees need considerably longer than that to successfully raise a family, bees require more than one kind of wildflower near their nest.  In fact, in order to support a broad diversity of bee species, a prairie needs an equally diverse set of wildflower species.  That way, a bee can find sufficient food throughout the growing season, even if drought, grazing, or other events keep some plant species from blooming in a particular year.

On the flip side, most wildflowers rely on the diversity of bees and other pollinators to ensure successful pollination.  While some insect-pollinated plants are very selective about who they let in, most rely on the availability of many potential pollinators.  If some species of bees are suffering from a disease, or have a weather-related population crash, it’s awfully nice to know that there are other bees (along with butterflies, moths, wasps, and other insects) that will still be able to transfer pollen from one flower to another.  A diverse pollinator community relies on a diverse wildflower community, and vice versa.  Diversity, redundancy, and resilience.  No matter what happens, flowers make fruits and seeds – which, by the way, is pretty important all the various creatures that rely on those fruits and seeds for food.

Bees rely on plant diversity to ensure a consistent supply of pollen and nectar across the growing season. In this case, tall thistle, an important native wildflower, is supplying food to a bee in return for pollination services.

All of us have our favorite prairie species, whether we’re fans of flowers, butterflies, birds, or some other group of organisms.  It’s easy to focus our attention on those favorite species, and worry about whether they will survive all the challenges that face prairies today.  If we really care about prairies, however, we should probably focus more on (and celebrate) the richness of species that keep prairies humming along, no matter what gets thrown at them.  The variety of yellow-flowered sunflowerish plants, the broad array of latex-producing milkweed-like plants, the complexity of the plant-pollinator relationship, and countless other examples of diversity and redundancy help ensure the survival of prairies well into the future.  That resilience is why I remain optimistic about the future of prairies.

A Plot-Sized Biodiversity and Photography Project

Today, I’m beginning a new photography project aimed at exploring and celebrating the small scale diversity and complexity of prairies.   I’ve picked out a 1 x 1 meter plot in a small patch of restored prairie here in Aurora, Nebraska, and I will be photographing everything I can within that tiny area over the next year or so.  My objectives are to find and document as much beauty and diversity as I can and to show the dynamic nature of prairie life, even at a very small scale.

Lincoln Creek Prairie, with the yellow flags marking my square meter plot.

The plot sits in a narrow strip of land restored in the 1980’s by Bill Whitney and Prairie Plains Resource Institute.  I picked Lincoln Creek Prairie because it’s right across town from me, and therefore easy for me to get to frequently.  It’s also a great restored site that was planted with a diverse mixture of prairie species (over 100 species) and is well-established.  However, the prairie is small enough that it doesn’t host any grassland-nesting birds or other animal species that need relatively large and open prairie habitats, and suffers from all the other issues that come along with tiny prairies.  I anticipate that most or all of the organisms I photograph during the coming year will be plants and invertebrates, but I’m confident that I won’t find a shortage of subject matter.

A view of the 1 x 1 plot from above

I didn’t pick the small plot randomly, but I also didn’t try to find a spot with more diversity than any other nearby.  Instead, I looked for a place that would catch the light well during most of the year but was out of the way enough to not be disturbed by people hiking the nearby trail.  I freely admit that I chose the exact location of the 1 x 1 plot because it has a butterfly milkweed plant in it – it’s a nicely photogenic species.  This isn’t research, after all, and I don’t have to select my plot in a completely unbiased way!  However, I’m confident that the 1 x 1 plot I chose is representative of the rest of the prairie around it.

Switchgrass (Panicum virgatum) with a flower that never completely came out of its sheath last summer.

I began my photography journey within the plot yesterday, and took the photos you see here in this post.  I’ve already discovered one big challenge regarding my plans – it’s going to be difficult to avoid crushing or breaking the vegetation within the plot during my frequent visits.  I don’t see any way to avoid matting down the vegetation around the edge of the plot, but I’ll try not to do any more of that than necessary, and hopefully that won’t excessively impact what I see inside the plot.

The curled and dried leaf of stiff sunflower (Helianthus pauciflorus)

Right now, the plot is fairly uniformly brown, and perhaps drab looking from a distance.  However, I didn’t have much trouble finding interesting shapes and textures to photograph during the 10 minutes or so I spent there yesterday.  Even without green vegetation or crawling invertebrates, there was plenty to look at.  That bodes well for the coming year, I think!  Stay tuned…

Maximilian sunflower (Helianthus maximiliani) seed head, minus the seeds.  Birds, mammals, and/or other creatures likely picked it clean last fall.
A butterfly milkweed (Asclepias tuberosa) seed pod on a curled stem.

