GOMIDE, G. L. A.

SANQUETTA, C. R.

SILVA, J. N. M.

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••J 	 .1 12 • JE u 1 - ISSN 0101-2835 E s u m o s Simpósio sLICULTURA NA AMAZÔNIA ORIENTAL: CONTRIBUIÇÕES DOPROJETO EMBRAPAIDFID 1  4. - 	 • .:•.. E x p A N D • 00330 IIII 	III IIl D1 	lIi II  ereiro de 1999 - Pará DFID Documentos f'42  123 	 ISSN 0101-2835 Fevereiro, 1999 SIMPÓSIO SIL VICUL TURA NA AMAZÔNIA ORIENTAL: Contribuições do Projeto EmbrapaIDFID Belém, PA, 23 a 25 de fevereiro de 1999 Resumos Expandidos GROWTII «ATES AND DYNAMICS OF A TROPICAL SECONDARY FOREST IN AMAPÁ STATE, BRAZII41 Guilherme Luís Augusto Gomide2; José Natalino Macedo Silva 3 ; Carlos Roberto Sanquetta 4 Secondary forests, due to the large arca they occupy in the Amazon region and othr Brazilian eeosystems, as well due to their unique characteristies, have attracted the attention of many researehers. These researchers have emphasized their studies on eomprehending the ecological proeess alter clear-felling, the rates of recovery in speeies diversity and stand structure; as well their primary production and role iii .the environmental regulation at the local, regional and global scales. This study was carried out with the objective of analyzing the process of formation of a secondary forest, the changes in floristic composition and stand as well as the reeruitment, mortality and growth rates of the trees in the forest structure during a 1 1-year period alter clear-felling. The arca is located in Amapá State, Brazil (52°20"W and 00°55"S), where local altitude is approximately 150 m. The site is surrounded by Dense Tropical Rain Forest. The forest succession was monitored by means of continuous forest inventory. The first measurement was conductcd in 1985, with remeasurements in 1986, 1988, 1990, 1994, and 1996. The species were classified in three commercial groups in accordance with their wood quality and utilization, as foliows: group 1: eommercial species; group 11: species that might become commercial in next future; group III: non-commercial species. The mean tree density in 1985 was calculated as been 741.5 trees/ha with DBH over 5 cm. These trees belonged to 34 families, 55 genera and 76 species. The families with larger number of speeies were Mimosaceae, Moraceae, and Sapotaceae. In relation to the number of individuaIs, Moraceae was the most numerous family, mainly due to the remarkable Trabalho realizado com o apoio financeiro Embrapa Amazônia OrientaIJDFID. 2  Eng. Ftal M.Sc., Dourotando, Universidade Federal do Paraná, Curitiba, PR, ggomide@ece.ufpr.br  Eng. Ftal., Ph.D., limbrapa Amazônia Oriental, Caixa Postal 48, CEP 66.017-970, Bclim, PA, natalino@cmbrapa.cpatu.br  Eng. Ftal., Doutor, Professor da Universidade Federal do Paraná, Curitiba, PÁ. sanquettacce.ufpr.br  207 presence of the pioneer Cecropia (Ç, obtusa, with 133 trees/ha, and C. sciadophyiia, with 188 trees/ha). Regardingthe cornmerciaiization groups, 13 species were ciassified as commerciai, 28 species were potentiaily coxnmerciai, and 35 were considered as non-contmercial species (3.44%, 92.31%, 4.25% of the number of the number, of individuais, respectively). In 1985, the forest was at the beginning of fite succession process, which was • charaeterized by the predominance of pioneer species.,In 1996, 2,353 individualslha were counted in thc tree size class. These trees belonged to4l farnilies, 109 genera, and 174 species. During 1985 and 1996, there was au • appearance of 105 iew species and the disappearance of 7 secies in the tree • size eiass. The Moraceae family stili cont'mued to be that with the greatest nümber: of individuais, . especially Cecropia.:. In relation to the commercialization groups, there was a positive evoiution in relation to 1985, with 40 speciés (9.38% of the individuais) classified as conimercial, 66 • species (18.64 %) potentialiy commercial, and 68 species (71.87%) as non-commerciai Tu 1985, the non-commercial species represented 92.31% of the total density, whereas lii 1996 their participation in the stand density diminished to 71.89%. On the other hand, group 1 and II increased their participation, which contributed to the enrichment of the forest quaiity iii tFrms  ofvaluabie woody species. In 1985, Cecropi a sciadophylla and Cecropia 'obtusa were those species that showed the highest tree density, with 375.5 and265.5 trees/ha, respectiveiy, both together corresponding to 86.45% of the total tree density. Jn 1996, in the tree size class, the rnost abundant species were Ceeropia sciadophylla, . with 915.5 stems/ha, foilowed by Cecropia obtusa and Laetia procera, with 246 and 130 stemslha, respectively. The pioneer Ceeropia species corresponded, in the trees size ciass, to 86.40% of lhe total tree density in 1985 and 68.60%in 1996. - 	 2 The total basai area of the forest rn '1985 was 3.3 m /ha. Cecropta aione accounte1 for 2.44 m /ha, Le. 73:11% of the stand basai arca. Dúring 2 	 2 1985 and 1996, the change in basal area was of 25.4 m /ha, from 3.34m /ha in 1985 to 28.74 2rn Iha in 1996, which corresponded