The history of the INPA capoeira based on ecological studies of Lecythidaceae

The Lecythidaceae of a 2500 m2 area of the secondary forest of INPA was studied. The 91 individuais of Lecytlúdaceae present indicated a high number of primary forest species. It is concluded that most of the area was not burnt when the original forest was cut, and the regeneration of primary forest species is much greater in areas which are not burnt over after felling. Tlús is turther supported by parallel studies of Bignonia· ceae and Meliaceae of the same area .


INTRODUCTION
I was surprised by the number of Lecythidaceae present in the secondary forest. while I was making collections of the plants of the INPA campus in Manaus. The Lecythidaceae ls a family which occurs predominantly in the primary forests around Manaus, but is poorly represented in the secondary forests, locally called capoeiras. The presence of so many Lecythidaceae indicates that this area of forest is not the normal type of secondary forest which grows after cutting and burning an area of primary forest. Accordingly a study was made of the ecology and distribution of the Lecythidaceae of 2500 m 2 of the INPA forest.

METHOD AND SITE DESCRIPTION
AI' arca of fore5t wa"3 choscn whid1 was knOWll to be rich in Lecythidaceae and in which a similar study of Bignoniaceae by Dr . Gentry of M1ssouri Botanical Garden had shown the presence of many primary forest species of that famiiy. The area is situated below the bird lake on a slope. The pt'lth cleared for the ma in drainage pipeline served as a base line for the quadrat selected. An area of 50 x SOm was used and was divided into 5 strips of 50 x 10m. Ali individuais (including the smallest) ( •) -Instituto Nacional de Pesquisas da Amazônia.
ACTA AMAZONICA 5(3) : 261-263. 1975 Ghillean l. Prance ( *) of Lecythidaceae were found, marked. and mapped. Herbarium specimens were made of ali individuais for identification and documentation purposes. The bases of ali i ndividuais were examined, and it was found that ninety of the ninetyseven trees were growing from stump sprouts, rather than from seedlings . This indicates the capacity of these species for regeneration from sprouts. but it also indicates that the forest was not altogether burned over. Burning kills the primary forest trees and another type of secondary forest with many species of Cecropia etc. occurs.  Table 2. Tree heights in meters; x diameter for larger trees. Fig. 1 is a map of the distribution of the ninety-seven individuais in the area. lt can be seen that the top tEm meters or more of each section have few Lecythidaceae (10m. below Line W-X). In that area there is also a much greater frequency of typical secondary forest trees, Cecropia sp. Croton sp. etc. This area is also full of pits, burnt soil and charcoal. Enquiries into the history of the forest and onsite observations show that the area was used for making charcoal. The area without primary forest trees corresponds with the area charcoal pits where the forest was completely cut and burnE:d. The area which is dense in young primary forest species. including the Lecythi--dace&e studied, corresponds with an area where the original forest was cut to obtain wood for charcoal, but the area was not burnt over. lt can also be seen on the map (Fig. 1) that there is a greater density of Lecythidaceae tÓwâ.rds · the· Line X-Z than towards the Une 2.62_...-W-Y. I attribute this to the slope of tlhe quadrat. Une X-Z runs along the highest part of the area, which slopes -down gradually to Line W-Y which is almost at the bottom of a small valey. Apparently the Lecythidaceae grow better on the upper part, a fact that is also supported by forest inventaries in primary forest. Table 2 gives details of tree height showing that the individuais studied were young. Only one tree of Chytroma foetida was found in flower during the study.
A simi!ar study of Bignoniaceae was made by Dr. Alwyn Gentry of Missouri Botanical Garden who also found that the area contained predominantly primary forest species. The Meliaceae of the area were studied by Dr. T. D. Pennington of The Forest Herbarium, Oxford who also found Guarea duckei common in the quadrat. This is a species of primary forest and the majority of individuais were from stump sprouts. The Bignoniaceae were also from sprouts.
An interesting study of the regeneration of 3500 m 2 of felled fores in the Ducke Forest Reserve 26km from Manaus was recently made by W. Rodrigues (personal communication). The at ea studied by Rodrigues was not burned and had much regeneration of primary forest trees . H e found 74 individuais of Lecythida .. ceae, representing 14 species of 5 genera . Rodrigut:;s study shows that there is much regeration of primary forest species in areas not subjected to burning.

C<>NCLUSIONS
The area studied is definitely secondary forest, but it is characterised by the presence of a large number of young trees and vines of primary forest species, mainly growing from stump sprouts. Secondary forest species, such as-Cecropia grow abundantly only in the part of the quadrat near to the former charcoal kilns, where burning took place.
This study demonstrates that, in areas where the forest is destroyed, the regeneration of the primary forest trees is much more rapid if burning does not take place. Thus, far less damage is dane t o the native gene pool when the forest is not burnt. This is true not only because of the propensity of many felled trees to regenerate from stump sprouts, but also because seed material is not destroyed. nais . Observou-se que uma parte da área foi queimada, e lá ocorriam poucas Lecytbidaceae, e muitas árvores típicas de capoeira. A parte que não sofreu a ação do fogo tem muitos representantes da família (Lecythidaceae), mas também ocorrem cutras plantas características de mata primária, como por exemplo, espécimes das famílias Bignonia.. ceae e Meliaceae. Concluímos que grande parte da area nunca foi queimada, e nela a regeneração é muito mais rica em espécies de mata primária do que em uma área queimada. Isto porque muitas árvores têm capacidade de regeneração por brota-!:âo e muitas das sementes não chegam a ser destruídas.