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The subtropical dry forests are experiencing rapid clearing in the southamerican Great Chaco region, mainly for soybean production in Argentina. This is causing biodiversity loss and soil salinization. This forests are unique for the floristic richness and the dense forest cover in a region characterized by semiarid climatic conditions. The authors complain to the DRYFLOR team for their exclusion of the Gran Chaco, the world´s largest continuous dry forest, from their definition of tropical and subtropical dry forests in their paper "Plant diversity patterns in neotropical dry forests and their conservation implications".
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3 FEBRUARY 2017 • VOL 355 ISSUE 6324 465SCIENCE
The Gran Chaco harbors high biodiver-
sity, including many endemic species (3, 6,
7). This region is also a global deforestation
hotspot (8) due to the recently acceler-
ated expansion of cattle ranching and
soybean cultivation there (9, 10). Given the
agricultural potential of the region and the
growing global demands for agricultural
products, the pressure to convert addi-
tional natural ecosystems into agricultural
land remains very high. Yet, only 9% of the
Gran Chaco is currently protected (6). For
these reasons, the Gran Chaco is one of the
most threatened ecoregions worldwide.
Various definitions of dry forests exist, but
the Gran Chaco should not be neglected
when raising awareness to the urgent
conservation needs in the often forgotten
neotropical dry forests.
Tobias Kuemmerle,1,2* Mariana
Al tr ic ht er, 3 Germán Baldi,4 Marcel
Cabido,5 Micaela Camino,6 Erika Cuellar,7
Rosa Leny Cuellar,8 Julieta Decarre,9
Sandra Díaz,5 Ignacio Gasparri,10
Gregorio Gavier-Pizarro,9 Rubén
Ginzburg,11 Anthony J. Giordano,12
H. Ricardo Grau,10 Esteban Jobbágy,4
Gerardo Leynaud,12 Leandro Macchi,1
Matias Mastrangelo,13 Silvia D.
Matteucci,14 Andre w Noss,15 Jo sé Paru elo,16
Maria Piquer-Rodríguez,1 Alfredo Romero-
Muñoz,1 Asunción Semper-Pascual,1
Jeffrey Thompson,17,18 Seba stián Torrella,11
Ricardo Torres,19 José N. Volante,20
Alberto Yanosky,17 Marcelo Zak 5
1Geography Department, Humboldt-University
Berlin, Germany. 2Integrative Research Institute on
Transformations of Human-Environment Systems
(IRI THESys), Humboldt-University Berlin, Germany.
3Department of Environmental Studies, Prescott
Colle ge, AZ 863 01, USA. 4Grupo de Estudios
Ambientales (IMASL), Universidad Nacional de
San Luis & CONICET, San Luis, Argentina. 5Instituto
Multidisciplinario de Biología Vegetal (IMBIV)–
CONICET & Facultad de Filosofía y Humanidades,
Universidad Nacional de Córdoba, Argentina.
6Centro de Ecología Aplicada del Litoral (CECOAL)–
CONICET, Corrientes, Argentina. 7Santa Cruz, Bolivia.
8Fundación Kaa Iya, Santa Cruz, Bolivia. 9Centro de
Investigación en Recursos Naturales (CIRN-IRB),
Instituto Nacional de Tecnología Agropecuaria (INTA),
Buenos Aires, Argentina. 10Instituto de Ecología
Regional, Universidad Nacional de Tucumán, Yerba
Buena, Argentina. 11Departamento de Ecología,
Genética, y Evolución, Universidad de Buenos
Aires, Argentina. 12Society for the Preservation of
Endangered Carnivores and their International
Ecological Study (SPECIES), Ventura, CA 93003,
USA. 13Grupo de Estudio de Agroecosistemas y
Paisajes Rurales (GEAP), Universidad Nacional
de Mar del Plata, Balcarce, Argentina. 14Grupo de
Ecología del Paisaje y Medio Ambiente, Universidad
de Buenos Aires and CONICET, Argentina.
15Department of Geography, University of Florida,
Gainesville, FL 32611, USA. 16Departamento de
Métodos Cuantitativos y Sistemas de Información
(IFEVA), Universidad de Buenos Aires and CONICET,
Buenos Aires, Argentina. 17Guyra Paraguay,
Asunción, Paraguay. 18Consejo Nacional de Ciencia y
Tecnología (CONACYT), Asunción, Paraguay. 19Museo
de Zoología, Universidad Nacional de Córdoba,
Argentina. 20Estación Experimental Agropecuaria
Salta, INTA, Salta, Argentina.
*Corresponding author.
1. C. L. Parr, C. E. R . Lehma nn, W. J. Bond, W. A. Hoffm ann,
A. N. Andersen, Tre nd s E co l . E vo l . 29, 205 (2014).
2. D. M. Olson et al., Bioscience 51, 933 (2001).
3. E. H. Buc her, P. C. Huszar, J. Environ. Manage. 57, 99
4. H. R. Grau , N. I. Ga sparr i, T. M. Aide, Glob. Change Biol. 14,
985 (2008).
