 Hi, I'm Rick Knight, Professor of Wildlife Conservation at Colorado State University. Today I'm going to be sharing with you some emerging ideas that pertain to the management of biological diversity at the landscape level. We'll be saying a few words about habitat loss, something that is not a new idea. We'll be talking about habitat fragmentation and the effects of decrease in area, increase in edge, and increase in isolation following fragmentation. And these are relatively new ideas. Then I'll be going on to talking about the importance of the matrix, the dominant land use in landscapes and how that actually affects biological diversity. Following that, I'll be talking about metapopulations, wildlife movement corridors, and then three general approaches that conservationists are using today to promote the maintenance of biological diversity. They can manage for single species that promote the collections of other species. They can manage for ecological processes, and they can manage at the landscape level, where you focus on landscape elements. So let's talk first about these ideas of habitat loss, habitat fragmentation, and the quality of the matrix. I won't say much about habitat loss nor habitat nor the quality of the matrix. I'll tend to emphasize habitat fragmentation, largely because from a biological point of view right now, in the landscapes that many of you are actually working with habitat fragmentation, it's probably the newest idea, and it probably may be having the greatest impact on the maintenance of biological diversity. Well, first of all, habitat loss, that doesn't require a definition, and it probably doesn't require much to be said about it. We live in a landscape. We live in a country in which habitat is being wildlife habitat or ecosystems or natural ecosystems or increasingly just being converted to something else, something of a human land use. I wanted to actually show you a figure that these are just Western states that show annual population growth and then annual percent land loss. And by land loss, we're talking about land that is going out of primarily ranch lands, but also other forms of agriculture into residential development. Just to sort of give you an idea, when you're seeing these farms and ranches being subdivided wherever you live and work, and they're coming back in residential and commercial development, that the rate of that land loss, that habitat loss, is not proportional to the annual rate of growth, of population growth in your state. So for example, if any of you live in these states, the state where I'm from, Colorado, you can see the annual rate of population increase is just under 3%. But look at the rate of land loss in Colorado. It's just over 8%. And that seemingly doesn't make sense. You would think it would be more or less a 1 to 1 ratio there. What is happening, of course, is in Colorado a great deal of the growth. And in other Western states, actually, from coast to coast across America, a great deal of the population growth is occurring outside of incorporated city limits. And so you're seeing rural landscapes where people are not living on one lot per 10th of an acre or a quarter of an acre. You're seeing this rural population occurring on 35 acres or 40 acres or 10 acres, but at a much larger change than the actual population growth. And so habitat loss is something we've always had to deal with in our concern for the conservation of biological diversity. But it's actually becoming more serious of a problem. Now, some people call it sprawl. Some people call it urbanization. I actually call it exurban development because it's residential and commercial development beyond the city limits, where suburbs and urban areas are beyond incorporated city limits. But it's a very serious problem. What I want to do next, though, is actually go to, in a sense, the second component when you're trying to protect biological diversity at the landscape level. And that's habitat fragmentation. Habitat fragmentation, up until the quality of the matrix appeared, was the new kid on the block. It's now actually been with us for going on its second decade. People are showing concern, greater appreciation and understanding of the ecological aspects of habitat fragmentation. But let's first define it. Fragmentation is the process by which a natural landscape is broken up into small parcels of natural ecosystems, patches or remnants, that are isolated from one another in a matrix of lands dominated by human activities. So it's basically you take a natural ecosystem and you fragment it. You fragment it with lines across the land. You habitat loss is one aspect. That's the traditional form of habitat fragmentation. And you can see in this picture of farmland, this used to be grassland. It used to be short grass prairie, or it was mixed grass prairie, it was tall grass prairie. And then over time, fragmentation has occurred. And what we see increasingly in this picture is actually agricultural lands with only remnants of the native grasslands or woodlots. That's the traditional view of fragmentation. Other people from the Pacific Northwest, your traditional view of fragmentation may be looking at a landscape that once was forest. And then with logging activities, it increasingly becomes patches of remnant forest in a landscape dominated by former forests, clear cuts. So that's the traditional view of fragmentation. It is very important to understand that there's two other types of fragmentation. One is something called perforation. And in perforation, and what you see here is a rural housing development where I live in Colorado, where you have former ranch lands that have been sold and have been subdivided. The landscape is still, from an appropriate distance, still seems to be the original ecosystem. But what you have in this landscape are the location of homes that have perforated the landscape. So actually, on a spectrum of land use, the traditional view of fragmentation is the gradual loss of natural ecosystems being replaced, becoming a minority in a landscape that is dominated by human land uses. But in perforation, you still actually, the majority of the landscape is still the natural ecosystem that's now only perforated by human land uses, in this case homes. Now, there's another type of fragmentation called dissection or internal fragmentation. And this is at the far end of the spectrum from the traditional viewpoint of fragmentation, maybe somewhere in the middle of the spectrum would