Estudo da relação entre os tamanhos populacionais das espécies arbóreas na Amazônia e seus usos pelos humanos

For more than 13,000 years, Amazonia’s inhabitants have been using forest plants. Hypotheses about the association between plant abundance and their use suggest either that plant availability influences uses or that use influences abundance of useful plants in modern forests via long-term human activities. The relationship between usefulness of arboreal species and their population sizes in Amazonian forests at the continental-scale is, however, unknown. Here we show that Amazonian forests are dominated by useful arboreal species, which include at least 2326 species. Our model predicts that hyperdominant species have at least 80 % chance to be useful, whereas non-hyperdominants have only 9 % chance of being useful. Incipiently domesticated species are the most abundant in Amazonian forests, whereas domesticated species are less abundant. Our analyses elucidate the enormous usefulness of Amazonian forests, although this usefulness seems invisible today, which may explain why the forests have been destroyed to supply cattle and grain to world markets.Por mais de 13.000 anos os habitantes da Amazônia têm usado as plantas da floresta. Hipóteses sobre a associação entre a abundância das plantas e seus usos sugerem que (i) a disponibilidade da planta influencia seus usos ou que (ii) os usos influenciam a abundância de plantas úteis nas florestas modernas por meio de atividades antropogênicas de longo prazo. A relação entre a utilidade de espécies arbóreas e o tamanho de suas populações em florestas amazônicas na escala continental é desconhecida. Aqui mostramos que as florestas amazônicas são dominadas por espécies arbóreas úteis, que correspondem pelo menos 2326 espécies e 90% das espécies hiperdominantes. Nosso modelo prevê que as espécies hiperdominantes têm pelo menos 80% de chance de serem úteis, enquanto as não-hiperdominantes têm pelo menos 9 %. As categorias de uso as quais a supressão de indivíduos é mais frequente, como construção e lenha, não estão associadas às espécies com menores tamanhos populacionais. Espécies incipientemente domesticadas são as mais dominantes nas florestas amazônicas, enquanto as espécies totalmente domesticadas são menos abundantes. Nossas análises elucidam a grande utilidade das florestas amazônicas, embora essa utilidade pareça invisível hoje, o que explica porque as florestas estão sendo eliminadas para fornecer gado e grãos aos mercados mundiais

Direct evidence for phosphorus limitation on Amazon forest productivity

The productivity of rainforests growing on highly weathered tropical soils is expected to be limited by phosphorus availability1. Yet, controlled fertilization experiments have been unable to demonstrate a dominant role for phosphorus in controlling tropical forest net primary productivity. Recent syntheses have demonstrated that responses to nitrogen addition are as large as to phosphorus2, and adaptations to low phosphorus availability appear to enable net primary productivity to be maintained across major soil phosphorus gradients3. Thus, the extent to which phosphorus availability limits tropical forest productivity is highly uncertain. The majority of the Amazonia, however, is characterized by soils that are more depleted in phosphorus than those in which most tropical fertilization experiments have taken place2. Thus, we established a phosphorus, nitrogen and base cation addition experiment in an old growth Amazon rainforest, with a low soil phosphorus content that is representative of approximately 60% of the Amazon basin. Here we show that net primary productivity increased exclusively with phosphorus addition. After 2 years, strong responses were observed in fine root (+29%) and canopy productivity (+19%), but not stem growth. The direct evidence of phosphorus limitation of net primary productivity suggests that phosphorus availability may restrict Amazon forest responses to CO2 fertilization4, with major implications for future carbon sequestration and forest resilience to climate change.The authors acknowledge funding from the UK Natural Environment Research Council (NERC), grant number NE/L007223/1. This is publication 850 in the technical series of the BDFFP. C.A.Q. acknowledges the grants from Brazilian National Council for Scientific and Technological Development (CNPq) CNPq/LBA 68/2013, CNPq/MCTI/FNDCT no. 18/2021 and his productivity grant. C.A.Q., H.F.V.C., F.D.S., I.A., L.F.L., E.O.M. and S.G. acknowledge the AmazonFACE programme for financial support in cooperation with Coordination for the Improvement of Higher Education Personnel (CAPES) and the National Institute of Amazonian Research as part of the grants CAPES-INPA/88887.154643/2017-00 and 88881.154644/2017-01. T.F.D. acknowledges funds from FundacAo de Amparo a Pesquisa do Estado de SAo Paulo (FAPESP), grant 2015/50488-5, and the Partnership for Enhanced Engagement in Research (PEER) programme grant AID-OAA-A-11-00012. L.E.O.C.A. thanks CNPq (314416/2020-0)

Direct evidence for phosphorus limitation on Amazon forest productivity

The productivity of rainforests growing on highly weathered tropical soils is expected to be limited by phosphorus availability1. Yet, controlled fertilization experiments have been unable to demonstrate a dominant role for phosphorus in controlling tropical forest net primary productivity. Recent syntheses have demonstrated that responses to nitrogen addition are as large as to phosphorus2, and adaptations to low phosphorus availability appear to enable net primary productivity to be maintained across major soil phosphorus gradients3. Thus, the extent to which phosphorus availability limits tropical forest productivity is highly uncertain. The majority of the Amazonia, however, is characterized by soils that are more depleted in phosphorus than those in which most tropical fertilization experiments have taken place2. Thus, we established a phosphorus, nitrogen and base cation addition experiment in an old growth Amazon rainforest, with a low soil phosphorus content that is representative of approximately 60% of the Amazon basin. Here we show that net primary productivity increased exclusively with phosphorus addition. After 2 years, strong responses were observed in fine root (+29%) and canopy productivity (+19%), but not stem growth. The direct evidence of phosphorus limitation of net primary productivity suggests that phosphorus availability may restrict Amazon forest responses to CO2 fertilization4, with major implications for future carbon sequestration and forest resilience to climate change