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Rossi, V., Dolley, T., Cornu, G., Guitet, S., & Herault, B. (2015). GuyaSim : un outil d’aide à la décision pour l’aménagement d’un territoire forestier, la Guyane. Bois et Forets des Tropiques, 326(4), 67–78.
Abstract: Planning policies for rapid development in French Guiana will require the conversion of forested areas, thus contributing to glo- bal warming. Guiana’s policy-makers will need to integrate the preservation of eco- system services into their planning deci- sions. The GuyaSim project was conduc- ted to produce more in-depth knowledge on these services (carbon sequestration, biodiversity and soil quality) and to trans- fer a software application, GuyaSim, to policy-makers to facilitate the use of this knowledge in the development of plan- ning policies. This article presents the characteristics of the application. Guya- Sim is a freeware package of the GIS type designed initially for local authority plan- ners and forestry departments in French Guiana. The application has two main functions:
information delivery and sup-
port for planning decisions. The informa- tion provided includes socio-economic development scenarios, climate scenarios and valuations of ecosystem services. The decision-support component consists of tools for building planning scenarios (land use changes) and forestry scenarios (log- ging), with information on their environ- mental impacts. The functionalities of the software are currently limited by the state of knowledge on Guiana’s ecosystems. Advances made through current research projects are expected to upgrade the application in the medium term.
Keywords: GIS software; scenarios; ecosystem services; simulator; biodiversity; carbon stock; biomass; logging; deforestation; land use changes; tropical forest; French Guiana
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Amusant, N., Digeon, A., Descroix, L., Bruneau, O., Bezard, V., & Beauchene, J. (2015). Planting rosewood for sustainable essential oil production: Influence of surrounding forest and seed provenance on tree growth and essential oil yields. Bois et Forets des Tropiques, 326(4), 57–65.
Abstract: Essential oil from the Amazonian rosewood tree (Aniba rosaeodora Ducke) is valued as an important aromatic ingredient in luxury perfumes. Due to over-harvesting in recent decades, rosewood is now listed as an endangered species. Rosewood tree planting is now considered a viable alternative to logging as it can support both reforestation and sustainable agriculture thanks to sales of the essential oil extracted. We planted 605 rosewood trees in French Guiana from two seeds of local provenance, in a 5 445 m2 plot surrounded by primary forest. Nine years after planting, we assessed the effect of the position of the tree relative to the surrounding forest and of the seed provenance on dendrometric traits (height, circumference, above ground woody biomass) and hence on the yield of essential oil. Measurements were made on 99 trees. Average growth rates for the young trees were 0.7 m/year in height, 2.5 cm/year in stem circumference and 990.5 kg dry mass/ha/year in aboveground biomass, while essential oil yields ranged from 0.6% to 3.6% with a mean of 2.1%. The position of the tree relative to the surrounding forest was the main factor affecting tree growth and essential oil production: trees located close to the surrounding forest were significantly smaller and accumulated less essential oil due to the reduced availability of light. Seed provenance had less effect on dendrometric traits and essential oil yields. In conclusion, although planting practices will need to be adapted to avoid the edge effects of proximity to the forest, short-rotation cultivation of rosewood trees could be the optimum and most economically attractive system for the production of essential oil.
Keywords: Aniba rosaeodora Ducke; Dendrometric traits; Essential oil yield; French Guiana; Light effect; Plantation; Rosewood; Seed provenance
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Tremolieres, M., Noel, V., & Herault, B. (2009). Phosphorus and nitrogen allocation in Allium ursinum on an alluvial floodplain (Eastern France). Is there an effect of flooding history? Plant Soil, 324(1-2), 279–289.
Abstract: The change in phosphorus and nitrogen content in a common geophyte spring species, Allium ursinum, is studied in alluvial forests in relation to three flooding histories related to river regulation: (1) annually flooded, (2) unflooded for 30 years, and (3) unflooded for 200 years. Flood suppression leads to a reduction of available P soil content as well as decreasing the biomass and the amount of phosphorus in plants, but has no significant effect on N plant content. Plant N:P ratio increases with the suppression of floods and is primarily driven by soil N:P ratios, in turn markedly linked to the total nitrogen in the soil. We highlighted a lower nutrient accumulation in leaves during plant growth in unflooded forests. Overall, our results suggest that P was the main limiting factor in unflooded forests while nitrogen was the main limiting factor in annually flooded forests. Flood suppression strongly affects the morphology and nutrient uptake by Allium ursinum and thus nutrient cycling in riverine forests.
Keywords: Allium ursinum; Flooding history; Nitrogen; Nutrient bioavailability; Phosphorus; Rhine
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Phillips, O. L., Aragao, L. E. O. C., Lewis, S. L., Fisher, J. B., Lloyd, J., Lopez-Gonzalez, G., et al. (2009). Drought Sensitivity of the Amazon Rainforest. Science, 323(5919), 1344–1347.
Abstract: Amazon forests are a key but poorly understood component of the global carbon cycle. If, as anticipated, they dry this century, they might accelerate climate change through carbon losses and changed surface energy balances. We used records from multiple long-term monitoring plots across Amazonia to assess forest responses to the intense 2005 drought, a possible analog of future events. Affected forest lost biomass, reversing a large long-term carbon sink, with the greatest impacts observed where the dry season was unusually intense. Relative to pre-2005 conditions, forest subjected to a 100-millimeter increase in water deficit lost 5.3 megagrams of aboveground biomass of carbon per hectare. The drought had a total biomass carbon impact of 1.2 to 1.6 petagrams (1.2 x 10(15) to 1.6 x 10(15) grams). Amazon forests therefore appear vulnerable to increasing moisture stress, with the potential for large carbon losses to exert feedback on climate change.
