 The western Oregon coast range, a temperate rainforest that gets about 100 inches of rainfall a year here. And I thought it was a very good setting to begin our today's lecture on the role of disturbances on landscape structure and function. I'm standing right in the middle of a small creek and while it's a nice summer base flow right here, in the winter the flows may be well over our heads, scouring out the rocks and all of the vegetation and animals and insects and even fish in the creek would have to be evolved and certainly adapted to these disturbances. But what about the forest? Many of you look at this and see that, well gosh, this is a forest primeval, what's the disturbances here? Yet if you look very closely you begin to let the landscape tell you its story. This is what we call a high severity fire regime, long return intervals. It's so wet here we rarely see fires, yet when they do come through they come through with great severity and again virtually all the plants and animals are adapted to this sort of disturbance. The great historian Steve Pine once stated that the earth is not only a great water planet but it is also a great fire planet because virtually all of the terrestrial vegetation on this earth has burned and does burn at one time or another. And that's no exception to this forest today and a great deal of what I'd like to talk to you about today in today's lecture will be the role of disturbances, particularly disturbances like wildfires and floods in this ecosystem. Let's talk a little bit more in depth about disturbances and disturbance ecology and what that means for resource management. Like I said in the field, virtually every ecosystem on this earth, whether it be aquatic or terrestrial, have some sort of disturbance that greatly influences their composition, structure and productivity. And so we say that these disturbances, whether it be in a forest, a shrubland, a grassland or even a wetland, it's a natural part of the environment, it's a natural part of the ecosystem, every bit as much of a factor as say snow, wind or rain or temperature, relative humidity that would influence that ecosystem. What's the definition of disturbance basically? We might call a disturbance as any discrete event in time that disrupts ecosystem, community or population structure and therefore changes resources, substrates or the physical environment. There are just some examples of disturbances that we might all experience one or two of these in whatever ecosystem you're working in. It might be things such as floods if you're down on the river or the creek, wildfires in virtually all of the terrestrial ecosystems, ice flows again are very common in some of the northern latitudes, hurricanes for those of you on coastal areas and wind and ice storms whether it's wind throw or very, very severe ice storms say again in the northern part of the country. Just some examples, this is a flood, a flood that you can see here has eliminated a small stand of alders in a mountain stream in northeastern Oregon but at the same time while it's destroying this stand it's creating and depositing substrates for new stands to establish. Another example such as a wildfire here in a sagebrush community again performing a myriad of functions. Here's a picture of an ice flow, a very ice storm event on the Malhear River again in eastern Oregon near the Idaho border and what you see here is not only are we eliminating plant communities but if you'll notice the willows and the stems being picked up by the ice and this example many of these willow stems will actually be deposited into gravel bars and flow so it is a way that many plant communities renew themselves and that these stems are the next generation for the next plant community. When we talk about disturbance though it's very difficult quite often to just talk about one area or one event in time we need to look at them and view them as you look at your landscape on a wide scale of both time and space. If you were to think of an example here on this graph of time being on the y-axis and spatial scale on the x-axis both of them increasing typically a small point might be a small pebble in a creek where it is getting turned over perhaps on a daily basis. Stands may be influenced every two to ten years by a fire by a flood. Entire watersheds may be affected on very large disturbances perhaps again landscape scale disturbance events. Regions may be influenced by huge but very very long return on events say perhaps a volcano or something that would influence a large area of the world and then we might even see it continental scales severe ice age events very long time scale events that would have large influences at this scale so again depending upon your scale of things is the time and the space have strong interactions. If we look at though when we start to examine and view natural disturbances we can see that and how we perhaps do research how you may monitor or look at the response of a natural disturbance depends upon your objectives. You might want to look at the sub-organism level which would be perhaps how does a disturbance influence plant growth or rate of growth or productivity. The organismal level or the individual level might be does this disturbance event increase reproductive output does it increase the personal fitness or decrease the personal fitness of a particular individual. We might want to look at the whole population response how do populations respond a population of a single species respond to are they favored by disturbance events or perhaps are their numbers and or perhaps even to put completely extirpated by some disturbance event. And then finally we might