Contributors: Gripenberg, Sofia, Basset, Yves, Lewis, Owen T., Terry, J. Christopher D., Wright, S. Joseph, Simón, Indira, Fernández, D. Catalina, Cedeño-Sanchez, Marjorie, Rivera, Marleny, Barrios, Héctor
... The top-down and indirect effects of insects on plant communities depend on patterns of host use, which are often poorly documented, particularly in species-rich tropical forests. At Barro Colorado Island, Panama, we compiled the first food web quantifying trophic interactions between the majority of co-occurring woody plant species and their internally feeding insect seed predators. Our study is based on more than 200 000 fruits representing 478 plant species, associated with 369 insect species. Insect host-specificity was remarkably high: only 20% of seed predator species were associated with more than one plant species, while each tree species experienced seed predation from a median of two insect species. Phylogeny, but not plant traits, explained patterns of seed predator attack. These data suggest that seed predators are unlikely to mediate indirect interactions such as apparent competition between plant species, but are consistent with their proposed contribution to maintaining plant diversity via the Janzen-Connell mechanism.
Bryophyte stable isotope composition, diversity and biomass define tropical montane cloud forest extent
Contributors: Horwath, Aline B., Royles, Jessica, Tito, Richard, Gudiño, José A., Salazar Allen, Noris, Farfan-Rios, William, Rapp, Joshua M., Silman, Miles R., Malhi, Yadvinder, Swamy, Varun
... Liverworts and mosses are a major component of the epiphyte flora of tropical montane forest ecosystems. Canopy access was used to analyse the distribution and vertical stratification of bryophyte epiphytes within tree crowns at nine forest sites across a 3400 m elevational gradient in Peru, from the Amazonian basin to the high Andes. The stable isotope compositions of bryophyte organic material (13C/12C and 18O/16O) are associated with surface water diffusive limitations and, along with C/N content, provide a generic index for the extent of cloud immersion. From lowland to cloud forest Î´13C increased from -33â ° to -27â °, while Î´18O increased from 16.3â ° to 18.0â °. Epiphytic bryophyte and associated canopy soil biomass in the cloud immersion zone was estimated at up to 45 t dry mass ha-1, and overall water holding capacity was equivalent to a 20 mm precipitation event. The study emphasizes the importance of diverse bryophyte communities in sequestering carbon in threatened habitats, with stable isotope analysis allowing future elevational shifts in the cloud base associated with changes in climate to be tracked.
Contributors: Kimball, Rebecca T., Oliveros, Carl H., Wang, Ning, White, Noor D., Barker, F. Keith, Field, Daniel J., Ksepka, Daniel T., Chesser, R. Terry, Moyle, Robert G., Braun, Michael J.
... It has long been appreciated that analyses of genomic data (e.g., whole genome sequencing or sequence capture) have the potential to reveal the tree of life, but it remains challenging to move from sequence data to a clear understanding of evolutionary history, in part due to the computational challenges of phylogenetic estimation using genome-scale data. Supertree methods solve that challenge because they facilitate a divide-and-conquer approach for large-scale phylogeny inference by integrating smaller subtrees in a computationally efficient manner. Here, we combined information from sequence capture and whole-genome phylogenies using supertree methods. However, the available phylogenomic trees had limited overlap so we used taxon-rich (but not phylogenomic) megaphylogenies to weave them together. This allowed us to construct a phylogenomic supertree, with support values, that included 707 bird species (~7% of avian species diversity). We estimated branch lengths using mitochondrial sequence data and we used these branch lengths to estimate divergence times. Our time-calibrated supertree supports radiation of all three major avian clades (Palaeognathae, Galloanseres, and Neoaves) near the Cretaceous-Paleogene (K-Pg) boundary. The approach we used will permit the continued addition of taxa to this supertree as new phylogenomic data are published, and it could be applied to other taxa as well.
