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Seasonally dry tropical forests are distributed across Latin America and the Caribbean and are highly threatened, with less than 10% of their original extent remaining in many countries. Using 835 inventories covering 4660 species of woody plants, we show marked floristic turnover among inventories and regions, whichmay be higher than in other neotropical biomes, such as savanna. Such high floristic turnover indicates that numerous conservation areas across many countries will be needed to protect the full diversity of tropical dry forests. Our results provide a scientific framework within which national decision-makers can contextualize the floristic significance of their dry forest at a regional and continental scale.
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Plant diversity patterns in
neotropical dry forests and
their conservation implications
Seasonally dry tropical forests are distributed across Latin America and the Caribbean
and are highly threatened, with less than 10% of their original extent remaining in many
countries. Using 835 inventories covering 4660 species of woody plants, we show marked
floristic turnover among inventories and regions, which may be higher than in other neotropical
biomes, such as savanna. Such high floristic turnover indicates that numerous conservation
areas across many countries will be needed to protect the full diversity of tropical dry forests.
Our results provide a scientific framework within which national decision-makers can
contextualize the floristic significance of their dry forest at a regional and continental scale.
Neotropical seasonally dry forest (dry forest)
is a biome with a wide and fragmented
distribution, found from Mexico to Argen-
tina and throughout the Caribbean (1,2)
(Fig. 1). It is one of the most threatened
tropical forests in the world (3), with less than
10% of its original extent remaining in many
countries (4).
Following other authors (5,6), we define dry
forest as having a closed canopy, distinguishing
it from more open, grass-rich savanna. It occurs
on fertile soils where the rainfall is less than
~1800 mm per year, with a period of 3 to 6 months
receiving less than 100 mm per month (57), dur-
ing which the vegetation is mostly deciduous.
Seasonally dry areas, especially in Peru and Mexico,
were home to pre-Columbian civilizations, so
human interaction with dry forest has a
long history (8). The climates and fertile
soils of dry forest regions have led to higher
ing demand for energy and land, enhancing
degradation (9). More recently, destruction
of dry forest has been accelerated by inten-
sive cultivation of crops, such as sugar cane,
rice and soy, or by conversion to pasture
for cattle.
Dry forest is in a critical state because so
little of it is intact, and of the remnant areas,
little is protected (3). For example, only 1.2%
of the total Caatinga region of dry forest in
Brazil is fully protected compared with 9.9%
of the Brazilian Amazon (10). Conservation
actions are urgently needed to protect dry
forests unique biodiversitymany plant
species and even genera are restricted to it and
reflect an evolutionary history confined to this
biome (1).
We evaluate the floristic relationships of the
disjunct areas of neotropical dry forest and high-
light those that contain the highest diversity and
endemism of woody plant species. We also ex-
plore woody plant species turnover across geo-
graphic space among dry forests. Our results
provide a framework to allow the conservation
significance of each separate major region of
dry forest to be assessed at a continental scale.
Our analyses are based on a subset of a data set
of 1602 inventories made in dry forest and re-
lated semi-deciduous forests from Mexico and
the Caribbean to Argentina and Paraguay that
covers 6958 woody species, which has been com-
piled by the Latin American and Caribbean
Seasonally Dry Tropical Forest Floristic Network
[DRYFLOR,; (11)].
We present analyses that focus principally on
DRYFLOR sites in deciduous dry forest vegeta-
tion growing under the precipitation regime out-
lined above (57), as measured using climate
data from Hijmans et al.(12). We excluded most
Brazilian sites in the DRYFLOR database with
vegetation classified as semi-deciduousbecause
these have a less severe dry season and a massive
contribution of both the Amazonian and Atlantic
rain forest floras (11). The only semi-deciduous
sites retained from southeast Brazil were from
the Misiones region, which has been included in
numerous studies of dry forest biogeography
[e.g., (13,14)] (fig. S1), and we therefore wished
to understand its relationships. We also excluded
sites from the chaco woodland of central South
America because it is considered a distinct biome
with temperate affinities characterized by fre-
quent winter frost (13,15). Sites occurring in
the central Brazilian region are small patches
of deciduous forest that are scattered on areas
of fertile soil within savanna vegetation known
as cerrado.We performed clustering and or-
dination analyses on inventories made at 835
DRYFLOR sites that covered 147 families, 983
genera, and 4660 species (11).
Floristic relationships, diversity,
endemism, and turnover
Our clustering analyses, based on the unweighted
pair-group method with arithmetic mean (UPGMA)
and using the Simpson dissimilarity index as a dis-
tance measure (16), identified 12 floristic groups:
(i) Mexico, (ii) Antilles, (iii) Central Americanorthern
South America, (iv) northern inter-Andean valleys,
(v) central inter-Andean valleys, (vi) central Andes
coast, (vii) Tarapoto-Quillabamba, (viii) Apurimac-
Mantaro, (ix) Piedmont, (x) Misiones, (xi). central
Brazil, and (xii) Caatinga (Fig. 2 and table S1).
The relationships among the floristic
groups were similar in both the analysis
of 835 sites (Fig. 2) and another that
pooled all species lists from all sites in
each of the 12 floristic groups in order to
explore the support for relationships among
them (fig. S2). The placement of the geo-
graphically small Peruvian inter-Andean
groups of Apurimac-Mantaro and Tarapoto-
Quillabamba is uncertain as previously
reported by Linares-Palomino et al.(2),
and differs in the two cluster analyses (Fig.
2 and fig. S2), which is reflected in low
AU (approximately unbiased probability
support) values (0.71) (fig. S2). More detailed
floristic inventory is required in these poor-
ly surveyed forests, which is also suggested
by species accumulation curves that have
not leveled in these geographic areas (fig. S3).
The analysis pooling all species lists
in each floristic group (fig. S2) and a non-
metric multidimensional scaling (NMDS)
ordination (fig. S4A for all sites and fig.
S4B pooling all species in each floristic
group) recognizes a higher-level northern
SCIENCE 23 SEPTEMBER 2016 VOL 353 ISSUE 6306 1383
Latin American and Caribbean Seasonally Dry
Tropical Forest Floristic Network, Royal Botanic
Garden Edinburgh, 20a Inverleith Row, Edinburgh,
EH3 5LR, UK.
*All authors with their affiliations appear at the end of
this paper. Corresponding author. Email: t.pennington@
Fig. 1. Schematic dry forest distribution in the Neotropics.
[Based on Pennington et al.(13), Linares-Palomino et al.(2), Olson
et al.(45), and the location of DRYFLOR inventory sites (see Fig. 2)]
on September 22, 2016 from
cluster (Mexico, Antilles, Central Americanorthern
South America, and northern inter-Andean valleys).
The distinctiveness of Mexican dry forests has
been widely recognized (6), and the well-supported
Antillean floristic group reflects that the Caribbean
is also a distinctive neotropical phytogeographic
region with high endemism (17,18). The support
for a higher-level northern cluster confirms a
north-south division in neotropical dry forest
that was suggested by Linares-Palomino et al.
(2) based on a data set that was more sparse in
the northern Neotropics (57 sites compared with
276 here). The separation of a northern c luster of
neotropical dry forests, which includes all areas
in Colombia and Venezuela, from all other dry
forest areas further south in South America
may reflect the effectiveness of the rain forests
of Amazonia and the Chocó as a barrier for
migration of dry forest species, as suggested
by Gentry (19).
