Publication Search Results

ID: 159406
Type: article
Authors: Darragh, Kathy; Orteu, Anna; Black, Daniella; Byers, Kelsey J. R. P.; Szczerbowski, Daiane; Warren, Ian A.; Rastas, Pasi; Pinharanda, Ana; Davey, John W.; Fernanda Garza, Sylvia; Abondano Almeida, Diana; Merrill, Richard M.; McMillan, W. Owen; Schulz, Stefan; Jiggins, Chris D.
Abstract: Plants and insects often use the same compounds for chemical communication, but not much is known about the genetics of convergent evolution of chemical signals. The terpene (E)-beta-ocimene is a common component of floral scent and is also used by the butterfly Heliconius melpomene as an anti-aphrodisiac pheromone. While the biosynthesis of terpenes has been described in plants and microorganisms, few terpene synthases (TPSs) have been identified in insects. Here, we study the recent divergence of 2 species, H. melpomene and Heliconius cydno, which differ in the presence of (E)-beta-ocimene; combining linkage mapping, gene expression, and functional analyses, we identify 2 novel TPSs. Furthermore, we demonstrate that one, HmelOS, is able to synthesise (E)-beta-ocimene in vitro. We find no evidence for TPS activity in HcydOS (HmelOS ortholog of H. cydno), suggesting that the loss of (E)-beta-ocimene in this species is the result of coding, not regulatory, differences. The TPS enzymes we discovered are unrelated to previously described plant and insect TPSs, demonstrating that chemical convergence has independent evolutionary origins.

ID: 158553
Type: article
Authors: Davies, Stuart J.; Abiem, Iveren; Abu Salim, Kamariah; Aguilar, Salomon; Allen, David; Alonso, Alfonso; Anderson-Teixeira, Kristina; Andrade, Ana; Arellano, Gabriel; Ashton, Peter S.; Baker, Patrick J.; Baker, Matthew E.; Baltzer, Jennifer L.; Basset, Yves; Bissiengou, Pulcherie; Bohlman, Stephanie; Bourg, Norman A.; Brockelman, Warren Y.; Bunyavejchewin, Sarayudh; Burslem, David F. R. P.; Cao, Min; Cardenas, Dairon; Chang, Li-Wan; Chang-Yang, Chia-Hao; Chao, Kuo-Jung; Chao, Wei-Chun; Chapman, Hazel; Chen, Yu-Yun; Chisholm, Ryan A.; Chu, Chengjin; Chuyong, George; Clay, Keith; Comita, Liza S.; Condit, Richard; Cordell, Susan; Dattaraja, Handanakere S.; de Oliveira, Alexandre Adalardo; den Ouden, Jan; Detto, Matteo; Dick, Christopher; Du, Xiaojun; Duque, Alvaro; Ediriweera, Sisira; Ellis, Erle C.; Obiang, Nestor Laurier Engone; Esufali, Shameema; Ewango, Corneille E. N.; Fernando, Edwino S.; Filip, Jonah; Fischer, Gunter A.; Foster, Robin; Giambelluca, Thomas; Giardina, Christian; Gilbert, Gregory S.; Gonzalez-Akre, Erika; Gunatilleke, I. A. U. N.; Gunatilleke, C. V. S.; Hao, Zhanqing; Hau, Billy C. H.; He, Fangliang; Ni, Hongwei; Howe, Robert W.; Hubbell, Stephen P.; Huth, Andreas; Inman-Narahari, Faith; Itoh, Akira; Janik, David; Jansen, Patrick A.; Jiang, Mingxi; Johnson, Daniel J.; Jones, F. Andrew; Kanzaki, Mamoru; Kenfack, David; Kiratiprayoon, Somboon; Kral, Kamil; Krizel, Lauren; Lao, Suzanne; Larson, Andrew J.; Li, Yide; Li, Xiankun; Litton, Creighton M.; Liu, Yu; Liu, Shirong; Lum, Shawn K. Y.; Luskin, Matthew S.; Lutz, James A.; Hong Truong Luu; Ma, Keping; Makana, Jean-Remy; Malhi, Yadvinder; Martin, Adam; McCarthy, Caly; McMahon, Sean M.; McShea, William J.; Memiaghe, Herve; Mi, Xiangcheng; Mitre, David; Mohamad, Mohizah; Monks, Logan; Muller-Landau, Helene C.; Musili, Paul M.; Myers, Jonathan A.; Nathalang, Anuttara; Ngo, Kang Min; Norden, Natalia; Novotny, Vojtech; O'Brien, Michael J.; Orwig, David; Ostertag, Rebecca; Papathanassiou, Konstantinos; Parker, Geoffrey G.; Perez, Rolando; Perfecto, Ivette; Phillips, Richard P.; Pongpattananurak, Nantachai; Pretzsch, Hans; Ren, Haibo; Reynolds, Glen; Rodriguez, Lillian J.; Russo, Sabrina E.; Sack, Lawren; Sang, Weiguo; Shue, Jessica; Singh, Anudeep; Song, Guo-Zhang M.; Sukumar, Raman; Sun, I-Fang; Suresh, Hebbalalu S.; Swenson, Nathan G.; Tan, Sylvester; Thomas, Sean C.; Thomas, Duncan; Thompson, Jill; Turner, Benjamin L.; Uowolo, Amanda; Uriarte, Maria; Valencia, Renato; Vandermeer, John; Vicentini, Alberto; Visser, Marco; Vrska, Tomas; Wang, Xugao; Wang, Xihua; Weiblen, George D.; Whitfeld, Timothy J. S.; Wolf, Y.; Wright, S. Joseph; Xu, Han; Yao, Tze Leong; Yap, Sandra L.; Ye, Wanhui; Yu, Mingjian; Zhang, Minhua; Zhu, Daoguang; Zhu, Li; Zimmerman, Jess K.; Zuleta, Daniel
Abstract: ForestGEO is a network of scientists and long-term forest dynamics plots (FDPs) spanning the Earth's major forest types. ForestGEO's mission is to advance understanding of the diversity and dynamics of forests and to strengthen global capacity for forest science research. ForestGEO is unique among forest plot networks in its large-scale plot dimensions, censusing of all stems >= 1 cm in diameter, inclusion of tropical, temperate and boreal forests, and investigation of additional biotic (e.g., arthropods) and abiotic (e.g., soils) drivers, which together provide a holistic view of forest functioning. The 71 FDPs in 27 countries include approximately 7.33 million living trees and about 12,000 species, representing 20% of the world's known tree diversity. With >1300 published papers, ForestGEO researchers have made significant contributions in two fundamental areas: species coexistence and diversity, and ecosystem functioning. Specifically, defining the major biotic and abiotic controls on the distribution and coexistence of species and functional types and on variation in species' demography has led to improved understanding of how the multiple dimensions of forest diversity are structured across space and time and how this diversity relates to the processes controlling the role of forests in the Earth system. Nevertheless, knowledge gaps remain that impede our ability to predict how forest diversity and function will respond to climate change and other stressors. Meeting these global research challenges requires major advances in standardizing taxonomy of tropical species, resolving the main drivers of forest dynamics, and integrating plot-based ground and remote sensing observations to scale up estimates of forest diversity and function, coupled with improved predictive models. However, they cannot be met without greater financial commitment to sustain the long-term research of ForestGEO and other forest plot networks, greatly expanded scientific capacity across the world's forested nations, and increased collaboration and integration among research networks and disciplines addressing forest science.