5. A. Rubí Bianc hi, S. A. C. C ravero, Atlas climático digital de
la República Argentina (Instituto Nacional de Tecnología
Agropecuaria, Salta, Argentina, 2010), p. 56.
6. J. Nori et al., Divers. Distrib. 10.1111/ddi.12497 (2016).
7. K. H. Redfo rd, A. Taber, J. A . Sim onet ti, Conserv. Biol. 4, 328
8. M. C. Hansen et al., Science 342, 850 (2013).
9. M. Vallejos et al., J. Arid Environ. 123, 3 (2015).
10. M. Baumann et al ., Glob. Change Biol., 10.1111/gcb.13521
WE AGREE WITH Kuemmerle et al. that
the forests in the Gran Chaco region are
under massive threat, underprotected,
and deserving of greater attention from
scientists and conservationists. We could
have included the Chaco woodlands in
our analyses, and their distinctive flora
would have reinforced our conclusions of
high floristic turnover among neotropical
dry forests. However, level of threat and
the label of “dry forest,” a term that has
been notoriously loosely used across the
neotropics (13), were not the criteria used
in selecting sites for our study. Rather,
Forest conservation:
Remember Gran Chaco
around the globe are experiencing rapid
clearing and concomitant biodiversity
loss (1). In their Research Article “Plant
diversity patterns in neotropical dry forests
and their conservation implications” (23
September 2016, p. 1383), DRYFLOR et al.
highlight the often underappreciated, yet
exceptional floristic richness and unique-
ness of these forests, and they provide
compelling arguments for ramping up
efforts to protect them.
We applaud the DRYFLOR team for their
seminal work, but we are also concerned
about the exclusion of the Gran Chaco,
frequently considered the world’s largest
continuous tropical dry forest region (24).
The Gran Chaco covers more than 1,100,000
km2 in Northern Argentina, Bolivia, Brazil,
and Paraguay. The DRYFLOR team used
a restrictive definition of dry forest that
excludes the Gran Chaco because of some
temperate elements in the Chaco’s flora
and occasional freezing temperatures there.
However, that applies only to parts of the
Gran Chaco, and other neotropical dry
forests that were included in the analysis
also experience such temperatures (5).
Edited by Jennifer Sills
A mesquite tree
stands in the Gran
Chaco dry forest
habitat in Argentina.
DA_0203Letters.indd 465 2/1/17 10:21 AM
Published by AAAS
on February 2, 2017 from
we focused on sites in the neotropical dry
forest biome as defined based on climatic,
soil, hydrologic, physiognomic, and floristic
characteristics (4, 5). Based on these
criteria, it is more biologically meaningful
and relevant for conservation purposes to
consider the Chaco woodlands as a distinct
biome (6, 7)—essentially a separate evolu-
tionary metacommunity (4, 5, 8).
We did include sites from within the
Gran Chaco region in our analyses, such
as the Cerro León in Paraguay, because
these are floristically and ecologically dry
forests. However, we did not include sites
from the Chaco woodlands (6, 7) because
these are dominated by a different,
temperate-adapted flora. The Chaco wood-
lands receive regular and severe frost and
also suffer the highest summer tempera-
tures recorded in South America (9). We
suggest that these extreme climatic condi-
tions, added to saline soils and seasonal
flooding in many areas (6), which contrast
with the well-drained, fertile soils of tropi-
cal dry forests, have led to the distinctive
evolutionary assembly of the temperate-
adapted flora of the Chaco woodlands.
We agree with others (5) that there
is a need to arrive at better, universally
agreed-upon definitions of neotropical
biomes, especially in seasonally dry areas
and including the Gran Chaco region. For
this reason, there are 50 inventories of
Chaco woodland in the openly available
DRYFLOR database (10). Exploring biome
definitions at this continental scale will
require quantitative analysis of how flo-
ristic composition and ecosystem function
is influenced by environmental conditions
and geographic distance across all major
neotropical biomes, including rain forests,
dry forests, and savannas. We predict that
if the Chaco woodlands are included in
such a broad-scale analysis, their highly
distinctive flora would separate them as a
biome at a continental scale, underlining
the importance of conserving their unique
plant diversity.
DRYFLOR1: R. Toby Pennington,2*
Karina Banda-R,2,3 Alfonso Delgado-
Salinas,4 Kyle G. Dexter,2,5 Luciano
Galetti,6 Reynaldo Linares-Palomino,7,8
Hernán M. Maturo,6 Virginia Mogni,6
Luis Oakley,6 Ary Olivera-Filho,9
Darién Prado,6 Catalina Quintana,10
Ricarda Riina,11 Tiina Särkinen2
1Latin American and Caribbean Seasonally Dry
Tropical Forest Floristic Network, Royal Botanic
Garden Edinburgh, Edinburgh, EH3 5LR, UK. 2Royal
Botanic Garden Edinburgh, EH3 5LR, Edinburgh,
UK. 3Fundación Ecosistemas Secos de Colombia,
Bogotá, Colombia. 4Departamento de Botánica,
Universidad Nacional Autónoma de México, México
D.F., México. 5School of GeoSciences, University of
Edinburgh, Edinburgh, UK. 6Cátedra de Botánica,
IICAR-CONICET, Facultad de Ciencias Agrarias,
466 3 FEBRUARY 2017 • VOL 355 ISSUE 6324 SCIENCE
Universidad Nacional de Rosario, S2125ZAA Zavalla,
Argentina. 7Universidad Nacional Agraria La Molina,
Avenida La Molina, Lima, Perú. 8Smithsonian
Conservation Biology Institute, San Isidro, Lima,
Perú. 9Universidade Federal de Minas Gerais (UFMG),
Instituto de Ciências Biológicas (ICB), Departamento
de Botânica, Belo Horizonte, Minas Gerais, Brazil.