be perforation. But at the far end is something we call dissection. And that's actually things such as roads or any type of linear right of way. Even actually, a fence line could be a form of dissection. It internally fragments a landscape along a very narrow administrative line of some type of land use. Obviously, if a landscape only has dissection or internal fragmentation, it is still even much more still principally the natural ecosystem that defined that landscape. And then in this overhead actually showing a rural housing development in northern Colorado, you can see in the upper part of the overhead all these little dots that are building sites of homes. That's an example of perforation. And then in the lower part of the overhead, you can see all these year-round access roads to those home sites. That's an example of dissection or internal fragmentation. So whatever landscape you're working with, maybe it fits the traditional model of agriculture, for example, replacing grasslands or rangelands. That's more or less the traditional type of fragmentation. Or maybe in landscapes that are increasingly being subdivided, where you have examples of perforation and dissection, internal fragmentation. Habitat fragmentation is probably right now the principal threat to the maintenance of biological diversity. And we'll talk about this next, because there's three effects of fragmentation. One, a decrease in area. Two, an increase in edge. And three, an increase in isolation. And there are collections of species associated with a decrease in area, an increase in edge, and an increase in isolation that increasingly are becoming of conservation concern. Let's talk about the first group of species. Species we call area-sensitive species. And those are species defined. They require large areas to persist, either because they have large body size, because of their movement requirements, or because they have some specialized needs, such as diet. So area-sensitive species are species that become of conservation concern as a landscape is increasingly fragmented because of the reduction in area of the ecosystem. Remember, fragmentation is basically the conversion of a landscape to human uses. And so what you have left following fragmentation, even if it's perforation or internal dissection, what you have left are smaller, more isolated, more edgy patches. OK, that's the definition of area-sensitive species. And just as an example, an elk might be an example of an area-sensitive species because of its movement requirements. It is actually fairly broad ecological requirements. But in much of the range of the elk, not in the eastern part of the United States where populations are being reintroduced, but in much of the west, elk undergo seasonal movements. They have these movements that take them from a summering area to a wintering area. And so they actually become area-sensitive. They need large areas of suitable ecosystems in order to persist. Black bears are an example of an area-sensitive species, largely because they're simply of their large body size. They're an omnivore. They have very broad diets, but they have large body size, and they have large area requirements because they undergo large-scale movements. The bobcat is an example of an area-sensitive species because it has a specialized diet. It's a carnivore. It's not an omnivore. It can't eat vegetables. It can't eat fruit. It doesn't eat insects. It tends to focus on animals that it captures and kills. So it has a specialized diet requirement. And because of that, it has large area requirements to support adequate populations of its prey. OK, another aspect of fragmentation is an increase in edge. And you can see that in any overview of a fragmented landscape, particularly when you can compare it to it before it was fragmented, you'll see there's more edge, up to a point at least. I mean, as you fragment something increasingly, you'll actually have only tiny patches of it left. If you flew over parts of Iowa that are intensely farmed, you'll see only remnant woodlots. And there's actually much less edge there than when it was only partially fragmented. But anyhow, generally, there's an increase in edge. And what this has given us is a group of species called edge-sensitive species. And they're defined as species who have reduced fitness. And fitness is simply the ability to survive and reproduce. They have reduced fitness near habitat edges. Now, why is that? Why are there some species that simply don't thrive or don't do fine in association with habitat edges? Well, one of the reasons is another group of species called edge-generalist species. And it's probably not a surprise. Edge-generalist species are those species whose fitness, their ability to survive and reproduce, is enhanced near habitat edges. And these are the species that we know the most about. These are the species that most people can't identify. The raccoon is an excellent example of an edge-generalist species. Where I live in Colorado, the Blackbill Magpie is an excellent example of an edge-generalist species. These are the American robin. These are all species who actually they do best when they're near habitat edges. So edge-generalist species tend to thrive in fragmented landscapes. And either because they're predators or they're competitors, or in the case of the brown-headed cowbird, they're parasites, they cause a reduction in fitness and the ability to survive and reproduce of some species, which we call edge-sensitive species. An example of that is work we actually did in association with these rural homes in Colorado. I was talking earlier about landscapes being perforated by ex-urban development. And what you see in this overhead are elevated densities of what we call edge-generalist species. And these are all the largest densities, the highest densities are seen near the homes. The 30, 180, and 330 meters, that is at increasing distances into natural areas from these rural homes. And low and behold, the American robin has its highest densities in association with rural homes. The robin is a very successful competitor for nest sites and for food with other species. So it's an edge-generalist species. The black-billed magpie, its highest densities were found near the homes at 30 meters to a home. The black-billed magpie is a superb nest predator of songbirds. And the brown-headed cowbird, its densities were also at their highest level in association with these homes. And of course, the brown-headed cowbird