Soil pyrogenic carbon in southern Amazonia: Interaction between soil, climate, and above-ground biomass

The Amazon forest represents one of the world’s largest terrestrial carbon reservoirs. Here, we evaluated the role of soil texture, climate, vegetation, and distance to savanna on the distribution and stocks of soil pyrogenic carbon (PyC) in intact forests with no history of recent fire spanning the southern Amazonia forest-Cerrado Zone of Transition (ZOT). In 19 one hectare forest plots, including three Amazonian Dark Earth (ADE, terra preta) sites with high soil PyC, we measured all trees and lianas with diameter ≥ 10 cm and analyzed soil physicochemical properties, including texture and PyC stocks. We quantified PyC stocks as a proportion of total organic carbon using hydrogen pyrolysis. We used multiple linear regression and variance partitioning to determine which variables best explain soil PyC variation. For all forests combined, soil PyC stocks ranged between 0.9 and 6.8 Mg/ha to 30 cm depth (mean 2.3 ± 1.5 Mg/ha) and PyC, on average, represented 4.3% of the total soil organic carbon (SOC). The most parsimonious model (based on AICc) included soil clay content and above-ground biomass (AGB) as the main predictors, explaining 71% of soil PyC variation. After removal of the ADE plots, PyC stocks ranged between 0.9 and 3.8 Mg/ha (mean 1.9 ± 0.8 Mg/ha–1) and PyC continued to represent ∼4% of the total SOC. The most parsimonious models without ADE included AGB and sand as the best predictors, with sand and PyC having an inverse relationship, and sand explaining 65% of the soil PyC variation. Partial regression analysis did not identify any of the components (climatic, environmental, and edaphic), pure or shared, as important in explaining soil PyC variation with or without ADE plots. We observed a substantial amount of soil PyC, even excluding ADE forests; however, contrary to expectations, soil PyC stocks were not higher nearer to the fire-dependent Cerrado than more humid regions of Amazonia. Our findings that soil texture and AGB explain the distribution and amount of soil PyC in ZOT forests will help to improve model estimates of SOC change with further climatic warming

Necromass in forests of Madre de Dios, Peru: a comparison between terra firme and lowland forests

La cantidad de madera muerta o necromasa representa una importante porción de la biomasa y de los nutrientes en los bosques tropicales. Los objetivos de este estudio son: 1) hacer una evaluación y comparación entre la necromasa de los bosques de altura o tierra firme y los bosques inundables o bajíos, (2) estudiar las relaciones entre la necromasa, la biomasa aérea y la densidad de madera del bosque, y (3) proporcionar una primera estimación de la necromasa para todo el departamento de Madre de Dios. La necromasa gruesa y la masa aérea vegetativa fueron estudiados en tres diferentes lugares utilizando parcelas permanentes y líneas de intersección. El promedio del volumen de madera muerta gruesa fue de 72,9 m3 ha-1, con un peso entre 24,8 y 30,7 Mg ha-1 dependiendo de la densidad de madera muerta usada en los cálculos. Los bosques de tierra firme contienen significativamente más madera muerta que los bosques inundables. La necromasa constituye 11% de la masa aérea vegetativa almacenada en los bosques de Madre de Dios. Finalmente, se estima que el departamento de Madre de Dios contiene alrededor de 100 mega toneladas de carbono en su madera muerta. Este valor es bastante alto, siendo diez veces más que la emisión anual de combustibles fósiles de Perú entre 2000 – 2008. Esta substancial porción de la necromasa enfatiza la importancia de estos tipos de estudios de campo, considerando que este componente de carbono en el bosque tropical no se logra detectar con otros métodos como la detección remota por satélites.Stocks of dead wood or necromass represent an important portion of biomass and nutrients in tropical forests. The objectives of this study were: 1) to evaluate and compare the necromass of “terra firme” and lowlands forests, (2) to study the relationship between necromass, above-ground biomass and wood density, and (3) to estimate the necromass of the department of Madre de Dios, Peru. Stocks of necromass and above-ground biomass were estimated at three different locations using permanent plots and line intercept transects. The average volume of necromass for the three sites was 72.9 m3 ha-1 with an average weight varying between 24.8 and 30.7 Mg ha-1, depending on the estimations of dead wood density used for the calculations. Terra firme forests had significantly higher stocks of necromass than lowland forests. The amount of necromass was 11% of the total above-ground biomass in Madre de Dios forests. The total stock of carbon stored in dead wood for the entire department of Madre de Dios was estimated to be approximately 100 mega tonnes of carbon. This is ten times more than the annual fossil fuel emissions of Peru between 2000 and 2008. The substantial stocks of necromass emphasize the importance of these types of field studies, considering that this component of tropical forest carbon cannot be detected using other methods such as satellite remote sensing

