Species

The species is most often the unit of comparative ecology, although intraspecific comparisons of different populations can also be rewarding. If we are comparing species we have to consider what we mean by species. The definition has been a thorny problem in biology for many years, with considerable debate over the relative merits of biological and evolutionary definitions of species. From a practical point of view, it has to be realised that ecologists researching in tropical rain forests are nearly always working with a taxonomic species definition. They are forced to employ the species concepts of the taxonomist who wrote the flora or monograph that they are using. In most cases these are based on circumscription of morphological

Figure 1.1 A phylogeny of the vascular plants to ordinal level (in part after Nyffeler (1999) based on Angiosperm Phylogeny Group (1998)). Names of orders given in bold indicate the presence of extant tropical tree species. Names underlined indicate that a majority of extant member species are tropical trees.

Figure 1.1 A phylogeny of the vascular plants to ordinal level (in part after Nyffeler (1999) based on Angiosperm Phylogeny Group (1998)). Names of orders given in bold indicate the presence of extant tropical tree species. Names underlined indicate that a majority of extant member species are tropical trees.

Table 1.1. Taxonomic summary of extant tropical forest trees

Inclusion of a genus implies at least one species considered to be a tree in tropical rain forest. Monocot families are presented in order of roughly decreasing degree of arborescence. Classification follows Brummitt (1992).

Table 1.1. Taxonomic summary of extant tropical forest trees

Pteridophytes

Gymnosperms

Monocots

Dicots (important families)

FILICOPSIDA

PINOPSIDA

GNETOPSIDA

Woody:

Herbaceous:

Anacardiaceae

Malvaceae

Annonaceae

Melastomataceae

Cyatheaceae

Araucariaceae

Gnetaceae

Palmae

Musaceae

Apocynaceae

Meliaceae

Cyathea"

Agathis

Gnetum

(Arecaceae)

Ensete

Aquifoliaceae

Monimiaceae

Araucaria

(G. gnemon and G.

many genera

Musa

Araliaceae

Moraceae

Dicksoniaceae

costatum seem to

Bignoniaceae

Myristicaceae

Cibotium

Cupressaceae

be the only species

Pandanaceae

Strelitziaceae

Bombacaceae

Myrsinaceae

Culcita

Papuacedrus (mtn)

that are trees, the

Pandanus

Phenakospermum

Boraginaceae

Myrtaceae

Dicksonia

Widdringtonia

rest are woody

Sararanga

Ravenala

Burseraceae

Ochnaceae

(mtn)

climbers)

Capparidaceae

Olacaceae

Osmundaceae

Gramineae

Heliconiaceae

Celastraceae

Oleaceae

Leptopteris

Phyllocladaceae

(Poaceae)

Heliconia

Chrysobalanaceae

Piperaceae

Phyllocladus (mtn)

CYCADOPSIDA

bamboos

Combretaceae

Pittosporaceae

also, but less convincingly

Zingiberaceae

Cunoniaceae

Rhamnaceae

dendroid:

Pinaceae

Cycadaceae

Dracaenaceae

Alpinia

Dichapetalaceae

Rhizophoraceae

Pinus (dry)

Cycas

Cordyline

Dilleniaceae

Rosaceae

Blechnaceae

Dracaena

Araceae

Dipterocarpaceae

Rubiaceae

Blechnum

Podocarpaceae

Zamiaceae

Alocasia

Ebenaceae

Rutaceae

Brainea

Acmopyle (mtn)

Ceratozamia

Velloziaceae

Montrichardia

Elaeocarpaceae

Sapindaceae

Afrocarpus

Chigua

Vettozia

Ericaceae

Sapotaceae

Dacrycarpus

Dioon

Xerophyta

N.B. not all

Erythroxylaceae

Simaroubaceae

"in the broad sense, the

Dacrydium

Lepidozamia

members of these

Euphorbiaceae

Sterculiaceae

genus is split into two or

Falcatifolium

Zamia

Cyperaceae

genera attain tree

Fagaceae

Styracaceae

more by some pteridologists

Nageia

Microdracoides

size

Flacourtiaceae

Theaceae

Podocarpus

Guttiferae

Thymelaeaceae

Prumnopitys (mtn)

Xanthorrhoeaceae

(Clusiaceae)

Tiliaceae

Sundacarpus

Xanthorrhoea

Icacinaceae

Ulmaceae

Taxaceae Taxus mtn = genera only represented in montane regions dry = genera only represented in seasonally dry regions

Lauraceae Urticaceae

Lecythidaceae Verbenaceae

Leguminosae Vochysiaceae

(Fabaceae)

Loganiaceae

Magnoliaceae variation to the degree that the taxonomist considered typical of a species. Taxonomists can vary in their opinion of where to draw these lines (see, for example, Wong (1996) for discussion of Fagraea in Borneo), leaving ecolo-gists in the difficult position of choosing whom to follow.

Additional problems are faced with the identification of plants in the field. The high diversity makes identification difficult. It may be annoying and confusing to find that you have been using the wrong name for a species. For example, many papers were published concerning Virola surinamensis on Barro Colorado Island, Panama, but this was a mis-identification, and is correctly Virola nobilis. What is worse is when your species contains individuals of other species. This happened for a study of buttressed trees in Malaysia (Crook et al. 1997) where one pinnate-leaved species turned out to be several.

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