ID: 159196
Type: article
Authors: de Castro, Erika C. P.; Musgrove, Jamie; Bak, Soren; McMillan, W. Owen; Jiggins, Chris D.
Abstract: Host plant specialization is a major force driving ecological niche partitioning and diversification in insect herbivores. The cyanogenic defences of Passiflora plants keep most herbivores at bay, but not the larvae of Heliconius butterflies, which can both sequester and biosynthesize cyanogenic compounds. Here, we demonstrate that both Heliconius cydno chioneus and H. melpomene rosina have remarkable plasticity in their chemical defences. When feeding on Passiflora species with cyanogenic compounds that they can readily sequester, both species downregulate the biosynthesis of these compounds. By contrast, when fed on Passiflora plants that do not contain cyanogenic glucosides that can be sequestered, both species increase biosynthesis. This biochemical plasticity comes at a fitness cost for the more specialist H. m. rosina, as adult size and weight for this species negatively correlate with biosynthesis levels, but not for the more generalist H. c. chioneus. By contrast, H. m rosina has increased performance when sequestration is possible on its specialized host plant. In summary, phenotypic plasticity in biochemical responses to different host plants offers these butterflies the ability to widen their range of potential hosts within the Passiflora genus, while maintaining their chemical defences.

ID: 158488
Type: article
Authors: De Faria, Bruno L.; Marano, Gina; Piponiot, Camille; Silva, Carlos A.; Dantas, Vinicius de L.; Rattis, Ludmila; Rech, Andre R.; Collalti, Alessio
Abstract: In recent decades, droughts, deforestation and wildfires have become recurring phenomena that have heavily affected both human activities and natural ecosystems in Amazonia. The time needed for an ecosystem to recover from carbon losses is a crucial metric to evaluate disturbance impacts on forests. However, little is known about the impacts of these disturbances, alone and synergistically, on forest recovery time and the resulting spatiotemporal patterns at the regional scale. In this study, we combined the 3-PG forest growth model, remote sensing and field derived equations, to map the Amazonia-wide (3 km of spatial resolution) impact and recovery time of aboveground biomass (AGB) after drought, fire and a combination of logging and fire. Our results indicate that AGB decreases by 4%, 19% and 46% in forests affected by drought, fire and logging + fire, respectively, with an average AGB recovery time of 27 years for drought, 44 years for burned and 63 years for logged + burned areas and with maximum values reaching 184 years in areas of high fire intensity. Our findings provide two major insights in the spatial and temporal patterns of drought and wildfire in the Amazon: (1) the recovery time of the forests takes longer in the southeastern part of the basin, and, (2) as droughts and wildfires become more frequent-since the intervals between the disturbances are getting shorter than the rate of forest regeneration-the long lasting damage they cause potentially results in a permanent and increasing carbon losses from these fragile ecosystems.