A higher-level southern cluster comprises east-
ern and southern South American areas that divide
into two subclusters, the first formed by Piedmont
and Misiones and the second by central Brazil
and the Caatinga (Fig. 2). In the analysis of pooled
species lists, the Misiones group clusters with the
central Brazil and Caatinga floristic groups with
strong support (1.0 AU) (fig. S2), which is due to
the large number of species shared among them as
a whole (Misiones shares 409 spp. with central Brazil
and 264 spp. with Caatinga) (Fig. 3 and table S2).
There are six Andean dry forest floristic groups
(northern inter-Andean valleys, central inter-
Andean valleys, central Andes coast, Apurimac-
Mantaro, Piedmont, and Tarapoto-Quillabamba),
which are scattered across our UPGMA cluster-
ings (Fig. 2 and fig. S2) and ordinations (fig. S4);
this scattering reflects the great floristic hetero-
geneity of dry Andean regions first highlighted
by Sarmiento (20). For example, the northern
inter-Andean valleys of the Rio Magdalena and
Cauca are placed within the higher-level northern
South American cluster, whereas the Piedmont,
Tarapoto-Quillabamba, and Apurimac-Mantaro
floristic groups are placed in the higher-level
southern cluster in our pooled analysis (fig. S2).
The central Brazil, Caatinga, and Mexico flo-
ristic groups contain the most species (1344,
1112, and 1072 species, respectively) (table S1),
and the central inter-Andean valleys and Apurimac-
Mantaro inter-Andean valleys contain the least
(165 and 78 species, respectively). Overall regional
species richness may reflect an integrated time-
area effect (21).Theageofthedryforestbiomeis
not known throughout the Neotropics, but the
fossil record and dated phylogenies suggest a
Miocene origin in Mexico (22) and the Andes
(23). Our data suggest that larger areas of dry
forest, such as in the Caatinga and Mexico, have
accumulated more species. The small number
of species in inter-Andean dry forests reflects
their tiny area; the dry forests of the Marañón,
Apurimac, and Mantaro inter-Andean valleys in
Peru are estimated to occupy 4411 km
in total
(24) compared with ~850,000 km
estimated for
the Caatinga (25). What is notable is the lack of
an equatorial peak in regional species diversity
(fig. S5). The northerly Mexican dry forests, which
reach the Tropic of Cancer, have high species
1384 23 SEPTEMBER 2016 VOL 353 ISSUE 6306 SCIENCE
Fig. 2. Neotropical dry forest floristic groups based on woody plants. Geographical representation of UPGMA clustering of 835 dry forest sites using
the Simpson dissimilarity index as a measure of distance.
on September 22, 2016 from
numbers similar to the more equatorial Caa-
tinga (1072 compared with 1112), despite being
184) (fig. S6) and in one-third of the land area
[280,000 km
(26)]. It is intriguing that there
may be a peak in regional dry forest species
richness around 20 degrees latitude (fig. S5),
which may reflect a reverse latitudinal gradi-
entof regional species richness in neotropical
dry forest, which was suggested by Gentry (6).
Our inventories used heterogeneous method-
ologies (e.g., plots and transects of varying sizes
or general floristic surveys), which precludes any
definitive discussion of alpha diversity at indi-
vidual sites, but the high regional diversity of
Mexican forests, which are distant from the
equator, is remarkable. The high species richness
of Mexican dry forests merits further investiga-
tion and may reflect their Miocene age combined
with rates of species diversification that are po-
tentially higher than in other dry forest regions.
Species restricted to one of the 12 floristic
groups (exclusivespecies in table S1) may not
be strictly endemic to them, because they may be
found elsewhere in areas not covered by our sur-
veys. However, we believe that they do serve as a
proxy for species endemism, which is supported
by independent evidence from floristic check-
lists. For example, Linares-Palomino (27) re-
ported 43% endemism of woody plants for the
Marañón valley, Peru, which forms a major part
of our central Andean group and has 41% ex-
clusive species. Mexican and Antillean dry forests
have the highest percentages of exclusive species
(73% and 65%, respectively). The lowest percent-
age of exclusive species is found in central Brazil
dry forests, which reflects the larger numbers of
species shared with neighboring floristic groups.
Despite their close geographical proximity, Andean
floristic groups each have about 30 to 40% of
exclusive species, reflecting high floristic turnover at
relatively small spatial scales, which may be caused
by dispersal limitation among the geographic
Pairwise dissimilarity values for the whole data
set have a mean of 0.90 for Simpson dissimilarity
(median of 0.94) and 0.94 for Sørensen dissim-
ilarity (median of 0.97). The dissimilarity values
among the 12 floristic groups (using the entire
combined lists for each) (table S3, A and B)
ranged from 0.38 to 0.94 (mean, 0.79; median,
0.82) for Simpson dissimilarity and 0.43 to 0.98
(mean, 0.87; median, 0.90) for Sørensen dis-
similarity. High floristic turnover in dry forest
has been shown in Mexico (29), but our data set
allows a thorough assessment at a continental
scale. In general, few species are shared among
the floristic groups (Fig. 3), and this underlines
the high levels of species turnover. It is also
notable that dissimilarity values are high within
all the deciduous dry forest floristic groups as well,
with median Sørensen values ranging from 0.74
within the Caatinga to 0.90 within the Tarapoto-
Quillabamba group (table S4) (the median value
is slightly lower at 0.70 within the semi-deciduous
Misiones group). These dissimilarity values are
higher than those reported for the cerrado biome.
Bridgewater et al.(30) showed Sørensen dissim-
ilarities with a lower mean value of 0.58 among
cerrado floristic provinces separated by ~1000 km,
based on floristic lists similar to those in the
DRYFLOR data set. The probable higher species
turnover in dry forests at continental, regional,
and local scales is a result with considerable im-
plications for conservation.
The strongest floristic affinities are found
among (i) central Brazil, Caatinga, Piedmont,
and Misiones and (ii) Central America and
northern South America, Mexico and the north-
ern inter-Andean valleys (Fig. 3). The relation-
ship of the Caatinga and central Brazil dry
forests, which share almost 700 species, has
been highlightedpreviously(2,14,31), but what
is striking elsewhere is the low levels of floristic
similarity, even among geographically proximal
floristic groups (e.g., northern and central inter-
Andean valleys).
The high floristic turnover reflects that few
species are widespread and shared across many
areas of neotropical dry forest. No species is re-
ported for all 12 floristic groups; there are only
three species shared among 11 groups and nine
species among 10 groups (table S5). Some of the
species recorded across most sites are widespread
ecological generalists like Maclura tinctoria
(Moraceae), Guazuma ulmifolia (Malvaceae), and
Celtis iguanaea (Cannabaceae), which are com-
species tend to grow in disturbed areas, so their
presence in many dry forest sites could be a con-
sequence of their high level of degradation and
fragmentation. In other cases, highly recorded
species are dry forest specialists, such as Anade-
nanthera colubrina (Leguminosae)which oc-
curs in eight of the floristic groups and in more
than 74% of the sites in the Caatinga, central
Brazil, and Piedmontand Cynophalla flexuosa
(Capparaceae), which occurs in 11 groups and is
commonly recorded (~40% of the sites) in the
Antilles, Caatinga, and central Andes coast.
