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Item Open Access Above-ground biomass and structure of 260 African tropical forests.(Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 2013-01) Lewis, Simon L; Sonké, Bonaventure; Sunderland, Terry; Begne, Serge K; Lopez-Gonzalez, Gabriela; van der Heijden, Geertje MF; Phillips, Oliver L; Affum-Baffoe, Kofi; Baker, Timothy R; Banin, Lindsay; Bastin, Jean-François; Beeckman, Hans; Boeckx, Pascal; Bogaert, Jan; De Cannière, Charles; Chezeaux, Eric; Clark, Connie J; Collins, Murray; Djagbletey, Gloria; Djuikouo, Marie Noël K; Droissart, Vincent; Doucet, Jean-Louis; Ewango, Cornielle EN; Fauset, Sophie; Feldpausch, Ted R; Foli, Ernest G; Gillet, Jean-François; Hamilton, Alan C; Harris, David J; Hart, Terese B; de Haulleville, Thales; Hladik, Annette; Hufkens, Koen; Huygens, Dries; Jeanmart, Philippe; Jeffery, Kathryn J; Kearsley, Elizabeth; Leal, Miguel E; Lloyd, Jon; Lovett, Jon C; Makana, Jean-Remy; Malhi, Yadvinder; Marshall, Andrew R; Ojo, Lucas; Peh, Kelvin S-H; Pickavance, Georgia; Poulsen, John R; Reitsma, Jan M; Sheil, Douglas; Simo, Murielle; Steppe, Kathy; Taedoumg, Hermann E; Talbot, Joey; Taplin, James RD; Taylor, David; Thomas, Sean C; Toirambe, Benjamin; Verbeeck, Hans; Vleminckx, Jason; White, Lee JT; Willcock, Simon; Woell, Hannsjorg; Zemagho, LiseWe report above-ground biomass (AGB), basal area, stem density and wood mass density estimates from 260 sample plots (mean size: 1.2 ha) in intact closed-canopy tropical forests across 12 African countries. Mean AGB is 395.7 Mg dry mass ha⁻¹ (95% CI: 14.3), substantially higher than Amazonian values, with the Congo Basin and contiguous forest region attaining AGB values (429 Mg ha⁻¹) similar to those of Bornean forests, and significantly greater than East or West African forests. AGB therefore appears generally higher in palaeo- compared with neotropical forests. However, mean stem density is low (426 ± 11 stems ha⁻¹ greater than or equal to 100 mm diameter) compared with both Amazonian and Bornean forests (cf. approx. 600) and is the signature structural feature of African tropical forests. While spatial autocorrelation complicates analyses, AGB shows a positive relationship with rainfall in the driest nine months of the year, and an opposite association with the wettest three months of the year; a negative relationship with temperature; positive relationship with clay-rich soils; and negative relationships with C : N ratio (suggesting a positive soil phosphorus-AGB relationship), and soil fertility computed as the sum of base cations. The results indicate that AGB is mediated by both climate and soils, and suggest that the AGB of African closed-canopy tropical forests may be particularly sensitive to future precipitation and temperature changes.Item Open Access An estimate of the number of tropical tree species.(Proc Natl Acad Sci U S A, 2015-06-16) Slik, JW Ferry; Arroyo-Rodríguez, Víctor; Aiba, Shin-Ichiro; Alvarez-Loayza, Patricia; Alves, Luciana F; Ashton, Peter; Balvanera, Patricia; Bastian, Meredith L; Bellingham, Peter J; van den Berg, Eduardo; Bernacci, Luis; da Conceição Bispo, Polyanna; Blanc, Lilian; Böhning-Gaese, Katrin; Boeckx, Pascal; Bongers, Frans; Boyle, Brad; Bradford, Matt; Brearley, Francis Q; Breuer-Ndoundou Hockemba, Mireille; Bunyavejchewin, Sarayudh; Calderado Leal Matos, Darley; Castillo-Santiago, Miguel; Catharino, Eduardo LM; Chai, Shauna-Lee; Chen, Yukai; Colwell, Robert K; Chazdon, Robin L; Clark, Connie; Clark, David B; Clark, Deborah A; Culmsee, Heike; Damas, Kipiro; Dattaraja, Handanakere S; Dauby, Gilles; Davidar, Priya; DeWalt, Saara J; Doucet, Jean-Louis; Duque, Alvaro; Durigan, Giselda; Eichhorn, Karl AO; Eisenlohr, Pedro V; Eler, Eduardo; Ewango, Corneille; Farwig, Nina; Feeley, Kenneth J; Ferreira, Leandro; Field, Richard; de Oliveira Filho, Ary T; Fletcher, Christine; Forshed, Olle; Franco, Geraldo; Fredriksson, Gabriella; Gillespie, Thomas; Gillet, Jean-François; Amarnath, Giriraj; Griffith, Daniel M; Grogan, James; Gunatilleke, Nimal; Harris, David; Harrison, Rhett; Hector, Andy; Homeier, Jürgen; Imai, Nobuo; Itoh, Akira; Jansen, Patrick A; Joly, Carlos A; de Jong, Bernardus HJ; Kartawinata, Kuswata; Kearsley, Elizabeth; Kelly, Daniel L; Kenfack, David; Kessler, Michael; Kitayama, Kanehiro; Kooyman, Robert; Larney, Eileen; Laumonier, Yves; Laurance, Susan; Laurance, William F; Lawes, Michael J; Amaral, Ieda Leao do; Letcher, Susan G; Lindsell, Jeremy; Lu, Xinghui; Mansor, Asyraf; Marjokorpi, Antti; Martin, Emanuel H; Meilby, Henrik; Melo, Felipe PL; Metcalfe, Daniel J; Medjibe, Vincent P; Metzger, Jean Paul; Millet, Jerome; Mohandass, D; Montero, Juan C; de Morisson Valeriano, Márcio; Mugerwa, Badru; Nagamasu, Hidetoshi; Nilus, Reuben; Ochoa-Gaona, Susana; Onrizal; Page, Navendu; Parolin, Pia; Parren, Marc; Parthasarathy, Narayanaswamy; Paudel, Ekananda; Permana, Andrea; Piedade, Maria TF; Pitman, Nigel CA; Poorter, Lourens; Poulsen, Axel D; Poulsen, John; Powers, Jennifer; Prasad, Rama C; Puyravaud, Jean-Philippe; Razafimahaimodison, Jean-Claude; Reitsma, Jan; Dos Santos, João Roberto; Roberto Spironello, Wilson; Romero-Saltos, Hugo; Rovero, Francesco; Rozak, Andes Hamuraby; Ruokolainen, Kalle; Rutishauser, Ervan; Saiter, Felipe; Saner, Philippe; Santos, Braulio A; Santos, Fernanda; Sarker, Swapan