Vegetation versus FloraAustralian grass savanna African grass savannaWhat lives where and why?Ecological hypotheses Do the species occur here because of similar latitude? animal grazing? climate? montane rain shadows? fire history? Australian grass savanna African grass savannaWhat lives where and why?Convergent adaptation or evolution operating?Ecological hypotheses Australian grass savanna African grass savannaThese hypotheses and questions are interested in the environmental stresses onspecies to produce these characteristic vegetation types, physiognomy, or life formsVegetation versus FloraHas there been long distance dispersal between the two areas?Are the two areas related geologically - once sharing a common biota?Australian grass savanna African grass savannaWhat lives where and why?Are the species occurring in both areas related?Historical hypotheses Australian grass savanna African grass savannaVegetation versus FloraAustralian grass savanna African grass savannaWhat lives where and why?Historical hypotheses These hypotheses and questions are interested in the flora (actual speciescomposition) and history of the both the species and the areas they inhabitAustralian grass savanna African grass savannaVegetation versus FloraAustralian grass savanna African grass savannaSimilarity of Australian and African grass savannas largely explained byecological answersBoth have Acacia as the dominant small tree and grasses as the dominant herbs,but the species are unrelatedAustralian grass savanna African grass savannaVegetation versus FloraDo species occurring in Mediterranean biomes (5 of them) look similarbecause of ecological similarity or because they are floristically similar?Vegetation versus FloraDo species occurring in Mediterranean biomes (5 of them) look similarbecause of ecological similarity or because they are floristically similar?Because of the severe alternation of winter rain and summer aridity?Because of cold ocean currents flowing from high latitudes on west sides ofcontinents?Vegetation versus FloraDo many species have “holly”-like leaves because they are closely related?or, because tough leathery leaves, with spine tips are an adaptation to theMediterranean climate?Ilex (Aquifoliaceae)hollyAlchornea ilicifolia (Euphorbiaceae)Banksia ilicifolia(Proteaceae)Convergent evolution!Vegetation versus FloraDoes mountain sweet cicely have this amphi-tropicaldistribution because ecological conditions are similar inall three areas? or long distance dispersal? or previouscontinental connections?Osmorhiza chilensisMountain sweet cicelyApiaceaeVegetation versus FloraAre these amphi-Atlantic species pairs simply ecological replacements? or are theyclosely related species separated by a now expanding North Atlantic ocean?AA BBABVegetation versus FloraAlexander von Humboldt (1769-1859)• First naturalist to make explicit distinction betweenvegetation and flora and connection between climateand plant distributions• Funeral in 1859 wasone of the greatest thecity of Berlin ever sawWhat did he do that was so special?Vegetation versus Flora• landed in Venezuela and visited Cuba, Colombia,Ecuador, Peru, and Mexico• 1799 left for Latin America with Aine Bonplandfor 6 years• studied flora, fauna, geology, meterology, oceancurrentsVegetation versus Flora• traversed the Upper Orinoco in southernVenezuela, documenting its unusual flow• made first plant collections for the area - manynew species with H.B.K. authority designationCinchona - quinineVegetation versus Flora• traversed the Upper Orinoco in southernVenezuela, documenting its unusual flow• made first plant collections for the area - manynew species with H.B.K. authority designation• wrote extensively on indigenous inhabitants forthe first timeVegetation versus Floramost notable writings include “Essays onthe Geography of Plants” (1805)1. Observations concerning the effect ofaltitudinal differences on vegetationCerro Avila, north of Caracas, firstmountain “zoned”Vegetation versus Floramost notable writings include “Essays onthe Geography of Plants” (1805)1. Observations concerning the effect ofaltitudinal differences on vegetationChimborazo, Ecuador, described ingreater detail (1.5° S; 20,703ft - 6,310m)Vegetation versus FloraChimborazo, Ecuador, described ingreater detaile.g., at 1,950m left savannas andentered sclerophyllous shrub vegetationbelt (ericads - Ericaceae or blueberryfamily)Vegetation versus Floramost notable writings include “Essays onthe Geography of Plants” (1805)1. Observations concerning the effect ofaltitudinal differences on vegetation2. Compilation of species for both SouthAmerica and Eurasia (floristics)Demonstrated that the sclerophyllousshrub belt is found in Andes, Himalayas,and Alps, and often dominated byEricaceae, but different genera andspecies!Vegetation versus Flora“The substitution, or the repetition, of similar, almostidentical morphological types in different regions separatedfrom each other by oceans or wide areas of land, is amarvelous law of nature”“Even if nature does not produce the same species insimilar climates, nevertheless the vegetation exhibits themost striking visual similarities in habit even in themost distant regions. This phenomenon is one of themost remarkable in the history of organic creations”— same vegetation not same floravon Humboldt— implies convergent evolution!Vegetation versus Flora“Each plant community consists of adefinite group of life forms. Each habitatfavors certain groups of life forms andalmost excludes others. The more extremethe habitat conditions the sharper theselection and the more pronounced are theecological characteristics of the lifeforms.”Josias Braun-Blanquet, 1932Vegetation versus Flora“Quite apart from the influence ofclimates in the distribution ofindividual plant species, climatestrikes at the structure of vegetationeverywhere in the same way, whateverits floristic composition. That is tosay, similar climates in widelyseparated parts of the world inducethe emergence of similar kinds ofplant formations in the physiognomicsense.”Pierre Dansereau, 1951Vegetation versus Flora3. Reduced variety of plant life forms to 15 basic types - first of its kindVegetation versus Flora• The simplest and most well known classificationof plant forms that disregards their systematics isthat of the Danish botanist Raunkiaer (1934) Raunkiaer, C. (1934) The life forms of plants. Oxford University Press