02 AGROECOSYSTEM CONCEPT AGROECOLOGY What is an ecosystem

02. AGROECOSYSTEM CONCEPT AGROECOLOGY

What is an ecosystem, and how can we study one? � Is the earth an open or closed system with respect to energy and elements? � How do we define "biogeochemical cycles, " and how are they important to ecosystems? � What are the major controls on ecosystem function? � What are the major factors responsible for the differences between ecosystems? �

The concept of the agroecosystem is based on ecological principles NATURAL ECOSYSTEMS

Gen Sel Organisme Populasi Komunitas Mineral/materi Sel Organ Sistem Organisme Sistem Populasi Sistem Gambar. Spektrum Ekologi Ekosistem

Organization of Life Biosphere Ecosystems Communities Populations Organisms

Scales of Ecological Organization

INDIVIDU? POPULASI ? KOMUNITAS ? C A B

INDIVIDUAL ORGANISM Molecules Cells Tissues Organs systems Autecology/Physiological ecology Concerned : how is a organism response the environmental factors? How is a individual organism tolerance to stresses in environment where it will live? Organism

POPULATIONS �A population is a group of individuals of the same species inhabiting the same area at the same time. � Important characteristics: ○ Population size, density, and dispersion ○ Birth and death rates ○ Growth rates ○ Age structure ○ Genetic Diversity

Characteristics of Populations 1. 2. 3. 4. 5. Population size, density, and dispersion Birth and death rates Growth rates Age structure Genetic Diversity

POPULATIONS Population ecology � Concerned : Important in determining the factors that control population size and growth relation to the capacity of the environment to support population over time

Population Ecology �A population is a group of plants, animals, or other organisms, all of the same species, that live together and reproduce. � The important of population ecology 1. Numbers of individuals in a population 2. Population dynamics: how and why those numbers increase or decrease over time 3. Population ecologists try to determine the processes common to all populations

Population Ecology in Action � Biologists in applied disciplines such as �Forestry �Agronomy (crop science) �Wildlife management � Must manage populations of economic importance � Prevent threatened or endangered species from extinction

COMMUNITIES � Communities an assemblage of populations of many species living together in the same location at the same time. � The important thing : 1. Community structure and functioning 2. Community Biodiversity ○ Number and types of species ○ Relative abundance of species ○ Interactions among species 3. Community Development ○ Community resilience to disturbance ○ Nutrient and energy flow

COMMUNITIES Community ecology � Concerned : How the interactions of organism affect the distribution and abundance of the different species

ECOSYSTEMS � Ecosystems are composed of all the communities and their physical, chemical, and biological processes. �Ecosystems sustain themselves entirely through energy flow through food chains, and nutrient recycling.

Example: In Watershed

Components of Ecosystem ABIOTIC COMPONENTS Sunlight Primary producers Temperature Herbivores Precipitation Carnivores Water or moisture Omnivores Soil or water chemistry (e. g. , P, NH 4+) Detritivores etc. All of these vary over space/time

Biosphere The biosphere is the global sum of all ecosystems. It can also be called the zone of life on Earth. From the broadest biophysiological point of view, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, hydrosphere and atmosphere

Structural Properties of Communities � Species Diversity � Dominance and Relative Abundance � Vegetative Structure (ex: grassland, forest ) � Trophic Structure � Stability

Figure. Relationships within an ecosystem

NATURAL ECOSYSTEM

Processes of Ecosystems How ecosystems function: 1. Ecosystems have energy flows and ecosystems materials cycles. 2. Ecosystems have nutrient cycles

1. Energy flows and materials cycles Figure. Energy flows and material cycles.

2. Energy flows and nutrient cycles Figure. Relationship between energy flow and nutrient cycle

Biochemical cycles in ecosystem 1.

2. The carbon cycle

3. The phosphorus cycle

AGROECOSYSTEM

AGROECOSYSTEM VS. NATURAL ECOSYSTEM � Natural ecosystem is closed, or at least, unmanaged ecosystem � Closed ecosystem—all elements recycled through ecosystem— not often pure closed ecosystems anymore—humans frequently involved � Agroecosystem is an open ecosystem, or managed ecosystem: � Producer moves plants, animals, environmental factors (fertilizers, feed) in & out of ecosystem � Will not continue on its own without management � If left alone, would progress toward closed ecosystem, but probably not the same as original ecosystem before agriculture without human input again

Characteristics Productivity Species diversity Genetic diversity within species Plant life-cycles present Competition Flowering, plant maturing Nutrient Cycles Permanence Human Control Ecological Maturity Agroecosystem High Low (monoculture) —can use crop rotation and intercropping to stabilize more Low Few Natural Ecosystem Low High Synchronized All, more perennial Tolerable (ecological niche) Seasonal Open Short High Early, immature Closed Long Low Mature, climax Negative

ENERGY FLOW

Figure 2. 7 Functional components of an agroecosystem.

POPULATION REGULATING MECHANISM Crop Populations Natural Plant Population (also true of weeds) Seed brought in by producer Seed produced mostly by local plants High seed viability Uniform seed dispersal Low dormancy, carryover of seed Variable seed viability Non-uniform seed dispersal Possibility of dormancy, delayed germination (carryover) Uniform soils Uniform population age, genetics Variable soil types Diverse population age, genetics Even spacing within species Variable spacing within species High allocation of plant resources to reproduction (seed) Allocation to seed production may be lower

NUTRIENT CYCLING NATURAL ECOSYSTEM AGROECOSYSTEM Ø Inputs: Plant residue Animal wastes Animal residue Atmosphere Nitrogen fixation Ø Using the soil as a pool of nutrients: Ø Inputs: Fertilizers Crop residues Atmosphere Nitrogen fixation Ø Outputs: Crops then removal from area Erosion Leaching Ø Run-off www. themegallery. com Ø Outputs: Plants animals grazing on plants Denitrification Run-off leaching Company Logo

ASSIGNMENT 1. Cari contoh suatu ekosistem. 2. Tuliskan semua komponen yang ada di dalam komunitas tersebut 3. Jelaskan proses yang terjadi di dalam komunitas tersebut