* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download LECTURE 14 Soil Organisms
Survey
Document related concepts
Biological Dynamics of Forest Fragments Project wikipedia , lookup
Crop rotation wikipedia , lookup
Human impact on the nitrogen cycle wikipedia , lookup
Natural environment wikipedia , lookup
Perovskia atriplicifolia wikipedia , lookup
No-till farming wikipedia , lookup
Microbial metabolism wikipedia , lookup
Lake ecosystem wikipedia , lookup
Regenerative agriculture wikipedia , lookup
Sustainable agriculture wikipedia , lookup
Transcript
LECTURE 14 Soil Organisms Diversity… • Size of organisms. • Types of diversity • Species diversity • Functional diversity • Ecosystem dynamics • Functional redundancy (= ecosystem stability and resilience) • NB keystone species! • Genetic resources (contribution to global biodiversity). Types of organisms… • Primary producers • Utilize water, energy and carbon to make organic molecules and living tissues. • Primary consumers • Animals and microflora that use energy stored in plant residues. • Actions of microflora mostly biochemical, those of microfauna both physical and chemical. • Secondary consumers • Bodies (i.e. cells) of primary consumers become food sources for predators and parasites. • Include microflora (e.g. fungi) and carnivores. • Tertiary consumers • These organisms prey on secondary consumers. • Microflora NB in every level of the process. Factors affecting organism abundance… • Food (amount & quality) • Physical factors – Moisture – Temperature, etc. • Biotic factors, e.g. – Predation – Competition • Chemical characteristics of soil – Acidity – Dissolved nutrients – Salinity Conditions affecting growth of soil microorganisms • • • • Organic matter requirements Oxygen requirements Moisture & temperature Exchangeable calcium and pH Benefits of soil organisms… • • • • • Organic material decomposition. Breakdown of toxic compounds Inorganic transformations Nitrogen fixation Plant protection Earthworms as an example of important macro-organisms… • 3000 species worldwide • Influence soil fertility and productivity – – – – Burrows Casts Nutrients Physical effects • Factors affecting activity – – – – – – – Air, temperature & water Organic matter pH Predators Texture Fertilizer & Pesticides Tillage Soil Bacteria… • Small, single-celled organisms • Most diverse group of soil organisms – 1g of soil typically contains 20 000 species! – Can live in very diverse environments • Can be autotrophs or heterotrophs • Why are they important? – Take part in almost all organic transactions that characterize a healthy soil system. – Nitrogen fixation. – Cyanobacteria contain chlorophyll and can photosynthesize.