Popolazione - ZyXEL NSA210

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Initially ecologists tried toexplain outbreaks by directimpact of environmentalfactors. However, themagnitude of change inthese factors was alwaysmuch smaller than themagnitude of change inpopulation density.Attempts to find a "releasingfactor" usually fail. Thus,there should be an"amplifier" of a small initialdisturbance.These amplifiers can be triggered only at specific state of thepopulation system. When an outbreak is already in progress,additional disturbances have almost no effect.Only when an outbreak cycle is finished, then the populationmay again respond to another disturbance. In some cases, evensmall disturbances cause an outbreak, and then the population ispermanently in an outbreak cycle.Outbreaks collapse usually due to one of the followingmechanisms:- Destruction of resources- Natural enemies- Unfavorable weather
Tree-ring width index% of affected trees2.0 Chronologies of:1.8 (a)L decidua1.6P cembra1.41.21.00.80.60.40.20.010090(b)807060504030201001760 1780 1800 1820 1840 1860 1880 1900 1920 1940 1960 1980 2000Years2.5Spectral density2.01.51.00.5Spectral density of:L decidua chronologyP cembra chronology0.00 3 6 9 12 15 18 21 24 27 30Period
Page 1 and 2: Corsi di Laurea in SFA ed in DISMIT
Page 3 and 4: Parametri di una popolazione:•Den
Page 5 and 6: La grandezza della popolazione può
Page 7 and 8: Rapporto tra i sessi costante♂=
Page 9 and 10: Density-dependent population growth
Page 11 and 12: Examples of Sigmoidal GrowthEsempi
Page 14 and 15: Red Queen DynamicsResults from a co
Page 16 and 17: Populations exist in heterogeneousl
Page 18 and 19: Interazioni interspecificheNessunai
Page 20 and 21: Bufaga africana(Buphagus africanus)
Page 23 and 24: Remora(Echeneisnaucrates)Predazione
Page 25 and 26: Antibiosi e allelopatiaInterazioni
Page 27 and 28: Nicchia ecologicaLa nicchia ecologi
Page 29 and 30: - 3 niche dimensions:Nicchia ecolog
Page 31 and 32: • co-existence- competing can co-
Page 33 and 34: Esperimenti di Park (1962)Esperimen
Page 35 and 36: Feeding positions of fivesympatric
Page 37 and 38: K - strategists• Popolazione aliv
Page 39 and 40: Curve di sopravvivenzaType I -high
Page 44: O.N. Bjørnstad, M. Peltonen, A.M.

Popolazione - ZyXEL NSA210

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