is a nest parasite. Female cowbirds lay their eggs in the nest of other species. Now, we go to this other group of species. The black-capped chickadee, the blue-gray neckcatcher, the dusky flycatcher, black-headed gross beak. And these species all have depressed populations in association with the edges of these rural homes. That's probably because of these edge-generalist species. If they nest near a home, they're gonna be nesting in a landscape, in that edgy landscape of a rural house, where you have a greater likelihood of having your nest parasitized by a cowbird, a greater likelihood of your nest being preyed on by a black-billed magpie, and a reduced likelihood of being able to successfully compete with American robins for nest sites and food. That's possibly the reason why we see depressed populations of these species, which we are now calling edge-sensitive species. Their ability to survive and reproduce, and therefore their population densities are reduced in association with edge. Now, because there is this edge effect from edge-generalist species, we find out as well that the depth of this edge effect from the habitat edge into the natural ecosystem, the depth of that edge effect is highly variable. That becomes relevant when you start examining the shape of these habitat patches. What is left behind following fragmentation? So in this idealized picture here, we have two different shapes, a rectangle and a circle. And what we have drawn a line here is a certain depth of edge effect, and the take-home message, of course, is the shape determines how much of these patches are actually immune from a particular edge effect. Maybe it's black-billed magpie nest predation, or brown-headed cowbird nest parasitism. How far from the habitat edge do you have to go before black-billed magpies are no longer willing to venture into, for example, a forested environment or brown-headed cowbirds? So the shape of these patches actually becomes very relevant in wildlife conservation, in the maintenance of these edge-sensitive species. And as you can see, only the circle and this sort of hypothetical contrast between two ecosystem remnants, only the circle has any habitat that is actually immune from this particular edge effect. So shape actually determines, these are both actually the same area, they're exactly the same size, the only thing they differ in is shape. And that may be of actually great value to you in conservation planning to the degree that when you're working with landowners, that you can help influence the actual shape of ecosystem remnants. Okay, the third consequence of habitat fragmentation, in addition to the reduction in area and the increase in edge, is obviously an increase in isolation. A landscape that was once contiguous that becomes fragmented, perforated, internally dissected over time is becoming increasingly isolated. These remnant patches from this natural ecosystem become increasingly isolated. And not surprisingly, we have a group of species called dispersal sensitive. And they're defined as species whose fitness, again, their ability to survive and reproduce, decreases in fragmented landscapes due to physical, behavioral, physiological limitations or simply elevated mortality from having to cross human-dominated landscapes as they go from one natural ecosystem remnant to another as they disperse. They either have limitations that decrease their ability to successfully disperse from one patch to another, or they experience elevated mortality as they cross that human-dominated landscape. For example, the turtle. Turtles are an excellent example of dispersal sensitive species. They actually have physical limitations, at least relative to something that's more fleets, something that's able to disperse at much greater speed. Turtles in their attempts to disperse across fragmented landscapes are physically constrained because they can't fly as fast as the bird, they can't run as fast as a coyote. They go at a much slower speed. So they would probably qualify as a dispersal sensitive species, species that you might have to show concern for as a landscape becomes increasingly fragmented. Chipmunks, believe it or not, chipmunks as popular as common as chipmunks are, they actually qualify as dispersal sensitive species. The eastern chipmunk, as many of you know, is diurnal. And so when it disperses from one woodlot to another, it can actually become physiologically stressed from the sun. If it's a clear day, it can only disperse so far before its physiology actually starts to shut down. It becomes heat stressed and it will die unless it goes back to the woodlot from where it came from or unless it hits another woodlot. The American Martin is a classic example of a species that is behaviorally constrained and therefore qualifies as a dispersal sensitive species. When it is trying to move across a landscape that is increasingly fragmented, where you have increasingly large open patches of former forests, for example, forest clear cuts, it behaviorally is uncomfortable. It's constrained. Its evolutionary history doesn't encourage it, doesn't allow it to cross these increasingly large open areas. It wants to disperse through contiguous forest. And then, of course, there's all those other species we encounter every day of our lives while we drive. All those species that are not morphologically, physiologically, or behaviorally constrained to disperse across ever increasingly fragmented landscapes. These are species that simply experience elevated mortality rates. And maybe when you were driving to work today, you saw a garter snake dead on a highway or you saw a squirrel or a rabbit or a raccoon or maybe a very uncommon species that was simply trying to disperse and it was hit by an automobile. In fact, I call those metallic carnivores. They sweep the highways 24 hours a day, seven days a week, uncaringly, and of course unintentionally, in most cases, killing wildlife. Wildlife that's simply trying to disperse across an increasingly human dominated landscape. All right, so what are the implications about habitat fragmentation? Do you, as a conservationist, you have a reduction in area? You have an increase in edge and you have an increase in isolation. On this hypothetical landscape, the landscape on the left is not fragmented. The landscape on the right is. Those three ecosystem types have been fragmented, as you can see. The landscape on the left will, all things being equal, you will probably have fewer area-sensitive