Most ecological or floristic studies of lowland tropical American forests on mesic sites demonstrate the importance of the Lecythidaceae. The family is often abundant in both numbers of species and individuals present. For example, Prance et al (1976) found 18 species, represented by 67 individuals over 15 cm DBH, in a one hectare study plot near Manaus, Brazil. These figures represented 10.1% of the species and 22% of the individuals over 15 cm DBH present in the plot. Only the Leguminosae sensu lato, with 25 species, was more diverse, and no other family had more individuals. Other studies have also demonstrated the prevalence of Lecythidaceae in lowland tropical forests. Pires et al (1953) recorded 273 individuals of Lecythidaceae over 10 cm DBH in a 3.5 hectare plot near the village of Tres de Outubro, Para, Brazil. In their study area only Leguminosae sensu lato (30 species) and Sapotaceae (25 species) were more diverse and no family had more individuals. In another study of primeval terra firme forest near Mocambo, Pari, Brazil, Cain et al (1956) calculated the importance value (= sum of relative densities, frequencies, and dominances) of Lecythidaceae to be 37.77, second only to Bur-seraceae (47.92). However, not all lowland tropical forests are as rich in Lecythidaceae as the above areas. Schulz (1960) has demonstrated that Lecythidaceae in the rain forests of northern Surinam may be abundant in some areas and absent in others, i e individuals over 25 cm DBH of canopy and emergent species of Lecythidaceae represented 0 to 22.4% of all individuals depending on the study area. In a study of terra firme forest near Manaus Klinge (1973) found only 6.6% of the individuals over 10 cm DBH in or above the canopy to be Lecythidaceae. In summary, absolute densities of Lecythidaceae of 19-88 (over 10 cm DBH; Davis and Richards 1934), 78 (over 10 cm DBH; Pires et al, 1953), 69 (over 15 cm DBH; Pires unpublished data), 0-28 (over 25 cm DBH; Schulz, 1960), and 67 (over 15 cm DBH; Prance et al 1976) trees/hectare have been reported (Tables V-VII).

Pires (unpublished data) carried out a detailed study of 10.5 hectares in a forest reserve near Belem, Brazil. The rectangular study area of 420 x 250 m contains 5.7 hectares of terra firme forest called the Mocambo Reserve. It is surrounded by 4.8 hectares of tidal vdrzea forest which is inundated twice daily by the Catu stream which backs up at high tide. In addition Pires studied 5 hectares of periodically flooded forest in the nearby Aur£ Reserve (see Pires and Prance, 1977). The 15.5 hectare study area contained 1,072 trees of Lecythidaceae of 15 or more cm DBH, or 69.16 trees per hectare. However, the density of Lecythidaceae of the terra firme forest (Mocambo Reserve) was ,117.72 trees/ha whereas those of the periodically inundated forests (Catu and Aurd Reserves) were only 33.5 and 39 trees/ha respectively (Table VI). In a study of the vegetation of Moraballi Creek, Guyana, Davis and Richards (1933, 1934) recognized 5 forest types. Individuals of Lecythidaceae over 10 cm DBH were most abundant in their Greenheart forest (88/ha), less abundant in the Mixed (57.8/ha) and Morabukea (47/ha) forests and relatively uncommon in their Mora (30.9/ha) and Wallaba (18.8/ha) forests. The Mora and Wallaba forests are at the two extremes of a soil moisture-organic content continuum, the former grows on periodically waterlogged soils high in organic content whereas the latter is found on white sand which is relatively poor in

Species of Lecythidaceae of 15 cm diameter or more found on a hectare of forest on terra firme, Km 30, Manaus-Itacoatiara road (data from Prance et al, 1976)

Species _No. of trees

Corythophora alta Knutb 2

Corythophora rimosa Rodrigues 5

Couratari guianensis Aubl. 1

Couratari atrovinosa Prance 2

Eschweilera amara Ndz. (- Lecythis idatimon Aubl.) 4

Esch weilera fracta Knuth 2

Eschweilera odora (Poepp.) Miers 26

Eschweilerapolyantha A.C. Smith 3 Eschweilera sp 1

Eschweilera sp 2 4

Eschweilera sp 3 1

Eschweilera sp 4 1

Eschweilera sp 5 2

Eschweilera sp 6 4

Holopyxidium latifolium (A. C. Smith) Knuth (= Eschweilera jarana (Huber) 4

Ducke var latifolia Ducke)

Holopyxidium jaranum (Hub.) Ducke (= Eschweilera jarana (Huber) Ducke 2

Holopyxidium sp 1 {= Lecythis sp.) 2

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