However, most frequently recorded species,
defined as those registered in many sites, are sel-
dom shared among any of our 12 floristic groups.
For example, 85% of the top 20 most frequently
recorded species in each floristic group (table S6)
are restricted to a single group, with a few excep-
tions where the same species was frequent across
several groups (e.g., Anadenanthera colubrina
and Guazuma ulmifolia,infivegroupseach).In
other cases, there is a particular set of species
characteristic for pairs of geographically pro-
ximal floristic groups such as the central inter-
Andean valleys and central Andes coast, where
the dry forest specialist species, Loxopterygium
huasango (Anacardiaceae), Ceiba trichistandra
(Malvaceae), Coccoloba ruiziana (Polygonaceae),
and Pithecellobium excelsum (Leguminosae), are
recorded in >15% of the sites.
Our presence-absence database cannot assess
abundance in terms of numbers of stems or basal
area. However, the extensive field experience of
the DRYFLOR network team suggests that when
frequently recorded species are dry forest spe-
cialists, they tend to be locally abundant and
often dominant. Our observations are reinforced
by quantitative inventory data that indicate that
the most dominant species in dry forest plots
represent 8.5 to 62.1% of stems per plot, with a
median relative abundance of 17.9% (32). In con-
trast to dry forest specialist species, widespread
and frequently recorded ecological generalist spe-
cies are often not locally abundant.
Although frequently recorded dry forest spe-
cialist species in our data set may be locally
abundant and dominant, they generally have
geographically restricted total distributions. Wide-
spread species that are common in more than
one dry forest floristic group (Fig. 2), such as
Anadenanthera colubrina, which was empha-
sized in early discussions of neotropical dry forest
biogeography [e.g., (13,14)],aretheexception.In
summary, there is little evidence for any oligarchy
of species that dominates across neotropical dry
forest as a whole. These patterns contrast strongly
with the rain forests of Amazonia (33,34)andthe
savannas of central Brazil (30), which are often
large geographic areas. The lack of an oligarchy of
widespread, dominant dry forest species reflects
the limited opportunities for dispersal and success-
ful establishment among dry forest areas (1,28).
Our data show that variation in floristic compo-
sition at a continental scale defines 12 dry forest
floristic groups across the Neotropics. The floris-
tic differentiation of these main dry forest groups
is marked; 23 to 73% of the species found in each
are exclusive to it. These figures are likely to in-
dicate high levels of species endemism, which is
illustrative of the high floristic turnover (beta di-
versity) that our data reveal. This high endemism
and floristic turnover across the dry forest flo-
ristic groups indicate that failure to protect the
forest in every one would result in major losses
of unique species diversity.
lustrative in this context of the need for multiple
protected areas. Andean dry forests fall into six
floristic groups in our analysis (Fig. 2). Of these,
two geographically small but highly distinct
groups in Peru, Apurimac-Mantaro and Tarapoto-
Quillabamba, have no formal protection at all.
Only 1.4% (3846 ha) of the total remaining dry
forest in the northern inter-Andean valleysone
of the most transformed land areas in Colombia
(35)are protected (4), well short of Aichi bio-
diversity target 11 that calls for conservation of
diversity (36). In other Andean areas, accurate
maps of all remaining areas of dry forest are
unavailable, but given that DRYFLOR sites were
chosen because they represent well-preserved
areas of dry forest, we can ask the question of
how well protected these survey sites are. For
example, only 14% of the central inter-Andean
valleys, 18% of the central Andes coast, and
32% of Piedmont DRYFLOR sites occur within a
protected area. If we are to conserve the full flo-
ristic diversity of Andean dry forest from north to
south, future conservation planning must prioritize
SCIENCE 23 SEPTEMBER 2016 VOL 353 ISSUE 6306 1385
on September 22, 2016 from
areas in Peru and elsewhere in the Andes that
are globally unique but entirely unprotected.
These Andean forests, like virtually all neotropical
dry forests, have high local human populations
and are exploited for agriculture and fuelwood.
Conservation solutions therefore require a social
dimension, including opportunities and incentives
for human communities and private landowners (9).
Median pairwise floristic dissimilarity values
within the floristic groups of 0.73 for Simpson
dissimilarity and 0.85 for Sørensen dissimilarity
show that floristic turnover is also high at regional
scales, a result only previously shown for Mexico
(29). Major dry forest regions, such as the Caa-
tinga and Mexico, are each home to more than a
thousand woody species, and the high floristic
turnover within them means that to protect this
diversity fully will require multiple, geographi-
cally dispersed protected areas. Conservation of
sifying their endemic species using International
Union for the Conservation of Nature (IUCN) Red
List criteria, for which the distribution data in the
DRYFLOR database can provide a valuable basis.
Overall, only 14% of sites in the DRYFLOR
database, which were chosen to cover the max-
imum remaining area of neotropical dry forest,
fall within protected areas. Placed in the context
of our data set, which shows high diversity, high
endemism, and high floristic turnover, it is clear
that current levels of protection for neotropical
dry forest are woefully inadequate. It is our hope
that our data set for Latin American and Carib-
bean dry forests and the results shown here can
become a basis for future conservation decisions
that take into account continental-level floristic
versity of these threatened but forgotten forests.
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Fig. 3. Geographical patterns of species turnover among 12 dry forest floristic groups. (Fig. 2). Size of the circles is proportional to the number of
species per group; size of colored circles is proportional to the total number of species and of gray circles to the number of exclusive species. The species
turnover among areas is described by line widths proportional to the number of species shared (values from table S2).
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This paper is the result of the Lati n American and Caribbean Seasonally
Dry Tropical Forest Floristic Network (DRYFLOR), which has been
supported at the Royal Botanic Garden Edinburgh by a Leverhulme
Trust International Network Grant (IN-074). This work was also
supported by theU.K. NaturalEnvironmentResearchCouncil grantNE/
I028122/1; Colciencias Ph.D. scholarship 529; Synthesys Programme
GBTAF-2824; the NSF (NSF 1118340 and 1118369); the Instituto
Humboldt (IAvH)Red colombiana de investigación y monitoreo en
bosque seco; the Inter-American Institute for Global Change Research
(IAI;Tropi-Dry, CRN2-021, funded by NSF GEO 0452325); Universidad
Nacional de Rosario(UNR); and Consejo Nacional de Investigaciones
Científicas y Técnicas (CONICET). The data reported in this paper are
available at R.T.P. conceived the study. M.P., A.O.-F.,
K.B.-R., R.T.P., and J.W. designed the DRYFLOR databasesystem.