K; Satdichanh, Manichanh; Schmitt, Christine B; Schöngart, Jochen; Schulze, Mark; Suganuma, Marcio S; Sheil, Douglas; da Silva Pinheiro, Eduardo; Sist, Plinio; Stevart, Tariq; Sukumar, Raman; Sun, I-Fang; Sunderland, Terry; Suresh, HS; Suzuki, Eizi; Tabarelli, Marcelo; Tang, Jangwei; Targhetta, Natália; Theilade, Ida; Thomas, Duncan W; Tchouto, Peguy; Hurtado, Johanna; Valencia, Renato; van Valkenburg, Johan LCH; Van Do, Tran; Vasquez, Rodolfo; Verbeeck, Hans; Adekunle, Victor; Vieira, Simone A; Webb, Campbell O; Whitfeld, Timothy; Wich, Serge A; Williams, John; Wittmann, Florian; Wöll, Hannsjoerg; Yang, Xiaobo; Adou Yao, C Yves; Yap, Sandra L; Yoneda, Tsuyoshi; Zahawi, Rakan A; Zakaria, Rahmad; Zang, Runguo; de Assis, Rafael L; Garcia Luize, Bruno; Venticinque, Eduardo MThe high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of Fisher's alpha and an approximate pantropical stem total to estimate the minimum number of tropical forest tree species to fall between ∼ 40,000 and ∼ 53,000, i.e., at the high end of previous estimates. Contrary to common assumption, the Indo-Pacific region was found to be as species-rich as the Neotropics, with both regions having a minimum of ∼ 19,000-25,000 tree species. Continental Africa is relatively depauperate with a minimum of ∼ 4,500-6,000 tree species. Very few species are shared among the African, American, and the Indo-Pacific regions. We provide a methodological framework for estimating species richness in trees that may help refine species richness estimates of tree-dependent taxa.Item Open Access Biogeographic analysis of the woody plants of the Southern Appalachians: Implications for the origins of a regional flora.(Am J Bot, 2015-05) Manos, Paul S; Meireles, José EduardoPREMISE OF THE STUDY: We investigated the origins of 252 Southern Appalachian woody species representing 158 clades to analyze larger patterns of biogeographic connectivity around the northern hemisphere. We tested biogeographic hypotheses regarding the timing of species disjunctions to eastern Asia and among areas of North America. METHODS: We delimited species into biogeographically informative clades, compiled sister-area data, and generated graphic representations of area connections across clades. We calculated taxon diversity within clades and plotted divergence times. KEY RESULTS: Of the total taxon diversity, 45% were distributed among 25 North American endemic clades. Sister taxa within eastern North America and eastern Asia were proportionally equal in frequency, accounting for over 50% of the sister-area connections. At increasing phylogenetic depth, connections to the Old World dominated. Divergence times for 65 clades with intercontinental disjunctions were continuous, whereas 11 intracontinental disjunctions to western North America and nine to eastern Mexico were temporally congruent. CONCLUSIONS: Over one third of the clades have likely undergone speciation within the region of eastern North America. The biogeographic pattern for the region is asymmetric, consisting of mostly mixed-aged, low-diversity clades connecting to the Old World, and a minority of New World clades. Divergence time data suggest that climate change in the Late Miocene to Early Pliocene generated disjunct patterns within North America. Continuous splitting times during the last 45 million years support the hypothesis that widespread distributions formed repeatedly during favorable periods, with serial cooling trends producing pseudocongruent area disjunctions between eastern North America and eastern Asia.Item Open Access Calibrating single-ended fiber-optic Raman spectra distributed temperature sensing data.(Sensors (Basel), 2011) Hausner, Mark B; Suárez, Francisco; Glander, Kenneth E; van de Giesen, Nick; Selker, John S; Tyler, Scott WHydrologic research is a very demanding application of fiber-optic distributed temperature sensing (DTS) in terms of precision, accuracy and calibration. The physics behind the most frequently used DTS instruments are considered as they apply to four calibration methods for single-ended DTS installations. The new methods presented are more accurate than the instrument-calibrated data, achieving accuracies on the order of tenths of a degree root mean square error (RMSE) and mean bias. Effects of localized non-uniformities that violate the assumptions of single-ended calibration data are explored and quantified. Experimental design considerations such as selection of integration times or selection of the length of the reference sections are discussed, and the impacts of these considerations on calibrated temperatures are explored in two case studies.Item Open Access Climatic Influences on Seedlings in Eastern Nort America(2017) Kwit, MatthewUnprecedented rates of warming and an inability to curtail greenhouse gas production
has fueled the discussion of how to mitigate climatic impacts. Climate impacts
on forests are coarsely understood. A large number of interacting environmental
variables affect every aspect of forest life cycles, and studies incorporating local
factors are scarce. For this study, a large manipulative climate experiment in both
northern(Massachusetts) and southern(North Carolina) sites was used to examine the
effect of climate change on demographic and physiological rates of 11 tree species
representative of the Eastern Deciduous Forest.
