Lecture 14Outline of Last Lecture II. History III. Industrial Agriculture a. Modern Farming Practices b. Impacts on Wildlife IV. Farmland Restoration V. Conservation Reserve Program Outline of Current Lecture II. Grasslands III. Fire a. Why do grasslands like fire? b. Generalizations about fire c. Fire benefits to wildlife IV. Interactions a. Great Plains b. Serengeti c. Agriculture d. Overgrazing V. Management for Wildlife on Ranch/Grassland !Current Lecture If North Dakota farms (originally grasslands) are “going under”, how might we make restored grasslands economically feasible there? NRC 261 1st Edition!!!These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. !Edited with the trial version of Foxit Advanced PDF EditorTo remove this notice, visit:www.foxitsoftware.com/shopping!!Grasslands !Grassland/savannah distribution -great plains of north america, south america (south of the amazon), parts of Africa, most of Australia, and central Asia has huge grasslands !Precipitation -Tropical = Savanna in Kenya -same temp all year round -2 distinct rainy seasons (one much bigger than the other, from Feb to May) -temperate = prairie in USA -Temperate = Steppe in Soviet Union/Central Asia (summer & winter temperatures that are lower than other places, much less precipitation so vegetation is not as lush) !Species variation -hypothetical habitat gradient for North America -goes from low, scattered herbaceous cover to high dense vegetative cover -relative to this gradient of vegetation are certain animal species -have a large diversity of species that depend on them !Serengeti Plains -grassland, surrounded by savanna and even forests -national park about half the size of Massachusetts Seasonality/migration - in terms of rainfall not temperature - causes migration of big animals (zebras, wildebeest, gazelle etc.) - maps show relative amounts of different things in the Serengeti and how they vary over several months (september vs. march) - in september, low numbers of green biomass in the south and all of it is in the north - in march (in the rainy season), concentration of lots of green biomass down south, so the wildebeest and zebra come back down to the south during this month and have their young in place with maximum amount of food to ensure good growth - in december and april (rainy season) zebras in the south - gazelles move back and forth across the Serengeti instead of north to south because they have different food that they eat — results in different migration patterns Fire -one of the major features in grassland systems - without fire we don’t have grasslands, trees can be established and grow and it will no longer be a grassland!! Why do grasslands "like" fire? ! growing points of plants are at or below ground level - fire burns off the top part but leaves the growing part alone - grass adapted to fire ! Grasses regrow rapidly - especially if grasses are already established - if fires happen it doesn’t take long for grass to come back, especially if water is present ! only removes a year or two of growth - lots of roots and biomass below ground level, fire doesn’t remove very much growth comparatively - when fire goes through it eliminates other competition for the grasses ! Some generalizations about fire ! changes plant composition and structure - gets rid of some plants and some stay, there are also some forests that are better adapted to surviving a fire than others kills groundnesting birds - kills wildlife directly and indirectly - accumulation of bird species eating insects, because as fire goes through it chases up the insects that live there and more insects are available for the birds to eat ! usually increases nutrient content of vegetation - things like grasses in particular are going to resprout/regrow, causing new vegetation to emerge - human manipulation for livestock - but productivity is related to rainfall, so if you kill something at the wrong time you can end up drying things out and harming the ecosystem ! Examples of fire benefits to Wildlife ! Bobwhite quail (in text) — increased abundance of this quail because there is more opportunity for feeding because of insects being chased out, and the growth of lush new vegetation, this same vegetation creates a good cover to hide from predators Prairie grouse - fire gives them more open areas in which to display! - if there’s no fire and no open grasslands are maintained, so all possible places for these animals to display and do their mating are gone and the population disappears - can provide nesting habitat — females can nest more safely because of new dense vegetation which also provides good nutrients ! Rangeland grazers - grassland species that depend on vegetation itself as a major source of food — take advantage of new, fresh vegetation !Interactions ! Great Plains - prairie dog, black footed ferret, bison - used to be lots of bison that lived there, many different kinds of prairie dogs, and black-footed ferrets were thought to be extinct in the wild - black footed-ferrets are a prairie dog specialist - prairie dogs distribution had also matched up with distribution of bison - have huge colonies and are a very visual species - make mounds in ground to stand on and see each other and watch out for predator - when bison came through they served to knock down the vegetation to prevent the grass from getting too thick for the prairie dogs to watch for predators - so if they want the black-footed ferret to survive in the wild, need to make sure there are prairie dogs, but to ensure the presence of prairie dogs you need to have bison in that ecosystem as well Serengeti -similar kind of interaction between zebra, Thomson gazelles, wildebeest -zebras are non-selective feeders, they’re not very good digesters, not multi-chambered stomach -wildebeest are more efficient at breaking food down, they’re smaller and can be more selective in what they eat -zebras go through, clear out the big stuff, so the wildebeest can be more picky and get to the smaller stuff and can eat for quality -after