The Diversity, Beauty, and Secret Lives of Grasshoppers

I know I say this about a lot of different insects, but grasshoppers are truly amazing creatures.  Grasshoppers have a reputation as voracious consumers of crops and forage grasses, and that reputation is well-earned.  However, the pest tag is far too often and broadly applied.  There are something like 400 species of grasshoppers in the western United States, and only about 20 species are categorized pests.  In Nebraska, we have 108 grasshopper species, with only a handful that ever cause economic damage, and that damage occurs sporadically – mainly in years when those species have population booms.

The differential grasshopper is one of only a few grasshopper species that can cause economic damage to farmers, ranchers, and gardeners. It’s a native species that has adapted very well to the way we’ve altered its world.

Unfortunately, the “Grasshoppers Destroy Crops” headline tends to swamp the many and much more interesting grasshoppers stories we should be talking about.  Let’s start with the numbers I’ve already presented.  THERE ARE 400 SPECIES OF GRASSHOPPERS IN THE WESTERN UNITED STATES AND 108 SPECIES IN NEBRASKA ALONE!  That doesn’t include katydids or crickets, by the way, just grasshoppers.  I’m guessing most of you had no idea there were that many kinds of grasshoppers.  Am I right?

I’m including a half dozen grasshopper photos in this post to show off just a taste of the beauty and diversity of grasshoppers in prairies.  If you want to read more about this, you can read an article I wrote for the August/September issue of NEBRASKAland Magazine.  While you could be forgiven for thinking there are two kinds of grasshoppers in the world – green and brown – you would be very wrong.  There are grasshoppers with much more color and pattern variation than many species of birds, but nobody makes movies about people circling the globe to see more grasshopper species than anyone else, do they?  Many band-winged grasshoppers show off gorgeous red or yellow wings as they fly, wings that rival those of butterflies, but you don’t hear about historically-prominent British Prime Ministers collecting grasshoppers, do you?

The painted grasshopper (Dactylotum bicolor) rivals any bird for beauty in color and pattern.

Now let’s discuss grasshoppers’ diet, which can include far more than just grasses.  Some grasshopper species feed high up in the canopy of prairie vegetation, while others stay on the ground.  Many have a very wide diet, including both grasses and wildflowers, but others are much more specialized, including grasshoppers that feed almost completely on one or a few wildflower species.  Grasshoppers are often seen feeding on the pollen of flowers, especially sunflowers, providing further evidence that they are much more than just grass eaters.  Most grasshopper species prefer the newest, most tender leaves of plants, but some – especially those that live mostly on the ground – make their living off of older leaves, including some dropped by their brethren living above them.  Regardless of what they like to eat, grasshoppers have very sensitive organs on the tips of their antennae that help them determine the forage quality of a leaf before they eat it.

The cudweed grasshopper (Hypochlora alba) is named for its favorite food plant – cudweed sagewort, aka white sage (Ambrosia ludoviciana), on which it is supremely well camouflaged.

When you think about animals that have sophisticated communication systems, you probably think about creatures like apes, whales, and even prairie dogs, right?  You might be surprised to learn that grasshoppers have their own complex methods of communication as well.  Every grasshopper species produces its own unique set of sounds, most of them created by rubbing their hind legs against their abdomen.  In addition, some employ what’s called “crepitation” – a loud clacking sound made by snapping their hind wings while flying.

The huge and flightless plains lubber (Brachystola magna) is as gorgeous as it is large.

Grasshoppers can also communicate visually.  They can do this by rubbing their legs against their wings, flashing their wings, and making a variety of motions with their legs.  Those visual signals can help them attract mates, defend breeding territories and feeding areas, and ward off unwanted suitors.  I’m not saying we should make documentaries about people trying to teach grasshoppers how to communicate with American Sign Language, but I’m not NOT saying it either…

This bandwing grasshopper (Oedepodinae) is about as well camouflaged as you could hope for against its sandy background.  When it flies, though, it displays very colorful wings (color and pattern varies by species).

