1
|
Kim JE, Wang JA, Li Y, Czimczik CI, Randerson JT. Wildfire-induced increases in photosynthesis in boreal forest ecosystems of North America. Glob Chang Biol 2024; 30:e17151. [PMID: 38273511 DOI: 10.1111/gcb.17151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 10/11/2023] [Accepted: 12/12/2023] [Indexed: 01/27/2024]
Abstract
Observations of the annual cycle of atmospheric CO2 in high northern latitudes provide evidence for an increase in terrestrial metabolism in Arctic tundra and boreal forest ecosystems. However, the mechanisms driving these changes are not yet fully understood. One proposed hypothesis is that ecological change from disturbance, such as wildfire, could increase the magnitude and change the phase of net ecosystem exchange through shifts in plant community composition. Yet, little quantitative work has evaluated this potential mechanism at a regional scale. Here we investigate how fire disturbance influences landscape-level patterns of photosynthesis across western boreal North America. We use Alaska and Canadian large fire databases to identify the perimeters of wildfires, a Landsat-derived land cover time series to characterize plant functional types (PFTs), and solar-induced fluorescence (SIF) from the Orbiting Carbon Observatory-2 (OCO-2) as a proxy for photosynthesis. We analyze these datasets to characterize post-fire changes in plant succession and photosynthetic activity using a space-for-time approach. We find that increases in herbaceous and sparse vegetation, shrub, and deciduous broadleaf forest PFTs during mid-succession yield enhancements in SIF by 8-40% during June and July for 2- to 59-year stands relative to pre-fire controls. From the analysis of post-fire land cover changes within individual ecoregions and modeling, we identify two mechanisms by which fires contribute to long-term trends in SIF. First, increases in annual burning are shifting the stand age distribution, leading to increases in the abundance of shrubs and deciduous broadleaf forests that have considerably higher SIF during early- and mid-summer. Second, fire appears to facilitate a long-term shift from evergreen conifer to broadleaf deciduous forest in the Boreal Plain ecoregion. These findings suggest that increasing fire can contribute substantially to positive trends in seasonal CO2 exchange without a close coupling to long-term increases in carbon storage.
Collapse
Affiliation(s)
- Jinhyuk E Kim
- Department of Earth System Science, University of California, Irvine, California, USA
| | - Jonathan A Wang
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Yue Li
- Department of Geography, University of California, Los Angeles, California, USA
| | - Claudia I Czimczik
- Department of Earth System Science, University of California, Irvine, California, USA
| | - James T Randerson
- Department of Earth System Science, University of California, Irvine, California, USA
| |
Collapse
|
2
|
Donkpegan ASL, Doucet JL, Hardy OJ, Heuertz M, Piñeiro R. Miocene Diversification in the Savannahs Precedes Tetraploid Rainforest Radiation in the African Tree Genus Afzelia (Detarioideae, Fabaceae). Front Plant Sci 2020; 11:798. [PMID: 32625223 PMCID: PMC7313659 DOI: 10.3389/fpls.2020.00798] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 05/19/2020] [Indexed: 06/11/2023]
Abstract
The dating of diversification events, including transitions between biomes, is key to elucidate the processes that underlie the assembly and evolution of tropical biodiversity. Afzelia is a widespread genus of tropical trees, threatened by exploitation for its valuable timber, that presents an interesting system to investigate diversification events in Africa. Africa hosts diploid Afzelia species in the savannahs north and south of the Guineo-Congolian rainforest and autotetraploid species confined to the rainforest. Species delimitation and phylogenetic relationships among the diploid and tetraploid species remained unresolved in previous studies using small amounts of DNA sequence data. We used genotyping-by-sequencing in the five widespread Afzelia species in Africa, the savannah species A. africana and A. quanzensis and the rainforest species A. bipindensis, A. pachyloba, and A. bella. Maximum likelihood and coalescent approaches resolved all species as monophyletic and placed the savannah and rainforest taxa into two separate clades corresponding to contrasted ploidy levels. Our data are thus compatible with a single biome shift in Afzelia in Africa, although we were unable to conclude on its direction. SNAPP calibrated species trees show that the savannah diploids started to diversify early, at 12 (9.09-14.89) Ma, which contrasts with a recent and rapid diversification of the rainforest tetraploid clade, starting at 4.22 (3.12 - 5.36) Ma. This finding of older diversification in a tropical savannah clade vs. its sister rainforest clade is exceptional; it stands in opposition to the predominant observation of young ages for savannahs lineages in tropical regions during the relatively recent expansion of the savannah biome.
