Ecophysiology of fabaceae tree species during forest restoration in the balbina hydroeletric dam in Amazonas state

Plants can adjust functional traits according to the variations in the availability of resources. Under low soil water and nutrient availability, as found in degraded areas, the growth of tree species can be drastically reduced. Tree legumes evolved different strategies to efficiently uptake and use nutrients, securing high survival and growth rates, thus facilitating the restoration of important biogeochemical cycles during forest restoration. Early successional species may increase fast (aquisitive) traits under high resources, while slow (conservative) traits can be enhanced under limited resources and for late successional species. Variations in functional traits such as growth, gas exchange, water potential, nutrients, non-structural carbohydrates (soluble sugars and starch) (NSC), photosynthetic pigments and chlorophyll fluorescence of six tree legumes species were studied according with low vs. high water and nutrient availabilities during a forest restoration plantation in Hydroelectric dam Balbina. The species selected were five native species from Amazonia Cenostigma tocantinum, Senna reticulata, Dipteryx odorata, Clitoria fairchildiana and Inga edulis, and one alien species from Australia Acacia sp.. The individuals were either fertilized or remain unfertilized throughout the 24 month experiment. Three main hypotheses were tested: a) economics spectrum; b) functional equilibrium; and c) NSC dynamics and source-sink allocations. Economics spectrum was mostly confirmed under high water and nutrient availabilities increasing transpiration (E), photosynthesis (P n ), relative growth rates in diameter and performance index of chlorophyll fluorescence (PI ABS ). Traits from the slow spectrum such as dissipation energy flux (DI 0 /RC), intrinsic water use efficiency (IWUE) and root mass fraction (RMF) were enhanced under limited conditions. Functional equilibrium hypothesis was also confirmed as unfertilized plants increased twice the RMF as compared with high nutrient plants. Further RMF was positively correlated with starch and soluble sugars in root tissues indicating an active process of increased root fraction involving energy costs. Acacia sp. which respond differently than economics spectrum had significant growth under severe nutrient limitations, increasing nutrient and energy use efficiency, and the pool of NSC in leaf biomass. S. reticulata also diverge from economics assumptions being unable to adjust traits such as gas exchange and showing responses to drought stress which were related with increased leaf calcium and starch content. The fast acquisition of resources according (increased E and P n ) was considered the main strategy of species in a degraded and fertilized environment, as adjustments in energy use efficiency and NSC pools were essential for plants acclimation. Tree legumes especially N 2 -fixing species are proven to be well succeeded in forest restoration plantations producing eight times more biomass than non N 2 -fixing. Photosynthesis was the most responsive variable to evaluate species responses to resource variations in our study, nonetheless chlorophyll fluorescence appears to be an alternative efficient technique to evaluate the performance and responses to abiotic stress factors. This study makes a significant contribution to the understanting of the ecophysiology of tropica tree legumes and also to provide data to enhance Dynamic Global Vegetation Models. Additionally, from the conceptual view this thesis provide data to enhance climate change predictions models on the interface of soil-plant-atmosphere (during 2015/16 El Niño event) in Amazon forest. In conclusion, the mixing of different successional cological groups and including biological N 2 fixation process appears to be an efficient way to achieve ecological forest restoration goals in nutrient limited soils such as in Amazon basin.Diferentes espécies são capazes de ajustar suas características funcionais de acordo com as variações na disponibilidade de recursos do ambiente. Sob baixa disponibilidade de água e nutrientes no solo como em áreas degradadas, o crescimento das plantas pode ser drasticamente reduzido. Por outro lado, espécies leguminosas arbóreas desenvolveram evolutivamente diferentes estratégias para adquirir e utilizar nutrientes de maneira eficiente, garantindo altas taxas de sobrevivência e crescimento, facilitando a restauração de importantes ciclos biogeoquímicos em plantios de restauração florestal. De acordo com a hipótese do espectro econômico espécies iniciais podem aumentar respostas relacionadas as características do rápido espectro sob alta disponibilidade de recursos, enquanto respostas de crescimento lento (conservacionistas) são encontradas em condições limitantes e em espécies tardias. As variações das características funcionais como crescimento, trocas gasosas, nutrientes foliares, potencial hídrico, carboidratos não estruturais (açucares solúveis e amido), pigmentos fotossintetizantes e fluorescência da clorofila de seis espécies leguminosas arbóreas foram estudados de acordo com a alta X baixa disponibilidade de agua e nutrientes em um plantio de restauração florestal na UHE Balbina. Foram selecionadas cinco espécies nativas da região Cenostigma tocantinum, Senna reticulata, Dipteryx odorata, Clitoria fairchildiana e Inga edulis, e uma espécie nativa da Austrália Acacia sp. as quais foram fertilizadas ou permaneceram sem adubação durante os 24 meses de experimento. Três principais hipóteses foram avaliadas: a) espectro econômico; b) equilíbrio funcional; e c) dinâmica de carboidratos e relações fonte-dreno. A hipótese do espectro econômico foi confirmada em condições de alta disponibilidade de água e nutrientes com o aumento da transpiração (E), fotossíntese (P n ), taxa de crescimento relativo em diâmetro e índice de desempenho da fluorescência da clorofila (PI ABS ). Características do espectro lento como dissipação do fluxo de energia (DI 0 /RC), eficiência intrínseca no uso de água (IWUE) e fração de biomassa de raízes (RMF) foram incrementadas em condições limitantes. A hipótese do equilíbrio funcional também foi confirmada com um aumento de 100% dos valores de RMF em plantas não adubadas. Além disso, o aumento da RMF foi correlacionado com os teores de amido e açúcares solúveis nas raízes indicando um carregamento ativo com gastos de energia durante o processo. Acacia sp. contrariando o espectro atingiu um crescimento significativo mesmo não fertilizada, através do ajuste de suas características funcionais com eficiência no uso de energia (PI ABS ) e nutrientes, além do alto conteúdo de carboidratos e produção de biomassa de folhas. S. reticulata também divergiu das respostas do espectro, apresentando sinais de estresse fisiológico como o aumento dos teores de cálcio e amido nas folhas. A rápida aquisição de recursos como o aumento da P n e da E foi a principal estratégia das espécies nos ambientes degradados e fertilizados, por outro lado o ajuste na eficiência do uso de energia e na dinâmica de carboidratos tem papel fundamental na aclimatação das espécies. Espécies leguminosas arbóreas principalmente fixadoras de N 2 são comprovadamente bem sucedias em plantios de restauração produzindo oito vezes mais biomassa do que espécies não fixadoras. A fotossíntese foi a variável mais responsiva para avaliar as respostas das espécies em relação às variações ambientais, no entanto a fluorescência da clorofila parece ser uma técnica alternativa robusta e eficaz para avaliar a desempenho e as respostas aos fatores abióticos de estresse. Concluindo, a inclusão de espécies de diferentes grupos sucessionais e do processo de fixação biológica de nitrogênio parece ser uma técnica eficiente de restauração ecológica em áreas com fortes limitações nutricionais como em solos da bacia Amazônica