Estimating above ground net biomass change in tropical and subtropical forests: refinement of IPCC default values using forest plot data

As countries advance in greenhouse gas (GHG) accounting for climate change mitigation, consistent estimates of above ground biomass (AGB) net change are needed for the tropics and subtropics. Countries with limited forest monitoring capabilities rely on 2006 IPCC default AGB net change values, which are averages per ecological zone, per continent. These previous defaults come from single studies, provide no uncertainty indications, and aggregate old secondary forests and old-growth forests. In this study, we update these default values using forest plot data. In comparison with previous estimates, new values include data published from 2006 onwards, are derived from multiple sites per global ecological zone, provide measures of variation, and divide forests >20 years old into older secondary forests and old-growth forests. We compiled 176 AGB chronosequences in secondary forests and AGB net change rates from 536 permanent plots in old-growth and managed or logged forests. In this dataset, across all continents and ecozones, AGB net change rates in younger secondary forests (go years) are higher than rates in older secondary (>20 years and ≤100 years) forests and managed or logged forests, which in turn are higher than rates in old-growth forests (> 100 years). Data availability is highest for North and South America, followed by Asia then Africa. We provide a rigorous and traceable refinement of the IPCC 2006 AGB net change default rates, identify which areas in the tropics and subtropics require more research on AGB change, and reflect on possibilities for improvement as more data becomes available

An assessment of soil phytolith analysis as a palaeoecological tool for identifying pre-Columbian land use in Amazonian rainforests

Phytolith analysis is a well-established archaeobotanical tool, having provided important insights into pre-Columbian crop cultivation and domestication across Amazonia through the Holocene. Yet, its use as a palaeoecological tool is in its infancy in Amazonia and its effectiveness for reconstructing pre-Columbian land-use beyond archaeological sites (i.e., ‘off-site’) has so far received little critical attention. This paper examines both new and previously published soil phytolith data from SW Amazonia to assess the robustness of this proxy for reconstructing pre-Columbian land-use. We conducted the study via off-site soil pits radiating 7.5 km beyond a geoglyph in Acre state, Brazil, and 50 km beyond a ring-ditch in northern Bolivia, spanning the expected gradients in historical land-use intensity. We found that the spatio-temporal patterns in palm phytolith data across our soil-pit transects support the hypothesis that pre-Columbian peoples enriched their forests with palms over several millennia, although phytoliths are limited in their ability to capture small-scale crop cultivation and deforestation. Despite these drawbacks, we conclude that off-site soil phytolith analysis can provide novel insights into pre-Columbian land use, provided it is effectively integrated with other land-use (e.g., charcoal) and archaeological data

The Linkages Between Photosynthesis, Productivity, Growth and Biomass in Lowland Amazonian Forests

Understanding the relationship between photosynthesis, net primary productivity and growth in forest ecosystems is key to understanding how these ecosystems will respond to global anthropogenic change, yet the linkages among these components are rarely explored in detail. We provide the first comprehensive description of the productivity, respiration and carbon allocation of contrasting lowland Amazonian forests spanning gradients in seasonal water deficit and soil fertility. Using the largest data set assembled to date, ten sites in three countries all studied with a standardized methodology, we find that (i) gross primary productivity (GPP) has a simple relationship with seasonal water deficit, but that (ii) site-to-site variations in GPP have little power in explaining site-to-site spatial variations in net primary productivity (NPP) or growth because of concomitant changes in carbon use efficiency (CUE), and conversely, the woody growth rate of a tropical forest is a very poor proxy for its productivity. Moreover, (iii) spatial patterns of biomass are much more driven by patterns of residence times (i.e. tree mortality rates) than by spatial variation in productivity or tree growth. Current theory and models of tropical forest carbon cycling under projected scenarios of global atmospheric change can benefit from advancing beyond a focus on GPP. By improving our understanding of poorly understood processes such as CUE, NPP allocation and biomass turnover times, we can provide more complete and mechanistic approaches to linking climate and tropical forest carbon cycling

Rarity of monodominance in hyperdiverse Amazonian forests.

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors

A Regional Red List of Montane Tree Species of the Tropical Andes: Trees at the top of the world