Estimating aboveground net biomass change for tropical and subtropical forests: refinement of IPCC default rates using forest plot data
Contributors: Requena Suarez, Daniela, Rozendaal, Danaë M. A., De Sy, Veronique, Phillips, Oliver L., Alvarez-Dávila, Esteban, Anderson-Teixeira, Kristina, Araujo-Murakami, Alejandro, Arroyo, Luzmila, Baker, Timothy R., Bongers, Frans
... As countries advance in greenhouse gas (GHG) accounting for climate change mitigation, consistent estimates of aboveground net biomass change (?AGB) are needed. Countries with limited forest monitoring capabilities in the tropics and subtropics rely on IPCC 2006 default ?AGB rates, which are values per ecological zone, per continent. Similarly, research on forest biomass change at large scale also make use of these rates. IPCC 2006 default rates come from a handful of studies, provide no uncertainty indications, and do not distinguish between older secondary forests and old-growth forests. As part of the 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, we incorporate ?AGB data available from 2006 onwards, comprising 176 chronosequences in secondary forests and 536 permanent plots in old-growth and managed/logged forests located in 42 countries in Africa, North and South America, and Asia. We generated ?AGB rate estimates for younger secondary forests (=20 years), older secondary forests (>20 years and up to 100 years) and old-growth forests, and accounted for uncertainties in our estimates. In tropical rainforests, for which data availability was the highest, our ?AGB rate estimates ranged from 3.4 (Asia) to 7.6 (Africa) Mg ha-1 yr-1 in younger secondary forests, from 2.3 (North and South Ameri09ca) to 3.5 (Africa) Mg ha-1 yr-1 in older secondary forests, and 0.7 (Asia) to 1.3 (Africa) Mg ha-1 yr-1 in old-growth forests. We provide a rigorous and traceable refinement of the IPCC 2006 default rates in tropical and subtropical ecological zones, and identify which areas require more research on ?AGB. In this respect, this study should be considered as an important step towards quantifying the role of tropical and subtropical forests as carbon sinks with higher accuracy; our new rates can be used for large-scale GHG accounting by governmental bodies, non-governmental organisations and in scientific research. This article is protected by copyright. All rights reserved.
Contributors: Obiang, Nestor Laurier Engone, Kenfack, David, Picard, Nicolas, Lutz, James A., Bissiengou, Pulchérie, Memiaghe, Hervé R., Alonso, Alfonso
A key to the North American genera of Stipeae (Poaceae, Pooideae) with descriptions and taxonomic names for species of Eriocoma, Neotrinia, Oloptum, and five new genera: Barkworthia, ×Eriosella, Pseudoeriocoma, Ptilagrostiella, and Thorneochloa
Contributors: Peterson, Paul M., Romaschenko, Konstantin, Soreng, Robert J., Valdés Reyna, Jesus
... Based on earlier molecular DNA studies we recognize 14 native Stipeae genera and one intergeneric hybrid in North America. We provide descriptions, new combinations, and 10 illustrations for species of Barkworthia gen. nov. , Eriocoma , Neotrinia , Oloptum , Pseudoeriocoma gen. nov. , Ptilagrostiella gen. nov. , Thorneochloa gen. nov. , and × Eriosella nothogen. nov. The following 40 new combinations are made: Barkworthiastillmanii , Eriocomaalta , E.arida , E.arnowiae , E.bloomeri , E.bracteata , E.contracta , E.coronata , E.curvifolia , E.hendersonii , E.latiglumis , E.lemmonii , E.lemmoniissp.pubescens, E.lettermanii , E.lobata , E.nelsonii , E.nelsoniissp.dorei, E.nevadensis , E.occidentalis , E.occidentalisssp.californica, E.occidentalisssp.pubescens, E.parishii , E.parishiissp.depaupertata, E.perplexa , E.pinetorum , E.richardsonii , E.robusta , E.scribneri , E.swallenii , E.thurberiana , E.wallowaensis , × Eriosellacaduca , Pseudoeriocomaacuta , P.constricta , P.editorum , P.eminens , P.hirticulmis , P.multinodis , Ptilagrostiellakingii , and Thorneochloadiegoensis . A key to the native and introduced genera of North American Stipeae, and an overview of the tribe in North America and worldwide are given. Lectotypes are designated for Eriocomacuspidata Nutt., Fendleriarhynchelytroides Steud., Stipabloomeri Bol., Stipacoronata Thurb., Stipamembranacea Pursh, Stipamormonum Mez, Stiparichardsonii Link, and Stipawilliamsii Scribn. Achnatherum s.s. and Piptatherum s.s. are now restricted to Eurasia and the Mediterranean/Asia, respectively.
Contributors: Detto, Matteo, Visser, Marco D., Wright, S. Joseph, Pacala, Stephen W.
... Data on paired seed traps from Barro Colorado Island in Panama. 200 paired traps were installed 2 m distance in March 2011 and censused weekly through February 2013 along the trails of the 50ha plot. Each trap consisted of a square ½ m2, open-topped, 1-mm mesh bag supported 0.8 to 1 m above the ground by a polyvinyl chloride frame. Fruits and seeds were identified to species, counted and further categorized as immature, mature (endosperm filled), or damaged by animals. PART definitions: 0 reproductive buds, 1 mature fruit, 2 seeds, 3 capsules, 4 fragments, 5 immature fruit, 6 flowers (female or perfect), 7 fruit with insect emergence holes / insect damaged, 8 aborted fruit, 9 male flowers, 10 fruit eaten by animal (bird, monkey, squirrel o others), 11 category for leaves, 12 "unknown", 13 leaf pedicel, 14 fragment og branch, less than 2 cm in diameter, 15 fine litter, 16 flower pedicel, 17 fruit pedicel, 18 monkey feces.
Contributors: Kitchell, Kenneth, Jr., Dundee, Harold A.