want to look at the ecosystem or landscape level how does disturbance influence productivity influence biological diversity at various many spatial scales of all the species taking all the species all the structures all the stands that we might see at that landscape level. I just want to give you an example here that would be very similar to what we saw in the old growth forest. Here's an example of sort of the cycle and how a single disturbance event this very discrete event in time may influence the composition and structure for hundreds of years. And again this is what we saw in that example from the forest and the coast range. We might start off with a fire being the disturbance event and we are looking at the size of the fire the frequency or how often the fires occur and then the behavior of the fire. This is sort of the fire regime that I'll get to and describe a little bit more in detail in a few minutes. What drives that fire certainly fire weather the weather events at the time of the fire the topography and aspect but also the fuels which is the vegetation how much is out there what's the continuity. So we see the fuels feeding the fire and then we have the first effects of that fire are the immediate fire effects. We see the immediate fire effects would either be the biogeochemical responses these would be things such as the nutrient loss by a fire, how pyromineralization might be an increase in available nitrogen, changes in soil pH, ass deposition these all occur either during the fire or immediately after. Another immediate fire effect would be the biotic response which species are killed by the fire. Which ones are we creating habitat conditions via creating new seed beds by the disturbance event. Are there seeds in the environment that are scarified or stimulated to germinate by the fire. All of these are created immediately after the fire. These two things these physical and biotic aspects interact to create the long term impacts on the environment. And these are the long term fire effects the biotic and abiotic processes over a scale of many many years think back on that old growth forest. After a hundred years you still see the composition of where the fire was severe. We have the western hemlock in the low intensity areas. We have the big old growth Douglas fir. Here's what we see here on this graph. The ecosystem composition, productivity, nutrient cycling etcetera is still being influenced. Now if a fire were to occur this summer on that site and we would follow this graph around these sorts of attributes that were created and by the last fire are now going to play in and influence the fuel loads again on this site that if a fire were to occur today much of its behavior size and frequency would be a direct result of the fuels and the composition which were set up again by the last fire. So again it gives you a good idea of how cyclical and how disturbances may play on each other over very very long time periods. Let's move on to elaborate on that ecosystem landscape level. We can see again that disturbances may influence successional pathways. The severity of the disturbance may influence or will influence the succession of any given site through time. It's going to influence the age and structure and composition particularly depending upon the frequency of the disturbance event. It's going to influence the mosaic of vegetation landscape so that spatial scale of biological diversity in your ecosystem. Insects and pathogens, many insects and pathogens as are all components of the biota are either favored or hurt or harmed by the presence of a disturbance whether it be fire floods or ice flows. It's going to influence habitats available for fish and wildlife. Many species again of vertebrates are adapted to the early serral post disturbance environments and others are adapted to say late serral environments that may not become suitable for many many years decades to centuries after the disturbance event. A biotic productivity can be influenced again you may enhance nutrients or at the same token nutrients and substrates may be lost by the disturbance event. And finally it has tremendous impacts on nutrient cycling and energy flows which of course is going to influence the composition, the structure, the productivity but particularly examples such as fire which may increase nutrients to a degree available to plant growth but at the same time, volatilize nutrients or we may lose nutrients by erosional processes. So a couple of other very important related concepts to disturbance is two that I'd like to cover now. One is environmental stress and the other one would be perturbations or human disturbances or what we call here anthropogenic disturbances. Let me define these and give you some of what I mean by this. The first one I'd like to talk about is stress is not like disturbance. I said disturbance is any discrete event in time which alters the ecosystem. A stress is those factors which are going to decrease net primary productivity of the plants or the animal and it may influence their productivity, their growth rate, their fecundity if again if it was a wildlife species. And here we're talking about things like water deficits, maybe forage deficits again if it was a wildlife species, nutrient deficits, flooding, salinization, any of those that may not kill the plants may not change substrate or resource availability but does cause a stress on the individuals. So you can see that's quite different than a disturbance. Just some examples of a stressful environment here is a mangrove swamp that you might see in South Florida. This particular one is actually from Mexico but here we have the stresses