K.B.-R. and K.G.D.carried out mostanalyses. K.B.-R. R.T.P., and K.G.D.
wrote the manuscript with substantial input from A.D.-S., R.L.-P.,
A.O.-F., D.P., C.Q., and R.R. All the authors contributed data,
discussed further analyses, and commented on various versions of
the manuscript. K.B.-R. thanks G. Galeano who introduced her to dry
forest research. We thank J. L. Marcelo, I. Huamantupa, C. Reynel,
S. Palacios, and A. Daza for help with fieldwork and data entry in Peru.
DRYFLOR authors
Materials and Methods
Figs. S1 to S6
Tables S1 to S6
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26 February 2016; accepted 11 August 2016
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stem cellderived human enteroids
Khalil Ettayebi,
*Sue E. Crawford,
*Kosuke Murakami,
*James R. Broughman,
Umesh Karandikar,
Victoria R. Tenge,
Frederick H. Neill,
Sarah E. Blutt,
Xi-Lei Zeng,
Lin Qu,
Baijun Kou,
Antone R. Opekun,
Douglas Burrin,
David Y. Graham,
Sasirekha Ramani,
Robert L. Atmar,
Mary K. Estes
The major barrier to research and development of effective interventions for human noroviruses
(HuNoVs) has been the lack of a robust and reproducible in vitro cultivation system. HuNoVs
are the leading cause of gastroenteritis worldwide.We report the successful cultivation of
multiple HuNoV strains in enterocytes in stem cellderived, nontransformed human intestinal
enteroid monolayer cultures. Bile, a critical factor of the intestinal milieu, is required for strain-
dependent HuNoV replication. Lack of appropriate histoblood group antigen expression in
intestinal cells restricts virus replication, and infectivity is abrogated by inactivation (e.g.,
irradiation, heating) and serum neutralization. This culture system recapitulates the human
intestinal epithelium, permits human host-pathogen studies of previously noncultivatable
pathogens, and allows the assessment of methods to prevent and treat HuNoV infections.
Human noroviruses (HuNoVs) are the most
common cause of epidemic and sporadic
cases of acute gastroenteritis worldwide,
and are the leading cause of food-borne
gastroenteritis (13). Since the introduction
of rotavirus vaccines, HuNoVs have become the pre-
dominant gastrointestinal pathogen within pediat-
ric populations in developed countries (4). HuNoVs
arehighlycontagious,withrapid person-to-person
transmission directly through the fecal-oral route
SCIENCE 23 SEPTEMBER 2016 VOL 353 ISSUE 6306 1387
Karina Banda-R,
Alfonso Delgado-Salinas,
Kyle G. Dexter,
Reynaldo Linares-Palomino,
Ary Oliveira-Filho,
Darién Prado,
Martin Pullan,
Catalina Quintana,
Ricarda Riina,
Gina M. Rodríguez M.,
Julia Weintritt,
Pedro Acevedo-Rodríguez,
Juan Adarve,
Esteban Álvarez,
Anairamiz Aranguren B.,
Julián Camilo Arteaga,
Gerardo Aymard,
Alejandro Castaño,
Natalia Ceballos-Mago,
Álvaro Cogollo,
Hermes Cuadros,
Freddy Delgado,
Wilson Devia,
Hilda Dueñas,
Laurie Fajardo,
Ángel Fernández,
Miller Ángel Fernández,
Janet Franklin,
Ethan H.Freid,
Luciano A. Galetti,
Reina Gonto,
Roy González-M.,
Roger Graveson,
Eileen H. Helmer,
Álvaro Idárraga,
René López,
Humfredo Marcano-Vega,
Olga G. Martínez,
Hernán M. Maturo,
Morag McDonald,
Kurt McLaren,
Omar Melo,
Francisco Mijares,
Virginia Mogni,
Diego Molina,
Natalia del Pilar Moreno,
Jafet M. Nassar,
Danilo M. Neves,
Luis J. Oakley,
Michael Oatham,
Alma Rosa Olvera-Luna,
Flávia F. Pezzini,
Orlando Joel Reyes Dominguez,
María Elvira Ríos,
Orlando Rivera,
Nelly Rodríguez,
Alicia Rojas,
Tiina Särkinen,
Roberto Sánchez,
Melvin Smith,
Carlos Vargas,
Boris Villanueva,
R. Toby Pennington
Royal Botanic Garden Edinburgh, 20a Inverleith Row, EH3 5LR,
Edinburgh, UK.
Departamento de Botánica, Universidad
Nacional Autónoma de México, México D.F., México.
School of
GeoSciences, University of Edinburgh, Edinburgh, UK.
Nacional Agraria La Molina, Avenida La Molina, Lima, Perú.
Universidade Federal de Minas Gerais (UFMG), Instituto de Ciências
Biológicas (ICB), Departamento de Botânica, Avenida Antônio.
Carlos, 6627-Pampulha, Belo Horizonte, Minas Gerais, Brazil.
Cátedra deBotánica, IICAR-CONICET, Facultad de Ciencias
Agrarias, Universidad Nacional de Rosario, C.C. Nº 14, S2125ZAA
Zavalla, Argentina.
Pontificia Universidad Católica del Ecuador,
Facultad de Ciencias Exactas, Escuela de Biología, Avenida 12
de Octubre 1076 y Roca, Quito, Ecuador.
Real Jardín Botánico,
RJB-CSIC, Plaza de Murillo 2,28014 Madrid, Spain.
Ecosistemas Secos de Colombia, Calle 5 A No. 70 C-31, Bogotá,
Smithsonian Conservation Biology Institute, Los
Libertadores 215, San Isidro, Lima, Perú.
Smithsonian National
Museum of Natural History, West Loading Dock, 10th and
Constitution Avenue, NW, Washington, DC 20560-0166, USA.
Parque Regional El Vínculo”–INCIVA, El VínculoKilometro 3
al sur de Buga sobre la Carretera Panamericana, Valle del Cauca,
Jardín Botánico de Medellín Joaquín Antonio
Uribe,Calle 73 No. 51D-14, Medellín, Colombia.
Instituto de
Ciencias Ambientales y Ecológicas, Facultad de Ciencias,
Núcleo Pedro Rincón, La Hechicera, 3er Piso, Universidad
de los Andes (ULA), Mérida, Venezuela.
Herbario SURCO,
Universidad Surcolombiana, Neiva, Colombia.
Programa de
Ciencias del Agro y el Mar, Herbario Universitario (PORT),
UNELLEZ-Guanare, Mesa de Cavacas, Estado Portuguesa
3350, Venezuela.
Jardín Botánico Juan María CéspedesINCIVA,
Mateguadua, Tuluá, Valle del Cauca, Colombia.
Proyecto Mono
de Margarita and Fundación Vuelta Larga, Isla de Margarita,
Estado Nueva Esparta, Venezuela.
Universidad del Atlántico,
Kilometro 7 Vía Puerto, Barranquilla, Atlántico, Colombia.
de Investigaciones y Servicios Ambientales (ECOVIDA),
Delegación Territorial del Ministerio de Ciencia, Tecnología,
y Medio Ambiente, Pinar del Río, Cuba.
Unidad Central del Valle
del Cauca (UCEVA), Carrera 25 B No. 44-28, Tulúa, Valle
del Cauca, Colombia.
Centro de Ecología, Instituto
Venezolano de Investigaciones Científicas, Apartado 20632,
Caracas 1020-A, Venezuela.
Centro de Biofísica y Bioquímica
(Herbarium), Instituto Venezolano de Investigaciones Científicas,
Apartado 20632, Caracas 1020-A, Venezuela.
Botanist, Yopal, Casanare, Colombia.
School of Geographical
Sciences and Urban Planning, Arizona State University, Post
Office Box 875302, Tempe, AZ 85287-5302, USA.
National Trust, Leon Levy Native Plant Preserve, Eleuthera,
Instituto de Investigación de Recursos Biológicos
Alexander von Humboldt, Avenida Paseo Bolívar 16-20, Bogotá,
D.C., Colombia.