Collapse
Affiliation(s)
- Armel S. L. Donkpegan
- Forest is Life, TERRA Teaching and Research Centre, Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
- Evolutionary Biology and Ecology Unit, Faculté des Sciences, Université Libre de Bruxelles, Brussels, Belgium
- INRAE, BFP, University of Bordeaux, Villenave d’Ornon, France
| | - Jean-Louis Doucet
- Forest is Life, TERRA Teaching and Research Centre, Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Olivier J. Hardy
- Evolutionary Biology and Ecology Unit, Faculté des Sciences, Université Libre de Bruxelles, Brussels, Belgium
| | | | - Rosalía Piñeiro
- Department of Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
- Evolutionary Genomics, Centre for Geogenetics – Natural History Museum of Denmark, Copenhagen, Denmark
| |
Collapse
|
3
|
Gagnon E, Ringelberg JJ, Bruneau A, Lewis GP, Hughes CE. Global Succulent Biome phylogenetic conservatism across the pantropical Caesalpinia Group (Leguminosae). New Phytol 2019; 222:1994-2008. [PMID: 30536385 DOI: 10.1111/nph.15633] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 12/01/2018] [Indexed: 05/21/2023]
Abstract
The extent to which phylogenetic biome conservatism vs biome shifting determines global patterns of biodiversity remains poorly understood. To address this question, we investigated the biogeography and trajectories of biome and growth form evolution across the Caesalpinia Group (Leguminosae), a clade of 225 species of trees, shrubs and lianas distributed across the Rainforest, Succulent, Temperate and Savanna Biomes. We focused especially on the little-known Succulent Biome, an assemblage of succulent-rich, grass-poor, seasonally dry tropical vegetation distributed disjunctly across the Neotropics, Africa, Arabia and Madagascar. We reconstructed a time-calibrated phylogeny, assembled species occurrence data and assigned species to areas, biomes and growth forms. These data are used to estimate the frequency of transcontinental disjunctions, biome shifts and evolutionary transitions between growth forms and test for phylogenetic biome conservatism and correlated evolution of growth forms and biome shifts. We uncovered a pattern of strong phylogenetic Succulent Biome conservatism. We showed that transcontinental disjunctions confined within the Succulent Biome are frequent and that biome shifts to the Savanna, Rainforest and Temperate Biomes are infrequent and closely associated with shifts in plant growth forms. Our results suggest that the Succulent Biome comprises an ecologically constrained evolutionary arena spanning large geographical disjunctions across the tropics.