might be salinization extremely anoxic or waterlogged soils, nutrient or oxygen deficient soils where these plants must be adapted and of course we have the tides and the floods being another stress on this ecosystem and of course hurricanes might be the dominant disturbance that we would see in this particular landscape. And now let's move on to perturbations. These are human activities as we defined. A very esoteric, say, definition might be a departure from the normal state or structure of composition, behavior or trajectory of ecological systems and basically another simpler definition would be just alteration of ecological systems by human land uses and this may take on the form of either a new type of disturbance or it might be the elimination of a disturbance by human land uses, fire exclusion and flood control are two good examples of this or again it might be a stress, pollution might be a good example of an anthropogenic stress. Just some of the perturbations that we might talk about, I just mentioned fire exclusion, removing fire, natural fires from an ecosystem, exotic vasons and competition might be a stress on many of the native species. Deforestation can be a tremendous perturbation, changing the overstory structure and carbon pools of a site and then land cover, land use change. Conversion, say a forest or of native prairies to agricultural or tamed pastures is an example of a land cover, land use change. A couple of other ones would be the introduction of non-native herbivores. This may take on the both, the certainly causing stress by herbivory is another example of an ecological stress or it could be a disturbance if it is a severe enough herbivory event or degree or intensity of livestock or bivory. Other diversions again dams alter anything that would alter the hydro dynamics or the natural flow regime that we would see in a creek. Finally channelization which would be severing that linkage between the stream and its flood plain and again pollution whether it's nitrogen deposition, acid rain, environmental estrogens, a whole variety of man-made chemicals that effect structure, function and composition of the environment. Just some examples, some photos that I would show you of the areas. If you actually were to look up in the top right corner you'll see the high mountain that's just barely cut off is where we were yesterday in that old growth forest. Unfortunately the vast majority of the coast range looks like this with these clear cuts and you can see the difference here. We lost the coarse woody debris, we have changes in relative humidity and soils. We can see there's very few buffer zones here in these riparian zones and so we have severe changes in the landscape structure composition productivity when landscapes are altered to this degree. Another example would be just the role of pesticides and herbicides. Here's a historical photo of spraying sagebrush. We would lose a number of species perhaps particularly those large seeded species or species that may have deep branches, large roots that would be slow to reinvade sites, maybe lost from sites for many, many years from these sorts of environments. We see livestock particularly where in environments like the inner mountain west, the pacific northwest, interior Columbia basin where larger beavers did not co-evolve with the landscapes they can be pretty severe stresses and changes to the environment structure and function. What are the direct effects of livestock? These are almost like the principles of range of management. Livestock or any other larger beaver for that matter is going to eat grass, remove verbiage or not only grass but shrubs and forbs and even maybe young tree seedlings. We're going to see trailing and trampling damage and influencing the soil water holding capacity perhaps infiltration rates. We're going to see nutrient inputs and redistribution say via defecation of the animals via urine and finally they may disperse exotic species through either their coats or through disease transmission or through transporting seeds via their gut. All of these then will interact to create what we call the secondary influences. If the livestock for example are eating up all of the grasses and forages you may see altered fire cycles as we've seen throughout much of the western United States. You may see through increased trailing and trampling increased rates of erosion if we lose the ground cover. Altering the hydrology if we start to see species composition changes certainly competition interactions the more palatable species are undergoing a greater stress than the ones that perhaps the animals would not be utilizing. And finally we might see decreases and diminished reproductive success particularly if the through the stress the plants are not producing as many seeds or flowers as they were in the absence of livestock. And then finally we see the interaction of all of these responses creating what we took to call the tertiary influences where we see a long-term change in vegetation structure productivity and composition changes in the wildlife the final structures in composition we might see changes in streams and soils as I'll show you some examples here in a minute and even influences on water quality whether it be temperature nutrients chemistry or or biotic okay let's then change the subjects a little bit and talk about what we term as disturbance regimes in every aquatic or terrestrial system the general pattern of disturbances occur where there will be a frequency a size a magnitude of that disturbance type and we call this the disturbance regime we define that then as just the general pattern or occurrence of disturbances in