Range Ecology

Ecology Ecology involves the study of the interrelationships between organisms and their environment.

A fundamental concept in range management is that plants and animals depend on each other for their welfare.

Group discussion 1. How do animals depend on plants? 2. How do plants depend on animals?

Humans regulating animals Control of grazing animal numbers + Timing of grazing + Frequency of grazing = Low Input and low vegetative productivity

Humans regulating plants Fertilization + Cultivations + Seeding+ Irrigation = High input and high vegetative productivity

THEREFORE Range management focusses on manipulating vegetation and soil by controlling the grazing animal.

Rangeland Ecosystem The living and nonliving elements that make up a piece of rangeland.

Components of the Range Ecosystem 1. Abiotic components (non-living) 2. Biotic components (living) 3. Decomposers 4. Manipulators

Abiotic components Usually consists of soil and climatic factors Usually little or no manipulation by the range manager

Soil functions: anchor the plant hold water until the plants can use it store nutrients for the plant until the nutrients are needed serve as a habitat for soil animals and microorganisms Soil Manipulation – fertilizer and mechanical treatments to increase infiltration, water storage, etc.

Group discussion What kinds of animals and microorganisms live in the soil?

Climatic factors: temperature and precipitation Both of these affect plant and animal activity

Biotic components Producers, consumers, and decomposers

Primary producers – plants with the pigment “chlorophyll” which is responsible for converting solar energy to chemical energy that can be used by the plants, as well as those that eat the plants.

Biomass – the weight of all the organisms at a given time Herbage – the biomass of all of the herbaceous vegetation at a given time Note: not all herbage is available to the consumer at all times Forage – the herbage available and acceptable to grazing animals

Group discussion What would make some herbage “unavailable” for grazing animals What would make some herbage “unacceptable” to grazing animals

Group discussion Which value is always larger: herbage or forage? Why?

Browse – the part of the leaf and current twig growth of shrubs, woody vines, and trees available for animal consumption

Outdoor activity 1. We will mark off a given area 2. We will mark all of the herbage 3. We will mark all of the forage 4. We will compare the biomass of the two

Consumers Consumers eat something else. Rangeland primary consumers (herbivores): – Livestock, Big game animals, grasshoppers, and rodents Herbivores are considered “ecosystem regulators” that directly impact the vegetation AND are a food source for predators.

Decomposers Decomposers are the essential piece of the puzzle that keeps the nutrient cycle going. Without them, there would be an overload of undecomposed organic matter piled up.

Decomposers: bacteria, fungi, actinomycetes, algae, and lichens Detrital decomposers: ants, termites, and nematodes

Manipulators (humans) Humans intentionally and deliberately rearrange the components of the world ecosystems for our own benefit. The affects are both positive and negative

Typically ecosystem manipulation has been directed towards increasing wood, meat, minerals, and fiber. There is typically little regard for wild ungulates, rabbits, rodents, reptiles, birds, insects, and other invertebrates.

New concept in range management Multi-use management – managing for livestock, lumber, wildlife, minerals, water, and recreation simultaneously over a broad area.

Energy flow Energy flows through the ecosystem from “the ground” up. It begins with Primary Producers (plants), followed by Primary Consumers, followed by Predators. The decomposers are there to pick up the leftovers and keep the cycle going.

Food Chains and Biomass Pyramids on Rangelands USDA-ARSJ. Peterson

Trophic Levels Feeding levels with respect to primary source of energy Producers & consumers each occupy a different trophic level Energy is lost at each level

Trophic Levels and grasslands

Biomass Pyramid The total weight of all living organisms Biomass at each trophic level  biomass pyramid Biomass pyramid (grams/m 2 ) Producers Herbivores Primary carnivores Top carnivores Detrivores/ decomposers 5

Trophic Levels 1 st Trophic Level Producers Plants 2 nd Trophic Level Primary Consumers Herbivores 3 rd Trophic Level Secondary Consumers Carnivores Decomposer