If you’re someone who doesn’t care about the beauty, diversity, or communication abilities of grasshoppers, maybe their utilitarian value will make an impression.  As a major consumer of vegetation in prairies, grasshoppers play a huge role in nutrient cycling, a role that becomes even more important in prairies without large vertebrate grazers.  Perhaps most importantly, though, grasshoppers are a crucial food source for many other animals, including birds and other wildlife species you (hopefully?) enjoy having around.  They are large and packed with nutrients, as well as abundant and fairly easy to catch.  In addition, while they aren’t a particularly popular food item among people here in North America, grasshoppers are an important source of protein for humans in other parts of the globe.

When grasshoppers start to emerge next spring, please take a little extra time to notice and appreciate them.  See how many different colors and shapes of grasshoppers you can find in your neighborhood prairies (remembering that if their antennae are as long as their body or more, they are katydids, not grasshoppers.)  Look for the grasshoppers with big colorful wings as they clatter noisily away from your feet.  And if you’re a person of financial means, and are interested in making a movie about grasshopper watchers or people trying to teach grasshoppers how to talk to humans, call me.  I know people who know people.

How can you not like and admire the green fool grasshopper (Acrolophitus hertipes), with its raised back ridge, bright red antennae and charming face?

More Than One Milkweed

I recently wrote an article for NEBRASKAland magazine about milkweed and the surprising number of milkweed species that can be found in Nebraska.  (See the most recent online issue here).  In total, there are seventeen species known to the state, and only a handful look anything like most people’s mental vision of milkweed – tall, with broad oval leaves and big pink flowers.  Milkweed can be found in habitats ranging from wetlands to woodlands to dry sandy prairies, and can have flower colors of green, white, and orange (and, of course, various shades of pink and red).

Growing concern over monarch butterflies has raised awareness of milkweeds and their importance, but milkweeds are far more than just monarch caterpillar food.  They have an incredible (in the sense that it doesn’t seem possible) pollination strategy, host an array of insect species that have evolved to handle the toxic latex produced by milkweed plants, and are among the most important nectar plants to many butterflies and other pollinators.  We’re still learning about the relative value of each milkweed species as monarch caterpillar food, but there is no question about their overall beauty and diversity.

This is a great time of year to find many different milkweed species in bloom.  See how many different milkweed species you can find in your favorite natural areas.

Here is a series of milkweed photos I’ve taken over just the last couple of weeks.

Common
Common milkweed (Asclepias syriaca)- the species most people envision when they think of milkweed.
Sullivant's
Sullivant’s milkweed (Asclepias sullivantii) looks much like common, but the leaves are waxy smooth and completely without fuzz.  It is a much less common species in Nebraska.
sand
Sand milkweed (Asclepias arenaria) is common on dry sandy hilltops in the Nebraska Sandhills.
Green milkweed
Green milkweed (Asclepias viridiflora) is common in the mixed-grass portion of Nebraska, but also many other places.  It’s creamy whitish-green flowers hang downward from the stems.
Narrowleaf
Narrow-leaf milkweed (Asclepias stenophylla) has very long slender leaves.  
Whorled
Whorled milkweed (Asclepias verticillata) is small, with tiny skinny leaves that whorl around the stem.

Prairie Word of the Day – Habitat Heterogeneity

Do you know what time it is?  It’s time for another PRAIRIE WORD OF THE DAY!

Today’s Prairie Word of the Day (fine, it’s actually two words) is:

Habitat Heterogeneity

Heterogeneity is really just a longer word for Diversity, which is another way of saying “lots of different things”.  So why use the word “heterogeneity” instead of just saying “lots of different things”?  Well, for one thing, using big words makes a person sound smart, and when you’re a prairie ecologist and no one really understands what it is you do for a living, it’s good to at least sound smart.

More importantly, there’s a nice alliterative (another big word!) feel to the phrase Habitat Heterogeneity, which happens to be one of the most important phrases in prairie ecology.  In fact, I would argue that the foremost objective of any prairie manager should be to create habitat heterogeneity within the prairie(s) they manage.

Habitat heterogeneity simply means diversity or variety in habitat types.  Habitat homogeneity is the opposite – a lot of habitat that is all the same.