any given ecosystem what might then we use to define disturbance regimes is the frequency of the disturbance event like how many like what's the time or the return interval what's the size of that disturbance event is in a very large say landscape level fire that you might see in the boreal forest of Alaska or northern Canada or is it a small fire event that may occur say only in very patchy areas of either very wet environments or maybe subalpine environments what's the magnitude of that event which it would be the severity and the intensity how severe how much does it change substrate soil species composition etc and that again the intensity would be what is the the the energy release rate is it a very severe stand replacing fire or very low intensity surface fire let's use some examples to start off with of just fire regimes we've done a lot of work a lot of research in fire regimes in the western United States as well as the world and in Canada on fire regimes and basically we can break down how fires occur into three very general regimes the low severity regimes are frequent low intensity surface fires again maybe occurring as say in a ponderosa pine site every eight to ten years and then we get to the very complex moderate severity regimes which are these frequent perhaps low intensity surface fires but every now and then we have very large infrequent stand replacing fires this is what we might see on the western cascade range in the Douglas fir forest and then finally we see in the wetter forest and in some of the boreal forest regions the high severity regimes these are termed the infrequent maybe a long return of all of 100 to 350 years severe stand replacing fires very large fires on the environment just to give you some examples again let's start by looking at the high severity regime again this is the sort of environment this is Tanner Gulch fire up in the Elkhorn Mountains of northeastern Oregon here we see the fire came through and virtually killed all of the standing trees in this environment so long return intervals usually stand replacing fires meaning that all above ground vegetation typically killed and usually large in area particularly areas like the boreal forest areas where you have large continuous fuels or structures of forest just another example here this would be a severe stand replacing fire while it's actually occurring you see the fire moving through the crowns here in this particular example and then we see the long-term impacts here we are in Idaho south fork of the salmon and notice the structure of the forest this is where you get to read the landscape look at the age class of that forest what does it tell you all of those trees are very even aged in a in size telling us that perhaps a fire swept through here 100 150 years ago and these forest regenerated following that fire we can use that by stark contrast to the low severity fire regimes here we have what many people have turned the friendly fire fires creeping through burning just the surface fuels in this case a pond rosa pine mixed conifer down in the Sierra Nevada of California where we're just burning the understory vegetation the trees are adapted to this sort of disturbance through thick bark deep root systems many of these trees depend upon fire for reproduction creating seed beds that are suitable for reproduction like sugar pine pond rosa pine and again these would occur very frequently every eight to ten years when we see then the fire regime is the complex results of virtually all of the components in the ecosystem how the are the anthropogenic roles are the humans ignition sources say as many Native Americans were for manipulating the ecosystem arsonist and accidents today the biota particularly the productivity of the plants which are the fuels that will carry the fire the climate what time of year do we see dry conditions for the fires to carry and then again the climate might be the source of the ignition again if it's lightning and then finally the physical attributes is it a very continuous environment where the fires may carry for years or for a very very long period of time or long large area or is it a very steep broken up environment where you might see natural breaks like large rivers or wetlands or or rocky ridges that would would limit the size of the fire so all of these are going to influence the fire regime well let's then move down into the riparian zone the riverine ecosystems and talk about another type of of regime that might be flood regimes here we can define floods as occurring when the flows fill the alluvial channel at bank full discharge and at this point in time we're starting to see significant changes in substrate availability we're seeing suspended sediments moving downstream as well as bed load transport this is where we might see gravel bars and stream side communities inundated or scoured out and at the same time creating gravel bars and new areas for plant communities repairing communities to establish we break out and we can use flood regimes like any other disturbance we look at the frequency of the floods how often do we see them what's the magnitude of the floods is a two-year flood a five-year a 10-year 100-year flood event what is the season of flooding that is very important and we see that the plant communities quite often particularly the riparian zones as well as the fishes are adapted to seasonal predictable levels of seasonal floods in many ecosystems and finally what's the duration of flooding is it a very spike event as you might see in a flashy rainfall event or systems say the southwestern deserts where where the floods are associated with flash floods or monsoonal rains