Collapse
Affiliation(s)
- Edeline Gagnon
- Institut de Recherche en Biologie Végétale & Département de Sciences Biologiques, Université de Montréal, H1X 2B2, Montréal, QC, Canada
- Département de Biologie, Université de Moncton, E1A 3E9, Moncton, NB, Canada
- Royal Botanic Garden Edinburgh, 20a Inverleith Row, Edinburgh, EH3 5LR, UK
| | - Jens J Ringelberg
- Department of Systematic & Evolutionary Botany, University of Zurich, Zollikerstrasse 107, 8008, Zurich, Switzerland
| | - Anne Bruneau
- Institut de Recherche en Biologie Végétale & Département de Sciences Biologiques, Université de Montréal, H1X 2B2, Montréal, QC, Canada
| | - Gwilym P Lewis
- Comparative Plant and Fungal Biology Department, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, UK
| | - Colin E Hughes
- Department of Systematic & Evolutionary Botany, University of Zurich, Zollikerstrasse 107, 8008, Zurich, Switzerland
| |
Collapse
|
4
|
Affiliation(s)
- Michael J Donoghue
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06520-8106, USA
| |
Collapse
|
5
|
Crisp MD, Cook LG, Bowman DMJS, Cosgrove M, Isagi Y, Sakaguchi S. Turnover of southern cypresses in the post-Gondwanan world: extinction, transoceanic dispersal, adaptation and rediversification. New Phytol 2019; 221:2308-2319. [PMID: 30367483 PMCID: PMC6587739 DOI: 10.1111/nph.15561] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 10/15/2018] [Indexed: 05/23/2023]
Abstract
Cupressaceae subfamily Callitroideae has been an important exemplar for vicariance biogeography, but its history is more than just disjunctions resulting from continental drift. We combine fossil and molecular data to better assess its extinction and, sometimes, rediversification after past global change. Key fossils were reassessed and their phylogenetic placement for calibration was determined using trait mapping and Bayes Factors. Five vicariance hypotheses were tested by comparing molecular divergence times with the timing of tectonic rifting. The role of adaptation to fire (serotiny) in its spread across a drying Australia was tested for Callitris. Our findings suggest that three transoceanic disjunctions within the Callitroideae probably arose from long-distance dispersal. A signature of extinction, centred on the end-Eocene global climatic chilling and drying, is evident in lineages-through-time plots and in the fossil record. Callitris, the most diverse extant callitroid genus, suffered extinctions but surviving lineages adapted and re-radiated into dry, fire-prone biomes that expanded in the Neogene. Serotiny, a key adaptation to fire, likely evolved in Callitris coincident with the biome shift. Both extinction and adaptive shifts have probably played major roles in this chronicle of turnover and renewal, but better understanding of biogeographical history requires improved taxonomy of fossils.
Collapse
Affiliation(s)
- Michael D. Crisp
- Research School of BiologyThe Australian National UniversityRN Robertson Building, 46 Sullivans Creek RoadActon (Canberra)ACT2601Australia
| | - Lyn G. Cook
- School of Biological SciencesThe University of QueenslandBrisbaneQld4072Australia
| | - David M. J. S. Bowman
- School of Natural SciencesThe University of TasmaniaPrivate Bag 55HobartTas7001Australia
| | - Meredith Cosgrove
- Research School of BiologyThe Australian National UniversityRN Robertson Building, 46 Sullivans Creek RoadActon (Canberra)ACT2601Australia
| | - Yuji Isagi
- Graduate School of AgricultureKyoto UniversityKyoto606‐8502Japan
| | - Shota Sakaguchi
- Graduate School of Human and Environmental StudiesKyoto UniversityKyoto606‐8501Japan
| |
Collapse
|
6
|
Antonelli A, Zizka A, Carvalho FA, Scharn R, Bacon CD, Silvestro D, Condamine FL. Amazonia is the primary source of Neotropical biodiversity. Proc Natl Acad Sci U S A 2018; 115:6034-9. [PMID: 29760058 DOI: 10.1073/pnas.1713819115] [Citation(s) in RCA: 149] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Amazonia is not only the world’s most diverse rainforest but is also the region in tropical America that has contributed most to its total biodiversity. We show this by estimating and comparing the evolutionary history of a large number of animal and plant species. We find that there has been extensive interchange of evolutionary lineages among different regions and biomes, over the course of tens of millions of years. Amazonia stands out as the primary source of diversity, which can be mainly explained by the total