species because they're larger than what you see on the right. It will probably have fewer edge-sensitive species because there's less edge. Remember, it's not as fragmented as what you would see on the right. And it will have fewer dispersal-sensitive species because it's more contiguous. Again, it hasn't been fragmented to the level that it can be. So with the increasing edge after following habitat fragmentation, what we tend to see is a decrease in edge-sensitive species, largely due to edge-generalist species. And of course, remember, edge-generalist species are those that thrive in association with habitat edges. Invasive species are an excellent example of an edge-generalist species. Their ability to survive and reproduce is enhanced in association with habitat edges. So one of the results of increasing fragmentation, following this increasing amount of edge, is an increasing dominance of a landscape by invasive species. And I think everybody has firsthand experience with seeing once you've disturbed a landscape, in a sense created an edge, say bladed a road or built a road, built a house, cut a field as you see edge species, invasive species thriving in that disturbed area. So I guess we sometimes tend to think of edge-generalist species as just being things like robins and magpies and cowbirds, but they're also plants. And of course, if you're concerned about natural ecosystems, we're also concerned about those communities of native plants, of native species of insects, and these invasive species can actually result in the decline of those. When I began this presentation, I highlighted three landscape-level changes that affect the conservation of biological diversity. The first one was habitat loss. That's been with us forever, as long as we've started to replace natural ecosystems with some human land use. The second one was habitat fragmentation, which only actually recently has come to the forefront in concern for the conservation of biological diversity, largely because rural landscapes are being increasingly used by humans, we're fragmenting them. And of course, habitat fragmentation is inseparable from habitat loss until you have the total replacement of an ecosystem. The third one, the newest idea that conservationists are starting to show concern for is something called matrix. Now matrix is defined as the most connected and extensive landscape element type. It can include importantly both human land uses as well as vegetation communities, as well as natural ecosystems. So for a second stop and think about what is the matrix where you live and work? If you lived in Denver, your matrix is urban. Remember I said in the definition of matrix, it can include human land uses. But if you were a ranger in Rocky Mountain National Park, 70 miles to the west, your matrix would be coniferous forest. If you live and work in eastern Colorado, your matrix might very well be dry land wheat or irrigated agriculture. Or depending on how much of that had been converted from short grass prairie to agriculture, your matrix might actually be short grass prairie. Now matrix is becoming important because what we're seeing across America is the quality of our matrix, particularly when it's natural ecosystems is being degraded. Parts of Colorado that are being converted to residential development, the rural landscapes, the quality of that matrix. Remember I said those rural homes only perforate the landscape, still leaving actually the natural ecosystem relatively intact. It's not that traditional type of habitat fragmentation. The natural ecosystem is only being perforated, but the quality of the matrix is decreasing. So it turns out that the quality of the matrix of your landscape matrix is probably almost as important as habitat loss and as habitat fragmentation in determining the type of biological diversity you're gonna have in your landscape. If it's a high quality matrix, if for example the extreme would be if the principal element were natural ecosystems as we find in ranches, you're probably gonna have a relatively intact species composition. But if that landscape, if the quality of the matrix is being increasingly degraded, the natural ecosystems are being increasingly degraded because an intensification of human land use, you're probably gonna see a very altered collection of species. And obviously there's a conservation challenge with that dilemma because you're gonna wanna promote the maintenance of those sensitive species. Now this is a figure that illustrates two different matrices. The one on the left, the matrix is farmland. So for example, this could be in Wisconsin where I spent time. The matrix is farmland and what we have are woodlots. These are the sort of the remnant natural ecosystems embedded in a matrix of intensive agriculture. And on the right, what we find is a forest matrix where what we have embedded are forest openings or forest clear cuts. Now think of this for a second. We have forest in both of these and we have openings in both of these matrices. We have edge. As you can see, there's edge going around the perimeters of the woodlots in the agricultural matrix and there's edge going around the forest clear cuts in the matrix of forest. Then you start asking a question, well, what about an edge generalist species like the brown-headed cowbird in these two different landscapes, these different matrices? After all, brown-headed cowbirds are an edge generalist species. They look for bird's nests along edges, along forest edges, that they can parasitize. Is brown-headed cowbird parasitism of equal importance on along edges of these two different matrices? It turns out not. When the matrix is forest, we have reduced populations of cowbirds so cowbird parasitism is not a greater threat to edge-sensitive species. In a matrix of agriculture, in other words, a principally open matrix, it turns out we have elevated populations of brown-headed cowbirds and they exert undue influence and the forest songbirds close to the forest woodlot edges. So this is just an example of how matrix actually can be used as another predictor. You, again, as the land doctor, can actually make generalizations about the type of biological diversity you're going to have based on the matrix. What we're finding out and research being done in Colorado, if your matrix is ranch lands, you're probably gonna have largely the same biological diversity than if the matrix was protected areas. We're assuming the same elevation, the same soil