or they very long events as we might see where we would have in monsoonal environments where you might have a wet season where the the river levels would maintain a very high level for a long period of time just some examples of different floods different flooding regimes here's a small creek that we've worked on a lot west chicken creek in the blue mountains of northeastern Oregon this is during summer base flow this is a very intact small ecosystem wet meadow and if you could look right through the middle of that picture is the channel but we can't see it because of the riparian wetland vegetation is completely overhanging the bank at this time of the year but keep your attention to the large conifer right in the middle of the landscape we come back in about seven or eight months and this is that same site during peak flows here we see water spread out along throughout the environment again depositing sediments at the same time picking up alachnus and vegetation materials creating channels enhancing diversity but also recharging much of the water table here as well so again just a very nice example of a snowmelt hydrograph coming back to the western Oregon this is the Willamette Valley again a winter rain type flood cycle here's a very large flood flooding an ash forest an ash floodland floodplain here very close to my town in Corvallis Oregon and then we come back to the southeast United States and we see here again a more of a rainfall driven system and again the Cyprus Tupelo and all of the vegetation plants and animals as well are going to be adapted to the flooding regime of this system and then finally we can look at the Amazon and many of the tropical rivers of the world where we have long periods of a rainy season where the floodplain or Varzia forest may be inundated from long periods of time and then dry season such as you see here where the floodplain forest are exposed what we see here and then one other example again back up into the Cascades where we might have a here's one would be a combination of both snowmelt hydrograph as well as rainfall events but all of these we this is a good example again of looking at the interaction between floods and the environment perhaps fires is another disturbance again creating the large woody debris that is so important in influencing the structure of this aquatic system here again in in the Cascades of Oregon let's move on then and talk a little bit about how disturbance processes are so important in land management and how we need to gear land management or consider these disturbance histories in our land management activities there's three important points that I want you to think about today one is that disturbances these natural disturbances are very important in maintaining productivity biological diversity the biota out there evolved with these disturbances and if we once we remove these disturbances or change these disturbances either by increasing their severity or perhaps excluding them then a whole new biota may result what are the negative consequences from altering disturbances we may see declines in productivity we may see declines in biological diversity accelerated levels of erosion and perhaps in the cases of wildfires with fuel build-ups in the low severity regimes we may see greater hazards to both human health and losses of property and natural resource values and finally it's very important to remember that when you're restoring ecosystems as a part of ecological restoration restoring the disturbances are very very important consideration as well let's give a few examples then of these it's important to remember that many species are disturbance dependent they evolved these disturbances and particularly when you get down to the riparian zone where we have these frequent flooding events and many of the early serral plants and animals that exist and that thrive in the post-fire environments very much are are stimulated their populations are stimulated or enhanced by these disturbance events many require disturbances either flooding or or scarification by heat for germination others we see enhanced reproduction because perhaps nutrients are more available in time period for the survivors after the fire in increasing the flowering output we see this for grasses as well as many orchids and lilies following fires in many parts of the world we see substrates are created for successful establishment many willows many cottonwoods many of these plants that are keystone features on the landscape in terms of biological diversity depend upon floods for their establishment and again cottonwood communities are perhaps about the best examples and then finally we see many habitats are created by disturbances we can go to the aquatic system and think about how the floods are scouring pools undercuts all are which are very important salmonid habitats we may also think about how habitats in a stand replacing fire would be created for cavity nesting species for many of the species like woodpeckers that depend upon dead trees say as foraging sources just some examples again here is a young gravel bar on rush creek in california following a disturbance event we see how the vegetation here has co-evolved with flooding events the floods occur about the same time that willows and cottonwoods are disseminating and dispersing seeds and then suitable to establish on this gravel bar we see two or three generations notice in the foreground where the red hat is seedlings that were deposited this year notice this ecotone right here here's some willows that are two years old that were established perhaps in the last flood event and then again we see those that are maybe three