Every organism in a prairie has its own unique habitat requirements, so the number of different habitat types in a particular prairie is correlated with number of species that can live there.   Let’s use prairie birds as an example.  Birds such as upland sandpipers like to nest in large patches of relatively short-stature grassland.  Around here, a big hay meadow is great habitat for them, especially if it was cut fairly late in the previous year and is still short in stature when the subsequent breeding season starts.  On the other hand, Henslow’s sparrows want to nest in prairie habitats with relatively tall and dense vegetation.  It would be highly unusual to find Henslow’s sparrows and upland sandpipers nesting in the same patch of prairie because their habitat preferences are very different.  So, if you want both species in your prairie, you have to provide both short and tall/dense habitat.  Other birds have their own unique habitat requirements, including nearly bare ground (e.g., horned lark), relatively short, but with abundant thatch (grasshopper sparrow), tall with lots of tall/weedy wildflowers (dickcissels), tall and nearly impenetrably dense vegetation (sedge wrens), and many others.  Only if your prairie provides all those different habitat conditions will you attract all those different bird species.

Dickcissels prefer
Dickcissels prefer habitat with lots of tall wildflowers or weeds.  They often weave their nest into the stems of a tall clump of vegetation.

The same diversity of habitat preferences exists in other groups of prairie species as well.  Among small mammals, for example, voles tend to prefer habitats with abundant thatch, while pocket mice are more often found where bare ground is abundant – and there are many others.  Insects and other invertebrates have the same kind of diversity in habitat preferences

Scale is important.  While a bird, mammal, or insect might have a broad preference for a certain kind of habitat structure, it is likely to need some heterogeneity within that habitat too.  A mouse, for example, might prefer patches of prairie with fairly sparse vegetation, but it is likely to need a few clumps of vegetation dense enough to hide in when predators are near.  Insects and reptiles are ectothermic (cold blooded) and need to regulate temperature, so while a snake might like to hide in tall dense so it can bite your ankle as you walk by (I’M KIDDING!), it also needs some places to bask in the sun.  All of this means that habitat heterogeneity is important any many different scales.  Heterogeneity at a fairly large scale (acres) helps provide places for many different animals to live in a prairie, but heterogeneity within the home range or territory of each animal (square meters, or even centimeters) can be important too.

Some habitat heterogeneity occurs simply because soil texture, nutrients, and moisture, along with topography all vary across a landscape.  A prairie is likely to have areas of more productive soils where vegetation grows tall and thick, and less productive soils where vegetation is more sparse, for example.  In addition, water will pool in some areas of a prairie more than others because of topography, altering the habitat for both plants and animals.  However, despite this “naturally occurring” heterogeneity, it’s still important for prairie managers to look for ways to provide more.

This landscape at The Nature Conservancy's Broken Kettle Grasslands in northwest Iowa shows the kind of natural heterogeneity that occurs in many landscapes.
This landscape at The Nature Conservancy’s Broken Kettle Grasslands in northwest Iowa shows the kind of natural heterogeneity that occurs in many landscapes.  Topography, soil variability, and other factors create a diverse set of conditions for plant growth and habitat structure.  Land management can add to that heterogeneity and improve it even more.

Prescribed fire and haying/mowing do a great job of altering habitat structure at a fairly large scale (acres).  By applying those treatments in different parts of a large prairie each year (and varying the timing of each from year to year), a manager can create a shifting mosaic of habitat patches that supports a wide diversity of animals.  However, both fire and mowing are pretty non-selective – most or all of the vegetation within a burned or mowed area gets the same treatment.  Leaving unmowed patches of grass here and there and varying the height of the mower as it moves across the site can help leave more heterogeneity behind.  Designing prescribed fires so that not all vegetation burns (e.g., mowing around some patches ahead of time, burning on days with lower temperatures or higher humidity, etc.) can also help with habitat heterogeneity – though those kinds of fire might also be less effective at killing trees or accomplishing other objectives.

In prairies where livestock grazing (cattle or bison, for example) is feasible, it is much easier to create small scale heterogeneity because grazers pick and choose which plants, and how much of each plant, to eat at any one time.  By controlling grazing intensity, and varying it across both time and space, managers can create prairie patches that are ungrazed, almost completely grazed, and in various stages of partial grazing – with a mixture of tall vegetation and nearly bare ground.  The uneven application of “fertilizer” from the rear ends of grazers contributes even more to habitat heterogeneity by temporarily altering soil productivity in lots of little spots across the prairie.

These cattle at Konza Prairie in Kansas
These cattle at Konza Prairie in Kansas have created a nice example of small scale habitat heterogeneity by grazing many of the grasses short while leaving leadplant, purple prairie clover, and other wildflowers ungrazed.