First, to clarify how environmental conditions of the next century will alter
seedling carbon assimilation, a hierarchical multivariate model that synthesizes over
16,000 instantaneous carbon exchange measurements from 285 trees of four species
was developed. Estimates of species-level light response curve parameters were used
to predict individual-level seasonal carbon budgets. This model revealed how the
balance between respiration and photosynthesis shifts with temperature, moisture,
and overstory canopy status. Furthermore, it showed that elevated temperatures
(3C and 5C) shift the seasonal species carbon budget allowing some Lirodendron
tulipifera to grow as much a 5.5 times more massive in elevated temperatures.
In addition, for certain species, demographic rates of seedlings can be scaled to
above-ground growth using short-term physiological responses.
Second, the relationship between seedling size and water-use was examined.
Trees grow from environmentally sensitive seedlings to large canopy individuals
capable of buffering environmental stress. At some intermediate size, a threshold is reached
where greater resilience results when increased resource gain overcomes the added
costs of size. For two seasons of this manipulative warming experiment, 123 external
heat pulse sapflow sensors were applied to 4 species (Acer rubrum, Lirodendron tulipifera,
Quercus alba, and Quercus rubra). The experimental seedlings, which vary in
mass from less than a tenth of a gram to 41 grams, were included to demonstrate
that both size and species influence water use. While larger size leads to increased
transpiration, reduced soil moisture paired with larger size leads to unpredictable
reductions in sapflow. Small seedlings were predictably reactive, but large seedlings
were both the least and most reactive to soil moisture reductions. When soil moisture
improved, after periods of moisture limitations, small individuals quickly recovered
and large individuals to a lesser extent. These results suggest that the seedlings of
this experiment were not consistently big enough to gain an advantage in water-use
like their larger canopy counter parts.
Lastly, this climate-warming experiment was expanded to include 4000 seedlings
of 11 total species across both the northern and southern sites. High-resolution subannual
growth measurements and a hierarchal Bayesian state-space model provided
a more accurate picture of seedling growth responses to sub-annual climatic variation,
by focusing on determinate vs. indeterminate growers and the interactions
between growth phenology, temperature tolerances, and climatic shifts. Determinate
species enhanced annual growth by shifting growth earlier in the season when
temperatures were more suitable, avoiding hot and dry conditions of summer. Indeterminate
species annual growth, which is focused within the summer, is dependent
on their ability to maintain growth during increasingly warmer and dryer summers.
Co-occurring species may respond differently and competitive regimes are shifted by
how growth phenology aligns with the seasonal patterns of climate change.
Questions of forest responses to climate change are multi-scaled. Responses depend
on local conditions, life-stage, natural history, and the scale of inference. Climate
change does not occur in isolation all factors must be weighed when evaluating
a response. For this study a manipulative climate experiment was used to address
these questions and investigate the effect of climate change on trees of the Eastern
Deciduous Forest.
Item Open Access Comparative analyses of clinical and environmental populations of Cryptococcus neoformans in Botswana.(Mol Ecol, 2015-07) Chen, Yuan; Litvintseva, Anastasia P; Frazzitta, Aubrey E; Haverkamp, Miriam R; Wang, Liuyang; Fang, Charles; Muthoga, Charles; Mitchell, Thomas G; Perfect, John RCryptococcus neoformans var. grubii (Cng) is the most common cause of fungal meningitis, and its prevalence is highest in sub-Saharan Africa. Patients become infected by inhaling airborne spores or desiccated yeast cells from the environment, where the fungus thrives in avian droppings, trees and soil. To investigate the prevalence and population structure of Cng in southern Africa, we analysed isolates from 77 environmental samples and 64 patients. We detected significant genetic diversity among isolates and strong evidence of geographic structure at the local level. High proportions of isolates with the rare MATa allele were observed in both clinical and environmental isolates; however, the mating-type alleles were unevenly distributed among different subpopulations. Nearly equal proportions of the MATa and MATα mating types were observed among all clinical isolates and in one environmental subpopulation from the eastern part of Botswana. As previously reported, there was evidence of both clonality and recombination in different geographic areas. These results provide a foundation for subsequent genomewide association studies to identify genes and genotypes linked to pathogenicity in humans.Item Open Access Cryptococcus gattii VGIII isolates causing infections in HIV/AIDS patients in Southern California: identification of the local environmental source as arboreal.