or four years old here in the background a little bit larger species that established with a previous flood so again we see this sort of banding and this this this very sharp and close association of willows and cottonwoods establishing with flooding events the floods that occur at the same time a seed dispersal creating these substrates these gravel bars that are so important for establishment of these species we can come up into fire areas and we see another example of here's in the foreground you see the flowers our snowbrush see an oathus that's a species that may persist as a seed in the soil for 250 300 years yet when a fire comes along it stimulates the seeds to germinate the heat will break the dormancy of the seed and again that seed will then germinate one of the beautiful things about this as the wildfire comes across the landscape you may see lots of nitrogen being volatilized yet that same fire that volatiles the nitrogen then stimulates the snowbrush see an oathus to germinate and the snowbrush see an oathus are nitrogen fixing species they're replenishing the nitrogen on that site in the early serral stages that perhaps was lost by the volatilization again it's another good example of the cycle of nature and how disturbances and plants are well adapted to maintain an equilibrium a dynamic equilibrium on the landscape again just one other example this is a a stand in the hell's canyon of Idaho following a very large fire the eagle bar fire and here we see very severe stand replacing fire virtually all the above ground vegetation was killed but notice all the greenery in the bottom those are all scalars willow or another name for this is fire willow here we have over 400 000 fire willows per hectare on this site all of them were were brought in by windborn seeds the first few weeks after this fire or the first spring after this fire occurred the seeds will only live for six to twelve days and there before the fire there's only one or two willows per hectare so you can see the millions of seeds that must blow on to this site and find the suitable substrate for germination in the stand replacing fire virtually no other place on the landscape where you see fire willow or scalars willow certainly in these densities except in the areas where the fire burned most severely okay let's talk a little then about what happens when your americans are when humans come in and alter disturbance regimes the first example i'd like to talk to is altering the flood regimes how might we alter peak flows base flows the the falling limb after the peak flow how would these influence the landscape when we might see flood regimes being altered then via flow regulations this might be dams upstream for power generation or for recreation or for irrigation holding back the flows for these or flood control we might see water diversions upstream actual water taking out for irrigation purposes upstream which may influence base flows as well as perhaps rates of the falling limb and then channel incision through other activities but any sort of activity either purposeful channelization or incision by poor land management practices that sever that link between the flood plain and its associated stream just some examples here of course when we put in large dams and change the flows we're going to see huge impacts both downstream as well as upstream as well as influencing the exchange the biotic exchange of anadromous fish as well as the perhaps vegetation and plants and seed materials as well as nutrients and sediments moving downstream we see here's another example trout creek in eastern Oregon an area where that is diverted for the most part by agricultural activities here we see daring base flow the stream completely going dry again because of upstream diversions and then another example the green river in utah here we have because of the flow management we don't have the peak flows and the falling limb that are suitable for cottonwood germination now with the much more regulated flows we see the exotic tamarisk or salt cedar establishing on many of the flood plains that are again once dominated largely by native cottonwood willow populations again an example here of channel incision by land use activities in this case overgrazing we can look at the soils of these riparian zones and see that at one time this dry meadow was a wetland we can see it by the rhodoxymorphic or soil characteristics in the the surface soils we also see that we're losing the species composition we're losing the willows as you can see in the background as well as the aspen communities are starting to break apart and die as well so here's an example of incision severing that hydrologic link of the stream and its associated flood plain just another example stinking water creek so named because of the numbers of salmon carcasses of course with dams downstream severing that linkage that this stream had with the ocean and therefore the influences on nutrients as well as channel incision again you see here the former flood plain now occupied by sagebrush yet if you look at the soils you get good evidence of this site one time had wetland very wet riparian reduced soil conditions that dominated this flood plain so tremendous changes in the landscape associated with changes in hydrology so look at another example then is what happens when we alter fire regime and and two general ways in which we alter fire regimes are going to be either through fire exclusion removing fire through active fire suppression or changing fuel loads on the ecosystem via land management or we can see we might see increases in fire occurrences just some examples of where we have eliminated fire the