to 760.0% of augment ofthe initial basai area. This greatvariation in a short tim! (11 years) was 'dueto the rapid growth and the great abundance ofthe pioneer species that found a favorable environment to their establishment and development inthe beginning of the succession process. Jn 1996, Cecropia-ciadophylla and Cecropia obtusa still continued to be the dominant species in the forest. The basai arca of both summed accounted for 73,74% ofthe stand basai arca. 208 In 1985 oniy 5 species had individuais wilh DBH larger than 20 cm and, therefore, participated in volume calculation. The total stem volume in 1985 was ealculaled to be 4.97 m /ha, being 96.38% ofthis volume belonged to the species of thc non-commercial species group and lhe remainder 3.62% to the polentially commereial species. In 1996, lhe stem volume increased to 40.27 m /ha, which corresponded to na increase of 710% in relation to the initial volume calculated for 1985. The species lhat presented larger volumes were Cecropia seiadophylla, Cecropia obtusa, jj]gj alba, and Didymopanax morototoni, being lhe species of the Cecropia genus responsible for 88% volume. The average annual periodic increment (PAI) in diameter of the trees was 0.60 cm/year, considering ali individuais over 5 em DBH. The species that composed lhe group 11 ofcommercialization showed the fastest diameter growlh (0.63 em/year), but for groups 1 and II no significant difference was notieed in terms of DBH growth. Another faet revealed by the data was the decreased in DBH growth rales wilh time as resull of increasing plant compelilion. During lhe first period of observation (1985-1988), the average rale was 1.93 cmlyear, which decreased lo 0.34 cmlyear within lhe Iast two years. The reduction in growth rate was more remarkable for group of commereialization III, which further indieates the progréssive decline of the pioneers. The increment rate in basal area 2.33 m /ha.year , which changed 2 	-1  from ca.6.00m /ha.year rn lhe first pen 	2od lo less lhan 1.00 m Iha.year in the last period of observalion. This trend was similar lo lhe individual stem diameter growth rale, i.e. lhis decrease reflects lhe canopy closure and competition for limiled resources. The change in basal area growth in terms ofcommercialization groups was also similar lo DBH growth, where group 1 (pioneers) showed lhe faslest growlh rales. The average stem volume groh for 14 years was 3.53 m /ha.year The mortalily rale during lhe period 1985-1996 was calculaled aI 111.22 treeslha.year , which represenled 5.28% of lhe initial number oftrees (in 1985). MosI of lhe dead slems (97.8%) belonged lo group III (non-commercial species), where are included Ibose ephemeral pioneer taxa, Ceeropia and olher Moraceae. The annual morlalily rale varied with time, bul no general trend was found. AMR was low during lhe firsl lhree years of succession, increased abruplly during lhe nexl two years, lumed lo decrease lwo years laler, and inereased considerably during lhe lasI two years. The annuat recniitmenl rate was 263.59 lrees/ha.year , corresponding lo 14.63% 209 ofthe initial number of trees (in 1985)..Reeruitment rate was greater for the group of eommerciaiization III, which ineludes most of the pioneer speeies. Most troes were recruited immediately after the disturbance (during 1985-1988). fle findings of this study ailowed to take several conclusions, which are exposed in the foliowing paragraphs. This 1 4-year secondary forest shówed a great vàriatioii ia lis floristic compoition of woody speciés during the study periàd, pràsenting 76 spècies distributed in 55 genus and 34 families in 1985 and, 174 species distnbuted ia 109 genus and 42 families, ia 1996. Ia 1985, a 1 mong the 76 species that apjeared in the troe size ciass, 40 were the sarne ofthe surrounding primary forest, whereas ia 1996 among thë 174 woody species recorded, 93 occurred lii the primary forest During 14 years ±0 forest faced a trèmendouí augrnent ia terms of basai area and stem volume. It was caused by the great recruitrnent rates o!' the pioneer species during the first six years after eieâr-feiling as well as to their very fast diameter growth ratés. During 14 years, Moraceae was the dominant family ia the forest, especially by the presente of piânéer sçecies of the Cecropia genus; Ceeronia and other pioneers ia spite of continuing to dominate the sito in ffie tree sue ciass, itwas noticed a proressive decline. Thé mortality rates were greater than recruitment ratos ia the troes size class within the iast years, and a drastic reduction of thesespecies in the sapling and seedling class has been observed as welt. fle forest becaine enriched in tenus of vood value. It was noticed an inerease in the the number of individuais of the commercial species, from 3.44% in 1985 to 9.38% in 1996. The group of potentially commerciai species increase its troe density from 4.25% in 1985 to 18.64% in 1996. 210 

Growth rates and dynamics of a tropical secondary forest in Amapa State, Brazil.

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