Whether it’s fire, mowing, grazing, herbicides or various combinations of those, creating habitat heterogeneity may the most important job of a prairie manager.  We still have a lot to learn about how the scale and configuration of habitat patches affect wildlife and insect populations.  What we do know, however, is that the prairies thrive when they have a lot of different types of habitat.  …When they have habitat heterogeneity.

And that, folks, is your Prairie Word of the Day.

Contrasting Approaches to Prairie Management: Leopold, Land Health and Cabbages.

“A Land Ethic” is the concluding essay in Aldo Leopold’s 1949 book, A Sand County Almanac, and is the most powerful and relevant piece of conservation writing I’ve ever read.   Leopold’s essay spells out the changes we need to make in the way we view our relationship with the land, and it is both impressive and frustrating that nearly everything in that essay still reads true today.  If anyone reading this blog post has never read A Sand County Almanac, please stop reading this, go pick up a copy of the book, and read it.

I’ll wait…

Instilling a land ethic in my kids is one of my highest priorities as a parent.
Instilling a land ethic in my kids is one of my highest priorities as a parent.

One of my favorite parts of “A Land Ethic” is the section titled “Land Health and the A-B Cleavage”.  I’m always blown away by how neatly Leopold synthesizes the field of conservation into the first three sentences of that section:

A land ethic, then, reflects the existence of an ecological conscience, and this in turn reflects a conviction of individual responsibility for the health of the land. Health is the capacity of the land for self-renewal. Conservation is our effort to understand and preserve this capacity.

The very next paragraph introduces an issue I’ve been wrestling with for a long time.

Conservationists are notorious for their dissensions. Superficially these seem to add up to mere confusion, but a more careful scrutiny reveals a single plane of cleavage common to many specialized fields. In each field one group (A) regards the land as soil, and its function as commodity-production; another group (B) regards the land as a biota, and its function as something broader.

Leopold goes on to describe how some in his field of forestry are “quite content to grow trees like cabbages” while others have a less agronomic and more ecological approach.  He also points out that the fields of wildlife management and agriculture each have their own parallel examples of this dichotomy.  These contrasting views of the world still exist in various forms, from the way farmers think about their fields to the way people in cities value natural resources.

I see Leopold’s A-B cleavage very clearly in prairie management.  One example can be found in the way prairies are used for livestock production.  Many livestock producers see prairies primarily as grass farms, and the worth of a plant is determined by its palatability and nutritional value to livestock.  Broadcast herbicide application is commonly used in an attempt to remove “weeds” and leave only the grasses cattle or other livestock most like to eat.  Optimization of grass production also manifests itself in grazing strategies; particularly systems that move cattle through multiple paddocks with the primary goal of increasing the production and dominance of grass.  Grass farmers are exasperated by the perennial reoccurrence of “weeds”, despite their best efforts to prevent them. They don’t see that those weeds fill ecological roles grasses can’t, including roles that improve the overall health and productivity of the land.

A grass farmer's nightmare, these ragweed plants and other "weeds" play important ecological roles and fill in open spaces created by intensive grazing or drought.
A grass farmer’s nightmare, these ragweed plants and other “weeds” play important ecological roles, including filling open spaces created by intensive grazing or drought.  Removing them with herbicide application only results in more “weeds”, which fill the same spaces again.  Perennial grasses easily outcompete these opportunistic plants under light or no grazing pressure.  In fact, a year after this photo was taken, this site was dominated by big bluestem.

Other ranchers, however, see prairies as much more than grass farms.  Instead, they recognize that their livelihood relies on an extraordinarily diverse community of organisms above and below ground.  To these ranchers, the only weeds are those that reduce the diversity of the prairie community and make the land less healthy by Leopold’s definition of health: the capacity of the land for self-renewal.  Livestock producers on this side of the cleavage understand that they and their livestock depend upon soil, plants, pollinators, predators, pathogens, and the interactions between them.  A plant’s importance is not judged only by whether or not a cow will eat it, but also by the roles it fills in the larger community.  Those contributions include the communities of microbes living in the plant’s root system, pollen and nectar for pollinators, and food for herbivores, which in turn support predators that regulate populations of their prey.  Ranchers with an ecological perspective gain as much appreciation from watching bees buzzing from plant to plant as they do from watching the weight gains of their cattle, even though the latter is what allows them to pay their taxes and keep their land.

