Chapter 6 Ecosystems and Communities Succession Series of regular predictable changes in community structure over time Result in climax community

Chapter 6 Primary Succession Terrestrial Total lack of organisms and bare rock or water Terrestrial Pioneer Community First to colonize bare rocks--lichens Successional or Seral Stage Multiple sequence of stages/communities Climax Community Relatively stable, long lasting, complex community Entire sequence of stages called a sere.

Chapter 6 Characteristics of Climax Communities: 1. able to maintain mix of species for a long period of time 2. in energy balance 3. larger number and more kinds of organisms and interactions between organisms   è complexity and energy efficiency

Chapter 6 Secondary Succession Succession in area after destruction or major disturbance, flood, fire, agriculture More common and rapid than primary succession Usually some soil, seeds or root mass that can re-establish Adjacent area can be source of seed, etc

Chapter 6 Aquatic  Except for oceans, most aquatic ecosystems are considered temporary.  Ever increasing entrapment of soil particles and organic matter. Less depth means establishment of submerged plants  è terrestrial succession  

Chapter 6 Types of Climax Communities Biomes terrestrial climax communities with a wide geographic distribution. Variation of species exist within biomes but exhibit similar pattern and processes Same general structure of ecosystem Same kinds of niches present

Chapter 6 2 primary factors which determine biome type: Precipitation: total amount form (rain, snow) seasonal distribution—concentrated at particular time Temperature: temperature swings length of seasons Other factors: fires, winds, organisms  Altitude and latitude can mimic these effects

Chapter 6 Desert: Lack of water is primary factor Less than 25 centimeters (10 inches) precipitation per year.  Lack of clouds means no insulation  Can be quite cold/hot Many types of plants and animals, most are quite adapted to conditions. Large space between plants, dispersed animals too

Chapter 6 Grassland (aka: prairies or steppes): Between 25 and 75 centimeters precipitation per year (10-30 inches). Windy, hot summers: cold or mild winters.  Fire is important in maintaining biome Prevent invasion of trees Cycles nutrients  Large herds of grazing mammals, many insects, many birds. Most converted to agriculture 0.004% of Texas Blackland Prairie remains

Chapter 6 Savanna:  Similar in appearance to grassland, but has more trees. Precipitation is between 50 and 150 centimeters per year (20 - 65 inches), but it comes in a few heavy events, with drought in between. Plants and animals behave accordingly. Wildlife quite similar to grasslands. Fire still important so trees fire resistant Texas Post Oak Savanna

Chapter 6 Tropical Rain Forest: Near equator Africa, C&S America, SE Asia, some islands More than 200 centimeters precipitation per year (80 inches). Some over 500 centimeters (200 inches). Warm temperatures/relatively constant. Many species. Soils are poor since nutrients are stored in biomass of vegetation or washed out. Highly weathered so clayey—sun and heat make?

Chapter 6 Temperate Deciduous Forest: Distinct summer/winter seasons. Trees loose leaves in winter 100 centimeters (or more) of precipitation (40 inches). Mild winters, 6 month growing season  Relatively few species of trees. Two or three major producers  Many flowers, insects, birds and mammals. Texas—Eastern and Western Crosstimbers

Chapter 6 Taiga (aka: Northern Coniferous Forest or Boreal Forest): Short cool summer, long hard winter. Up to 6 months, soil freezes Precipitation between 25 and 100 centimeters per year (10 to 40 inches), with constant high humidity. Trees see winters as dry due to precipitation in form of snow. Needle shaped leaves. Flexible branches

Chapter 6 Tundra: No trees, permanently frozen soil (permafrost)—north of Coniferous forests Low precipitation (less than 25 centimeters), but comes in summer when snow melts.  Permafrost does not allow water to soak in....many small pools.  Damage to systems takes long time to fix. Same conditions on high mountains (alpine tundra) but different species

Chapter 6 Aquatic Ecosystems: Factors: Marine—high dissolved salts - sun light penetrability - nature of bottom substrate - water temperature - amount of dissolved material Marine—high dissolved salts Freshwater—low dissolved salts

Chapter 6 Marine systems Pelagic Ecosystems Open ocean system, with free swimming organisms.  Fish, whales, crustaceans,etc not attached to anything phytoplankton (producer) in euphotic zone. zooplankton other consumers nutrients are in short supply, except in few concentrated areas.

Chapter 6 Benthic Ecosystems Systems at bottom of ocean. Critters attached or not  If light can penetrate, plants exist.  Substrate determines types of organisms which can occur.  No light: abyssal zone.  Warm waters è coral reefs Mangrove swamps Near shore region Can lead to terrestrial ecosystem development

Chapter 6 Estuaries Shallow partially enclosed area where freshwater enters marines systems. Relatively few organisms capable of tolerating salt fluctuations seen in this system. Large amount of nutrient inflow. Typically, entire area has sunlight penetrating to bottom. Many organisms use as nursery. Trap sediment—salt marsh—terrestrial ecosystem

Chapter 6 Freshwater Systems Lakes and Ponds: Productivity: littoral zone (has rooted plants) limnetic zone (no rooted plants) Productivity: Temperature Depth Nutrients in water oligotrophic lakes—longer life eutrophic lakes—shorter life

Chapter 6 Dissolved oxygen (DO) determines what type of organisms will occur. Free oxygen O2  Biochemical oxygen demand (BOD) A measure of how much decomposable organic matter is in the water.  Enter through critter waste in lake, inflows of organic wastes, critter death, etc

Chapter 6 Streams and Rivers: periphyton - organisms attached to rocks and bottom material. Not much chance for plants, so most energy comes from material that falls in stream rather than from photosynthesis. Many insects, fungi and bacteria use this organic matter. Dissolved oxygen: less in slow, muddy rivers Wetlands: transition areas