Carbon and nutrient stocks of three Fabaceae trees used for forest restoration and subjected to fertilization in Amazonia

Amazonia is crucial to global carbon cycle. Deforestation continues to be one of the main causes of the release of C into the atmosphere, but forest restoration plantations can reverse this scenario. However, there is still diffuse information about the C and nutrient stocks in the vegetation biomass. We investigated the carbon and nutrient stocks of Fabaceae trees (Inga edulis, Schizolobium amazonicum and Dipteryx odorata) subjected to fertilization treatments (T1 - no fertilization; T2 - chemical; T3 - organic; and T4 - organic and chemical fertilization) in a degraded area of the Balbina Hydroelectric Dam, AM - Brazil. As an early successional species, I. edulis stocked more C and nutrients than the other two species independent of the fertilization treatment, and S. amazonicum stocked more C than D. odorata under T1 and T4. The mixed species plantation had the potential to stock 4.1 Mg C ha-1 year-1, while I. edulis alone could stock 9.4 Mg C ha-1 year-1. Mixing species that rapidly assimilate C and are of significant ecological and commercial value (e.g., Fabaceae trees) represents a good way to restore degraded areas. Our results suggest that the tested species be used for forest restoration in Amazonia. © 2017, Academia Brasileira de Ciencias. All rights reserved