Just as there is a broad range of perspectives among livestock producers, there are wide contrasts among those who manage prairies for recreation and conservation purposes as well.  Some prairie managers have a single species or narrow set of species as their primary management target.  Those targets are include game species such as ring-necked pheasants, white-tailed deer or ducks, but may also be butterflies or a particular class of plants or grassland birds.  Narrowly-focused managers tend to manage their prairies in much the same way each year so as to provide a consistent set of conditions that best suit their preferred species.  Over time, prairie species not favored by that kind of repetitive management regime diminish in number or disappear, decreasing the overall diversity of the prairie community.  Since ecological resilience (today’s term for Leopold’s “land health”) relies heavily on species diversity, the loss of species from the community weakens its ability to support others, including the managers’ favorites.  Ironically, as the community weakens, managers tend to become even more agronomic in their approach by adding food plots, controlling predators, or increasing herbicide use to suppress plants taking advantage of a less diverse community.

Prairie managers with a broader ecological perspective start with the premise that a diverse prairie community is of utmost importance.  They manage in ways that prevent any particular species or group from becoming too dominant at the expense of others.  These managers don’t judge success by the abundance of one species or another, they focus on processes such as pollination, predator/prey interactions, and other indicators of community diversity and ecological resilience.  Variation in the species composition of a prairie between years is a cause for celebration rather than trepidation.  Year-to-year variation means that many different species (especially insects and animals) experience success over time, rather than just the few who thrive under more stagnant conditions.  Managing for diversity is not a simple process, and requires a careful eye and flexible approach, but the result usually produces strong and stable populations of all species – including those desired by more narrowly-focused managers.

Prairies managed for overall diversity have strong ecological processes that support all species - including game animals, songbirds, insects, plants and livestock. Prairies managed for overall diversity have strong ecological processes that support all species - including game animals, songbirds, insects, plants and livestock.
Prairies managed for overall diversity have strong ecological processes that support all species – including game animals, songbirds, insects, plants and livestock.

Whether we are managing for livestock, game species, butterflies, or flowers, the approach we take is critically important.  There is a strong temptation to continually maximize what we think are the enabling conditions for the species we’re most interested in, but that approach ignores the broader complex system those species depend upon.  The grass that cattle eat relies on productive soil, and that soil’s productivity is supported by a diversity of plants, microbes, pollinators and other prairie community members.  Similarly, the fate of butterflies, pheasants, and deer all depend upon the roles played by their fellow citizens of the prairie.

Trying to deal with all of that complexity may seem daunting, but take another look at Leopold’s definition of land health and conservation: Health is the capacity of the land for self-renewal. Conservation is our effort to understand and preserve this capacity.  Note that Leopold doesn’t say conservation entails fully grasping and perfectly managing the complexities of the land.  Instead, he defines conservation as the effort to do so.   I like that.  We don’t have to know everything to be successful.  Instead, conservation is an adaptive process of learning, incorporating new knowledge into our actions, and then trying again.  That means that conservation is accessible to anyone who appreciates the broad complexity of natural systems and attempts to work within them, rather than against them.

…And isn’t that more fun than just growing cabbages?

Disclaimer:  The author of this post intends no disrespect to those who grow cabbages.  Instead he was simply referring to a quote from earlier in the post to reinforce a point and attempt to end a long and heavy essay with something a little lighter.  Cabbage growing is a perfectly legitimate and important activity, especially when done with appropriate consideration for the broader ecological context of soil and other ecosystem processes required to sustain long-term production…  …Ok, I’ll just stop now.

Previous related posts you might be interested in:

Calendar Prairies

Are Botanists Ruining Prairies?

Why I Care About Prairies and You Should Too

Lately, I’ve been trying to figure out why I think prairie conservation is so important.  I’m not questioning my conviction – I feel very strongly that prairies are worth my time and effort to conserve – but if I can figure out exactly what it is that makes me care so much, maybe I can be more effective at convincing others to feel the same way.

I can list off all kinds of logical and aesthetic reasons that prairies are important.  Prairies build soil, capture carbon, trap sediment, grow livestock, and support pollinators.  Depending upon our individual preferences, prairies also provide us with flowers to enjoy, birds and butterflies to watch, and/or wildlife to hunt.

The buckeye is one of the more striking-looking butterflies that can be found in prairies.