type. But if your matrix is ex-urban development, it's gonna be quite different. As I showed you earlier, there's gonna be more black-billed magpies, more brown-headed cowbirds, more American robins. Populations of those edge-general species are gonna be reduced in a matrix of ranch lands and of protected areas. So when we're trying to think of landscape-level changes in terms of the natural communities, the natural biological diversity of those landscapes, we need to, of course, never to lose sight of the importance of habitat loss. We are increasingly showing concern for the ecological effects, the unintentional effects, obviously, of habitat fragmentation. But now we wanna add the quality of the matrix, of the principal land use to our concern at the landscape level. It turns out that matrix quality is something that we can work as conservationists to improve and that matrix quality also influences the biological diversity of an area. So habitat loss, habitat fragmentation, and matrix quality. Don't think of these independently. All three of these should be thought of simultaneously. And we need to be clever, or more clever, in working with landowners to try to improve the matrix quality while we, at the same time, try to minimize habitat fragmentation as well as minimize habitat loss to the degree that these are compatible with human land uses on private lands. As landscapes are increasingly fragmented, as we see the loss of habitat, as we see the degradation of matrix quality, there's an emerging idea called metapopulations that conservationists are finding to be extremely useful into reversing the population declines associated with landscape level conversions. Now, what is a metapopulation? Metapopulation is defined as a population existing as a number of spatially discreet, in other words, separate populations distributed among these habitat fragments that we've been speaking about, and that are connected via dispersal. They are connected, these spatially discreet populations are connected via individuals being able to successfully disperse from one patch, one remnant to the next. So very powerful concept. I mean, habitat fragmentation, decrease in matrix quality, decrease in area, this idea of metapopulations, increasingly those are the landscapes that we're living and working in. They're actually defined as metapopulations. Historically, they may have been contiguous populations, but with habitat loss and with fragmentation, they're becoming increasingly isolated. Now, associated with this idea of metapopulations come three very powerful concepts in understanding how metapopulations actually work. First are these habitat remnants that serve as sources. Habitat remnants that serve as sources, in other words, areas these discreet populations where productivity exceeds mortality, in other words, a self-sustaining population. Source populations exist, they're either large enough, they're appropriately shaped, they're high enough quality habitat, so they're actually serving as sources for these dispersing individuals that will keep metapopulations viable. Now, what happens when these remnants, these habitat patches are too small or the quality of those have degraded or the shape is inappropriate? They say they exist largely as edge. They're more rectangular than they are circular. Well, these populations then are called sinks and that's where mortality is exceeding productivity. So there is no net surplus of individuals that can disperse to these other populations, these spatially discreet populations that comprise the metapopulation. The rescue effect is something we see in metapopulations from time to time. It's where a population, one of these spatially discreet populations existing in a remnant, a patch of this fragmented ecosystem, disappears and then it reappears. In other words, individuals from source populations successfully disperse into that population. They either keep it from going extinct or if it is gone extinct because it was a sink, it may reappear and in effect actually sink populations, if they're in a metapopulation where the rescue effect is going on, sink populations may literally be going extinct and reappearing from year to year. So the metapopulation concept is very dynamic and it actually reflects land use and land use change on working landscapes. Here's a figure that shows a hypothetical metapopulation and hopefully all of you live in landscapes where you have some experience once you're aware of this concept of a metapopulation where you know you have patches that have robust populations that are viable year after year, those are sources. And maybe you've seen these remnant patches where the quality of the habitat is low, maybe because of the area, because of the shape, because of what's going on. Maybe it's being overwhelmed with invasive species, weeds and things where that these populations are existing as sinks and you may be seeing native species populations going extinct over time. Well, to the degree that dispersal occurs from one of these spatially discrete populations to the next and to the degree that you still have source populations on this landscape, you're witnessing a metapopulation and in this hypothetical landscape, the largest circle, the largest population in the center, that's obviously on a patch, a habitat patch that must be high quality, maybe because of the size or maybe because it has still principally native species in it, it hasn't been overwhelmed through invasive species. But for whatever reason, it's producing a surplus of individuals that are dispersing to adjacent populations. And maybe some of this, for example, the smaller circle to the right of that large source population, that smaller population is a sink population and it's only persisting because of dispersal of individuals out of the source population. So it'd be a real challenge for you to, for appropriate species, species where this works, where the idea of metapopulations works to start thinking about the landscape where you're working and see if for certain species, you actually indeed have a metapopulation. That may actually be a powerful tool in helping you to prioritize habitats where you wanna protect or actually helping you make decisions where you have habitat remnants that are of decreasing quality because of some increasing land use. Do you actually wanna go in there and try to improve the habitat quality? Turn those from sinks into sources. Maybe some sort of conservation practice like fencing out