Consultant Botanist, Cas en Bas Road, Gros Islet,
St. Lucia.
Forest Service, Southern Research Station,
International Institute of Tropical Forestry, Jardín Botánico
Sur, 1201 Calle Ceiba, San Juan, PR00926, Puerto Rico.
de Estudios Botánicos, Universidad de Antioquia, AA 1226
Medellín, Colombia.
Universidad Distrital Francisco José de
Caldas, Carrera 5 Este No. 15-82, Bogotá, Colombia.
de Ciencias Naturales, Universidad Nacional de Salta, Avenida
Bolivia 5150, 4400 Salta, Argentina.
School of Environment,
Natural Resources, and Geography, Thoday Building, Room G21,
Bangor University, Bangor LL57 2DG, UK.
Department of
Life Sciences, University of West Indies, Mona, Jamaica.
del Tolima, Barrio Santa Helena Parte Alta, Código Postal 730006299,
Ibagué, Tolima, Colombia.
Fundación Orinoquia Biodiversa,
Calle 15 No. 12-15, Tame, Arauca, Colombia.
Instituto de Ciencias
Naturales, Universidad Nacional de Colombia, Sede Bogotá, Código
Postal 111321, Avenida Carrera 30 No. 45-03, Edificio 425,
Bogotá, Colombia.
Department of Life Sciences, The University of
The West Indies St. Augustine, Natural Sciences Building,
Old Wing, Room 222, St. Augustine, Trinidad and Tobago.
Oriental de Ecosistemas y Biodiversidad BIOECO, Cuba.
de Pamplona, Ciudad Universitaria, Pamplona, Norte de
Santander, Colombia.
Departamento de Biología, Universidad
Nacional de Colombia, Sede Bogotá, Código Postal 111321,
Avenida Carrera 30No. 45-03, Edificio 476, Bogotá, Colombia.
Jardín Botánico Eloy Valenzuela, Avenida Bucarica, Floridablanca,
Santander, Colombia.
Jardín Botánico de Bogotá
José Celestino Mutis,Avenida Calle 63 No. 68-95, Bogotá, Colombia.
Facultad de Ciencias Naturales y Matemática, Universidad
del Rosario, Carrera 26 No. 63B-48, Bogotá, Colombia.
on September 22, 2016 from
(6306), 1383-1387. [doi: 10.1126/science.aaf5080]353Science
Villanueva and R. Toby Pennington (September 22, 2016)
Särkinen, Roberto Sánchez, Melvin Smith, Carlos Vargas, Boris
Ríos, Orlando Rivera, Nelly Rodríguez, Alicia Rojas, Tiina
Flávia F. Pezzini, Orlando Joel Reyes Dominguez, María Elvira
Neves, Luis J. Oakley, Michael Oatham, Alma Rosa Olvera-Luna,
Molina, Natalia del Pilar Moreno, Jafet M. Nassar, Danilo M.
McLaren, Omar Melo, Francisco Mijares, Virginia Mogni, Diego
Olga G. Martínez, Hernán M. Maturo, Morag McDonald, Kurt
Helmer, Álvaro Idárraga, René López, Humfredo Marcano-Vega,
Galetti, Reina Gonto, Roy González-M., Roger Graveson, Eileen H.
Miller Ángel Fernández, Janet Franklin, Ethan H. Freid, Luciano A.
Wilson Devia, Hilda Dueñas, Laurie Fajardo, Ángel Fernández,
Ceballos-Mago, Álvaro Cogollo, Hermes Cuadros, Freddy Delgado,
Arteaga, Gerardo Aymard, Alejandro Castaño, Natalia
Adarve, Esteban Álvarez, Anairamiz Aranguren B., Julián Camilo
Rodríguez M., Julia Weintritt, Pedro Acevedo-Rodríguez, Juan
Prado, Martin Pullan, Catalina Quintana, Ricarda Riina, Gina M.
Dexter, Reynaldo Linares-Palomino, Ary Oliveira-Filho, Darién
DRYFLOR, Karina Banda-R, Alfonso Delgado-Salinas, Kyle G.
conservation implications
Plant diversity patterns in neotropical dry forests and their
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... Neotropical seasonally dry forest -NSDFspecies occur from Mexico to Argentina and in the Antilles (Banda et al., 2016). They have a disjunct distribution that is mainly associated with climatic conditions such as high temperatures (above 25 ºC), low rainfall regimes (< 1 800 mm), and strong rainfall seasonality (i.e., three to six months with less than 100 mm of precipitation (Banda et al., 2016). ...
... Neotropical seasonally dry forest -NSDFspecies occur from Mexico to Argentina and in the Antilles (Banda et al., 2016). They have a disjunct distribution that is mainly associated with climatic conditions such as high temperatures (above 25 ºC), low rainfall regimes (< 1 800 mm), and strong rainfall seasonality (i.e., three to six months with less than 100 mm of precipitation (Banda et al., 2016). Pennington et al. (2009) suggest that these climatic conditions have shaped species ranges without immigrational subsidy and, therefore, they influence richness and patterns of endemism. ...
... Pennington et al. (2009) suggest that these climatic conditions have shaped species ranges without immigrational subsidy and, therefore, they influence richness and patterns of endemism. Furthermore, according to the same authors climatic constraints have produced three features (emergent from phylogenetic studies) in taxa confined to this type of forest: (a) endemic species are confined to a single geographic areas (NSDF nuclei, sensu Banda et al. (2016)), which are (b) monophyletic and relatively old (predating the Pleistocene) and (c) sister species often tend to inhabit the same NSDF nuclei, suggesting phylogenetic niche conservatism (-PNC). Phylogenetic niche conservatism refers to lineages that tend to retain ancestral ecological characteristics over time (Angulo et al., 2012;Donoghue, 2008;Pennington et al., 2009). ...
Full-text available
Introduction: Neotropical seasonally dry forest (NSDF) climatic constraints increased endemism, and phylo-genetic niche conservatism in species that are restricted to this biome. NSDF have a large number of endemic Capparaceae taxa, but it is unknown if phylogenetic niche conservatism has played a role in this pattern. Objective: We carried out an evolutionary analysis of the climatic niche of neotropical species of Capparaceae to identify whether the climatic constraints of NSDF have played a major role throughout the family's evolutionary history. Methods: Using three chloroplastic (ndhF, matK, rbcL) and one ribosomal (rsp3) DNA sequences, we proposed a date phylogeny to reconstruct the evolutionary climatic niche dynamics of 24 Neotropical species of Capparaceae. We tested the relationship between niche dissimilarity and phylogenetic distance between species using the Mantel test. Likewise, we used a set of phylogenetic comparative methods (PGLS) on the phylogeny of Capparaceae to reconstruct the main evolutionary historic events in their niche. Results: Capparaceae originated in humid regions and subsequently, convergent evolution occurred towards humid and dry forest during the aridification phases of the Middle Miocene (16-11 Mya). However, adaptation towards drought stress was reflected only during the precipitation of the coldest quarter, where we found phylo-genetic signal (Pagel λ) for gradual evolution and, therefore, evidence of phylogenetic niche conservatism. We found convergent species-specific adaptations to both drought stress and rainfall during the Miocene, suggesting a non-phylogenetic structure in most climatic variables. Conclusions: Our study shows how the Miocene climate may have influenced the Capparaceae speciation toward driest environments. Further, highlights the complexity of climatic niche dynamics in this family, and therefore more detailed analyses are necessary in order to better understand the NSDF climatic constrictions affected the evolution of Capparaceae.