ID: 156761
Type: article
Authors: De Guzman, Mark E.; Acosta-Rangel, Aleyda; Winter, Klaus; Meinzer, Frederick C.; Bonal, Damien; Santiago, Louis S.
Abstract: Wood density (WD) is often used as a proxy for hydraulic traits such as vulnerability to drought-induced xylem cavitation and maximum water transport capacity, with dense wooded species generally being more resistant to drought-induced xylem cavitation, having-lower rates of maximum water transport, and lower sapwood capacitance than light-wooded species. However, relationships between WD and the hydraulic traits that they aim to predict have not been well established in tropical forests, where modeling is necessary to predict drought responses for a high diversity of unmeasured species. We evaluated WD and relationships with stem xylem vulnerability by measuring cavitation curves, sapwood water release curves, and minimum seasonal water potential (Ψmin) on upper canopy branches of six tree species and three liana species from a single wet tropical forest site in Panama. The objective was to better understand coordination and trade-offs among hydraulic traits and the potential utility of these relationships for modeling purposes. We found that parameters from sapwood water release curves such as capacitance, saturated water content, and sapwood turgor loss point (Ψtlp,x) were related to WD, whereas stem vulnerability curve parameters were not. However, the water potential corresponding to 50% loss of hydraulic conductivity (P50) was related to Ψtlp,x and sapwood osmotic potential at full turgor (πo,x). Furthermore, species with lower Ψmin showed lower P50, Ψtlp,x and πo,x suggesting greater drought resistance. Our results indicate that WD is a good easy-to-measure proxy for some traits related to drought resistance, but not others. The ability of hydraulic traits such as P50 and Ψtlp,x to predict mortality must be carefully examined if WD values are to be used to predict drought responses in species without detailed physiological measurements.

ID: 159597
Type: article
Authors: de Lima, Robson Borges; Rutishauser, Ervan; Aleixo da Silva, Jose Antonio; Guedes, Marcelino Carneiro; Herault, Bruno; de Oliveira, Cinthia Pereira; Aparicio, Perseu da Silva; Sotta, Eleneide Doff; Silva da Silva, Diego Armando; Caraciolo Ferreira, Rinaldo Luiz
Abstract: Accurate estimates of commercial volume in tropical forests are key for the implementation of sustainable forest management plans. Because of the lack of local or generic volumetric equations, most forest managers and forestry services are still using traditional expansion factors (i.e., multiplication of the diameter by a given value) to estimate the volume of commercial tree species in the Amazon. Volumetric models were developed through a unique data set of 1,264 fallen trees fully measured in 150 sample plots located across a broad range of forests in Amapa, Brazil. Forest-specific volumetric models were developed and compared with a generic (i.e., across all forests) model and with published equations developed elsewhere in the Amazon. The generic equation performed well in all forest types and allowed precise predictions. The most efficient sampling design to develop volumetric models consists of measuring approximately 50 trees across four different size classes representing the whole population. The form factors (FF) developed locally generated substantial bias but performed better than the traditional FF (0.7). Overall, our results suggest that it is possible to develop accurate generic models to estimate commercial timber volume, and this study can serve as a guideline for forest managers or scientists interested in calibrating volumetric models in a cost-efficient way. Study Implications: This work provides useful information on volumetric modeling methods for Brazilian Amazon tropical forests. Most of the studies in the literature only investigate the classical modeling using regression models considering only boom metrics with or without bark, and, in this way, they provide incomplete and biased total knowledge and estimates for a given population. Therefore, detailed and accurate analyzes are crucial tools for decisionmaking. If the harvesting interventions are carried out without considering the most appropriate method to estimate the total wood stock, there may be damages or even extinction of some species, as has happened with other forest domains in Brazil and in other rainforest regions in the world. In this work, the results clearly show the importance of testing different methodologies and selecting the one best suited for a particular site, as well as carrying out techniques for the sustainable and correct management of the forest. Because the analysis procedures provide only information on how methodologies behave statistically, our results may contribute to a more refined analysis to be applied in the future in similar environments. Currently, the Brazilian forestry sector is looking for alternatives to obtain forest resources within the concept of sustainability. For the Brazilian Amazon tropical forest domain, it is extremely important to achieve a sustainable management of resources through forest management. Most studies in the literature investigate the management of tropical rainforest, whereas there is a lack of scientific information on the transition range for the cerrado.