Ecofunctional traits and biomass production in leguminous tree species under fertilization treatments during forest restoration in Amazonia

Background: Choosing the correct species and fertilization treatments is a determining factor in the success of forest restoration. Methods: A field study was conducted in a degraded area near the Balbina hydroelectric dam in Amazonas State (AM), Brazil, to evaluate two hypotheses: (i) leguminous tree species exhibit differences in growth, leaf nutrient content, and photosynthetic nutrient use efficiencies; and (ii) differences in these characteristics depend on the fertilization treatments to which the species have been subjected. Dipteryx odorata, Inga edulis and Schizolobium amazonicum were subjected to the following treatments: (T1) unfertilized control; (T2) post-planting chemical fertilization; (T3) post-planting organic fertilization and (T4) combined chemical and organic post-planting fertilization. Results: In general, I. edulis had the highest absolute growth rate of biomass under all of the fertilization treatments. I. edulis and S. amazonicum showed the highest growth rates under the T4 treatment. D. odorata showed the greatest responses under the T2 and T4 treatments. Native leguminous trees with higher photosynthetic performance and better nutrient use efficiency exhibited greater growth and biomass production. Conclusion: The results suggest that an adequate balance between leguminous species selection and fertilization will aid in the success of forest restoration in Amazonia. © 2016 by the authors

Crescimento inicial e respostas fotossintéticas de três espécies leguminosas arbóreas submetidas à adubação verde e química em um plantio florestal na Amazônia

