6 public questions tagged with this topic.
Primary succession occurs in areas without previous life, while secondary succession happens where life existed before.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Population Interactions - Competition - Competitive Exclusion
“Predator impacts” for what does the 'top-down' control emphasize in an ecosystem. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Rates depend on temperature, moisture, substrate quality, consumer physiology, and the elemental balance between organisms and their food. These controls explain why the same process can differ among terrestrial, freshwater, and marine systems without changing its definition. The remaining alternatives—“Nutrient availability”, “Abiotic factors”, “Primary productivity”—
Ref: Fundamentals of Ecology, Odum & Barrett, 5th Ed., Ch. 4
Topsoil usually contains the greatest concentration of fresh litter, fine roots, oxygen, moisture, and decomposer organisms. Fungi, bacteria, and detritivores fragment and enzymatically break down dead organic material there, releasing mineral nutrients and converting part of the carbon into microbial biomass or carbon dioxide. Ecosystem production is measured over a stated area and interval because it is a flux, not simply material present at one moment. Producers convert inorganic carbon into organic compounds, respiration returns some carbon to the environment, and heterotrophs redistribute
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 17
Lignin decomposes slowly because it is a heterogeneous, cross-linked aromatic polymer with irregular bonds rather than a repeating structure readily attacked by common hydrolases. It encrusts cellulose in secondary cell walls, reducing enzyme access to otherwise degradable carbohydrates. A limited set of fungi and bacteria produce oxidative enzymes such as lignin peroxidase, manganese peroxidase, and laccase, and these reactions are energetically costly. High protein would generally improve substrate quality, whereas structural complexity and chemical recalcitrance prolong persistence. Environ
Ref: Fundamentals of Ecology, Odum & Barrett, 5th Ed., Ch. 3
Mineralization releases inorganic nutrients when decomposers convert organically bound elements into forms such as ammonium, phosphate, and sulfate. Immobilization runs in the opposite direction: microbes absorb inorganic ions and incorporate them into cellular biomass because detritus does not supply nutrients in the proportions required for growth. Whether net mineralization or net immobilization occurs depends strongly on substrate stoichiometry, especially carbon-to-nitrogen and carbon-to-phosphorus ratios, and on microbial demand rather than on decomposition alone. At ecosystem scale, the
Ref: Fundamentals of Ecology, Odum & Barrett, 5th Ed., Ch. 3
“Both gaseous and sedimentary” for the sulfur cycle includes which of the following phases. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Rates depend on temperature, moisture, substrate quality, consumer physiology, and the elemental balance between organisms and their food. These controls explain why the same process can differ among terrestrial, freshwater, and marine systems without changing its definition. The remaining alternatives—“Only atmospheric”, “Only sedimentary”, “Only lithospheric
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 18