10Pontificia Universidad Católica del Ecuador, Facultad
de Ciencias Exactas, Escuela de Biología, Quito,
Ec ua do r. 11Real Jardín Botánico, RJB-CSIC, 28014
Madrid, Spain.
*Corresponding author.
1. P. Murphy, A. E. Lugo, in Seasonally Dry Tropical Forests, S.
H. Bullock, H. A. Mooney, E. Medina, Eds. (Cambridge Univ.
Press, 1 995), p p. 146194.
2. O. Hu ber, R. Rii na, Glosario Fitoecológico de las Américas,
vol. 1. América del Sur: países hispanoparlantes (Caracas,
Venezuela, 1997).
3. O. Hub er, R. Riin a, Glosario Fitoecológico de las Américas,
vol. 2. México, Centroamérica e Islas del Caribe (U NESCO,
Paris, 2003).
4. T. Särkinen, J. R. I. Iganci, R. Linares-Palomino, M. F. Simon,
D. E. Prado, BMC Ecol. 11, 27 (2011).
5. C. E. Hughes, R. T. Pennington, A. Antonelli, Bot. J. Li nn.
Soc. 171, 1 (2013).
6. D. E. Prad o, Candollea 48, 145 (1993).
7. D. E. Prado, Candollea 48, 615 (1993).
8. R. T. Pennington, M. Lavin, A. Oliveira-Filho, Ann. Rev. Ecol.
Syst. 40, 437 (2009).
9. H. Conti, G. Cazenave, R. Giagnoni, in Flora Chaqueña,
Asteraceae , A. Molina, Ed. (Instituto Nacional de
Tecnología Agropecuaria, Argentina, 2009), pp. 926.
10. DRYFLOR: Latin American Seasonally Dry Tropical Forest
Floristic Network (
Forest conservation:
Humans’ handprints
home to humans since the end of the
Pleistocene, and large pre-Columbian
societies emerged in tropical dry forests in
Central and South America and in wetter
forests of the Amazon basin during the
past several millennia. The role of humans
in shaping species distributions, how-
ever, tends to be overlooked in ecological
studies. For example, in their Research
Article analyzing the largest data set
of floristic inventories in neotropical
dry forests (“Plant diversity patterns in
neotropical dry forests and their conserva-
tion implications,” 23 September 2016, p.
1383), DRYFLOR et al. mentioned humans
occasionally, but not as a potential driver
of the patterns observed.
Although DRYFLOR et al. showed
neotropical dry forests to be dominated
by woody plant species with geographi-
cally restricted distributions, 17 of the
4660 species recorded were widespread
across dry forests, occurring in at least 9
of 12 floristic groups. Interestingly, 8 of
these 17 widespread species are known to
be cultivated today (1), and two of those
have populations that were cultivated and
probably domesticated by pre-Columbian
societies (Sapindus saponaria and Tre ma
micrantha) (1). Surprisingly, all eight
widespread species of the dry biome
that were cultivated by past or modern
Amerindians also occur in Amazonian
forests (2). Amazonian forests are partly
dominated by useful species, a pattern
that might result from past management
activities (2). The widespread distribution
of cultivated and/or domesticated spe-
cies across wet and dry biomes suggests
that human-plant interactions transcend
ecological boundaries and supports the
hypothesis of a substantial effect of past
human societies in shaping plant distribu-
tions across the neotropics. Accordingly,
it is important that ecological studies take
into account the potential role of prehis-
torical and historical human dispersal as
a driver of plant distributions within and
among neotropical biomes.
Carolina Levis,1,2* Charles R. Clement,3
Hans ter Steege,4,5 Frans Bongers,2
André Braga Junqueira,6 Nigel Pitman,7
Marielos Peña-Claros,2 Flavia R. C. Costa8
1Programa de Pós-Graduação em Ecologia, Instituto
Nacional de Pesquisas da Amazônia, Manaus,
Amazonas, 69067-375, Brazil. 2Forest Ecology and
Forest Management Group, Wageningen University &
Research, Wageningen, 6700 AA, The Netherlands.
3Coordenação de Tecnologia e Inovação, Instituto
Nacional de Pesquisas da Amazônia, Manaus,
Amazonas, 69067-375, Brazil. 4Biodiversity
Dynamics, Naturalis Biodiversity Center, Leiden,
The Netherlands. 5Systems Ecology,
Trema micrantha has
been cultivated in both
tropical dry forests and
Amazonian forests.