Currently 20% of the Amazon is degraded or altered. The need to restore these ecosystems becomes greater every day, once we recognize the services provided by the forest. Knowing the silvicultural needs of native species, and their ecophysiological responses to different methods of fertilization, is of great importance for the development of forest plantations, that can better use the resources available. In this sense, we evaluated the influence of different fertilization treatments on the growth, photosynthetic and nutritional responses, and biomass production of three leguminous trees, native of the Amazon region, in a mixed forest plantation. The experiment was conducted in a degraded area in the vicinity of the Balbina Hydroelectric Power Plant (UHE - Balbina) in the county of Presidente Figueiredo, AM. The fertilization treatments were: T1 = no fertilizer, T2 = manure pit, T3 = chemical fertilization, T4 = green manure, and T5 = green manure more chemical fertilization. We also assessed the performance of three species Dipteryx odorata, Inga edulis and Schizolobium amazonicum. Thus, we determined the percentage of survival, growth rates absolute and relative, in height and diameter, biomass production, nutrient content and chloroplastidic pigments in the leaves, gas exchange and chlorophyll fluorescence. D. odorata had 100% survival in all treatments. The lowest survival rate for I. edulis was found in the T5, and S. amazonicum in T2 and T4. The highest rates of absolute growth in height were obtained at T5 for the species I. edulis and S.amazonicum, 23.02 cm month-1 and 20.11 cm month-1 respectively. The species D. odorata had the highest height growth in T3 months 10.16 cm month-1. The same behavior was observed in the rates of absolute growth in diameter. In general, the species I. edulis had the highest absolute growth rates compared to other species. The relative growth rates were higher in the S. amazonicum both in height and diameter. The species I. edulis produced more biomass than other species in all treatments. The biggest difference between species for total biomass was found in T4, where I. edulis biomass produced 23 times more than D. odorata and 7 times more than S. amazonicum. The best treatment of fertilization in biomass production for I. edulis (7350.27 g) and S.amazonicum (1877.60 g) was T5, and the species D. odorata presented values very close on the T3 (455.00 g) and T5 (443.83 g). The high productivity of the species reflected the high photosynthetic rates found in the T5 treatment for the three species D. odorata (13.08 mmol CO2 m-2 s-1), I. edulis (20.65 mol CO2 m-2 s-1) and S.amazonicum (18.24 mol CO2 m-2 s-1). The highest rates for stomatal conductance and transpiration were obtained for the species I. edulis, in all fertilization treatments. With respect to chlorophyll fluorescence, the highest values of FV / FM were found in the T5 treatment for the species S. amazonicum (0.80), the lowest values occurred for the species I. edulis on T1. For the performance index the highest values were also observed for the species S. amazonicum on treatment T5, and the lowest values were determined in T1 and T2 for the species D. odorata and I. edulis, respectively. The highest total chlorophyll levels were found in T3 (1.74 mmol g-1) and T5 (1.82 mmol g-1) for D. odorata and I. edulis respectively. We conclude then the necessity to restore soil fertility prior to the establishment of forest plantations in degraded areas. It is also recommended the development of new research with native species, in the area of tropical forestry, to develop new planting techniques for reforestation in the Amazon.Atualmente 20% da Amazônia Legal encontra-se degradado ou alterado. A necessidade de se restaurar estes ecossistemas torna-se cada dia maior, uma vez que reconhecemos os serviços prestados pela floresta. Conhecer a necessidade silvicultural de espécies nativas, e suas respostas ecofisiológicas à diferentes métodos de adubação, é de grande relevância para o desenvolvimento de plantios florestais, capazes de melhor utilizar os recursos disponíveis. Neste sentido, foi avaliada a influência de diferentes tratamentos de adubação no crescimento inicial, nas respostas fotossintéticas e nutricionais, e na produção de biomassa de três espécies leguminosas arbóreas, nativas da região amazônica, em um plantio florestal misto. O experimento foi instalado em uma área degradada no entorno da Usina Hidrelétrica Balbina (UHE Balbina) no município de Presidente Figueiredo, AM. Os tratamentos de adubação foram: T1 = sem adubação, T2 = adubação de cova, T3 = adubação química, T4 = adubação verde e T5 = adubação verde mais química. Também foi avaliado o desempenho de três espécies Dipteryx odorata, Inga edulis e Schizolobium amazonicum. Para tanto, foram determinadas a porcentagem de sobrevivência, as taxas de crescimento absoluto e relativo, em altura e diâmetro, a produção de biomassa, os teores de nutrientes e pigmentos cloroplastídicos nas folhas, as trocas gasosas e a fluorescência da clorofila a. D. odorata teve 100% de sobrevivência em todos os tratamentos. A menor taxa de sobrevivência para I. edulis foi verificada no T5, e para S. amazonicum no T2 e T4. As maiores taxas de crescimento absoluto em altura foram obtidas no T5 para as espécies I. edulis e S.amazonicum, 23,02 cm mês-1 e 20,11 cm mês-1 respectivamente. A espécie D. odorata obteve o maior crescimento em altura no T3 10,16 cm mês-1. O mesmo comportamento foi observado nas taxas de crescimento absoluto em diâmetro. De maneira geral a espécie I. edulis obteve as maiores taxas de crescimento absoluto em comparação as demais espécies. As taxas de crescimento relativo foram maiores na espécie S. amazonicum tanto em altura como em diâmetro. A espécie I. edulis produziu maior biomassa que as demais espécies em todos os tratamentos. A maior diferença entre as espécies, para biomassa total, foi encontrada no tratamento T4, onde I. edulis produziu 23 vezes mais biomassa do que D. odorata e 7 vezes mais do que S. amazonicum. O melhor tratamento de adubação na produção de biomassa para I. edulis (7350,27 g) e S.amazonicum (1877,60 g) foi o T5, sendo que a espécie D. odorata apresentou valores muito próximos nos tratamentos T3 (455,00 g) e T5 (443,83 g). As altas taxas fotossintéticas encontradas no tratamento T5 para as três espécies D. odorata (13,08 μmol CO2 m-2 s-1), I. edulis (20,65 μmol CO2 m-2 s-1) e S.amazonicum (18,24 μmol CO2 m-2 s-1) refletiram a alta produtividade das espécies. As maiores taxas para condutância estomática e transpiração foram obtidas para a espécie I. edulis, em todos os tratamentos de adubação. Com relação à fluorescência da clorofila a, os maiores valores de FV/FM foram encontrados no tratamento T5 para a espécie S. amazonicum (0,80), os menores valores ocorreram para a espécie I. edulis no tratamento T1. Para o índice de desempenho os maiores valores também foram observados para a espécie S. amazonicum no tratamento T5, e os menores valores foram determinados nos tratamentos T1 e T2 para as espécies D. odorata e I. edulis, respectivamente. Os maiores teores de clorofila total foram encontrados nos tratamentos T3 (1,74 μmol g-1 ) e T5 (1,82 μmol g-1), para D. odorata e I. edulis respectivamente. Conclui-se desta forma a necessidade em se recuperar a priori a fertilidade do solo, para o estabelecimento de plantios florestais em áreas degradadas. Recomenda-se também o desenvolvimento de novas pesquisas com espécies nativas, na área de silvicultura tropical, a fim de desenvolver novas técnicas de plantios em reflorestamentos na Amazônia