Andean montane forests are a major global conservation priority owing to their biological richness and high level of species endemism. Botanically the Andes are very rich in species but they remain relatively unstudied. In common with montane forests elsewhere in the world, Andean forests are of great value for the provision of ecosystem services relating to water supply, regulation of regional climate and the capture and storage of carbon. The forests and their component species are however under threat. This report summarises information drawn from a wide variety of sources to provide a regional Red List of trees of Andean tropical montane forests. The species evaluation process has drawn on published national red lists of threatened species, botanical literature, specimen databases, forestry information and expert knowledge. The IUCN Red List Categories and Criteria have been used for the evaluation and a component of Natalia?s PhD study has been to evaluate their use for species with limited and dispersed data. Understanding the geographical distribution of the species is very important in conservation assessment. The maps produced for this study are a valuable starting point for the Red Listing and a baseline for monitoring impacts of climate change. In this assessment 70 species are recorded as globally threatened based on the IUCN Red List of Categories and Criteria out of 127 tree species evaluated. In addition 165 national endemic trees of the region have previously been evaluated as globally threatened based on the same IUCN process. In total therefore 235 tree species are currently considered to be threatened with extinction within the Andean montane forests.Fil: Tejedor Garavito , Natalia. Bournemouth University; Reino UnidoFil: Álvarez Dávila, Esteban. Jardín Botánico de Medellín; ColombiaFil: Caro, Sandra Arango. Missouri Botanical Garden; Estados UnidosFil: Murakami, Alejandro Araujo. Museo de Historia Natural Noel Kempff Mercado; BoliviaFil: Baldeón, Severo. Universidad Nacional Mayor de San Marcos; PerúFil: Beltrán, Hamilton. Universidad Nacional Mayor de San Marcos; PerúFil: Blundo, Cecilia Mabel. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Laboratorio de Investigaciones Ecológicas de las Yungas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: Boza Espinoza, Tatiana Erika. Missouri Botanical Garden; Estados UnidosFil: Fuentes Claros, Alfredo. Herbario Nacional de Bolivia; BoliviaFil: Gaviria, Juan. Universidad de Los Andes; VenezuelaFil: Gutiérrez, Néstor. Universidad de Los Andes; VenezuelaFil: Khela, Sonia. Botanic Gardens Conservation International; Reino UnidoFil: León, Blanca. University of Texas at Austin; Estados UnidosFil: la Torre Cuadros, Maria De Los Angeles. Universidad Nacional Agraria; PerúFil: López Camacho, René. Universidad Distrital; ColombiaFil: Malizia, Lucio Ricardo. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias. Centro de Estudios Ambientales Territoriales y Sociales; ArgentinaFil: Millán, Betty. Universidad Nacional Mayor de San Marcos; PerúFil: Moraes R., Mónica. Herbario Nacional de Bolivia; BoliviaFil: Newton, Adrian C.. Bournemouth University; Reino UnidoFil: Pacheco, Silvia. Fundación Proyungas; ArgentinaFil: Reynel, Carlos. Universidad Nacional Agraria; PerúFil: Ulloa Ulloa, Carmen. Missouri Botanical Garden; Estados UnidosFil: Vacas Cruz,Omar. Pontificia Universidad Católica del Ecuador; Ecuado

Seasonal trends of Amazonian rainforest phenology, net primary productivity, and carbon allocation.:Seasonal trends of Amazonian forests.

The seasonality of solar irradiance and precipitation may regulate seasonal variations in tropical forests carbon cycling. Controversy remains over their importance as drivers of seasonal dynamics of net primary productivity in tropical forests. We use ground data from nine lowland Amazonian forest plots collected over 3 years to quantify the monthly primary productivity (NPP) of leaves, reproductive material, woody material, and fine roots over an annual cycle. We distinguish between forests that do not experience substantial seasonal moisture stress (“humid sites”) and forests that experience a stronger dry season (“dry sites”). We find that forests from both precipitation regimes maximize leaf NPP over the drier season, with a peak in production in August at both humid (mean 0.39 ± 0.03 Mg C ha−1 month−1 in July, n = 4) and dry sites (mean 0.49 ± 0.03 Mg C ha−1 month−1 in September, n = 8). We identify two distinct seasonal carbon allocation patterns (the allocation of NPP to a specific organ such as wood leaves or fine roots divided by total NPP). The forests monitored in the present study show evidence of either (i) constant allocation to roots and a seasonal trade-off between leaf and woody material or (ii) constant allocation to wood and a seasonal trade-off between roots and leaves. Finally, we find strong evidence of synchronized flowering at the end of the dry season in both precipitation regimes. Flower production reaches a maximum of 0.047 ± 0.013 and 0.031 ± 0.004 Mg C ha−1 month−1 in November, in humid and dry sites, respectively. Fruitfall production was staggered throughout the year, probably reflecting the high variation in varying times to development and loss of fruit among species

Large range sizes link fast life histories with high species richness across wet tropical tree floras