... A large portion of the South American territory is classified as seasonally dry tropical forests-SDTF [12], with a distribution pattern known as the Pleistocene Arc [12,13]. Although South America holds over six hundred termite species [14], most research efforts have targeted only a few taxa, such as Constrictotermes cyphergaster (Termitidae:Nasutitermitinae) (Silvestri, 1901). ...
... A large portion of the South American territory is classified as seasonally dry tropical forests-SDTF [12], with a distribution pattern known as the Pleistocene Arc [12,13]. Although South America holds over six hundred termite species [14], most research efforts have targeted only a few taxa, such as Constrictotermes cyphergaster (Termitidae:Nasutitermitinae) (Silvestri, 1901). ...
Full-text available
Termites have global distributions and play important roles in most ecosystems, often with high nest densities and interesting associations with other organisms. Constrictotermes cyphergaster, is a termite endemic to South America, widely distributed and very conspicuous, and has therefore been considered a good model for filling in gaps in general termite ecology and their relationships with other organisms (e.g., termitophily). A systematic review (content and bibliometric analyses) was used to gather all published scientific knowledge related to C. cyphergaster as well as to observe trends, verify gaps, and direct new perspectives for future studies of this species. We identified 54 studies, of which more than 50% were published in the last five years (28 articles). The majority of the articles investigated the relationships between C. cyphergaster and macroorganisms (44.4%), followed by specific aspects of its biology (25.9%). The collaboration network revealed that links between researchers are still limited and modular, but trending topics have changed over time. Additionally, there are differences in the aims of the studies being carried out in the Caatinga and Cerrado domains, with some information focusing only on one of those environments. Our results show that some gaps in the biology and ecology of C. cyphergaster remain to be explored, although collaborative efforts between researchers open opportunities for suggesting future studies that would make relevant contributions to the general knowledge of termites.
... The intra-annual amount and distribution of rainfall strongly modulate TDF structure and function, especially the carbon (C) cycle (Campo & Merino, 2016;Mendes et al., 2020;Rojas-Robles et al., 2020), with interannual variation in rainfall providing secondary controls (Allen et al., 2017;Huang et al., 2021). Additionally, the TDF biome is associated with high intensities of land use that create dynamic mosaics of forest, land under agricultural use and land supporting other human practices (Banda et al., 2016;Blackie et al., 2014). These uses often alter TDF composition, structure and function, and for this reason, we describe the TDF biome as comprising both forest and non-forest vegetation that together form tropical dry landscapes (TDLs). ...
... Conversely, the overlap could relate to the lack of floristic differences between Africa and Asia, with floristic differences for the TDLs of the Neotropics (Dexter et al., 2015). Future research could focus whether TDL flora share a common biogeographical origin (Slik et al., 2018), whereby selection for drought and fire resistance has favoured the dominance of similar plant lineages globally (Banda et al., 2016;Ratnam et al., 2016). ...
Spatial patterns in resource supply drive variability in vegetation structure and function, yet quantification of this variability for tropical dry forests (TDFs) remains rudimentary. Several climate‐driven indices have been developed to classify and delineate TDFs globally, but there has not been a climo‐edaphic synthesis of these indices to assess and delineate the extent of TDFs. A statistical climo‐edaphic synthesis of these indices is therefore required. Pantropical. Modern. Vascular plants. We assembled most known prior descriptions of TDFs into a single data layer and assessed statistically how the TDF biome, which we call tropical dry landscapes (TDLs) composed of forest and non‐forest vegetation, varied with respect to the normalized difference vegetation index (NDVI) sensed by MODIS (250 m pixel resolution). We examined how the NDVI varied with respect to mean annual temperature (MAT) and rainfall (MAR), precipitation regime, evapotranspiration and the physical, chemical and biological properties of TDL soils. Overall, the NDVI varied widely across TDLs, and we were able to identify five principal NDVI categories. A regression tree model captured 90% of NDVI variation across TDLs, with 14 climate and soil metrics as predictors. The model was then pruned to use only the three strongest metrics. These included the Lang aridity index, total evapotranspiration (ET) and MAT, which aligned with identified NDVI thresholds and accounted for 70% of the variation in NDVI. We found that across a global TDL distribution, ET was the strongest positive predictor and MAT the strongest negative predictor of the NDVI. The remote sensing‐based approach described here provides a comprehensive and quantitative biogeographical characterization of global TDL occurrence and the climatic and edaphic drivers of these landscapes.
... A limitation of the TREECHANGE dataset is that its underlying datasets do not have a coherent and consistent design and sampling scheme, but as described below, it complements the calculation of the estimated total number of tree species worldwide based on GFBI data. We extracted taxonomic data and associated geographic coordinates from five main data aggregators of species occurrences: the Global Biodiversity Information Facility [accessed through rgbif R package (41)], the public domain of the (43)], the RAINBIO database (44), and the Atlas of Living Australia [ALA; accessed through the ALA4 R package (45)]. The species list was initially extracted from a world tree species checklist [GlobalTreeSearch (46)]. ...
... We checked for taxonomic correctness using the Taxonomic Name Resolution online tool (47), following a quality assessment and control of the data using the workflow outlined in ref. 26. This workflow minimized common errors associated with occurrence data (43). GlobalTreeSearch uses the tree definition agreed on by IUCN's GTSG above mentioned. ...
Full-text available
One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknown. Here, based on global ground-sourced data, we estimate the total tree species richness at global, continental, and biome levels. Our results indicate that there are ∼73,000 tree species globally, among which ∼9,000 tree species are yet to be discovered. Roughly 40% of undiscovered tree species are in South America. Moreover, almost one-third of all tree species to be discovered may be rare, with very low populations and limited spatial distribution (likely in remote tropical lowlands and mountains). These findings highlight the vulnerability of global forest biodiversity to anthropogenic changes in land use and climate, which disproportionately threaten rare species and thus, global tree richness.
... El ecosistema de bosque seco es el más amenazado del mundo (Banda-Ralfonso et al., 2016). En Nicaragua abarca principalmente el Pacífico y una parte de los departamentos de Boaco, Madriz y Estelí, y se encuentra en fragmentos de bosque seco con diferentes grados de madurez. ...
Full-text available
El extractivismo minero en Nicaragua hunde sus raíces históricas desde el período colonial. Posterior a la independencia, la minería se expandió a nuevos territorios, como el Caribe Norte, e intensificó su actividad extractiva a través de los enclaves mineros dominados por compañías extranjeras, predominantemente norteamericanas y canadienses, bajo la lógica de la reproducción y acumulación globalizada del capital. Al igual que en otros países latinoamericanos, la minería en Nicaragua, ha estado determinada por la demanda de materia prima por parte de las grandes economías, la volatilidad de los precios internacionales de los minerales, la calidad de las instituciones nacionales y su impacto en la gobernanza socioambiental, y más recientemente, por los efectos de los acuerdos políticos entre las élites económicas y políticas transnacionales y nacionales. En contexto de la nueva ola extractivista, del siglo XXI, el gobierno de Daniel Ortega y actores del sector privado han justificado su apuesta por la minería como una estrategia de desarrollo económico, a pesar de la arraigada situación de pobreza y extrema pobreza que caracteriza a los distritos mineros y pese a la resistencia de comunidades campesinas, que se ven amenazadas por sus múltiples impactos. Este trabajo analiza desde una perspectiva histórica ¿Qué ha significado el extractivismo minero en Nicaragua? En el actual contexto de crisis sociopolítica y una posible transición política ¿Qué desafíos plantea la problemática del extractivismo minero en un país como Nicaragua? Así mismo, se formularán algunos principios que abonen a la discusión de un horizonte de desarrollo democrático y sostenible.