Physiological responses of young Brazil nut (Bertholletia excelsa) plants to drought stress and subsequent rewatering

The Brazil nut tree (Bertholletia excelsa Bonpl.) is widely distributed in the Amazon region. It is subject to different rainfall regimes, particularly in El Niño years. Here, we demonstrate how biomass growth, gas exchange and biochemical traits of young B. excelsa plants were affected by imposed drought stress and subsequent rehydration. Four-month-old young plants were acclimated in a greenhouse for 15 days and received daily irrigation, after this period they were separated into two treatment: well-watered (control plants, WW) and water deficit (drought-stressed plants, DS). After 58 days of water deficit, the net photosynthetic rate (P n ) of the plants in the DS treatment regime reached values close to zero, water use efficiency significantly increased, and midday leaf water potential (Ѱ leaf ) reached a mean value of −4.7 MPa. The recovery of P n and Ѱ leaf to control levels was re-established after 16 days of rehydration. The DS treatment regime led to lower level of biomass (37%) when compared to plants in the WW treatment regime. The DS treatment plants had higher leaf concentrations of total soluble sugars, whereas the starch content was higher in the WW treatment regime. Our results suggest that (i) B. excelsa has a high physiological plasticity with respect to drought stress and (ii) the recovery of physiological traits was followed by the recovery of the absolute growth rates of the DS plants in the short term. These ecophysiological responses demonstrate the strong potential of this species for establishment in forest plantations in the Amazon region and its resilience during drought events. © 2019 Elsevier Gmb

Fertilization and seasonality influence on the photochemical performance of tree legumes in forest plantation for area recovery in the Amazon.

N-fixing leguminous species can reach atmospheric dinitrogen gas (N2), having an advantage under N-limited degraded environments. These N-fixers are constantly used as facilitative species. Chlorophyll a fluorescence (ChF) acknowledges how different species take up and use light energy during photosynthesis. These techniques assess stress and performance responses to photosynthesis and are used for the selection of species with potential for reforestation. Six Fabaceae species were selected for this study: three nonfixing species (Cenostigma tocantinum, Senna reticulata and Dipteryx odorata) and three N-fixing species (Clitoria fairchildiana, Inga edulis and Acacia spp.). Variations in chlorophyll fluorescence under high vs. low water and nutrient conditions were studied. Multivariate analysis was performed to detect the effects of seasonality and fertilization on dark-adapted ChF two years after the experiment was established. The correlation among ChF variables and growth, photosynthesis and foliar nutrient concentrations was evaluated. Under high water- and nutrient-availability conditions, plants exhibited an enhanced performance index on absorption basis values correlated with electron transport fluxes. Under drought and nutrient-poor conditions, most species exhibit increased energy dissipation as photoprotection. High interspecific variation was found; therefore, species-specific responses should be considered in future ChF studies. Corroborating the ability to colonize high-light environments, N-fixers showed an increased performance index correlated with electron transport and Zn and N foliar concentrations. Negative correlations were found between photosynthesis and trapped fluxes. Diameter growth was positively correlated with electron transport fluxes. Given the different responses among species, ChF is an effective technique to screen for seasonality, fertilization and species effects and should be considered for use during forest restoration. Finally, the addition of fertilization treatments may facilitate tropical forest restoration due to the importance of nutrients in physiological processes. N-fixers showed high photochemical performance and tolerance to abiotic stress in degraded areas and therefore should be included to support ecosystem biomass restoration