probably the classic examples are the ponderosa pine forest of the western united states here we see an example from the Klamath basin in oregon the area on the left is a historical photo of a ponderosa pine forest notice that the there's a huge vertical separation between the overstory canopy of these trees as well and then with an understory of snowbrush cianthus again species that are encouraged to germinate but if a fire were to come through here at this point in time we would see a fire not making it up into the canopy but remaining a low intensity surface fire in fact you can even see where the Klamath man is standing that there are a cat face or a series of fire scars on that tree he's leaning up against we can go to that same area today and we see a dramatic difference in the composition and structure of the ecosystem we see what we have now with removing anywhere between six and ten fire cycles through purposeful fire exclusion in this environment we now see increases in what we term as shade tolerant fire intolerant species we have a very dense conifer layer in the understory now years of fuel buildup of litter and dead materials and now if a fire comes through here it's not just going to burn through the low intensity surface areas but it's going to carry up through that conifer layer and into the canopy of the tree so instead of having this low intensity surface fire we're going to see a very severe stand replacing fires and this is a very severe problem that we have in terms of land management today just another example of a fire exclusion this is an old growth large that we see there's numerous fire scars on this big large in the middle but through fire exclusion now we have a very dense stand of lodgepole pine in the understory if a fire were to come through today it would not only destroy the lodgepole but would also kill this 250 300 year old large that has perhaps survived 30 or 40 fires before fire exclusion here it would take active restoration to restore this community back to a native open large forest again some of the other impacts of long-term effects of fire exclusion with this increase in the understory conifers increases in the density of the conifers we see greater stresses on the conifer and with greater stresses on the conifers we see scenarios such as we see here in the blue mountains as well as many parts throughout the west large bug die-offs by pine bark beetle by tussock moths a number of species a number of insects and pathogens that are giving us very large a wide-scale forest die-offs again largely associated with fire exclusion and this increased stand density so what we see then through this long this accumulation of fuels increases in stand densities is a conversion from the frequent low-intensity surface fires to now infrequent severe stand replacing fires changing the landscape and giving us a character of the landscape following the fires that really these landscapes have never seen before just an example this is not only prevalent in the forest but also is quite obviously in much of our range lands of the of the western united states here's an example from steens mountain oregon we see that this is a great picture i'm standing right in the riparian zone looking towards the uplands on the canyon this is the little blitz in canyon notice here's one aspen stand here one even age notice that there was a fire that probably created this aspen stand and notice boom right here you have another age class of aspen probably created from a different fire but with the combination of purposeful fire exclusion and livestock grazing which literally eats the fuels so we don't see fires on these sites anymore we see now junipers invading and increasing in this site we start to see notice in the understory of the aspen we're losing our aspen stands to juniper invasion and therefore the diversity the species diversity and value of avian habitats as we start to lose these stands notice in front of the juniper and the aspen in the riparian zone the sagebrush starting to increase we're drying out this riparian zone largely because of a small degree of channel incision in the riparian zone so we do see a whole series of anthropogenic perturbations which in this case are changing disturbance regimes flooding because of incision in the riparian zone and fire exclusion in the uplands changing this landscape structure over the long term here again through restoration through reintroduction of fire into this landscape we could restore the aspen quite easily so finally then we want to look at how do we use or consider disturbances natural disturbances in ecological restoration what do we mean by ecological restoration basically we can define ecological restoration as the return of ecosystem structure and function that have been altered or degraded by human activities in other words we want to reverse the effects of the perturbations on the environment basically another definition is reestablishing ecosystem features to the bounds of their range of natural variability so when we talk about trying to restore features to the bounds of the natural range of variability then that would also by definition mean that we want to try to restore many of the disturbances whether they're fires floods ones that we might have affected within their natural regime their natural periodicity magnitude as well as as as is possibly as is feasibly possible let me just give you an example here from this conceptual diagram of our suggested approaches to ecological restoration we'll start off with perhaps our goals of restoration would be some sort of dynamic or potential natural ecosystem now we can look at is over the last