ID: 159072
Type: article
Authors: de Tombeur, Felix; Laliberte, Etienne; Lambers, Hans; Faucon, Michel-Pierre; Zemunik, Graham; Turner, Benjamin L.; Cornelis, Jean-Thomas; Mahy, Gregory
Abstract: The resource availability hypothesis predicts that plants adapted to infertile soils have high levels of anti-herbivore leaf defences. This hypothesis has been mostly explored for secondary metabolites such as phenolics, whereas it remains underexplored for silica-based defences. We determined leaf concentrations of total phenols and silicon (Si) in plants growing along the 2-million-year Jurien Bay chronosequence, exhibiting an extreme gradient of soil fertility. We found that nitrogen (N) limitation on young soils led to a greater expression of phenol-based defences, whereas old, phosphorus (P)-impoverished soils favoured silica-based defences. Both defence types were negatively correlated at the community and individual species level. Our results suggest a trade-off among these two leaf defence strategies based on the strength and type of nutrient limitation, thereby opening up new perspectives for the resource availability hypothesis and plant defence research. This study also highlights the importance of silica-based defences under low P supply.

ID: 159458
Type: article
Authors: Dibala, Ryan; Jose, Shibu; Gold, Michael; Hall, Jefferson S.; Kallenbach, Robert; Knapp, Benjamin
Abstract: Silvopasture, an agroforestry practice combining forages, livestock, and trees, has been shown to optimize productivity and mitigate the effects of environmental stress on livestock, yet few ranchers in Panama deliberately incorporate trees into pastures. Panama's Azuero Peninsula experiences a five-month dry season that results in substantial losses in grass productivity. We studied three cultivars of Guinea grass (Megathyrsus maximus cv. Massai, cv. Mombaza, and cv. Tanzania) under open (O), moderate (M), and dense (D) tree canopies. We hypothesized that changes in soil properties, herbage mass, and nutritive value would be optimized in M in agreement with the stress gradient hypothesis, which predicts an increase in facilitation with increasing environmental stress. Results after two years showed few changes in soil chemical properties, but bulk density decreased with increasing tree cover. Annually, O produced more herbage mass than M and D and Massai produced more herbage mass than Mombaza, but not compared to Tanzania. Nutritive value improved under tree cover, with D and M showing higher relative feed values than O. Massai demonstrated the greatest tolerance to drought in M, producing more herbage mass in February when compared to D and O. Results partially support the hypothesis, suggesting that herbage mass is greatest in M for Massai during the dry season, but greatest in O over the year. The observed productivity under moderate tree densities could result in improved animal welfare between the months of December and May, the critical dry period for this region.

ID: 158678
Type: article
Authors: Dick, Christopher W.

ID: 158768
Type: article
Authors: Dietzel, Andreas; Bode, Michael; Connolly, Sean R.; Hughes, Terry P.
Abstract: Approximately half a trillion reef-building corals live across the Pacific Ocean, based on estimates of the population sizes of more than 300 species. Knowledge of a species' abundance is critically important for assessing its risk of extinction, but for the vast majority of wild animal and plant species such data are scarce at biogeographic scales. Here, we estimate the total number of reef-building corals and the population sizes of more than 300 individual species on reefs spanning the Pacific Ocean biodiversity gradient, from Indonesia to French Polynesia. Our analysis suggests that approximately half a trillion corals (0.3 x 10(12)-0.8 x 10(12)) inhabit these coral reefs, similar to the number of trees in the Amazon. Two-thirds of the examined species have population sizes exceeding 100 million colonies, and one-fifth of the species even have population sizes greater than 1 billion colonies. Our findings suggest that, while local depletions pose imminent threats that can have ecologically devastating impacts to coral reefs, the global extinction risk of most coral species is lower than previously estimated.