... Despite the extremely rich diversity of organisms and high levels of endemism they harbor, tropical dry forests (TDFs) are among the most threatened and degraded of all biomes on Earth (Banda et al. 2016). Moreover, worldwide around 97% of the remaining areas of TDFs are severely endangered due to a variety of anthropogenic pressures (Miles et al. 2006). ...
Full-text available
Aims Although tropical dry forests are among the most degraded and fragmented biomes in the world, we still only have a poor understanding of their basic ecological features and conservation status, particularly in the Neotropics. Here, we assess the diversity, composition, structure, and conservation value of tropical dry forests in a highly fragmented landscape in Nicaragua. Methods We established 31 plots and transects in and along river corridors, secondary forests, living fences, and pasture-woodlands. We recorded all trees with diameters at breast height ≥ 2.5 cm using Hill numbers ( qD, where q = 0, 1, or 2) and estimated the richness and diversity of trees in each forest type. We calculated the Importance Value Index (IVI) to species and family levels and, finally, performed a Non-Metric Multidimensional Scaling (NMDS) ordination and an Analysis of Similarities (ANOSIM) using the Bray-Curtis index of similarity. Important Findings Diversity ( 1D, 2D) but not species richness ( 0D) differed between forest types (P = 0.01 and 0.66, respectively). The Importance Value Index (IVI) was highest for the legume family Fabaceae, followed by the Moraceae and Malvaceae (27.8, 11.1, and 10.5, respectively). Vachellia pennatula, Guazuma ulmifolia, and Bursera simaruba had IVIs >30%, the former two being the most abundant trees in all forest types. An analysis of community similarity found that each forest type had a distinct composition (P < 0.01, R2 = 0.30), thereby underlining the importance of conserving all these different types of land cover.
... The emergence of completely new environments created ecological opportunities for divergence of lineages of the regional species-pool within these edaphic islands. Indeed, edaphic specialization has been previously designated as an important driver of diversification, endemism, and spatial genetic structure of plants (e.g., Fine et al., 2005Fine et al., , 2013DRYFLOR et al., 2016;Cacho and Strauss, 2014), happening relatively rapidly in some lineages (Rajakaruna, 2017). Factors other than the chemical and textural nature of the substrate, however, may be responsible for the diversification, and the nature of the substrate may be only a surrogate for yet unmeasured factors. ...
Full-text available
The Brazilian Caatinga is considered the richest nucleus of the Seasonally Dry Tropical Forests (SDTF) in the Neotropics, also exhibiting high levels of endemism, but the timing of origin and the evolutionary causes of its plant diversification are still poorly understood. In this study, we integrate comprehensive sampled dated molecular phylogenies of multiple flowering plant groups and estimations of ancestral areas to elucidate the forces driving diversification and historical assembly in the Caatinga flowering plants. Our results show a pervasive floristic exchange between Caatinga and other neotropical regions, particularly those adjacent. While some Caatinga lineages arose in the Eocene/Oligocene, most dry-adapted endemic plant lineages found in region emerged from the middle to late Miocene until the Pleistocene, indicating that only during this period the Caatinga started to coalesce into a SDTF like we see today. Our findings are temporally congruent with global and regional aridification events and extensive denudation of thick layers of sediments in Northeast (NE) Brazil. We hypothesize that global aridification processes have played important role in the ancient plant assembly and long-term Caatinga SDTF biome stability, whereas climate-induced vegetation shifts, as well as the newly opened habitats have largely contributed as drivers of in situ diversification in the region. Patterns of phylogenetic relatedness of Caatinga endemic clades revealed that much modern species diversity has originated in situ and likely evolved via recent (Pliocene/Pleistocene) ecological specialization triggered by increased environmental heterogeneity and the exhumation of edaphically disparate substrates. The continuous assembly of dry-adapted flora of the Caatinga has been complex, adding to growing evidence that the origins and historical assembly of the distinct SDTF patches are idiosyncratic across the Neotropics, driven not just by continental-scale processes but also by unique features of regional-scale geological history.
CO2 is an important gas for the biological cycle, as it plays a fundamental role in regulating the planet's temperature. Modifications in ecosystems promote an imbalance in carbon dynamics, causing more significant release into the atmosphere. The Caatinga biome, a dry forest type, has been anthropized since before the beginning of Brazil's colonization. Knowledge about the consequences of this anthropization in carbon stock changes in the soil is still scarce. This work aimed to evaluate the soil CO2 efflux in preserved and degraded sites in the Caatinga. CO2 emissions were collected in the field using an Infrared Gas Analyzer at four sampling points in the dry and rainy seasons of 2017. Texture, reactivity, nutrient content, and soil porosity were measured. Base saturation and texture were similar in the preserved and degraded sites. Preserved sites have higher C, N, P, and available water contents. Emission of CO2 increased with available water after rain events. Temperature, soil moisture, and land use influenced CO2 efflux, indicating the complexity of understanding the phenomenon. Degraded sites registered lower C stock and CO2 influx as an indication of desertification.
Full-text available
El bosque seco tropical del Jardín Botánico de Cartagena es uno de los pocos remanentes protegidos cerca de esta ciudad. Su estado de conservación y la abundancia de nacimientos de agua en la zona lo hacen único entre los remanentes de este ecosistema en el Caribe colombiano. En este contexto, el objetivo del presente estudio fue evaluar la estructura, composición, diversidad funcional y filogenética de la comunidad vegetal del área mediante una parcela permanente. Para ello se registraron 2023 tallos de 62 especies y la familia con mayor Índice de Valor de Importancia (IVI) fue Moraceae. La biomasa aérea total fue de 61.8 t.ha-1. Se encontraron dos tipos funcionales de plantas: uno adaptado al sotobosque y otro al dosel, y un bajo agrupamiento filogenético. Se concluyó que el bosque se encuentra en un estado de sucesión secundario intermedio a tardío y que la alta disponibilidad de agua en la zona, además de su ubicación aislada, han sido factores determinantes para su vegetación.
Full-text available
This discussion paper assesses the state of knowledge on tropical dry forests1 as it relates to CIFOR’s strategy and identifies research opportunities that align with CIFOR’s strategic goals. Over the past two decades, CIFOR has accumulated a substantial body of work on dry forests, with a particular focus on African dry forests. This paper is intended to build on that work, by gathering wider research from around the world, as CIFOR seeks to widen the geographic scope of its research on dry forests. The present assessment explores five themes: climate change mitigation and adaptation; food security and livelihoods; demand for energy; sustainable management of dry forests; and policies and institutional support for sustainable management. These themes emerged as priority areas during discussions on dry forest research priorities held at CIFOR’s Dry Forests Symposium in South Africa in 20112. Research on these themes should be considered a priority, given the importance of dry forests to people and ecosystems around the world and the threats posed to them.