(PLoS Pathog, 2014-08) Springer, DJ; Billmyre, RB; Filler, EE; Voelz, K; Pursall, R; Mieczkowski, PA; Larsen, RA; Dietrich, FS; May, RC; Filler, SG; Heitman, JOngoing Cryptococcus gattii outbreaks in the Western United States and Canada illustrate the impact of environmental reservoirs and both clonal and recombining propagation in driving emergence and expansion of microbial pathogens. C. gattii comprises four distinct molecular types: VGI, VGII, VGIII, and VGIV, with no evidence of nuclear genetic exchange, indicating these represent distinct species. C. gattii VGII isolates are causing the Pacific Northwest outbreak, whereas VGIII isolates frequently infect HIV/AIDS patients in Southern California. VGI, VGII, and VGIII have been isolated from patients and animals in the Western US, suggesting these molecular types occur in the environment. However, only two environmental isolates of C. gattii have ever been reported from California: CBS7750 (VGII) and WM161 (VGIII). The incongruence of frequent clinical presence and uncommon environmental isolation suggests an unknown C. gattii reservoir in California. Here we report frequent isolation of C. gattii VGIII MATα and MATa isolates and infrequent isolation of VGI MATα from environmental sources in Southern California. VGIII isolates were obtained from soil debris associated with tree species not previously reported as hosts from sites near residences of infected patients. These isolates are fertile under laboratory conditions, produce abundant spores, and are part of both locally and more distantly recombining populations. MLST and whole genome sequence analysis provide compelling evidence that these environmental isolates are the source of human infections. Isolates displayed wide-ranging virulence in macrophage and animal models. When clinical and environmental isolates with indistinguishable MLST profiles were compared, environmental isolates were less virulent. Taken together, our studies reveal an environmental source and risk of C. gattii to HIV/AIDS patients with implications for the >1,000,000 cryptococcal infections occurring annually for which the causative isolate is rarely assigned species status. Thus, the C. gattii global health burden could be more substantial than currently appreciated.Item Open Access Deadwood stocks increase with selective logging and large tree frequency in Gabon.(Glob Chang Biol, 2017-04) Carlson, Ben S; Koerner, Sally E; Medjibe, Vincent P; White, Lee JT; Poulsen, John RDeadwood is a major component of aboveground biomass (AGB) in tropical forests and is important as habitat and for nutrient cycling and carbon storage. With deforestation and degradation taking place throughout the tropics, improved understanding of the magnitude and spatial variation in deadwood is vital for the development of regional and global carbon budgets. However, this potentially important carbon pool is poorly quantified in Afrotropical forests and the regional drivers of deadwood stocks are unknown. In the first large-scale study of deadwood in Central Africa, we quantified stocks in 47 forest sites across Gabon and evaluated the effects of disturbance (logging), forest structure variables (live AGB, wood density, abundance of large trees), and abiotic variables (temperature, precipitation, seasonality). Average deadwood stocks (measured as necromass, the biomass of deadwood) were 65 Mg ha-1 or 23% of live AGB. Deadwood stocks varied spatially with disturbance and forest structure, but not abiotic variables. Deadwood stocks increased significantly with logging (+38 Mg ha-1 ) and the abundance of large trees (+2.4 Mg ha-1 for every tree >60 cm dbh). Gabon holds 0.74 Pg C, or 21% of total aboveground carbon in deadwood, a threefold increase over previous estimates. Importantly, deadwood densities in Gabon are comparable to those in the Neotropics and respond similarly to logging, but represent a lower proportion of live AGB (median of 18% in Gabon compared to 26% in the Neotropics). In forest carbon accounting, necromass is often assumed to be a constant proportion (9%) of biomass, but in humid tropical forests this ratio varies from 2% in undisturbed forest to 300% in logged forest. Because logging significantly increases the deadwood carbon pool, estimates of tropical forest carbon should at a minimum use different ratios for logged (mean of 30%) and unlogged forests (mean of 18%).Item Open Access Decadal biomass increment in early secondary succession woody ecosystems is increased by CO2 enrichment.(Nature communications, 2019-02) Walker, Anthony P; De Kauwe, Martin G; Medlyn, Belinda E; Zaehle, Sönke; Iversen, Colleen M; Asao, Shinichi; Guenet, Bertrand; Harper, Anna; Hickler, Thomas; Hungate, Bruce A; Jain, Atul K; Luo, Yiqi; Lu, Xingjie; Lu, Meng; Luus, Kristina; Megonigal, J Patrick; Oren, Ram; Ryan, Edmund; Shu, Shijie; Talhelm, Alan; Wang, Ying-Ping; Warren, Jeffrey M; Werner, Christian; Xia, Jianyang; Yang, Bai; Zak, Donald R; Norby, Richard JIncreasing atmospheric CO2 stimulates photosynthesis which can increase net primary production (NPP), but at longer timescales may not necessarily increase plant biomass. Here we analyse the four decade-long CO2-enrichment experiments in woody ecosystems that measured total NPP and biomass. CO2 enrichment increased biomass increment by 1.05 ± 0.26 kg C m-2 over a full decade, a 29.1 ± 11.7% stimulation of biomass gain in these early-secondary-succession temperate ecosystems. This response is predictable by combining the CO2 response of NPP (0.16 ± 0.03 kg C m-2 y-1) and the CO2-independent, linear slope between biomass increment and cumulative NPP (0.55 ± 0.17). An ensemble of terrestrial ecosystem models fail to predict both terms correctly. Allocation to wood was a driver of across-site, and across-model, response variability and together with CO2-independence of biomass retention highlights the value of understanding drivers of wood allocation under ambient conditions to correctly interpret and predict CO2 responses.Item Open Access Dust accumulation in the canopy: a potential cause of dental microwear in primates.