kasvumäära

Kasvumäär is an Estonian term for growth rate, the speed at which a quantity increases over time. In biology and ecology it commonly describes the growth of organisms, populations, or biomass. The concept is used to quantify how quickly living systems expand or accumulate matter under given conditions.

Mathematically, growth rate can be described in several forms. Absolute growth rate is the change in quantity over a time interval, expressed as ΔQ/Δt. Relative growth rate is the change per unit of the quantity, often written as (1/Q)·ΔQ/Δt. Instantaneous growth rate uses derivatives, r = (1/N)·dN/dt, when the quantity is N and time t. Units depend on the measured quantity and time interval.

Two common models are exponential and logistic growth. Exponential growth follows N(t) = N0·e^(r·t), where r is the instantaneous growth rate; the doubling time is t_d = ln(2)/r. Logistic growth considers resource limits: dN/dt = rN(1 − N/K), with carrying capacity K that curbs growth as N approaches K.

In practice, kasvumäär is estimated from repeated measurements of parameters such as organism count, body size, or biomass. In plants and animals, growth rate can be assessed via height, mass, length, or leaf area at successive time points, using appropriate statistical or mechanistic models.

Factors influencing kasvumäär include resource availability, temperature, nutrients, competition, and age. Interpretation requires clear definitions of the measured quantity and time frame, as well as consideration of the model assumptions and environmental context.