BIOL 3500Ecology

1
Lecture 25

• BIOL 3500Ecology
• Chapter 26 Terrestrial Ecosystems II
• Grassland, Shrubland, Desert, and Tundra

2
Learning Objectives

• Discuss
• Why grasslands are extremely threatened
• Importance of ants and ungulates to grasslands
• Recall
• Geographical locations of various grasslands, as
  well as examples of organisms

3
Grassland Distribution

• Generally too arid to support trees, too moist
  for desert

4
Grassland Basics

• Most grasses tolerate both fire and herbivory
• Leafy tissues grow back fast
• All are monocots
• Lack woody tissues
• Fibrous underground root network not good for
  eating

5
Grasslands and Agriculture

• Think of a grain. Chances are its a grass
• Grasslands tend to have good abiotic conditions
  for
• Grain crops
• Cattle
• As a result, grasslands are the most threatened
  biomes on Earth

6
North American Grasslands

• Tallgrass prairie
• Relatively moist, dominated by Big Bluestem
  (Andropogon gerardii)
• Can be nearly two meters tall
• Mixed-grass prairie
• Moderate in moisture
• Shortgrass prairie
• Relatively dry
• Radford University prairies website

7
Steppe

• A word broadly meaning cold grassland
• Typically, we think of Eurasian steppe
• University of Texas Life on the Steppe

8
Pampas

• A South American grassland
• National Park Service What is Pampas Grass?
• Blueplanet website

9
7th Inning Stretch
10
Vertical Structure of Grasslands

• Herbaceous layer
• Ground layer
• Root layer

11
Herbaceous layer

• Includes all standing plants

12
Ground layer

• Has important leaf litter or mulch layer
• When thick, holds moisture
• Includes both new and decaying material
• Varies with time since last burn
• Important for rodents and their predators
• Voles website

13
Root layer

• Uniquely important to grasslands (over 50 of
  biomass is here!)
• May be important site for plant competition

14
Animal Life in Grasslands

• Ants
• Eat seeds, so can affect makeup of plant
  community
• Ungulates
• Hooved animals
• Grass difficult to eat
• Graminovorous diet has much silica
• High-crowned teeth
• Teeth have open roots for continuous growth
• Horsequest.com

15
American Bison

• Bison affect prairie with wallowing activities,
  grazing, defecation, urination
• Rolling in dust bath will crush some plants
  (disturbance)
• Moderate grazing opens canopy for light
• Interesting behavioral adaptation able to dig
  through snow for food (cattle wont)

16
Saiga

• Saiga antelope of Eurasian steppe
• Almost extinct in 1917, became focus of
  conservation efforts
• Note interesting nose
• Ultimate Ungulates
• National Wildlife Federation

17
Guanaco

• An interesting tiny camel of the Argentine pampas
• Closely related to the llama
• Guanacosales.com website