ID: 158611
Type: article
Authors: Einzmann, Helena J. R.; Weichgrebe, Letizia; Zotz, Gerhard
Abstract: Despite the ecological importance of vascular epiphytes in the tropics, even basic information on the processes that form epiphyte communities is scarce. This is partially due to an almost complete lack of long-term studies. Here, we present data that were collected in three consecutive censuses over 21 years in a monospecific host tree system that is about 100 years old and interpret them in an empirical and a metapopulation/metacommunity framework. We documented an ongoing increase in abundance and diversity at the level of the entire system (metacommunity) and at the level of communities (all epiphytes growing on individual Annona glabra tree stands). This was also reflected at the population level; >2/3 of the species showed positive population growth rates. Similarly, colonisation of empty Annona trees was still ongoing, with the most abundant species being also the first to colonise empty trees. The community composition of colonised trees became more similar with time. In all three censuses, habitat size of epiphytes explained much of the variation in species richness among stands (groups of trees with individual trees within 25 m of each other) and overall abundant species tended to be more abundant at the stand scale. The species frequency distribution was unimodal, regardless of whether considering all stands or only stands with very large epiphyte communities, indicating that the metacommunity still has not reached an equilibrium phase. Similarly consistent in both census intervals, population growth rates decreased with increasing population size with substantial asynchrony among populations. Synthesis. In contrast to a typical herbaceous plant community, this epiphyte metacommunity is still expanding after one century of development. Our study shows that previously reported short-term patterns of epiphyte community dynamics hold true in the long term. It remains to be shown, however, whether results from this monospecific host tree system are really representative for epiphyte community dynamics in more diverse tropical forests.

ID: 159132
Type: article
Authors: Ely, Kim S.; Rogers, Alistair; Agarwal, Deborah A.; Ainsworth, Elizabeth A.; Albert, Loren P.; Ali, Ashehad; Anderson, Jeremiah; Aspinwall, Michael J.; Bellasio, Chandra; Bernacchi, Carl; Bonnage, Steve; Buckley, Thomas N.; Bunce, James; Burnett, Angela C.; Busch, Florian A.; Cavanagh, Amanda; Cernusak, Lucas A.; Crystal-Ornelas, Robert; Damerow, Joan; Davidson, Kenneth J.; De Kauwe, Martin G.; Dietze, Michael C.; Domingues, Tomas F.; Dusenge, Mirindi Eric; Ellsworth, David S.; Evans, John R.; Gauthier, Paul P. G.; Gimenez, Bruno O.; Gordon, Elizabeth P.; Gough, Christopher M.; Halbritter, Aud H.; Hanson, David T.; Heskel, Mary; Hogan, J. Aaron; Hupp, Jason R.; Jardine, Kolby; Kattge, Jens; Keenan, Trevor; Kromdijk, Johannes; Kumarathunge, Dushan P.; Lamour, Julien; Leakey, Andrew D. B.; LeBauer, David S.; Li, Qianyu; Lundgren, Marjorie R.; McDowell, Nate; Meacham-Hensold, Katherine; Medlyn, Belinda E.; Moore, David J. P.; Negron-Juarez, Robinson; Niinemets, Ulo; Osborne, Colin P.; Pivovaroff, Alexandria L.; Poorter, Hendrik; Reed, Sasha C.; Ryu, Youngryel; Sanz-Saez, Alvaro; Schmiege, Stephanie C.; Serbin, Shawn P.; Sharkey, Thomas D.; Slot, Martijn; Smith, Nicholas G.; Sonawane, Balasaheb, V.; South, Paul F.; Souza, Daisy C.; Stinziano, Joseph Ronald; Stuart-Haentjens, Ellen; Taylor, Samuel H.; Tejera, Mauricio D.; Uddling, Johan; Vandvik, Vigdis; Varadharajan, Charuleka; Walker, Anthony P.; Walker, Berkley J.; Warren, Jeffrey M.; Way, Danielle A.; Wolfe, Brett T.; Wu, Jin; Wullschleger, Stan D.; Xu, Chonggang; Yan, Zhengbing; Yang, Dedi
Abstract: Leaf-level gas exchange data support the mechanistic understanding of plant fluxes of carbon and water. These fluxes inform our understanding of ecosystem function, are an important constraint on parameterization of terrestrial biosphere models, are necessary to understand the response of plants to global environmental change, and are integral to efforts to improve crop production. Collection of these data using gas analyzers can be both technically challenging and time consuming, and individual studies generally focus on a small range of species, restricted time periods, or limited geographic regions. The high value of these data is exemplified by the many publications that reuse and synthesize gas exchange data, however the lack of metadata and data reporting conventions make full and efficient use of these data difficult. Here we propose a reporting format for leaf-level gas exchange data and metadata to provide guidance to data contributors on how to store data in repositories to maximize their discoverability, facilitate their efficient reuse, and add value to individual datasets. For data users, the reporting format will better allow data repositories to optimize data search and extraction, and more readily integrate similar data into harmonized synthesis products. The reporting format specifies data table variable naming and unit conventions, as well as metadata characterizing experimental conditions and protocols. For common data types that were the focus of this initial version of the reporting format, i.e., survey measurements, dark respiration, carbon dioxide and light response curves, and parameters derived from those measurements, we took a further step of defining required additional data and metadata that would maximize the potential reuse of those data types. To aid data contributors and the development of data ingest tools by data repositories we provided a translation table comparing the outputs of common gas exchange instruments. Extensive consultation with data collectors, data users, instrument manufacturers, and data scientists was undertaken in order to ensure that the reporting format met community needs. The reporting format presented here is intended to form a foundation for future development that will incorporate additional data types and variables as gas exchange systems and measurement approaches advance in the future. The reporting format is published in the U.S. Department of Energy?s ESS-DIVE data repository, with documentation and future development efforts being maintained in a version control system.

