Unit Five Ecology and Conservation Biology Biogeochemical Cycles, Energy, and Ecosystems

Earth’s Environmental System  Ecologists study the interaction between abiotic and biotic factors in an ecosystem  Ecosystems, if healthy, are in a state of dynamic equilibrium i.e. they are always undergoing some type of fluctuation in number of individuals of a species or nutrient content  Dynamic equilibrium relates directly to the concept of a feedback loop

Earth’s Environmental System cont’d  All ecosystems are open systems in that energy and matter are exchanged between them  The Earth can be divided into parts: –Lithosphere – rock and sediment on the various land masses –Atmosphere – gases surrounding the planet –Hydrosphere – the water on the Earth –Biosphere – all parts of the Earth that support life

Earth’s Environmental System cont’d  Landscape Ecologists study broad areas and attempt to learn more about the gradual changes in vegetative associations that occur over hundreds of kilometers  While traditional ecologists focus their attention on ecosystems, landscape ecologists study many ecosystems at once  While conducting research, both ecologists and landscape ecologists study ecotones, transition areas between two ecosystems/biomes where plants from both ecosystems/biomes are found

Ecotone

Earth’s Environmental System cont’d  Producers a.k.a. flora, plants, and autotrophs, are always at the bottom of the food chain because all other living organisms depend directly or indirectly on them  Producers carry out photosynthesis which supplies their cells with energy to maintain themselves and extra energy to grow

Earth’s Environmental System cont’d  The overall production of energy by producers is called gross primary production  The extra energy that producers use to grow that is in addition to the energy needed to maintain cells is called gross primary production  Biomes such as desert, tundra, and open ocean have low net primary productivity

Biogeochemical Cycles  The availability of nutrients in addition to ample amounts of sunlight and water determine what areas of the Earth have high net primary productivity  In other words, it is not just water and sunlight that are important for plant growth  Nutrients such as carbon, nitrogen, and phosphorus are needed for substantial plant growth

Carbon Cycle

Nitrogen Cycle

Phosphorus Cycle

Hydrologic Cycle

Geological Systems: How Earth Works  The rock cycle is also very important to the existence of life  The rock cycle is directly involved in the recycling of phosphorus  Plants have to attach themselves to some type of substrate in order to survive; they cannot live freely in the air  Most plants grow out of soil  A few plants can live directly on top of rock - pioneer species  Additionally, a few plants called epiphytes live off the ground attached to the bark of trees

Geological Systems: How Earth Works cont’d  The rock cycle is defined as the means by which rock is formed, changed, and reformed by heat, pressure, and time  Rock is divided into three categories based on how it is formed and its chemical composition –Igneous – heat is required –Metamorphic - heat and pressure are required –Sedimentary - pressure is required

Geological Systems: How Earth Works cont’d  The majority of the fossil record used to construct the Geologic Time Scale and additionally support the theory of evolution is found in sedimentary rock.....why?