DA_0203Letters.indd 466 2/1/17 10:21 AM
Published by AAAS
on February 2, 2017 from
Free University Amsterdam, The Netherlands.
6Department of Soil Quality, Wageningen University
& Research, Wageningen, 6700 AA, The Netherlands.
7The Field Museum, Chicago, IL 60605, USA.
8Coordenação de Biodiversidade, Instituto Nacional
de Pesquisas da Amazônia, Manaus, Amazonas,
69067-375, Brazil.
*Corresponding author.
1. The Mansfeld’s World Database of Agriculture and
Horticultural Crops (http://mansfeld.
2. H. ter Steege et al., Science 342, 1243092 (2013).
10.1126/science. aal2175
WE AGREE WITH Levis et al. that humans
have influenced dry forests since their
first arrival in the neotropics. This long
interaction has had major effects, not least
in leading to widespread destruction of
this now highly threatened vegetation (1).
It is also possible, as pointed out by Levis
et al., that humans modified the distribu-
tions of useful woody plant species in dry
forests and that this human influence
could be partly responsible for their wide
geographic distribution. However, the
number of such species that are or were
cultivated as a proportion of the overall
flora of neotropical dry forests is small
(8 out of the 4660 species in our data set,
according to Levis et al.). We found high
floristic turnover among major geographic
areas of dry forest. This pattern is driven
by the large numbers of range-restricted
species in our data set: 3115 species are
restricted to only one of the 12 regional
floristic groups we identified. Therefore,
the effect of geographically widespread
species on our conclusions is negligible,
whatever the reasons underlying their
broad ranges.
Levis et al. suggest that the presence in
the Amazonian rain forest biome of the
same widespread, ecologically generalist,
human-cultivated species found in the
dry biome is surprising and may indicate
that human-plant interactions transcend
ecological boundaries. We find it more
likely that the preferences of these spe-
cies for disturbed areas underlie their
wide distribution, given the high level
of degradation of many dry forest sites.
This would ultimately be a human effect,
but one operating indirectly through the
pioneer nature and wide ecological toler-
ances intrinsic to these species.
We agree that ecological studies should
take into account the potential role of
human dispersal as a driver of plant dis-
tributions in the neotropics (2), but we do
not believe that the pattern of high floristic
turnover that we described for dry forests,
and its clear implication that many more
protected areas are urgently required, is
affected by previous human influence on
the species’ ranges.
DRYFLOR1: R. Toby Pennington,2*
Karina Banda-R,2,3 Alfonso Delgado-
Salinas,4 Kyle G. Dexter,2,5 Reynaldo
Linares-Palomino,6,7 Ary Olivera-Filho,8
Darién Prado,9 Catalina Quintana,10
Ricarda Riina11
1Latin American and Caribbean Seasonally Dry
Tropical Forest Floristic Network, Royal Botanic
Garden Edinburgh, Edinburgh, EH3 5LR, UK. 2Royal
Botanic Garden Edinburgh, EH3 5LR, Edinburgh,
UK. 3Fundación Ecosistemas Secos de Colombia,
Bogotá, Colombia. 4Departamento de Botánica,
Universidad Nacional Autónoma de México, México
D.F., México. 5School of GeoSciences, University of
Edinburgh, Edinburgh, UK. 6Universidad Nacional
Agraria La Molina, Avenida La Molina, Lima, Perú.
7Smithsonian Conservation Biology Institute, San
Isidro, Lima, Perú. 8Universidade Federal de Minas
Gerais (UFMG), Instituto de Ciências Biológicas
(ICB), Departamento de Botânica, Belo Horizonte,
Minas Gerais, Brazil. 9Cátedra de Botánica,
IICAR-CONICET, Facultad de Ciencias Agrarias,
Universidad Nacional de Rosario, S2125ZAA Zavalla,
Argentina. 10Pontificia Universidad Católica del
Ecuador, Facultad de Ciencias Exactas, Escuela de
Biología, Quito, Ecuador. 11Real Jardín Botánico,
RJB-CSIC, 28014 Madrid, Spain.
*Corresponding author.
1. L. Miles et al., J. Biogeogr. 33, 491 (2006).
2. C. N. H. McMichael, F. Matthews-Bird, W. Farfan-Rios, K. J.
Feeley, Proc. Natl. Aca d. Sci . U.S.A. 114, 522 (2017).