say maybe 100 150 years here in the united states through a series of degrading land use activities we're right here in some degraded ecosystem state our goals again are to restore it to some potential natural ecosystem we we separate out i have two boxes here dynamic natural ecosystems and potential natural ecosystems recognizing that humans are part of the landscape that we have exotics that people are living and depending upon the landscape it may not be possible to go back to the exact dynamic natural ecosystem but the potential natural ecosystem is operating within the bounds of the historical range and variability with the caveats of what's out there today so we're here in the degraded ecosystem state and our goals are to go back to potential natural ecosystem so our first step then in any sort of ecological restoration is what we define as passive restoration and basically passive restoration is just halting those activities that are causing degradation and or preventing recovery and because in many environments particularly in the riparian zone because these are so disturbance dependent and have evolved with frequent disturbances quite often just eliminating those anthropogenic perturbations is all that's going to be required to restore the ecosystem this are because again the biota is very very resilient and then we have found in numerous examples particularly in the riparian zones that passive restoration is all that's required for restoration again returning water returning the peak flows eliminating overgrazing by livestock have all been very successful means of restoring riparian zones reintroducing fire into ecosystems has been very good means of passive restoration but what happens is that we have passive restoration quite often it may be successful and the ecosystem would follow this pathway but what happens when we move to a new ecosystem trajectory an example might be that that i just showed you in the steens mountain if we eliminated livestock grazing today or or just quit suppressing fires in that site you know we still have the juniper on the site that juniper is not just going to disappear here it's going to take some sort of active restoration and no matter where you are wherever you're working when you try to make when you make the decision to implement active restoration three things can happen one you can be successful and you have effectively returned your ecosystem back to the potential natural ecosystem you get a raise you get a promotion and everybody likes you the second aspect though is you might fail you might have done a seedling it just fails there's no real harm you're back to ground one or ground zero and this is very often the case as well the third one that is most important and what you most want to be careful of is a misinterpretation of ecosystem needs and this is where you have misapplied the restoration or the treatment that your goals are for restoration yet it backfires on you and you actually might end up in a further degraded states you have either applied some sort of treatment that gives you an unnatural plant community or it actually degrades the ecosystem to a greater extent and there are another number of examples where this have occurred throughout the west and united states as well so just some quick examples in this is a young gravel bar again re-establishing on rush creek in california here the the restoration was to an area that had had water diverted for about 40 or 50 years again reinstituting flows into the creek as well as as eliminating livestock resulted in dramatic and rapid rates of increase in recovery of the riparian zone again in many areas reintroducing fire it may not be feasible close to the urban interface in areas of commercial timber stands areas of private lands of grazing it might not be feasible to have just to allow natural fires to occur here what we can use is prescribed fire as a surrogate or as a tool to start to restore the ecosystems again what we see as because of the complex nature of fire we know that from a biological and ecological perspective the only substitute for natural fire in these infinite and complex processes would be prescribed burning again fire creating having those impacts on the biota impacts on nutrient cycling there's really no other substitute other than prescribed fire just some very successful examples of fire and restoration fossil beds national monument restoring native bunch grass prairies areas that were where juniper and sagebrush were invading increasing in density here we see a very marvelous bunch grass stand the second post fire year and what what's important then is to try to come back to the landscape level what are the disturbances what are the linkages say between the riparian zone and the uplands how to disturb how have disturbances interacted in these areas to create the landscape that we've seen today that we can utilize the resources in a productive and sustainable manner and again it's important to remember the disturbances and how the disturbances influence these landscapes the great fire colleges jim lotan once stated that the closer an ecosystem is managed in harmony with those processes in which evolved the more successful that management strategy will be and i think this is very important quote again when we incorporate disturbances into the ecosystem so as land managers it's very important to learn to read the landscape this will be helpful for you to understand the disturbance history how your landscape perhaps evolved what disturbances are important and how maybe you can use disturbance or reincorporate disturbances to maintain biological diversity and productivity within your landscape