a riparian area and turning it from a sink into a source for yellow warbler populations. It also obviously makes you think about how can you affect successful dispersal across your fragmented landscape because the metapopulation emphasizes the quality of these remnants and a landscape as well as the importance of individuals being able to successfully disperse from one patch to the next. An example of why this is becoming of increasing importance across America. As all of you know, America is more private land than it is public lands. Let's look at these figures just for a second in the context of metapopulations. First of all, we find out that most conservation areas, in other words, protected areas, are on the least productive soils. As you can see, going from left to right, the vast majority of our protected areas, our areas set aside for their conservation values are on the least productive soils. They also occur, as you can see here, at the highest elevations. This is no surprise to any of you that the private lands occur on the most productive soils as we can see here. The most productive soils is where we find the vast majority of our private lands, and they also occur at the lowest elevations. So when you're starting to think about metapopulations, you're starting to think of a landscape of private and public lands. The public lands are probably the protected areas, not everywhere, of course, but if you look at this across America, those protected areas are more likely to have poor soils and occur at higher elevations than the private lands. A powerful take-home message here is that means the protected areas, all other things being equal, are more likely to serve as sinks than as sources. And so the work you do on private landscapes is of disproportionate importance because you're working with the landowners who control the most productive lands, who have the greatest capacity to support landscapes of sources instead of sinks. We will not protect the nation's natural heritage, just relying on our public lands, our protected areas. They can't do it. They're the least productive landscapes. Okay, so sort of a theme of the material that I'm sharing with you is of fragmented landscapes, of landscapes that may have once been contiguous with natural ecosystems that increasingly, our landscapes now that are fragmented, there's only remnant patches of these natural ecosystems. That was part of habitat loss, that was part of habitat fragmentation, that's part of the decrease in the quality of our matrices, that's central to the idea of metapopulations. We talked about dispersal sensitive species, and we talked about the importance of dispersal in performing the rescue effect from sources to sink populations. Well, let's talk about conservation actions, movement corridors devoted exclusively to reconnecting landscapes. This is a conservation action. Movement corridors can be designed. Landscapes and land uses sometimes can be configured in such a way to promote movement corridors, to protect movement corridors connecting important populations. First of all, what's the definition? There are linear strips of natural ecosystems that are connecting areas with conservation value. The rationale behind movement corridors is pretty straightforward, it's to increase the likelihood of successful movement and decrease extinction rates of isolated populations. If these populations are existing in smaller areas, reduce populations, the likelihood of them persisting of course also decreases, in other words of being sink populations. So the rationale behind movement corridors is our antidote in a sense to sink populations. It's our sort of formal conservation approach to promoting the rescue effect, to allowing populations to persist in increasingly fragmented landscapes. From a conservation point of view, it's probably important to look at a checklist to actually evaluate movement corridors, whether these are existing corridors or movement corridors you may be working with private landowners to develop in your landscape. And it's also important to be aware of parameters that improve the quality of movement corridors. So let's look at the checklist first and then we'll look at some design parameters that increase the usefulness of a movement corridor. First of all, a checklist to evaluate an existing corridor or to help actually design a movement corridor. First of all, you have to identify the sites the corridor is designed to connect. That's really important. You don't wanna connect a protected area to a city suburb. The movement corridor is obviously being designed to promote this idea of metapopulations. You may make the conscious decision that you wanna connect one protected area to another protected area, one high quality habitat to another. Actually, you may even wanna design a movement corridor to connect a high quality habitat remnant to a low quality, wanna sink, not obviously a city, but say a wood lot in which there's livestock grazing and the understory has largely been removed, but you may wanna consciously connect those with a movement corridor because you wanna see that sink persist over time. It's gonna have to have successful dispersal to persist. And maybe in the long term, you think you can through land use changes and land use practices convert that sink to a source. You also have to select a species of concern for wildlife movement corridors. And that's because you need to know the needs of this selected species when you're actually trying to design the movement corridor. It may have certain food habit requirements. It may have certain movement requirements, say it's a diurnal species or it's a nocturnal species. Those things actually become very relevant when you're trying to evaluate the characteristics of that movement corridor, whether or not it has gaps in it. How wide are those gaps? Is the species fast enough or is it nocturnal? So it's able to get across those gaps. You probably need to evaluate the disadvantages, the potential disadvantages of a corridor. I've spoken about movement corridors as being just nothing but very positive in this idea of metapopulations and fragmented landscapes. But what if you actually designed a movement corridor that allowed an invasive species, a weed to go to an area in which that weed does not occur and you need to look or what if, I guess, another potential disadvantage is, well, what if there was some sort of disease that you were actually trying, I mean, unintentionally, you