DA_0203Letters.indd 467 2/1/17 10:22 AM
Published by AAAS
on February 2, 2017 from
(6324), 465. [doi: 10.1126/science.aal3020]355Science
(February 2, 2017)
Torres, José N. Volante, Alberto Yanosky and Marcelo Zak
Semper-Pascual, Jeffrey Thompson, Sebastián Torrella, Ricardo
Piquer-Rodríguez, Alfredo Romero-Muñoz, Asunción
Silvia D. Matteucci, Andrew Noss, José Paruelo, Maria
Jobbágy, Gerardo Leynaud, Leandro Macchi, Matias Mastrangelo,
Rubén Ginzburg, Anthony J. Giordano, H. Ricardo Grau, Esteban
Decarre, Sandra Díaz, Ignacio Gasparri, Gregorio Gavier-Pizarro,
Cabido, Micaela Camino, Erika Cuellar, Rosa Leny Cuellar, Julieta
Tobias Kuemmerle, Mariana Altrichter, Germán Baldi, Marcel
Forest conservation: Remember Gran Chaco
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... Tropical dry forests cover about 20 % of the global terrestrial surface area, provide 30 % of global primary productivity, and harbor high and unique biodiversity (Myers et al., 2000). Despite their outstanding conservation value, many of these forests are under increasingly high human pressure, especially from agricultural expansion and overexploitation (Blackie et al., 2014;Kuemmerle et al., 2017;Prieto-Torres et al., 2021;Pendrill et al., 2022). Particularly in the Neotropics, tropical dry forests have recently turned into global deforestation hotspots (Prieto-Torres et al., 2018;Buchadas et al., 2022). ...
... Here, we focus on the Gran Chaco (hereafter, Chaco), the largest and most threatened tropical dry forest in South America (Nori et al., 2016;Kuemmerle et al., 2017;Prieto-Torres et al., 2022). The Chaco has recently experienced rampant deforestation (Baumann et al., 2017), as well as major waves of defaunation (Periago et al., 2014;Torres et al., 2014;Semper-Pascual et al., 2018). ...
... First, the current set of protected areas is inefficient in protecting Chaco biodiversity, since threatened and endemic species are weakly represented in these protected areas. Thus, an expansion of this network is urgently needed (Nori et al., 2016;Kuemmerle et al., 2017;Prieto-Torres et al., 2022). Moreover, the current protected areas overlap only marginally with areas used by forest-dependent people (i.e., forest smallholders and indigenous people). ...
... Tropical and subtropical dry forests worldwide are experiencing large-scale, rapid land use changes and associated biodiversity loss. The Gran Chaco ecoregion, the most extensive and threatened seasonally dry forest of South America, exempli es this concerning trend, as it is a global deforestation hotspot (Kuemmerle et al. 2017). The lowland areas are signi cantly impacted by soybean cultivation and cattle ranching, and mountains are affected by re, grazing, and the non-native species encroachment (Cabido et al. 2018;Piquer-Rodríguez et al. 2018). ...
... The development of these molecular markers is of vital importance for studying this species, given the current scenario of accelerated habitat loss and fragmentation in the Gran Chaco (Kuemmerle et al. 2017). These markers will enable the study of intraspeci c genetic diversity at different geographical scales, as well as the study of species' patterns of gene ow. ...
Full-text available
We develop and characterize 14 microsatellite primers in Lithraea molleoides, a dominant dioecious native tree to Gran Chaco mountains. Five of them were optimized for multiplex PCR and evaluated in natural populations of the species. In order to analyze the level of polymorphism, 63 individuals of L. molleoides were assessed from two localities of central Argentina. Two to six alleles per locus were found with an average effective number of 1.82 alleles. The mean expected heterozygosity in each studied locality was 0.405 and 0.436. In view of generating tools for the conservation of species in a context of ongoing habitat loss, this set of newly developed microsatellite markers will be fundamental for assessing the genetic diversity and differentiation, as well as gene flow patterns of L. molleoides populations throughout its distribution range.
... The analyses offer insights into why international conservation donors neglect certain ecoregions. First, many of South America's neglected but threatened ecoregions are dry forests and savannas (Alcorn et al., 2010;Dawson et al., 2021;Kuemmerle et al., 2017). These areas have lower biodiversity and carbon stocks than rainforests, experience high and rising human pressure (e.g., Gran Chaco and Cerrado), and are generally more accessible than the vast Amazonian landscape, all of which are associated with less funding in our analyses (Table 1, Fig. 2). ...
International conservation funding to low-and middle-income countries has increased significantly in recent years. However, understanding of the underlying factors driving the geographic distribution of such funding remains limited. This study aimed to identify the relative importance of five factors (i.e., conservation targets, threat levels, costs, Indigenous Peoples and local communities, and preexisting investment) that potentially influence conservation funding allocation at the subnational level in major deforestation regions of South America between 1987 and 2013. Overall, we found that funding was mainly allocated to remote areas with high species richness and carbon storage, while areas with high threat levels were often overlooked, especially until 2008. After 2008, international donors committed more funding to areas with high carbon storage, but not areas with high species richness, suggesting the prominence of climate-related concerns over biodiversity conservation. Although often advocated, we did not find evidence supporting Indigenous Peoples and local communities being important in explaining funding allocation. However, we identified a strong preference for the Amazon as a charismatic ecoregion. Our findings underscore the diverse and changing factors that drive conservation funding, highlighting the importance of subnational analyses in aligning international conservation funding with local conservation needs from the perspectives of different actors. We hope that our study will contribute to the ongoing conversation on diverse values in conservation and inform decision-making for future funding allocations.