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Brechet, L., Ponton, S., Roy, J., Freycon, V., Couteaux, M. M., Bonal, D., et al. (2009). Do tree species characteristics influence soil respiration in tropical forests? A test based on 16 tree species planted in monospecific plots. Plant Soil, 319(1-2), 235–246.
Abstract: The high spatial variability of soil respiration in tropical rainforests is well evaluated, but influences of biotic factors are not clearly understood. This study underlines the influence of tree species characteristics on soil respiration across a 16-monospecific plot design in a tropical plantation of French Guiana. A large variability of soil CO2 fluxes was observed among plots (i.e. 2.8 to 6.8 μmol m(-2) s(-1)) with the ranking being constant across seasons. There were no significant relationships between soil respiration and soil moisture or soil temperature, neither spatially, nor seasonally. The variability of soil respiration was mainly explained by quantitative factors such as leaf litterfall and basal area. Surprisingly, no significant relationship was observed between soil respiration and root biomass. However, the influence of substrate quality was revealed by a strong relationship between soil respiration and litterfall P (and litterfall N, to a lesser extent).
Keywords: Fine root; Litter quality; Nutrient cycling; Plant soil interactions; Soil respiration; Tropical plantations
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Prevost-Boure, N. C., Ngao, J., Berveiller, D., Bonal, D., Damesin, C., Dufrene, E., et al. (2009). Root exclusion through trenching does not affect the isotopic composition of soil CO2 efflux. Plant Soil, 319(1-2), 1–13.
Abstract: Disentangling the autotrophic and heterotrophic components of soil CO2 efflux is critical to understanding the role of soil system in terrestrial carbon (C) cycling. In this study, we combined a stable C-isotope natural abundance approach with the trenched plot method to determine if root exclusion significantly affected the isotopic composition (delta C-13) of soil CO2 efflux (R-S). This study was performed in different forest ecosystems: a tropical rainforest and two temperate broadleaved forests, where trenched plots had previously been installed. At each site, R-S and its delta C-13 (delta C-13(Rs)) tended to be lower in trenched plots than in control plots. Contrary to R-S, delta C-13(Rs) differences were not significant. This observation is consistent with the small differences in delta C-13 measured on organic matter from root, litter and soil. The lack of an effect on delta C-13(Rs) by root exclusion could be from the small difference in delta C-13 between autotrophic and heterotrophic soil respirations, but further investigations are needed because of potential artefacts associated with the root exclusion technique.
Keywords: Stable carbon isotopes; Natural abundance; Soil respiration; Trenched plot; Rainforest; Temperate forest
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Orivel, J., Corbara, B., & Dejean, A. (2010). Constraints and adaptation in the arboreal life of ants. Biofutur, 315, 34–37.
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Leroy, C., Cereghino, R., Camas, J. F., Pelozuelo, L., Dejean, A., & Corbara, B. (2010). Several aspects of the life of vascular epiphytes. Biofutur, 315, 38–41.
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Rockwell, C. A., Kainer, K. A., d'Oliveira, M. V. N., Staudhammer, C. L., & Baraloto, C. (2014). Logging in bamboo-dominated forests in southwestern Amazonia: Caveats and opportunities for smallholder forest management. For. Ecol. Manage., 315, 202–210.
Abstract: Guadua sarcocarpa and Guadua weberbaueri (Poaceae: Bambuseae) have a negative influence on tree regeneration and recruitment in bamboo-dominated forests of southwestern Amazonia. The lack of advanced regeneration and sparse canopy in this forest type present a considerable challenge for developing sustainable timber management plans. We conducted field studies in the Porto Dias Agroextractive Settlement Project in Acre, Brazil to assess influences of logging in bamboo-dominated forest sites. Taxonomic composition, stand structure, aboveground biomass, commercial timber volume, and commercial tree seedling and bamboo culm density were compared between five logged vs. unlogged sites in different landholdings, using modified 0.5. ha Gentry plots. No differences in taxonomic composition, aboveground biomass, adult and juvenile stem density, or woody seedling and bamboo culm density were detected between paired logged and unlogged sites. Commercial timber volume, however, was reduced by almost two-thirds in logged plots, suggesting that long-term timber management goals in this forest type are compromised since so few future crop trees remained onsite. Our findings indicate that in order to maximize local management objectives, community forest managers must approach logging in bamboo-dominated forests with caution. We suggest an integration of non-timber forest product extraction with low harvest intensity and low-impact logging, tending of natural regeneration, and diversification of commercial species. © 2014 Elsevier B.V.
Keywords: Bamboo; Community forest management; Guadua; Logging; Timber management; Tropical forest
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Melieres, M. A., Pourchet, M., Charles-Dominique, P., & Gaucher, P. (2003). Mercury in canopy leaves of French Guiana in remote areas. Sci. Total Environ., 311(1-3), 261–267.
Abstract: A study of total Hg concentration in the foliage of the canopy was carried out in two remote areas in French Guiana. The sampled canopy is representative of the French Guiana canopy. The concentration in the foliage, 64+/-14 ng g(-1) (dry wt.), is used to estimate the annual input of total Hg to the soil through the litterfall, found to be 45+/-10 mug m(-2) y(-1). As translocation is negligible, mercury in the canopy originates mainly from atmospheric uptake by the leaves and this litterfall deposit represents a direct atmospheric input from the background atmospheric load into the soil. (C) 2003 Elsevier Science B.V. All rights reserved.
Keywords: mercury; canopy; rainforest; Hg atmosphere soil transfer
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