Those are all very practical reasons to think prairies are important, but I don’t care deeply about prairies because they make soil and grow pretty flowers.  More importantly, those reasons are not enough to make someone stop and reconsider a decision to plow up a prairie to plant corn or broadcast spray 2,4-D just to reduce ragweed abundance.  If prairie conservation is going to succeed, you and I both need to understand and articulate the deeper reasons that we feel prairies are worth saving.

Which brings me to Dr. Seuss.

As I was mulling over why I cared so much about prairies, the story of “Horton Hears a Who” popped into my head.  In case you’re not familiar with the story, Horton the elephant accidentally discovers an entire community (Whoville) living on a speck of dust.  After he finds and starts talking with the Whos, Horton agrees to help protect them from harm.  The other characters in the book don’t believe Horton when he tries to tell them about the Whos, and actually go out of their way to steal and destroy the speck of dust he’s trying to protect.  Only when the Whos are finally successful at making enough noise to be heard do those other characters recognize the existence of the Whos and agree to help protect them.

Dr. Seuss’s intended moral to the story (repeated many times) is “A person’s a person, no matter how small.”  It’s a fine moral, but isn’t what drew me to the story as a metaphor of prairie conservation.  Instead, I was thinking about WHY the other characters in the story finally changed their minds.   The sour kangaroo and the Wickersham brothers didn’t give up their threats to boil the speck of dust in Beezelnut oil because Horton finally came up with the right logical argument to explain why the Whos were worth saving.  They changed their minds because when they finally heard the Whos making noise they recognized and identified with the Whos as fellow living creatures.

Can you see where I’m going with this?  I think the biggest thing that drives me to devote my career (and a fair amount of my free time) to prairie conservation is that I have developed a personal connection to the species that live in grasslands.  Not only do I know those species exist, I can also identify with them and what they’re doing to survive.  By becoming familiar with them, I became fond of them.

When I was in graduate school, I studied grassland nesting birds.  I got to know those bird species well, including where they lived, how they survived there, and what motivated and threatened them.  I saw prairies through their eyes, and that made me want to help make those prairies as hospitable to birds as I could.  Eventually, I began learning about prairie plants and insects as well.  I was fascinated to find that their stories were equally or more interesting than those of birds.  Each species had their own unique set of life strategies that allowed them to survive and interact with the world around them.  As a photographer, I usually learn about new species by taking a photograph of some interesting plant or insect, and then identifying it and researching its life later.  I’ve yet to come upon a prairie species that doesn’t have an amazing life story, which means the process of discovery continues to be fulfilling for me.

Pitcher sage (Salvia azurea) is one of my favorite flowers to photograph because of it's unique color and shape. It also seems to be a favorite haunt of many insect species, judging by the number that always seem to be crawling around on or near the flowers.

As the number of species I’ve gotten to know has increased, so has my commitment to prairie conservation.  Maintaining the resilience and vigor of prairie communities has grown from something that seemed like a good idea into a personal mission.  Now I’m working to protect things I love, not just species I’d read about or knew about only in the abstract.

Be honest, would you be more likely to send money to help people recovering from a natural disaster in a neighboring town or in a town on another continent?  With rare exceptions, we’d all choose the nearby town.  Why is that?  I think it’s because we can more easily identify with the people who live there.  We can imagine ourselves in their places.  We can see the disaster and their plight through their eyes.  It’s not that we don’t care about people on other continents, but they’re naturally a little less real to us.

By the way, forming sympathetic bonds with species can be dangerous when managing prairies.  The more I know about the species living in my prairies, the more I understand the ways in which those species are affected (positively and negatively) by management activities.  Any management treatment has negative impacts on some species, and impacts from activities such as prescribed fire can be quite dramatic.  Caring about individual species to the point where I’m unwilling to do anything to hurt them would paralyze me.  Management is all about tradeoffs, and while my management objectives are to sustain all the species I can, I have to be willing to knock populations of some species down periodically so that others can flourish.  I think the key is to become attached to the species, but not the individuals.  Tricky…     

Why does all this matter?  It matters because we need to recruit as many people to the cause of prairie conservation as we can.  Excluding a tiny minority of prairie enthusiasts, when the general public thinks about nature and conservation they look right past prairies to the mountains, lakes, and forests beyond – even when prairies are in their own backyard.  After all, what’s to care about in prairies?  It’s just grass.