... Within the jaguar's distribution, habitat conversion from expanding agricultural production has been acute during the last 20 years in dry forest and savanna systems in southern South America, particularly in the Dry Chaco of Argentina, Bolivia, and Paraguay which has undergone some of the highest rates of forest loss in the world (Curtis et al. 2018;Zalles et al. 2021;Da Ponte et al. 2021;Buchadas et al. 2022). Despite its high levels of habitat loss and often high levels of biodiversity, the Dry Chaco receives relatively little attention from the global conservation community due to a strong focus upon tropical humid systems (Redford et al. 1990;Kuemmerle et al. 2017;Qin et al. 2022). This pattern was discussed by Redford et al. (1990) who, in referring to the Dry Chaco, pointed out that "the attention to rainforest has acted like blinders" and "The concentration on rainforests, and the rhetoric that accompanies it, has led to the neglect of other severely threatened ecosystems." ...
Full-text available
Habitat loss and human-caused mortality have led to an approximate 50% reduction of the distribution of the jaguar (Panthera onca). The large contraction in the jaguar’s occurrence points to a need to understand its population size and habitat preferences to apply to the species’ conservation. Typically, jaguar densities are estimated with capture–recapture modeling of photographic captures of individually identifiable individuals, while habitat selection is estimated from telemetry data. However, advances in spatial capture-recapture modeling now permit the simultaneous estimation of density and habitat selection based solely upon photographic detection data from camera-trapping grids. Here, we used data from 356 double camera-trap stations across five sites in the Paraguayan Dry Chaco to simultaneously estimate jaguar density and resource selection. We found that jaguar densities ranged from 0.58 to 1.39 individuals/100 km2. At the spatial scale of our analysis, jaguars showed a strong preference for forest cover, while space use was not affected by the Human Footprint Index. Our density estimates were consistent with previous estimates based upon a subset of our data, as well as with estimates for jaguar populations in other dryland ecosystems. Furthermore, the strong selection for forest was also consistent with range-wide patterns in jaguar space use and habitat selection derived from telemetry data. Due to extensive and ongoing deforestation in the Dry Chaco, combined with high human-caused mortality, the jaguar is critically endangered in Paraguay. Although we show that jaguars can persist in anthropogenically altered landscapes in Paraguay, their long-term survival at the national level is strongly dependent upon the effective enforcement of the national jaguar conservation law, and application of the national jaguar management plan, to mitigate negative population effects from habitat loss and human-caused mortality.
... The South American Chaco ecoregion, extending over Argentina, Paraguay, Bolivia, and Brazil (Bucher 1982;Olson et al. 2001), has not received much attention until recently (Argañaraz et al. 2015a(Argañaraz et al. , b, 2018Kuemmerle et al. 2017;De Marzo et al. 2021, 2023. To the West, this region contains the second largest forest in South America after the Amazon, which is also the largest continuous dry tropical forest and one of the most important global reservoirs of native forests in the world, known as the Gran Chaco forest (Dry Chaco subregion; Torrella and Adámoli (2005)). ...
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Background Wildfires represent an important element in the bio-geophysical cycles of various ecosystems across the globe and are particularly related to land transformation in tropical and subtropical regions. In this study, we analyzed the links between fires, land use (LU), and meteorological variables in the South American Chaco (1.1 million km ² ), a global deforestation hotspot and fire-exposed region that has recently attracted greater attention as the largest and one of the last tropical dry forests in the world. Results We found that the Dry Chaco (73% of the total area of Chaco) exhibits a unimodal fire seasonality (winter-spring), and the Wet Chaco (the remaining 23%) displays a bimodal seasonality (summer-autumn and winter-spring). While most of the burnt area (BA) was found in the Wet Chaco (113,859 km ² ; 55% of the entire BA), the Dry Chaco showed the largest fraction of forest loss (93,261 km ² ; 88% of the entire forest loss). Between 2001 and 2019, 26% of the entire Chaco’s forest loss occurred in areas with BA detections, and this percentage varies regionally and across countries, revealing potential connections to LU and policy. Argentina lost 51,409 km ² of its Chaco tree cover, surpassing the forest losses of Paraguay and Bolivia, and 40% of this loss was related to fire detections. The effect of meteorological fluctuations on fuel production and flammability varies with land cover (LC), which emerged as the principal factor behind BA. While wet areas covered with herbaceous vegetation showed negative correlations between BA and precipitation, some dry regions below 800 mm/year, and mostly covered by shrublands, showed positive correlations. These results reveal the two different roles of precipitation in (a) moisture content and flammability and (b) production of biomass fuel. Conclusions As fires and deforestation keep expanding in the South American Chaco, our study represents a step forward to understanding their drivers and effects. BA is dependent on LC types, which explains the discrepancies in fire frequency and seasonality between the Wet and Dry Chaco subregions. The links between fires and deforestation also vary between regions and between countries, exposing the role of anthropic forcing, land management, and policy. To better understand the interactions between these drivers, further studies at regional scale combining environmental sciences with social sciences are needed. Such research should help policy makers take action to preserve and protect the remaining forests and wetlands of the Chaco.