(Am J Phys Anthropol, 1995-06) Ungar, PS; Teaford, MF; Glander, KE; Pastor, RFDental microwear researchers consider exogenous grit or dust to be an important cause of microscopic wear on primate teeth. No study to date has examined the accumulation of such abrasives on foods eaten by primates in the forest. This investigation introduces a method to collect dust at various heights in the canopy. Results from dust collection studies conducted at the primate research stations at Ketambe in Indonesia, and Hacienda La Pacifica in Costa Rica indicate that 1) grit collects throughout the canopy in both open country and tropical rain forest environments; and 2) the sizes and concentrations of dust particles accumulated over a fixed period of time differ depending on site location and season of investigation. These results may hold important implications for the interpretation of microwear on primate teeth.Item Open Access Estimating the effects of vegetation and increased albedo on the urban heat island effect with spatial causal inference.(Scientific reports, 2024-01) Calhoun, Zachary D; Willard, Frank; Ge, Chenhao; Rodriguez, Claudia; Bergin, Mike; Carlson, DavidThe urban heat island effect causes increased heat stress in urban areas. Cool roofs and urban greening have been promoted as mitigation strategies to reduce this effect. However, evaluating their efficacy remains a challenge, as potential temperature reductions depend on local characteristics. Existing methods to characterize their efficacy, such as computational fluid dynamics and urban canopy models, are computationally burdensome and require a high degree of expertise to employ. We propose a data-driven approach to overcome these hurdles, inspired by recent innovations in spatial causal inference. This approach allows for estimates of hypothetical interventions to reduce the urban heat island effect. We demonstrate this approach by modeling evening temperature in Durham, North Carolina, using readily retrieved air temperature, land cover, and satellite data. Hypothetical interventions such as lining streets with trees, cool roofs, and changing parking lots to green space are estimated to decrease evening temperatures by a maximum of 0.7-0.9 [Formula: see text], with reduced effects on temperature as a function of distance from the intervention. Because of the ease of data access, this approach may be applied to other cities in the U.S. to help them come up with city-specific solutions for reducing urban heat stress.Item Open Access Estimating the Impacts of Local Policy Innovation: The Synthetic Control Method Applied to Tropical Deforestation.(PLoS One, 2015) Sills, Erin O; Herrera, Diego; Kirkpatrick, A Justin; Brandão, Amintas; Dickson, Rebecca; Hall, Simon; Pattanayak, Subhrendu; Shoch, David; Vedoveto, Mariana; Young, Luisa; Pfaff, AlexanderQuasi-experimental methods increasingly are used to evaluate the impacts of conservation interventions by generating credible estimates of counterfactual baselines. These methods generally require large samples for statistical comparisons, presenting a challenge for evaluating innovative policies implemented within a few pioneering jurisdictions. Single jurisdictions often are studied using comparative methods, which rely on analysts' selection of best case comparisons. The synthetic control method (SCM) offers one systematic and transparent way to select cases for comparison, from a sizeable pool, by focusing upon similarity in outcomes before the intervention. We explain SCM, then apply it to one local initiative to limit deforestation in the Brazilian Amazon. The municipality of Paragominas launched a multi-pronged local initiative in 2008 to maintain low deforestation while restoring economic production. This was a response to having been placed, due to high deforestation, on a federal "blacklist" that increased enforcement of forest regulations and restricted access to credit and output markets. The local initiative included mapping and monitoring of rural land plus promotion of economic alternatives compatible with low deforestation. The key motivation for the program may have been to reduce the costs of blacklisting. However its stated purpose was to limit deforestation, and thus we apply SCM to estimate what deforestation would have been in a (counterfactual) scenario of no local initiative. We obtain a plausible estimate, in that deforestation patterns before the intervention were similar in Paragominas and the synthetic control, which suggests that after several years, the initiative did lower deforestation (significantly below the synthetic control in 2012). This demonstrates that SCM can yield helpful land-use counterfactuals for single units, with opportunities to integrate local and expert knowledge and to test innovations and permutations on policies that are implemented in just a few locations.Item Open Access Evidence for a Cenozoic radiation of ferns in an angiosperm-dominated canopy.