Additional co-authors: Luzmila Arroyo, Peter Ashton, Suspense A. Averti Ifo, Gerardo A. C. Aymard, Michel Baisie, William Balee, Michael Balinga, Lindsay F. Banin, Olaf Banki, Christopher Baraloto, Jorcely Barroso, Jean-Francois Bastin, Hans Beeckman, Serge Begne, Natacha Nssi Bengone, Nicholas Berry, Wemo Betian, Vincent Bezard, Lilian Blanc, Pascal Boeckx, Damien Bonal, Frans Bongers, Francis Q. Brearley, Roel Brienen, Foster Brown, Musalmah Bt. Nasaradin, Benoit Burban, David F. R. P. Burslem, Plinio Camargo, Jose Luis Camargo, Wendeson Castro, Carlos Ceron, Victor Chama Moscoso, Colin Chapman, Jerome Chave, Eric Chezeaux, Murray Collins, James Comiskey, David Coomes, Fernando Cornejo Valverde, Flavia R. C. Costa, Aida Cuni-Sanchez, Lola da Costa, Douglas C. Daly, Martin Dančák, Armandu Daniels, Greta Dargie, Stuart Davies, Charles De Canniere, Thales de Haulleville, Jhon del Aguila Pasquel, Geraldine Derroire, Kyle G. Dexter, Anthony Di Fiore, Marie-Noel K. Djuikouo, Jean-Louis Doucet, Vincent Droissart, Gerald Eilu, Thaise Emillio, Julien Engel, Bocko Yannick Enock, Fidele Evouna Ondo, Corneille Ewango, Sophie Fauset, Ted R. Feldpausch, Muhammad Fitriadi, Gerardo Flores Llampazo, Ernest G. Foli, Gabriella Fredriksson, David R.Galbraith, Martin Gilpin, Emanuel Gloor, Christelle Gonmadje, Rene Guillen Villaroel, Jefferson Hall, Keith C. Hamer, Alan Hamilton, Olivier Hardy, Terese Hart, Radim Hédl, Rafael Herrera, Niro Higuchi, Claude Marcel Hladik, Eurídice Honorio Coronado, Isau Huamantupa-Chuquimaco, Walter Huaraca Huasco, Wannes Hubau, Muhammad Idhamsyah, Sascha A. Ismail, Eliana Jimenez, Tommaso Jucker, Elizabeth Kearsley, Lip Khoon Kho, Timothy Killeen, Kanehiro Kitayama, William Laurance, Susan Laurance, Miguel Leal, Simon L. Lewis, Stanislav Lhota, Jeremy Lindsell, Gabriela Lopez-Gonzalez, Jon Lovett, Richard Lowe, William E. Magnusson, Jean-Remy Makana, Yadvinder Malhi, Beatriz Marimon, Ben Hur Marimon Junior, Andrew Marshall, Colin Maycock, Faustin Mbayu, Casimiro Mendoza, Irina Mendoza Polo, Faizah Metali, Vianet Mihindou, Abel Monteagudo-Mendoza, Sam Moore, Patrick Mucunguzi, Jacques Mukinzi, Pantaleo Munishi, Laszlo Nagy, Petrus Naisso, David Neill, Adriano Nogueira Lima, Percy Nunez Vargas, Lucas Ojo, Walter Palacios, Nadir Pallqui Camacho, Alexander Parada Gutierrez, Julie Peacock, Kelvin S.-H. Peh, Antonio Pena Cruz, Colin Pendry, Toby Pennington, Maria Cristina Penuela-Mora, Pascal Petronelli, Oliver L. Phillips, Georgia Pickavance, G. John Pipoly, Nigel Pitman, Axel Dalberg Poulsen, Ghillean T. Prance, Adriana Prieto, Richard B. Primack, Lan Qie, Simon A. Queenborough, Terry Sunderland, Carlos Quesada, Freddy Ramirez Arevalo, Hirma Ramirez-Angulo, Jan Reitsma, Maxime Réjou-Méchain, Anand Roopsind, Francesco Rovero, Ervan Rutishauser, Kamariah Abu Salim, Rafael Salomao, Ismayadi Samsoedin, Muhd Shahruney Saparudin, Juliana Schietti, Ricardo A. Segovia, Julio Serrano, Rafizah Serudia, Douglas Sheil, Natalino Silva, Javier Silva Espejo, Marcos Silveira, Murielle Simo-Droissart, James Singh, Bonaventure Sonké, Thaise Emilio Lopes De Sousa, Juliana Stropp, Rahayu Sukri, Terry Sunderland, Martin Svátek, Michael Swaine, Hermann Taedoumg, Joey Talbot, Sylvester Tan, James Taplin, David Taylor, Hans ter Steege, John Terborgh, Armando Torres-Lezama, John Tshibamba Mukendi, Darlington Tuagben, Peter van de Meer, Geertje van der Heijden, Peter van der Hout, Mark van Nieuwstadt, Bert van Ulft, Rodolfo Vasquez Martinez, Ronald Vernimmen, Barbara Vinceti, Simone Vieira, Ima Celia Guimaries Vieira, Emilio Vilanova Torre, Jason Vleminckx, Lee White, SimonWillcock, Mathew Williams, John T. Woods, Tze Leong Yao, Ishak Yassir, Roderick Zagt& Lise Zemagh