Phylogeographical studies combined with species distribution modelling can provide evidence for past climate refugia. During the Pleistocene, the Chaco phytogeographical province (ChPP) underwent changes in the distribution range, and the flora might have found refugia in different habitats according to their climatic requirements. This contribution aims to infer the effects of historical geoclimatic changes on the evolutionary history of Capsicum chacoense, the southernmost chilli pepper growing in the ChPP. We analysed 27 localities with plastid markers and 23 with nuclear markers, covering the geographical range of the species. We performed statistical phylogeography, in addition to current and past species distribution modelling. We found three haploclades, diverging 2.3–1 Mya, intermingled throughout the mountain ranges of the ChPP as a consequence of glacial cycles. According to the species distribution modelling, the expansion of the species distribution occurred during interglacial periods. We found two dispersal routes from south to north of the species distribution, concomitant with the migration routes of birds that disperse their fruits. The spatial distribution of genetic diversity showed the highest genetic diversity values at higher elevations. The main orographic systems of the study area were identified as areas of presumed population stability. Consequently, mountains are priority regions for conservation because they contain areas with high genetic diversity.
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In mountain ecosystems, plant regeneration might be constrained by multiple factors that change along elevation gradients and promote traits differentiation. Drought is a strong filter for seedling establishment that might be modified by herbivory co-occurrence. Populations of the tree Maytenus boaria support lower soil moisture and higher herbivory pressure at low elevations than at mid-elevations in Córdoba Mountains, central Argentina. Consequently, we expect that populations from the low elevation perform better in response to drought than populations from mid-elevations and that herbivory modifies these responses. Seedlings from the two elevation origins were exposed to two levels of simulated drought and herbivory in a greenhouse experiment. The selected elevations corresponded to the lowest edge of species distribution (with driest soils and highest herbivory pressure) and the central mid-elevation. Performance-related variables, biomass allocation patterns and several morphological and physiological traits were measured. Mortality patterns and most of morphological and physiological variables showed that drought is a stressful factor at the regeneration stage of M. boaria. The drought effect was increased by simulated herbivory in some variables (LMF, RM:SM and SPAD). In most variables, origin did not influence seedling performance, suggesting that drought response of seedlings is independent of populations’ elevation. Only leaf number and water potential were in line with our predictions and showed an origin response to drought.
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The Gran Chaco ecoregion is South America’s largest remaining continuous stretch of dry forest. It has experienced intensive deforestation, mainly in the western part known as Dry Chaco, resulting in the highest rate of dry forest loss globally between 2000 and 2012. The replacement of natural vegetation with other land uses modifies the surface’s biophysical properties, affecting heat and water fluxes and modifying the regional climate. This study examines land use and land cover changes (LULCCs) in Dry Chaco from 2001 to 2015, their effects on local and non-local climate, and explores the potential impacts of future agricultural expansion in the region. To this end, Weather Research and Forecasting (WRF) model simulations are performed for two scenarios: the first one evaluates the observed land cover changes between 2001 and 2015 that covered 8 % of the total area of Dry Chaco; the second scenario assumes an intensive agricultural expansion within the Dry Chaco. In both scenarios, deforestation processes lead to decreases in LAI, increases in albedo, and reductions in stomatal resistance, reducing the net surface radiation and, correspondingly, a decrease in turbulent fluxes suggesting a decline in available energy in the boundary layer. The result is an overall weakening of the water cycle in the Dry Chaco and, most prominently, implies a reduction in precipitation. A feedback loop develops since dry soil absorbs significantly less solar radiation than moist soil. Finally, the simulations suggest that the Dry Chaco would intensify its aridity, extending the drier and hotter conditions into the Humid Chaco.
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Aim To evaluate the representativeness of the current network of protected areas ( PA s) of one of the most threatened ecoregions in the world, the South American Gran Chaco, and determine priority conservation areas for endemic (and nearly endemic) terrestrial vertebrates of the region. Location South America. Methods We identified all those amphibians, mammals and birds whose distributions were at least 70% within the Gran Chaco. Then, we refined and corrected species’ distributional ranges, first, using records from collections and expert knowledge, and second, by incorporating environmental and topographic data using a technique for range polygon refinement. Lastly, we used Zonation , a spatial conservation prioritization software, to evaluate representativeness of the current protected areas ( PA s) network of the region and to define forest remnants to strategically expand PA s while maximizing the representativeness of the selected groups and considering human activities. Results Current PA s cover 9% of the region and represent 9.1% of the total distribution of endemic species. Considering our prioritization, increasing the coverage to 17% to match the Aichi targets would substantially increase the representativeness of the PA network, covering on average more than 30% of the ranges of all endemic species and 77% of the distributions of threatened and DD endemic species. Main conclusions Our results highlight that the need for well‐informed decisions in the Gran Chaco is imperative. While the current PA network in the region ensures a very poor representation of endemic terrestrial vertebrates, opportunities to efficiently expand the PA s network are really high. This emphasizes the potential of complementarity‐based systematic conservation planning tools as an essential support for conservation decisions. Given the great information gaps regarding biodiversity and human activities in the region, similar studies with updated data would improve conservation planning in the G ran C haco in the future.