(Proceedings of the National Academy of Sciences of the United States of America, 2009-07) Schuettpelz, E; Pryer, KMIn today's angiosperm-dominated terrestrial ecosystems, leptosporangiate ferns are truly exceptional--accounting for 80% of the approximately 11,000 nonflowering vascular plant species. Recent studies have shown that this remarkable diversity is mostly the result of a major leptosporangiate radiation beginning in the Cretaceous, following the rise of angiosperms. This pattern is suggestive of an ecological opportunistic response, with the proliferation of flowering plants across the landscape resulting in the formation of many new niches--both on forest floors and within forest canopies--into which leptosporangiate ferns could diversify. At present, one-third of leptosporangiate species grow as epiphytes in the canopies of angiosperm-dominated tropical rain forests. However, we know too little about the evolutionary history of epiphytic ferns to assess whether or not their diversification was in fact linked to the establishment of these forests, as would be predicted by the ecological opportunistic response hypothesis. Here we provide new insight into leptosporangiate diversification and the evolution of epiphytism by integrating a 400-taxon molecular dataset with an expanded set of fossil age constraints. We find evidence for a burst of fern diversification in the Cenozoic, apparently driven by the evolution of epiphytism. Whether this explosive radiation was triggered simply by the establishment of modern angiosperm-dominated tropical rain forest canopies, or spurred on by some other large-scale extrinsic factor (e.g., climate change) remains to be determined. In either case, it is clear that in both the Cretaceous and Cenozoic, leptosporangiate ferns were adept at exploiting newly created niches in angiosperm-dominated ecosystems.Item Open Access Four-decade responses of soil trace elements to an aggrading old-field forest: B, Mn, Zn, Cu, and Fe.(Ecology, 2008-10) Li, Jianwei; Richter, Daniel D; Mendoza, Arlene; Heine, PaulIn the ancient and acidic Ultisol soils of the Southern Piedmont, USA, we studied changes in trace element biogeochemistry over four decades, a period during which formerly cultivated cotton fields were planted with pine seedlings that grew into mature forest stands. In 16 permanent plots, we estimated 40-year accumulations of trace elements in forest biomass and O horizons (between 1957 and 1997), and changes in bioavailable soil fractions indexed by extractions of 0.05 mol/L HCl and 0.2 mol/L acid ammonium oxalate (AAO). Element accumulations in 40-year tree biomass plus O horizons totaled 0.9, 2.9, 4.8, 49.6, and 501.3 kg/ha for Cu, B, Zn, Mn, and Fe, respectively. In response to this forest development, samples of the upper 0.6-m of mineral soil archived in 1962 and 1997 followed one of three patterns. (1) Extractable B and Mn were significantly depleted, by -4.1 and -57.7 kg/ha with AAO, depletions comparable to accumulations in biomass plus O horizons, 2.9 and 49.6 kg/ha, respectively. Tree uptake of B and Mn from mineral soil greatly outpaced resupplies from atmospheric deposition, mineral weathering, and deep-root uptake. (2) Extractable Zn and Cu changed little during forest growth, indicating that nutrient resupplies kept pace with accumulations by the aggrading forest. (3) Oxalate-extractable Fe increased substantially during forest growth, by 275.8 kg/ha, about 10-fold more than accumulations in tree biomass (28.7 kg/ha). The large increases in AAO-extractable Fe in surficial 0.35-m mineral soils were accompanied by substantial accretions of Fe in the forest's O horizon, by 473 kg/ha, amounts that dwarfed inputs via litterfall and canopy throughfall, indicating that forest Fe cycling is qualitatively different from that of other macro- and micronutrients. Bioturbation of surficial forest soil layers cannot account for these fractions and transformations of Fe, and we hypothesize that the secondary forest's large inputs of organic additions over four decades has fundamentally altered soil Fe oxides, potentially altering the bioavailability and retention of macro- and micronutrients, contaminants, and organic matter itself. The wide range of responses among the ecosystem's trace elements illustrates the great dynamics of the soil system over time scales of decades.Item Open Access Hydraulic redistribution of soil water by roots affects whole-stand evapotranspiration and net ecosystem carbon exchange.(New Phytol, 2010-07) Domec, Jean-Christophe; King, John S; Noormets, Asko; Treasure, Emrys; Gavazzi, Michael J; Sun, Ge; McNulty, Steven G*Hydraulic redistribution (HR) of water via roots from moist to drier portions of the soil occurs in many ecosystems, potentially influencing both water use and carbon assimilation. *By measuring soil water content, sap flow and eddy covariance, we investigated the temporal variability of HR in a loblolly pine (Pinus taeda) plantation during months of normal and below-normal precipitation, and examined its effects on tree transpiration, ecosystem water use and carbon exchange. *The occurrence of HR was explained by courses of reverse flow through roots. As the drought progressed, HR maintained soil moisture above 0.15 cm(3) cm(-3) and increased transpiration by 30-50%. HR accounted for 15-25% of measured total site water depletion seasonally, peaking at 1.05 mm d(-1). The understory species depended on water redistributed by the deep-rooted overstory pine trees for their early summer water supply. Modeling carbon flux showed that in the absence of HR, gross ecosystem productivity and net ecosystem exchange could be reduced by 750 and 400 g C m(-2) yr(-1), respectively. *Hydraulic redistribution mitigated the effects of soil drying on understory and stand evapotranspiration and had important implications for net primary productivity by maintaining this whole ecosystem as a carbon sink.Item Open Access Long-term thermal sensitivity of Earth's tropical forests.