allowed to show up in a protected area or in a landscape that doesn't have that disease. So I guess there are potential disadvantages of movement corridors. You have to weigh those when you're evaluating a corridor or when you're trying to design a corridor. There's sometimes things you can do to minimize these potential disadvantages. Now, another step is you'd have to map the corridor. Obviously, you have to look at things like private ownership. When I say evaluate corridors features, you have to look at the width, you have to look at the gaps. Are there interstate highways? How many paved roads are there? Are there rivers in which it would be impossible for the species of concern to be able to cross? Are there urban areas that come near that? Is the landscape slated for some type of development in the future? So the surrounding matrix quality may actually be going through some sort of landscape change where it's going from ranch land to housing developments. Well, when you're designing a movement corridor, it's gonna have to be a lot wider if the surrounding land use are houses as opposed to ranches. So if you've looked at the areas where you're going to connect, you've picked a species of concern, you're aware of its ecological requirements and what it needs. You've thought about potential disadvantages of that corridor. You've actually placed it on a map where you start to look at gaps in the corridor, cities, highways, land ownership. You've evaluated the features and then it's probably best to the degree that you can to design and implement a monitoring program. In other words, a follow-up schedule to see if indeed the corridor is being used. The idea of movement corridors has met with widespread acceptance but very little critical evaluation and what we need to know is are wildlife actually using these? I mean, we're assuming that wildlife is smart enough to figure out or lucky enough to accidentally hit a movement corridor when it starts to disperse across a human-dominated landscape. So to the degree that you can actually develop a monitoring program to see if the corridor is used, that'll be extremely useful in terms of any modifications on the corridor's features over time as well as a justification for this conservation practice in the first place. Now what about some design parameters? These just serve as general guidelines in helping design a corridor or evaluate an existing corridor. Let's look at gap width. Now, obviously in most occasions, wildlife movement corridors are gonna have gaps in them. Those gaps in many cases are simply highways. Those gaps could actually exist as some piece of private property where the landowner isn't willing to cooperate or maybe it's gonna hit some other land use that is gonna make it difficult for wildlife to successfully disperse across it. Now as a general rule, what we find out is that with increasing mobility of a species, the gap width can be increasingly wide, up to a point. Obviously at some point, no matter how fast you are, the width, the gap width is going to be so wide that you're not going to be able to successfully disperse across it and into the movement corridor on the other side. So as a general rule, if the species you're really concerned about promoting the movement of across fragmented landscapes are fairly mobile, gap widths can be fairly wide. What about the landscape which the movement corridor passes across? Well, it turns out that this idea of matrix is really important there. The more human dominated that matrix is, in other words, the lower quality of that matrix, the wider the movement corridor needs to be. And that's simply because the external pressures from the human dominated matrix are going to have an impact on species. And so the corridor needs to be wider in a sense to buffer them from that increasingly human dominated landscape. Now a third general rule is that with the increasing length of a movement corridor, the width of the corridor needs to be wider. And that's based on the biological truth that the longer it is, the more time they're gonna spend in it, the more time they're gonna spend on it, spend in it, the greater likelihood they're going to have to have, they're going to meet, they're going to have to meet their life history requirements. So the wider the corridor is, maybe the greater likelihood it'll contain water or adequate food or roosting sites for the species that is dispersing through it. There's an excellent NRCS guidebook that details just about everything that's presently known today about wildlife movement corridors. It's in your field office. And I strongly encourage you to look at that if you're involved in either evaluating or helping design movement corridors in the landscape where you work. In natural resources management, we're seeing a transition. Increasingly, conservationists are getting away from focusing exclusively on single species and starting to manage for collections of species. There's many reasons why this is occurring and there's actually many reasons why this is a good idea. Probably the simplest one is there's simply too many species out there to manage one species at a time. This is not to say that we'll never stop single species management. For species of economic value, for species that are viewed as pests that threaten human economies, for species that are listed as federally threatened or endangered, there will probably always be some degree of single species management for those. But our collective society is showing increasing concern for all the other species, all the other little life things that comprise our nation's biological diversity. So how do you manage for collections of species? What we've been talking about up till now has been largely focusing on single species. Though I guess there's probably collections of edge-sensitive species, collections of area-sensitive species, collections of dispersal-sensitive species that we could manage landscapes for based on the ideas I've talked about earlier. But now let's actually look at three general approaches that are emerging across America that natural resource practitioners are using increasingly to manage for all the other species, these collections of species. Species assemblages are biological diversity. You're gonna be quite familiar actually with all three of these, but you may not have really thought of these as tools or approaches to managing for collections of species. Let's start with the first one, which is called the species approach. The