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Forest conservation: Remember Gran Chaco

February 2017
Science 355(6324):465-465

DOI:10.1126/science.aal3020

Authors:

Tobias Kuemmerle

Humboldt-Universität zu Berlin

Mariana Altrichter

Prescott College

Germán Baldi

National Scientific and Technical Research Council

Marcelo Cabido

National University of Cordoba, Argentina

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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 sciencemag.org

PHOTO: DANIEL GOMEZ/MINDEN

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.

Email: tobias.kuemmerle@hu-berlin.de

REFERENCES

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).

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985 (2008).

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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).

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(1990).

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10. M. Baumann et al ., Glob. Change Biol., 10.1111/gcb.13521

(2016).

10.1126/science.aal3020

Response

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 (1–3), were not the criteria used

in selecting sites for our study. Rather,

Forest conservation:

Remember Gran Chaco

TROPICAL AND SUBTROPICAL dry forests

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 (2–4).

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

LETTERS

A mesquite tree

stands in the Gran

Chaco dry forest

habitat in Argentina.

DA_0203Letters.indd 465 2/1/17 10:21 AM

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on February 2, 2017http://science.sciencemag.org/Downloaded 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,

INSIGHTS |

LETTERS

466 3 FEBRUARY 2017 • VOL 355 ISSUE 6324 sciencemag.org SCIENCE

PHOTO: ALEX POPOVKIN/FLICKR

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.

Email: t.pennington@rbge.ac.uk

REFERENCES

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. 146–194.

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. 9–26.

10. DRYFLOR: Latin American Seasonally Dry Tropical Forest

Floristic Network (www.dryflor.info/).

10.1126/science.aal5010

Forest conservation:

Humans’ handprints

NEOTROPICAL FORESTS HAVE been

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

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SCIENCE sciencemag.org

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.

Email: carollevis@gmail.com

REFERENCES

1. The Mansfeld’s World Database of Agriculture and

Horticultural Crops (http://mansfeld.

ipk-gatersleben.de/).

2. H. ter Steege et al., Science 342, 1243092 (2013).

10.1126/science. aal2175

Response

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.

Email: t.pennington@rbge.ac.uk

REFERENCES

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).

10.1126/science.aal2602

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(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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Full-text available

Oct 2023

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.

Mountains as refugia in the Dry Chaco: phylogeography and species distribution modelling of the southernmost chilli pepper, Capsicum chacoense Hunz. (Solanaceae)

Article

Jul 2023

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.

Woody cover and pasture within the surrounding matrix drive puma (Puma concolor) occupancy in agroecosystems of the Argentine Dry Chaco

Article

Aug 2023
J NAT CONSERV

Drought and herbivory as modulators of intraspecific differentiation in seedlings of a mountain tree

Article

Full-text available

Aug 2023
PLANT ECOL

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.

The agricultural expansion in South America’s Dry Chaco: Regional hydroclimate effects

Preprint

Full-text available

Jul 2023

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.

Indigenous Lands with secure land-tenure can reduce forest-loss in deforestation hotspots

Article

Jul 2023
GLOBAL ENVIRON CHANG

Protected areas and spatial conservation priorities for endemic vertebrates of the Gran Chaco, one of the most threatened ecoregions of the world

Article

Full-text available

Oct 2016
DIVERS DISTRIB

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.

High-Resolution Global Maps of 21st-Century Forest Cover Change

Article

Full-text available

Nov 2013
SCIENCE

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.

Balancing food production and nature conservation in subtropical dry forests of NW Argentina

Article

Full-text available

Jan 2008
GLOBAL CHANGE BIOL

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.

Sustainable management of the Gran Chaco of South America: Ecological promise and economic constraints

Article

Full-text available

Oct 1999

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.

Terrestrial Ecoregions of the World: A New Map of Life on Earth

Article

Full-text available

Nov 2001

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Forest conservation: Remember Gran Chaco - Response

Article

Feb 2017

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 agricultural expansion and intensification in the Chaco

Article

Oct 2016
GLOBAL CHANGE BIOL

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.

Transformation dynamics of the natural cover in the Dry Chaco ecoregion: A plot level geo-database from 1976 to 2012

Article

Nov 2015
J ARID ENVIRON

Tropical grassy biomes: Misunderstood, neglected, and under threat

Article

Mar 2014
TRENDS ECOL EVOL

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.

There Is More to Biodiversity than the Tropical Rain Forests

Article