ID: 158962
Type: article
Authors: Epihov, Dimitar Z.; Saltonstall, Kristin; Batterman, Sarah A.; Hedin, Lars O.; Hall, Jefferson S.; van Breugel, Michiel; Leake, Jonathan R.; Beerling, David J.
Abstract: Legume trees form an abundant and functionally important component of tropical forests worldwide with N-2-fixing symbioses linked to enhanced growth and recruitment in early secondary succession. However, it remains unclear how N-2-fixers meet the high demands for inorganic nutrients imposed by rapid biomass accumulation on nutrient-poor tropical soils. Here, we show that N-2-fixing trees in secondary Neotropical forests triggered twofold higher in situ weathering of fresh primary silicates compared to non-N-2-fixing trees and induced locally enhanced nutrient cycling by the soil microbiome community. Shotgun metagenomic data from weathered minerals support the role of enhanced nitrogen and carbon cycling in increasing acidity and weathering. Metagenomic and marker gene analyses further revealed increased microbial potential beneath N-2-fixers for anaerobic iron reduction, a process regulating the pool of phosphorus bound to iron-bearing soil minerals. We find that the Fe(III)-reducing gene pool in soil is dominated by acidophilic Acidobacteria, including a highly abundant genus of previously undescribed bacteria, Candidatus Acidoferrum, genus novus. The resulting dependence of the Fe-cycling gene pool to pH determines the high iron-reducing potential encoded in the metagenome of the more acidic soils of N-2-fixers and their nonfixing neighbors. We infer that by promoting the activities of a specialized local microbiome through changes in soil pH and C:N ratios, N-2-fixing trees can influence the wider biogeochemical functioning of tropical forest ecosystems in a manner that enhances their ability to assimilate and store atmospheric carbon.

ID: 157994
Type: article
Authors: Eren, A. Murat; Kiefl, Evan; Shaiber, Alon; Veseli, Iva; Miller, Samuel E.; Schechter, Matthew S.; Fink, Isaac; Pan, Jessica N.; Yousef, Mahmoud; Fogarty, Emily C.; Trigodet, Florian; Watson, Andrea R.; Esen, Ozcan C.; Moore, Ryan M.; Clayssen, Quentin; Lee, Michael D.; Kivenson, Veronika; Graham, Elaina D.; Merrill, Bryan D.; Karkman, Antti; Blankenberg, Daniel; Eppley, John M.; Sjodin, Andreas; Scott, Jarrod J.; Vazquez-Campos, Xabier; McKay, Luke J.; McDaniel, Elizabeth A.; Stevens, Sarah L. R.; Anderson, Rika E.; Fuessel, Jessika; Fernandez-Guerra, Antonio; Maignien, Lois; Delmont, Tom O.; Willis, Amy D.
Abstract: Big data abound in microbiology, but the workflows designed to enable researchers to interpret data can constrain the biological questions that can be asked. Five years after anvi'o was first published, this community-led multi-omics platform is maturing into an open software ecosystem that reduces constraints in 'omics data analyses.

ID: 159405
Type: article
Authors: Ermgassen, Philine S. E. Zu; Mukherjee, Nibedita; Worthington, Thomas A.; Acosta, Alejandro; da Rocha Araujo, Ana Rosa; Beitl, Christine M.; Castellanos-Galindo, Gustavo A.; Cunha-Lignon, Marilia; Dahdouh-Guebas, Farid; Diele, Karen; Parrett, Cara L.; Dwyer, Patrick G.; Gair, Jonathan R.; Johnson, Andrew Frederick; Kuguru, Baraka; Lobo, Aaron Savio; Loneragan, Neil R.; Longley-Wood, Kate; Mendonca, Jocemar Tomasino; Meynecke, Jan-Olaf; Mandal, Roland Nathan; Munga, Cosmas Nzaka; Reguero, Borja G.; Ronnback, Patrik; Thorley, Julia; Wolff, Matthias; Spalding, Mark
Abstract: Mangroves are critical nursery habitats for fish and invertebrates, providing livelihoods for many coastal communities. Despite their importance, there is currently no estimate of the number of fishers engaged in mangrove associated fisheries, nor of the fishing intensity associated with mangroves at a global scale. We address these gaps by developing a global model of mangrove associated fisher numbers and mangrove fishing intensity. To develop the model, we undertook a three-round Delphi process with mangrove fisheries experts to identify the key drivers of mangrove fishing intensity. We then developed a conceptual model of intensity of mangrove fishing using those factors identified both as being important and for which appropriate global data could be found or developed. These factors were non-urban population, distance to market, distance to mangroves and other fishing grounds, and storm events. By projecting this conceptual model using geospatial datasets, we were able to estimate the number and distribution of mangrove associated fishers and the intensity of fishing in mangroves. We estimate there are 4.1 million mangrove associated fishers globally, with the highest number of mangrove fishers found in Indonesia, India, Bangladesh, Myanmar, and Brazil. Mangrove fishing intensity was greatest throughout Asia, and to a lesser extent West and Central Africa, and Central and South America.