Biomass Pyramids 1 st Trophic Level Producers Plants 2 nd Trophic Level Herbivores 3 rd Trophic Level Carnivores Decomposer

Biomass Pyramids 1 st Trophic Level Producers Plants 2 nd Trophic Level Herbivores 3 rd Trophic Level Carnivores Decomposer

Biomass Pyramids Decomposer At each level some biomass is not passed to next higher level

Biomass decreases at higher trophic levels Not all biomass is passed from one trophic level to next  Not all is consumed  Not all that is consumed is digestible  Not all that is digested is turned into mass  Part of mass is converted to energy or heat  Lost mass is available for decomposition

Is vegetarianism a viable solution to world hunger? Write ONE paragraph stating and defending your stance as to whether or not vegetarianism could alleviate world hunger.

Vegetarian Solution? Shorter food chain/web = less loss of energy – Vegetarianism results in a decrease of human position on food chain. – Is vegetarianism is the best way to feed a large population? Will this solve the world food problem?

1) Cellulose  most abundant, naturally occurring organic molecule on earth Humans can’t digest cellulose, Ruminants & Hind-gut fermentors can. We need cows, sheep, goats, horses, llamas, alpacas, etc. to digest cellulose for us. 2) Only about 10% of the earth land surface can be farmed. The rest is too rocky, too cold, or too dry. We need animals to harvest these land for us. Two Good Reasons Drawing by Mike Hale

Rangeland Succession

Succession The orderly change of plant communities over time. The gradual replacement of one plant community by another through natural processes over time – Primary = From parent material – Secondary = With soil in place

Primary Succession Soil and plants evolve together Primary succession on grassland rangelands. From Gay 1965

Primary Succession Begins in a place without any soil – Sides of volcanoes – Landslides – Flooding Starts with the arrival of living things such as lichens that do not need soil to survive Called PIONEER SPECIES

Overview of Primary Succession watch?v=rFLssJ2n5FY

Primary Succession Soil starts to form as lichens and the forces of weather and erosion help break down rocks into smaller pieces When lichens die, they decompose, adding small amounts of organic matter to the rock to make soil

An island of lichen and plants forming soil

Secondary Succession Begins in a place that already has soil and was once the home of living organisms Occurs faster and has different pioneer species than primary succession Example: after forest fires – Others?

Overview of Secondary Succession Succession After WildfireSuccession After Wildfire: by University of Wyoming Cooperative Extension

Basic idea of Succession The simple plants die, adding more organic matter. The soil layer thickens, and grasses, wildflowers, and other plants begin to grow (annuals & herbaceous). These plants die, and they add more nutrients to the soil. Shrubs and tress can then survive. Insects, small birds, and mammals begin to inhabit. ** What was once bare rock now supports a variety of life. ** We manage forces that cause these changes.

Forces of Ecosystem Change Immigration and establishment of plants Competition between plants Site Modification – Add organic matter – Change available moisture and nutrients Stabilization – Reduced yearly variation in kind and amount of plants and animals.

Climax Community The end point of succession = Climax A stable group of plants and animals that is the end result of the succession process – Trees in forests – Grasses in prairies – Cacti in deserts – Lichens and shrubs in the tundra The end point depends on climate

Climate Change Rangelands Grasslands, Shrublands, Woodlands Forces & Impacts Fire Herbivory Invasion Human Uses Development, Fragmentations, & Recreation Ecological Services & Resources forage for livestock wildlife habitat watershed management biodiversity conservation open space carbon sequestration

Climate Change Rangelands Grasslands, Shrublands, Woodlands Forces & Impacts Fire Herbivory Invasion Human Uses Development, Fragmentations, & Recreation Tools for Stewardship Fire Livestock Grazing Weed Mgmt Human Impacts Restoration/ Rehabilitation Ecological Services & Resources forage for livestock wildlife habitat watershed management biodiversity conservation open space carbon sequestration