species approach is defined on focusing on manipulating a single species that affects many other species. Species chosen might be an invasive species. In other words, a weed that is actually affecting the entire collection of native grasses and maybe even forbs. It could be a keystone species. In other words, a species like the beaver that is disproportionately important in affecting a whole collection of other species. In the absence of beaver, we lose, we see reduced populations are actually the elimination of species. The prairie dogs, an excellent example of a keystone species, you could be managing, for example, the black-tailed prairie dog. Not for the black-tailed prairie dog's sake, that would be our traditional single species management. But what if you were managing black-tailed prairie dogs because they actually affect a whole collection of other species? That would be a great example of using the species approach. But it can be any species, a weed, a keystone species. It can be any species that has an important ecological interactions that other species either depend on or are affected by. Another example, when we were talking about edge generalist species, remember that was affecting all those edge-sensitive species. So what if you consciously managed to decrease brown-headed cowbird populations? Well, if you were doing that because you knew it would promote the fitness, the ability to survive and reproduce of all these forest songbirds who are affected, who are negatively affected by the brown-headed cowbird, that's the species approach. Again, there's an important distinction here. Don't confuse this with the single species approach that we've always done. When we managed elk historically, we managed elk because they were of great economic value. So we could hunt them. When we managed red-winged blackbirds, we managed those because they threatened our economies as a pest bird on grain crops. What we're talking about now is you're picking a species consciously because it affects many other species, either negatively like an invasive species, an invasive species might, might or a native species whose populations have increased like the brown-headed cowbird. Or you may be consciously picking a species in which many other species depend upon like the beaver or prairie dogs. Okay, the second approach, another approach, is called the ecological process approach. And the ecological process approach focuses on reinstating natural ecological processes. Obviously, you wanna reinstate those processes in such a way that they fit within the natural range of variability, both spatially and temporally. Now, a very common example of an ecological process approach is putting fire back on the land. In fire-dependent ecosystems, in the absence of fire, those ecosystems turn into something else, something different. They actually are dependent upon fire. They need fire. And so, reinstating fire within its natural range of variability, spatial the size of the fire, and temporally the interval and time of the year in which fire occurs, that's an example of using the ecological process approach. There are entire collections of species that in fire-dependent ecosystems, disappear or they turn into something else, the relative abundance of those species changes and is altered in the absence of fire. Another example of the ecological process approach is allowing flooding to occur in riparian areas. Obviously within the historical range of variability. The concept of grazing, there are ecosystems that are absolutely dependent upon being grazed. And you will lose plant communities or get something quite different in the absence of grazing. So these are the ecological process approach. Again, it's something the NRCS is aware of. It's a very important tool for managing for collections of species, for biological diversity. And the third approach is called the landscape approach. This is actually probably the more recent of these three approach. The landscape approach concentrates on landscape elements and their size, shape, and juxtaposition. So imagine a landscape that is increasingly fragmented. So you have remnant patches that are smaller, that are more edgier, that are more isolated. You're probably gonna get an increase in edge generalist species, collections of these species like we've spoken about earlier. You're gonna see decreases in collections of species that are edge sensitive, that are area sensitive, that are dispersal sensitive. So the landscape approach works at the landscape level trying to make these patches larger, less edgier, more connected. If their collections of species depended upon late successional stages of these elements, you're trying to promote older growth patches, for example in forests. You wanna have a landscape that has more old growth patches left, not one that is strictly early successional stage patches. The landscape approach really is dependent on using GIS as a technology. And it actually sort of dovetails nicely with everything I've spoken about earlier in terms of fragmentation and matrix quality and meta populations. What we're seeing increasingly in America is that conservationists are using all three of these tools. They're not using them in isolation. They are working on critically important species. In other words, they're taking the species approach. They're trying to control an invasive species because it's impacting a whole collection of other species. They're trying to reinstate fire as an ecological process because they're fire dependent ecosystems. They need fire. They're looking at the size, the area and the juxtaposition of habitat fragments because they realize there's collections of species dependent on areas that are larger, that are less edgy, that are more connected than what may presently exist at the landscape level. So the points that I've emphasized are all dependent upon finding ways to work across administrative boundaries and nobody has more experience at that than you do. You've always been comfortable working with private landowners, with people at the county and the state and at the federal government levels. You can't implement ideas behind meta populations. You can't deal with habitat fragmentation. You can't evaluate and help design movement corridors unless you're able to effectively work across borders, unless you're effectively able to promote stewardship across administrative boundaries. I know you can do it because you've done it your whole history. Good luck.