ID: 159056
Type: article
Authors: Estrada-Villegas, Sergio; Hall, Jefferson S.; van Breugel, Michiel; Schnitzer, Stefan A.
Abstract: Young successional tropical forests are crucial in the global carbon cycle because they can quickly sequester large quantities of atmospheric carbon. However, lianas (woody vines) can significantly decrease biomass accumulation in young regenerating forests. Lianas are abundant in tropical dry forests, and thus we hypothesized that lianas reduce biomass accretion in dry forests. Lianas may be particularly detrimental to the growth of young trees, which are vulnerable to competition from lianas. Alternatively, lianas may have a stronger negative effect on the largest trees because lianas seek the high-light environment at the top of the forest canopy. We tested these hypotheses using a liana-removal experiment in 13 dry forest stands that ranged from 1 to 70 years in southwestern Panama. We measured biomass accumulation annually for more than 10,000 stems from 2013 to 2017. Contrary to our expectations, liana removal had no effect on tree biomass accumulation across our successional forests and throughout our study period. Liana removal did not benefit smaller trees or larger trees. Lianas did not increase biomass accumulation on recruits, and did not increase biomass loss due to mortality. Surprisingly, removing lianas had a negative effect on three out of 41 tree species. Lianas had no effect on biomass accumulation and loss, possibly because: (1) trees allocated resources to roots instead of stems, (2) trees and lianas partitioned water, (3) higher irradiance after liana removal reduced soil moisture, or (4) low water availability might have been such a strong stressor that it reduced plant-plant competition.

ID: 159755
Type: article
Authors: Fang, Yilin; Leung, L. Ruby; Wolfe, Brett T.; Detto, Matteo; Knox, Ryan G.; McDowell, Nate G.; Grossiord, Charlotte; Xu, Chonggang; Christoffersen, Bradley O.; Gentine, Pierre; Koven, Charles D.; Chambers, Jeffrey Q.
Abstract: Water deficit in the atmosphere and soil are two key interactive factors that constrain transpiration and vegetation productivity. It is not clear which of these two factors is more important for the water and carbon flux response to drought stress in ecosystems. In this study, field data and numerical modeling were used to isolate their impact on evapotranspiration (ET) and gross primary productivity (GPP) at a tropical forest site in Barro Colorado Island (BCI), Panama, focusing on their response to the drought induced by the El Nino event of 2015-2016. Numerical simulations were performed using a plant hydrodynamic scheme (HYDRO) and a heuristic approach that ignores stomatal sensitivity to leaf water potential in the Energy Exascale Earth System Model (E3SM) Land Model (ELM). The sensitivity of canopy conductance (G(s)) to vapor pressure deficit (VPD) obtained from eddy-covariance fluxes and measured sap flux shows that, at both ecosystem and plant scale, soil water stress is more important in limiting G(s) than VPD at BCI during the El Nino event. The model simulations confirmed the importance of water stress limitation on G(s), but overestimated the VPD impact on G(s) compared to that estimated from the observations. We also found that the predicted soil moisture is less sensitive to the diversity of plant hydraulic traits than ET and GPP. During the dry season at BCI, seasonal ET, especially soil evaporation at VPD > 0.42 kPa, simulated using HYDRO and ELM, were too strong and will require alternative parameterizations.

ID: 158766
Type: article
Authors: Fremout, Tobias; Elena Gutierrez-Miranda, Claudia; Briers, Siebe; Luis Marcelo-Pena, Jose; Cueva-Ortiz, Eduardo; Linares-Palomino, Reynaldo; de los Angeles La Torre-Cuadros,Maria; Cristina Chang-Ruiz, Janette; Libertad Villegas-Gomez, Tania; Helen Acosta-Flota, Arantza; Plouvier, Dominiek; Atkinson, Rachel; Charcape-Ravelo, Manuel; Aguirre-Mendoza, Zhofre; Muys, Bart; Thomas, Evert
Abstract: Forest restoration projects involving active planting should prioritize species that are useful to local communities, while also considering species' threat status and resistance to local stress factors, but scientific knowledge on these criteria is scarce, especially in understudied tropical ecosystems. We hypothesized that local ecological knowledge can help to fill this gap. Through interviews with 47 local experts and 197 randomly selected households in 8 rural communities of the tropical dry forests of northwestern Peru and southern Ecuador, we identified the species perceived as most useful, most threatened, and most resistant to local stress factors. To better understand the studied local ecological knowledge, we also explored the following research questions and their implications for species selection decisions: (1) How does species' potential usefulness compare to their active use? (2) How does species' perceived threat status relate to their usefulness? (3) Does local knowledge on species' resistance to local stress factors corroborate scientific knowledge? We found large differences between the potential and active use of species and illustrate how data on both can yield useful insights. Furthermore, we found that species' perceived threat status was mainly linked to their usefulness for construction wood, and that the vast majority of local perceptions on species' threat status and stress resistance coincided with scientific knowledge. Our findings illustrate the large potential of local ecological knowledge for improving species selection strategies and thereby increasing the success of forest restoration efforts worldwide.