(Science (New York, N.Y.), 2020-05-21) Sullivan, Martin JP; Lewis, Simon L; Affum-Baffoe, Kofi; Castilho, Carolina; Costa, Flávia; Sanchez, Aida Cuni; Ewango, Corneille EN; Hubau, Wannes; Marimon, Beatriz; Monteagudo-Mendoza, Abel; Qie, Lan; Sonké, Bonaventure; Martinez, Rodolfo Vasquez; Baker, Timothy R; Brienen, Roel JW; Feldpausch, Ted R; Galbraith, David; Gloor, Manuel; Malhi, Yadvinder; Aiba, Shin-Ichiro; Alexiades, Miguel N; Almeida, Everton C; de Oliveira, Edmar Almeida; Dávila, Esteban Álvarez; Loayza, Patricia Alvarez; Andrade, Ana; Vieira, Simone Aparecida; Aragão, Luiz EOC; Araujo-Murakami, Alejandro; Arets, Eric JMM; Arroyo, Luzmila; Ashton, Peter; Aymard C, Gerardo; Baccaro, Fabrício B; Banin, Lindsay F; Baraloto, Christopher; Camargo, Plínio Barbosa; Barlow, Jos; Barroso, Jorcely; Bastin, Jean-François; Batterman, Sarah A; Beeckman, Hans; Begne, Serge K; Bennett, Amy C; Berenguer, Erika; Berry, Nicholas; Blanc, Lilian; Boeckx, Pascal; Bogaert, Jan; Bonal, Damien; Bongers, Frans; Bradford, Matt; Brearley, Francis Q; Brncic, Terry; Brown, Foster; Burban, Benoit; Camargo, José Luís; Castro, Wendeson; Céron, Carlos; Ribeiro, Sabina Cerruto; Moscoso, Victor Chama; Chave, Jerôme; Chezeaux, Eric; Clark, Connie J; de Souza, Fernanda Coelho; Collins, Murray; Comiskey, James A; Valverde, Fernando Cornejo; Medina, Massiel Corrales; da Costa, Lola; Dančák, Martin; Dargie, Greta C; Davies, Stuart; Cardozo, Nallaret Davila; de Haulleville, Thales; de Medeiros, Marcelo Brilhante; Del Aguila Pasquel, Jhon; Derroire, Géraldine; Di Fiore, Anthony; Doucet, Jean-Louis; Dourdain, Aurélie; Droissart, Vincent; Duque, Luisa Fernanda; Ekoungoulou, Romeo; Elias, Fernando; Erwin, Terry; Esquivel-Muelbert, Adriane; Fauset, Sophie; Ferreira, Joice; Llampazo, Gerardo Flores; Foli, Ernest; Ford, Andrew; Gilpin, Martin; Hall, Jefferson S; Hamer, Keith C; Hamilton, Alan C; Harris, David J; Hart, Terese B; Hédl, Radim; Herault, Bruno; Herrera, Rafael; Higuchi, Niro; Hladik, Annette; Coronado, Eurídice Honorio; Huamantupa-Chuquimaco, Isau; Huasco, Walter Huaraca; Jeffery, Kathryn J; Jimenez-Rojas, Eliana; Kalamandeen, Michelle; Djuikouo, Marie Noël Kamdem; Kearsley, Elizabeth; Umetsu, Ricardo Keichi; Kho, Lip Khoon; Killeen, Timothy; Kitayama, Kanehiro; Klitgaard, Bente; Koch, Alexander; Labrière, Nicolas; Laurance, William; Laurance, Susan; Leal, Miguel E; Levesley, Aurora; Lima, Adriano JN; Lisingo, Janvier; Lopes, Aline P; Lopez-Gonzalez, Gabriela; Lovejoy, Tom; Lovett, Jon C; Lowe, Richard; Magnusson, William E; Malumbres-Olarte, Jagoba; Manzatto, Ângelo Gilberto; Marimon, Ben Hur; Marshall, Andrew R; Marthews, Toby; de Almeida Reis, Simone Matias; Maycock, Colin; Melgaço, Karina; Mendoza, Casimiro; Metali, Faizah; Mihindou, Vianet; Milliken, William; Mitchard, Edward TA; Morandi, Paulo S; Mossman, Hannah L; Nagy, Laszlo; Nascimento, Henrique; Neill, David; Nilus, Reuben; Vargas, Percy Núñez; Palacios, Walter; Camacho, Nadir Pallqui; Peacock, Julie; Pendry, Colin; Peñuela Mora, Maria Cristina; Pickavance, Georgia C; Pipoly, John; Pitman, Nigel; Playfair, Maureen; Poorter, Lourens; Poulsen, John R; Poulsen, Axel Dalberg; Preziosi, Richard; Prieto, Adriana; Primack, Richard B; Ramírez-Angulo, Hirma; Reitsma, Jan; Réjou-Méchain, Maxime; Correa, Zorayda Restrepo; de Sousa, Thaiane Rodrigues; Bayona, Lily Rodriguez; Roopsind, Anand; Rudas, Agustín; Rutishauser, Ervan; Abu Salim, Kamariah; Salomão, Rafael P; Schietti, Juliana; Sheil, Douglas; Silva, Richarlly C; Espejo, Javier Silva; Valeria, Camila Silva; Silveira, Marcos; Simo-Droissart, Murielle; Simon, Marcelo Fragomeni; Singh, James; Soto Shareva, Yahn Carlos; Stahl, Clement; Stropp, Juliana; Sukri, Rahayu; Sunderland, Terry; Svátek, Martin; Swaine, Michael D; Swamy, Varun; Taedoumg, Hermann; Talbot, Joey; Taplin, James; Taylor, David; Ter Steege, Hans; Terborgh, John; Thomas, Raquel; Thomas, Sean C; Torres-Lezama, Armando; Umunay, Peter; Gamarra, Luis Valenzuela; van der Heijden, Geertje; van der Hout, Peter; van der Meer, Peter; van Nieuwstadt, Mark; Verbeeck, Hans; Vernimmen, Ronald; Vicentini, Alberto; Vieira, Ima Célia Guimarães; Torre, Emilio Vilanova; Vleminckx, Jason; Vos, Vincent; Wang, Ophelia; White, Lee JT; Willcock, Simon; Woods, John T; Wortel, Verginia; Young, Kenneth; Zagt, Roderick; Zemagho, Lise; Zuidema, Pieter A; Zwerts, Joeri A; Phillips, Oliver LThe sensitivity of tropical forest carbon to climate is a key uncertainty in predicting global climate change. Although short-term drying and warming are known to affect forests, it is unknown if such effects translate into long-term responses. Here, we analyze 590 permanent plots measured across the tropics to derive the equilibrium climate controls on forest carbon. Maximum temperature is the most important predictor of aboveground biomass (-9.1 megagrams of carbon per hectare per degree Celsius), primarily by reducing woody productivity, and has a greater impact per °C in the hottest forests (>32.2°C). Our results nevertheless reveal greater thermal resilience than observations of short-term variation imply. To realize the long-term climate adaptation potential of tropical forests requires both protecting them and stabilizing Earth's climate.Item Open Access Observed change of the standardized precipitation index, its potential cause and implications to future climate change in the Amazon region.(Philos Trans R Soc Lond B Biol Sci, 2008-05-27) Li, Wenhong; Fu, Rong; Juárez, Robinson I Negrón; Fernandes, KatiaObservations show that the standard precipitation index (SPI) over the southern Amazon region decreased in the period of 1970-1999 by 0.32 per decade, indicating an increase in dry conditions. Simulations of constant pre-industrial climate with recent climate models indicate a low probability (p=0%) that the trends are due to internal climate variability. When the 23 models are forced with either anthropogenic factors or both anthropogenic and external natural factors, approximately 13% of sampled 30-year SPI trends from the models are found to be within the range of the observed SPI trend at 95% confidence level. This suggests a possibility of anthropogenic and external forcing of climate change in the southern Amazon. On average, the models project no changes in the frequency of occurrence of low SPI values in the future; however, those models which produce more realistic SPI climatology, variability and trend over the period 1970-1999 show more of a tendency towards more negative values of SPI in the future. The analysis presented here suggests a potential anthropogenic influence on Amazon drying, which warrants future, more in-depth, study.Item Open Access Oil and gas projects in the Western Amazon: threats to wilderness, biodiversity, and indigenous peoples.