amount of time Amazonian lineages have occupied the region. The exceedingly rich and heterogeneous diversity of the American tropics could only be achieved by high rates of dispersal events across the continent. The American tropics (the Neotropics) are the most species-rich realm on Earth, and for centuries, scientists have attempted to understand the origins and evolution of their biodiversity. It is now clear that different regions and taxonomic groups have responded differently to geological and climatic changes. However, we still lack a basic understanding of how Neotropical biodiversity was assembled over evolutionary timescales. Here we infer the timing and origin of the living biota in all major Neotropical regions by performing a cross-taxonomic biogeographic analysis based on 4,450 species from six major clades across the tree of life (angiosperms, birds, ferns, frogs, mammals, and squamates), and integrate >1.3 million species occurrences with large-scale phylogenies. We report an unprecedented level of biotic interchange among all Neotropical regions, totaling 4,525 dispersal events. About half of these events involved transitions between major environmental types, with a predominant directionality from forested to open biomes. For all taxonomic groups surveyed here, Amazonia is the primary source of Neotropical diversity, providing >2,800 lineages to other regions. Most of these dispersal events were to Mesoamerica (∼1,500 lineages), followed by dispersals into open regions of northern South America and the Cerrado and Chaco biomes. Biotic interchange has taken place for >60 million years and generally increased toward the present. The total amount of time lineages spend in a region appears to be the strongest predictor of migration events. These results demonstrate the complex origin of tropical ecosystems and the key role of biotic interchange for the assembly of regional biotas.
Collapse
|
7
|
Spriggs EL, Clement WL, Sweeney PW, Madriñán S, Edwards EJ, Donoghue MJ. Temperate radiations and dying embers of a tropical past: the diversification of Viburnum. New Phytol 2015; 207:340-354. [PMID: 25644136 DOI: 10.1111/nph.13305] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 12/16/2014] [Indexed: 06/04/2023]
Abstract
We used a near-complete phylogeny for the angiosperm clade Viburnum to assess lineage diversification rates, and to examine possible morphological and ecological factors driving radiations. Maximum-likelihood and Bayesian approaches identified shifts in diversification rate and possible links to character evolution. We inferred the ancestral environment for Viburnum and changes in diversification dynamics associated with subsequent biome shifts. Viburnum probably diversified in tropical forests of Southeast Asia in the Eocene, with three subsequent radiations in temperate clades during the Miocene. Four traits (purple fruits, extrafloral nectaries, bud scales and toothed leaves) were statistically associated with higher rates of diversification. However, we argue that these traits are unlikely to be driving diversification directly. Instead, two radiations were associated with the occupation of mountainous regions and a third with repeated shifts between colder and warmer temperate forests. Early-branching depauperate lineages imply that the rare lowland tropical species are 'dying embers' of once more diverse lineages; net diversification rates in Viburnum likely decreased in these tropical environments after the Oligocene. We suggest that 'taxon pulse' dynamics might characterize other temperate plant lineages.
Collapse
Affiliation(s)
- Elizabeth L Spriggs
- Department of Ecology and Evolutionary Biology, Yale University, PO Box 208106, New Haven, CT, 06520, USA
| | - Wendy L Clement
- Department of Biology, The College of New Jersey, 2000 Pennington Rd, Ewing, NJ, 08628, USA
| | - Patrick W Sweeney
- Division of Botany, Peabody Museum of Natural History, Yale University, PO Box 208118, New Haven, CT, 06520, USA
| | - Santiago Madriñán
- Laboratorio de Botánica y Sistemática, Departamento de Ciencias Biológicas, Universidad de los Andes, Apartado Aéreo 4976, Bogotá, Colombia
| | - Erika J Edwards
- Department of Ecology and Evolutionary Biology, Brown University, Box G-W, 80 Waterman Street, Providence, RI, 02912, USA
| | - Michael J Donoghue
- Department of Ecology and Evolutionary Biology, Yale University, PO Box 208106, New Haven, CT, 06520, USA
| |
Collapse
|