ID: 159747
Type: article
Authors: Gamisch, Alexander; Winter, Klaus; Fischer, Gunter A.; Comes, Hans Peter
Abstract: Despite growing evidence that niche shifts are more common in flowering plants than previously thought, little is known of whether such shifts are promoted by changes in photosynthetic pathways. Here we combine the most complete phylogeny for epiphytic Malagasy Bulbophyllum orchids (c. 210 spp.) with climatic niche and carbon isotope ratios to infer the group's spatial-temporal history, and the role of strongly expressed crassulacean acid metabolism (CAM) in facilitating niche shifts and diversification. We find that most extant species still retain niche (Central Highland) and photosynthesis (C-3) states as present in the single mid-Miocene (c. 12.70 million yr ago (Ma)) ancestor colonizing Madagascar. However, we also infer a major transition to CAM, linked to a late Miocene (c. 7.36 Ma) invasion of species from the sub-humid highland first into the island's humid eastern coastal, and then into the seasonally dry 'Northwest Sambirano' rainforests, yet without significant effect on diversification rates. These findings indicate that CAM in tropical epiphytes may be selectively advantageous even in high rainfall habitats, rather than presenting a mere adaptation to dry environments or epiphytism per se. Overall, our study qualifies CAM as an evolutionary 'gateway' trait that considerably widened the spatial-ecological amplitude of Madagascar's most species-rich orchid genus.

ID: 159699
Type: article
Authors: Gaubert-Boussarie, Julie; Altieri, Andrew H.; Duffy, J. Emmett; Campbell, Justin E.
Abstract: Seagrass meadows are valued coastal habitats that provide ecological and economic benefits around the world. Despite their importance, many meadows are in decline, driven by a variety of anthropogenic impacts. While these declines have been well documented in some regions, other locations (particularly within the tropics) lack longterm monitoring programs needed to resolve seagrass trends over time. Effective and spatially-expansive monitoring within under-represented regions is critical to provide an accurate perspective on seagrass status and trends. We present a comprehensive dataset on seagrass coverage and composition across 24 sites in Bahia Almirante, a lagoon along the Caribbean coast of Panama. Using a single survey, we focus on capturing spatial variation in seagrass physical and elemental characteristics and provide data on key seagrass bio-indicators, such as leaf morphology (length and width), elemental content (% nitrogen and phosphorus) and stable isotopic signatures (delta C-13 and delta N-15). We further explore relationships between these variables and water depth (proxy for light availability) and proximity to shore (proxy for terrestrial inputs). The seagrass assemblage was mostly monospecific (dominated by Thalassia testudinum) and restricted to shallow water (<3 m). Above-ground biomass varied widely, averaging 71.7 g dry mass m(-2), yet ranging from 24.8 to 139.6 g dry mass m(-2). Leaf nitrogen content averaged 2.2%, ranging from 1.76 to 2.57%, while phosphorus content averaged 0.19% and ranged from 0.15 to 0.23%. These values were high compared to other published reports for T. testudinum, indicating elevated nutrient availability within the lagoon. Seagrass stable isotopic characteristics varied slightly and were comparable with other published values. Leaf carbon signatures (delta C-13) ranged from 11.74 to 6.70h and were positively correlated to shoreline proximity, suggesting a contribution of terrestrial carbon to seagrass biomass. Leaf nitrogen signatures (delta N-15) ranged from 1.75 to 3.15h and showed no correlation with shoreline proximity, suggesting that N sources within the bay were not dominated by localized point-source discharge of treated sewage. Correlations between other seagrass bio-indicators and environmental metrics were mixed: seagrass cover declined with depth, while biomass was negatively correlated with N, indicating that light and nutrient availability may jointly regulate seagrass cover and biomass. Our work documents the response of seagrass in Bahia Almirante to light and nutrient availability and highlights the eutrophic status of this bay. Using the broad spatial coverage of our survey as a baseline, we suggest the future implementation of a continuous and spatially expansive seagrass monitoring program within this region to assess the health of these important systems subject to global and local stressors.