If we’re going to fix that, we’ll need to do more than describe how prairies can help sequester carbon, filter water run-off, or support pollinator populations.   We’ll need to introduce people to the camouflaged looper inchworm that disguises itself with pieces of the flowers it eats – and to the regal fritillary caterpillar which, after hatching from its egg in the fall, sets out on a hike that will end by either finding a violet to feed on or starving to death.  They’ll need to become acquainted with sensitive briar, the sprawling thorny plant with pink koosh ball flowers whose leaves fold up when you touch them.  And who wouldn’t love to meet the bobolink – a little bird that looks like a blackbird after a lobotomy and flies in circles sounding like R2D2 from Star Wars?

The charming and vociferous bobolink.

Through this blog, as well as through numerous presentations, articles, and tours, I spend much of my time sharing what I’ve learned about prairie species with anyone who will listen – hoping that those stories will spur people to explore prairies on their own and start to form their own individual relationships with the species and communities they find.  My photographs and narratives aren’t themselves sufficient to convert people to the cause, but maybe they can at least get some of them to put on their hiking boots and go for a walk.

What about you?  Have you met the citizens of the prairie?  If not, let me help introduce you.  If you have met them, what stories can you tell?  How will you spread your passion about prairies to others?

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Here are some accounts I’ve written about prairie species I find fascinating.  If you find them interesting too, please share these links with others!

Camouflaged Looper – An inchworm that disguises itself with bits of the flowers it eats.

Yucca Moth – A terrific relationship between a plant and the single species of moth that has the capability to pollinate it.

Submarine Sora – Ever wonder why soras and other rails are so hard to find?

Sensitive Briar – A plant with a koosh ball flower, thorny stems, and leaves that fold up.

Pussytoes – One of the first spring-blooming flowers, and a surprisingly important resource for early season pollinators.

Of Mice and Clover – A great example of the complexity of interactions in prairies.

Crab Spiders – One of the great ambush predators of the world.

Flies – An unbelievably diverse group of insects with a wide range of ecological roles.

Grasshoppers – From their cute little faces to their complex communication strategies, it’s hard to beat grasshoppers.

Photo of the Week – December 1, 2011

The diversity of insect species in prairies – and other ecosystems – is simply mind boggling.  One of my favorite activities with kids is to hand them an insect sweep net and let them find out for themselves just how many different kinds of “bugs” there are in a prairie.  There’s a lot more than just grasshoppers out there…

I also like to quote impressive insect statistics when I give presentations, and one of my favorites comes from a 2000 report by Richard Redak.  Do you know which group of insects has the most species in North America? (The group includes 37% of all insect species on the continent.)  I’ll make it multiple choice, and you can choose from the following:

a) beetles

b) flies

c) wasps/bees/ants

d) butterflies/moths

e) true bugs

Made your guess?  Ok, scroll down to see if you’re right.

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A flower fly (Syrphidae) on yellow/hairy stargrass (Hypoxis hirsuta) along the Platte River in Nebraska.

Surprisingly – to me, anyway – the answer is Flies (the order Diptera).  Would you have guessed that there are more than 36,000 species of flies in North America?  That means that one in three insect species in North America is a fly.  How many species of fly can you name??  Three? (house fly, horse fly, …uh….)  No, butterfly and dragonfly don’t count.

I think it’s fantastic that there are 36,000 variations on those noisy flies that buzz around my head.  Because I’ve been paying attention to pollinators recently, I know that there are many kinds of flies that are valuable pollinators – in fact, flies are second only to bees in terms of effectiveness and importance.  As a photographer, I see a lot of flies hanging around flowers and elsewhere, and I’ve got quite a few fly photos that do look fairly different from each other.  But I still wouldn’t have guessed there were that many kinds.

A robber fly photographed along the Platte River in Nebraska. I love the eyes and claws, especially. ...Just another one of the 36,000 species out there.

Why is it important to have 36,000 kinds of flies?  I’m not sure, but isn’t it great to know they’re out there?  We could discuss the diversity of the ecological roles that flies fill – and they ARE important in many ways – but for me, those things are secondary to the simple fact that they exist.  We live in a great world.

By the way, if you guessed beetles on the quiz above, it’s a great guess – and you’d have been right if the question was about the entire earth.  The tropics have astounding numbers of beetle species, and that pushes them above flies.  But in North America it really is flies.