(PLoS One, 2008-08-13) Finer, Matt; Jenkins, Clinton N; Pimm, Stuart L; Keane, Brian; Ross, CarlBACKGROUND: The western Amazon is the most biologically rich part of the Amazon basin and is home to a great diversity of indigenous ethnic groups, including some of the world's last uncontacted peoples living in voluntary isolation. Unlike the eastern Brazilian Amazon, it is still a largely intact ecosystem. Underlying this landscape are large reserves of oil and gas, many yet untapped. The growing global demand is leading to unprecedented exploration and development in the region. METHODOLOGY/PRINCIPAL FINDINGS: We synthesized information from government sources to quantify the status of oil development in the western Amazon. National governments delimit specific geographic areas or "blocks" that are zoned for hydrocarbon activities, which they may lease to state and multinational energy companies for exploration and production. About 180 oil and gas blocks now cover approximately 688,000 km(2) of the western Amazon. These blocks overlap the most species-rich part of the Amazon. We also found that many of the blocks overlap indigenous territories, both titled lands and areas utilized by peoples in voluntary isolation. In Ecuador and Peru, oil and gas blocks now cover more than two-thirds of the Amazon. In Bolivia and western Brazil, major exploration activities are set to increase rapidly. CONCLUSIONS/SIGNIFICANCE: Without improved policies, the increasing scope and magnitude of planned extraction means that environmental and social impacts are likely to intensify. We review the most pressing oil- and gas-related conservation policy issues confronting the region. These include the need for regional Strategic Environmental Impact Assessments and the adoption of roadless extraction techniques. We also consider the conflicts where the blocks overlap indigenous peoples' territories.Item Open Access Organic nitrogen enhances nitrogen nutrition and early growth of Pinus sylvestris seedlings.(Tree physiology, 2022-03) Lim, Hyungwoo; Jämtgård, Sandra; Oren, Ram; Gruffman, Linda; Kunz, Sabine; Näsholm, TorgnyBoreal trees are capable of taking up organic nitrogen (N) as effectively as inorganic N. Depending on the abundance of soil N forms, plants may adjust physiological and morphological traits to optimize N uptake. However, the link between these traits and N uptake in response to soil N sources is poorly understood. We examined Pinus sylvestris L. seedlings' biomass growth and allocation, transpiration and N uptake in response to additions of organic N (the amino acid arginine) or inorganic N (ammonium nitrate). We also monitored in situ soil N fluxes in the pots following an addition of N, using a microdialysis system. Supplying organic N resulted in a stable soil N flux, whereas the inorganic N resulted in a sharp increase of nitrate flux followed by a rapid decline, demonstrating a fluctuating N supply and a risk for loss of nitrate from the growth medium. Seedlings supplied with organic N achieved a greater biomass with a higher N content, thus reaching a higher N recovery compared with those supplied inorganic N. In spite of a higher N concentration in organic N seedlings, root-to-shoot ratio and transpiration per unit leaf area were similar to those of inorganic N seedlings. We conclude that enhanced seedlings' nutrition and growth under the organic N source may be attributed to a stable supply of N, owing to a strong retention rate in the soil medium.Item Open Access Planning a Sustainable Tree Canopy for Durham(2020-04-24) Hancock, Grace; Vanko, Alex; Xiong, MingfeiTrees are a vital part of a city’s infrastructure. The urban forest provides many ecosystem services to residents including health benefits, air pollution removal, extreme heat reduction, stormwater mitigation, and even lower violent crime rates. Durham, North Carolina is 52% covered by trees, but its canopy is declining from urban development, and it is unevenly distributed due to a history of racial and socioeconomic inequity. Parts of the city that are more urbanized, non-white, and poor tend to have far less tree cover than more rural, white, affluent areas. This Masters Project sought to help TreesDurham and the City of Durham plan a sustainable tree canopy that meets the city’s goal of 55% cover by 2040. Expansion of Durham’s urban forest must address the concerns of the community, maximize ecosystem services, and consider possible changes to city development codes. We addressed these needs by (1) conducting a community survey to understand Durham residents’ attitudes towards city trees, (2) creating a tree-planting prioritization map based on ecosystem services, and (3) modeling the future of Durham’s urban forest under multiple development scenarios. We recommend that TreesDurham and the City of Durham (1) incorporate input from Durham residents, (2) target tree-planting to the areas that need tree ecosystem services the most, including heavily urbanized areas and roadside rights-of-way, and (3) greatly increase tree protection requirements in Durham’s development code. This will ensure that all residents of Durham enjoy access to the benefits of the urban forest.