chapter5lifehistorystrategies-全文預(yù)覽
【正文】 39 Chapt. 05 Life History Strategies ? Success of populations – Reproductive strategies – Survival strategies – Habitat usage – Competition with other anisms 40 Chapt. 05 Life History Strategies – KSelected ? Populations increase slowly toward the carrying capacity ? (K) of the environment ? Low reproductive allocations ? Iteroparous ? High petitive abilities 41 Chapt. 05 Life History Strategies ? Ex. Mature forest – Nondisturbed habitat – Grow slowly – Reach reproductive age late – Devote large amounts of energy to growth and maintenance 42 Chapt. 05 Life History Strategies ? Ex. Mature forest (cont.). – Grow to large sizes and shadeout rselected species – Longlived and produce seeds repeatedly every year while mature – Seeds are bigger than rselected species – provide food reserves to help them get started 43 Chapt. 05 Life History Strategies ? Alternatives to the r and K continuum – Ruderals, petitors, and stress tolerators (Grime 1977 and 1979) ? Ruderals (botanical term for weed) – Adapted to cope with habitat disturbances 44 Chapt. 05 Life History Strategies ? Competitors – Adapted to live in highly petitive but benign environments (., tropics) ? Stress tolerators – Adapted to cope with severe environmental conditions (., salt marsh plants) 45 Chapt. 05 Life History Strategies ? Stress, disturbance and petition triangle – Figure 46 Chapt. 05 CHARACTERISTIC COMPETITORS RUDERALS STRESS TOLERATORS Life form Leaf size Life span Seed production Growth rate Palatability Vegetative spreadLeaf litter production Large herbs, shrubs or trees ?Large ?Long ?Small ?Rapid ?Various ?Yes ?High Small herbs ?Large ?Short ?Large ?Rapid ?High ?No ?Low Lichens, herbs,shrubs ?Small ?Long ?Small ?Slow ?Low ?Yes ?Low Competitors Stress Low High Ruderals Stress tolerators Intermediate Life histories Trees Perennial herbs Bryophytes Annual plants Lichens 47 Chapt. 05 Life History Strategies ? Demographic interpretation (Silverton et al. 1992, 1993) – Growthsurvival and fecundity triangle – Figure 48 Chapt. 05 G Fecundity Semelparous herbs Iteroparous herbs in open habitats Iteroparous herbs in forests Woody trees S F 49 Chapt. 05 Applied Ecology ? Life history and the risk of extinction ? Kselected species – All attributes set them at risk to extinction – Tend to be bigger – need bigger habitat 50 Chapt. 05 Applied Ecology ? Kselected species (cont.). – Fewer o
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