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Forests in Flux Forests worldwide are in a state of flux, with accelerating losses in some regions and gains in others. Hansen et al. (p. 850 ) examined global Landsat data at a 30-meter spatial resolution to characterize forest extent, loss, and gain from 2000 to 2012. Globally, 2.3 million square kilometers of forest were lost during the 12-year study period and 0.8 million square kilometers of new forest were gained. The tropics exhibited both the greatest losses and the greatest gains (through regrowth and plantation), with losses outstripping gains.
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The growing human population and the increase in per capita food consumption are driving agriculture expansion and affecting natural ecosystems around the world. To balance increasing agriculture production and nature conservation, we must assess the efficiency of land-use strategies. Soybean production, mainly exported to China and Europe, has become the major driver of deforestation in dry forest/savanna ecosystems of South America. In this article we compared land cover patterns (based on satellite imagery) and land-use and human population trends (based on government statistics) in regions with two contrasting development pathways in the Chaco dry forests of northern Argentina, since the early 1970s. The area (ca. 13 million hectares) includes one of the largest continuous patches of tropical dry forests and has experienced rapid land-use change. In the region where land use has been driven by government-sponsored colonization programs, the expansion of extensive grazing has led to a growing rural population, low food production, and widespread environmental degradation. In contrast, in the region dominated by market-driven soybean expansion, the rural population has decreased, food production is between 300% and 800% greater, and low-density extensive cattle production has declined over extensive remaining forested areas, resulting in a land-use trend that appears to better balance food production and nature conservation.
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The vast plain known as the Gran Chaco is a natural region of more than 1·3 million square kilometres, the second largest natural biome in South America, with only the Amazon region being larger. It extends over parts of Argentina, Bolivia, Paraguay and, marginally, Brazil. The original landscape of the region was mostly a park land with patches of hardwoods intermingled with grasslands. Increasing human encroachment, largely by poor campesinos, with associated overgrazing, excessive timber harvesting, charcoal production and over-exploitation of wildlife, is transforming the region into a dense and unproductive shrub land and is contributing to increasing rural poverty. A management system for the sustainable use of the Chaco has been developed based on a multiple-species ranching system that includes beef, timber, charcoal and wildlife production. An evaluation of the management system finds that it is capable of protecting and enhancing the resource base, while providing higher economic returns in a sustainable manner. However, high initial costs, as well as a divergence between the «best» interests of campesinos and society, jeopardize the feasibility of the managed system.
WE AGREE WITH Kuemmerle et al. that the forests in the Gran Chaco region are under massive threat, underprotected, and deserving of greater attention from scientists and conservationists. We could have included the Chaco woodlands in our analyses, and their distinctive flora would have reinforced
Carbon emissions from land-use changes in tropical dry forest systems are poorly understood, although they are likely globally significant. The South American Chaco has recently emerged as a hot spot of agricultural expansion and intensification, as cattle ranching and soybean cultivation expand into forests, and as soybean cultivation replaces grazing lands. Still, our knowledge of the rates and spatial patterns of these land-use changes and how they affected carbon emissions remains partial. We used the Landsat satellite image archive to reconstruct land-use change over the past 30 years and applied a carbon bookkeeping model to quantify how these changes affected carbon budgets. Between 1985 and 2013, more than 142 000 km(2) of the Chaco's forests, equaling 20% of all forest, was replaced by croplands (38.9%) or grazing lands (61.1%). Of those grazing lands that existed in 1985, about 40% were subsequently converted to cropland. These land-use changes resulted in substantial carbon emissions, totaling 824 Tg C between 1985 and 2013, and 46.2 Tg C for 2013 alone. The majority of these emissions came from forest-to-grazing-land conversions (68%), but post-deforestation land-use change triggered an additional 52.6 Tg C. Although tropical dry forests are less carbon-dense than moist tropical forests, carbon emissions from land-use change in the Chaco were similar in magnitude to those from other major tropical deforestation frontiers. Our study thus highlights the urgent need for an improved monitoring of the often overlooked tropical dry forests and savannas, and more broadly speaking the value of the Landsat image archive for quantifying carbon fluxes from land change.
Tropical grassy biomes (TGBs) are globally extensive, provide critical ecosystem services, and influence the earth-atmosphere system. Yet, globally applied biome definitions ignore vegetation characteristics that are critical to their functioning and evolutionary history. Hence, TGB identification is inconsistent and misinterprets the ecological processes governing vegetation structure, with cascading negative consequences for biodiversity. Here, we discuss threats linked to the definition of TGB, the Clean Development Mechanism (CDM) and Reducing Emissions from Deforestation and Forest Degradation schemes (REDD+), and enhanced atmospheric CO2, which may facilitate future state shifts. TGB degradation is insidious and less visible than in forested biomes. With human reliance on TGBs and their propensity for woody change, ecology and evolutionary history are fundamental to not only the identification of TGBs, but also their management for future persistence.