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Studies of the distributions of species of seasonal woodland habitats in South America by means of dot-mapping and phytosociological analyses indicate the presence of three nodal areas: the Caatingas nucleus of arid northeastern Brazil; the Misiones nucleus, comprising a roughly right-angled triangular area enclosed by lines connecting Corumba-Puerto Suarez (Brazil/Bolivia) southward to Resistencia-Corrientes in northern Argentina, and eastward to the upper Uruguay River valley system in Argentinian Misiones and Brazilian Santa Catarina, and thus including most of eastern Paraguay and the west bank of the Paraguay River; and the Piedmont nucleus, which extends from Santa Cruz de la Sierra in Boliva to Tucuman and the sierras of east Catamarca in northwestern Argentina. Distribution maps are presented for over 70 taxa that show this kind of distribution pattern or its modifications. Most of the seasonal woodland species of this affinity are notable by their absence from the cerrado vegetation of central Brazil, although some occur on calcareous outcrops in the general cerrados area, and they also avoid the Chaco of northern Argentina. It is proposed that these fragmentary and mostly disjunct distributional patterns are vestiges of a once extensive and largely contiguous seasonal woodland formation, which may have reached its maximum extension during a dry-cool climatic period ca. 18,000-12,000 BP, coinciding with the contraction of the humid forest.
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Studies of the variation in tropical plant species diversity and itsrelationship with environmental factors are largely based on research intropical moist/wet forests. Seasonally dry tropical forests (SDTFs), incontrast, have been poorly investigated. In this paper we present data from 20Mexican SDTF sites sampled to describe the magnitude of floristic diversity inthese forests and to address the following questions: (i) to what extent isspecies diversity related to rainfall? (ii) Are there other climatic variablesthat explain variation in species diversity in SDTFs? (iii) How does speciesidentity vary spatially (species turnover) within the country? We found thatspecies diversity was consistently greater (a ca. twofold difference) than wouldbe expected according to the sites' precipitation. Rainfall did notsignificantly explain the variation in species diversity. Likewise, the numberof dry and wet months per year was unrelated to species diversity. In contrast,a simple measure of potential evapotranspiration (Thornthwaite's index)significantly explained the variation in species diversity. In addition to thegreat diversity of species per site (local diversity), species turnover wasconsiderable: of a total of 917 sampled species, 72% were present only in asingle site and the average similarity (Sorensen's index) among sites wasonly 9%. These aspects of floristic diversity and the high deforestation ratesof these forests in Mexico indicate that conservation efforts should be directedto tropical forests growing in locations of low and seasonal rainfall.
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While the Caribbean is a recognized “biodiversity hotspot”, plant conservation has not received adequate attention; particularly, given the high levels of endemism in many plant groups. Besides establishing protected areas, there needs to be a sustained effort to study the taxonomy, systematics and ecology of the flora. Recent phylogenetic studies have shown high levels of endemism and conservation studies indicate a large propotion of the flora is threatened with extinction. Eight recommendations are given for plant conservation in the region.
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We developed interpolated climate surfaces for global land areas (excluding Antarctica) at a spatial resolution of 30 arc s (often referred to as 1-km spatial resolution). The climate elements considered were monthly precipitation and mean, minimum, and maximum temperature. Input data were gathered from a variety of sources and, where possible, were restricted to records from the 1950-2000 period. We used the thin-plate smoothing spline algorithm implemented in the ANUSPLIN package for interpolation, using latitude, longitude, and elevation as independent variables. We quantified uncertainty arising from the input data and the interpolation by mapping weather station density, elevation bias in the weather stations, and elevation variation within grid cells and through data partitioning and cross validation. Elevation bias tended to be negative (stations lower than expected) at high latitudes but positive in the tropics. Uncertainty is highest in mountainous and in poorly sampled areas. Data partitioning showed high uncertainty of the surfaces on isolated islands, e.g. in the Pacific. Aggregating the elevation and climate data to 10 arc min resolution showed an enormous variation within grid cells, illustrating the value of high-resolution surfaces. A comparison with an existing data set at 10 arc min resolution showed overall agreement, but with significant variation in some regions. A comparison with two high-resolution data sets for the United States also identified areas with large local differences, particularly in mountainous areas. Compared to previous global climatologies, ours has the following advantages: the data are at a higher spatial resolution (400 times greater or more); more weather station records were used; improved elevation data were used; and more information about spatial patterns of uncertainty in the data is available. Owing to the overall low density of available climate stations, our surfaces do not capture of all variation that may occur at a resolution of 1 km, particularly of precipitation in mountainous areas. In future work, such variation might be captured through knowledge-based methods and inclusion of additional co-variates, particularly layers obtained through remote sensing.
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A review of the available knowledge on the Gran Chaco vegetation and the modeling environmental factors is presented. The latter are the best studied, and the plant taxonomy is well established. While thorough and shallow phytogeographical surveys and inventories abound, very little is known on the phytosociology, ecology and plant physiology of the Chaco. Woody climaxic communities analyzed are, in E—W direction (following the environmental gradients): Gallery Forest, “Selva de Ribera“, Austro-Brazilian Transitional Forest, ”Quebrachales" of Schinopsis balansae, “Quebrachales” of three, of white and of two “quebrachos”, "Palosantales" of Bulnesia sarmientoi, Arid Chaco Woodland, Pampean and Subandean Sierra Chaco, and the Subandean Piedmont Forests. The azonal communities are “Algarrobales“ of Prosopis spp., “Cardonales” of Stetsonia coryne, “Palmares” of Capernicia alba, and “Vinalares’ of Prosopis ruscifolia. The Bolivian, Paraguayan and Brazilian Chaco problems are briefly discussed. The vegetation analysis shows that a number of communities of widely different floristic lineages, still regarded as “chaquenian“ in the literature, need further objective studies. Most authors have simply equated the Chaco Geographical Region with the Chaco Phytogeographical Province, which therefore requires an adequate redefinition.
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A new species of asymmetrically winged fruit is described from Miocene sediments of Andean Ecuador. The new fruit is readily placed in the genus Loxopterygium of the Anacardiaceae based on the size, position of the stigma, wing venation, and serration of the wing tip. The new fossil species is very similar to extant species of Loxopterygium now distributed in dry habitats of coastal Ecuador and Peru, as well as dry interior forests of Bolivia and northern Argentina. We use the fossil to calibrate a molecular-based phylogeny of some members of the Anacardiaceae, showing that dry forest habitats may have been present in South America for more than 10 million years.
At the end of the Cretaceous there was a possibility for relatively direct floristic interchange between South America and tropical North America via island hopping along the proto- Antilles. Uplift of the Andes, mostly in Neogene time, led to an incredible burst of speciation in a number of Gondwanan families. A similar evolutionary explosion in the same taxa also took place in Costa Rica and Panama. The taxonomic groups that have undergone this evolutionary explosion have distributional centers in the N Andean region and S Central America, are poorly represented in Amazonia, and consist mostly of epiphytes, shrubs, and palmettos; their pollination systems suggest that coevolutionary relationships with hummingbirds, nectar-feeding bats, and perhaps such specialized bees as euglossines, have played a prominent role in their evolution. The evolutionary phenomena associated with the Andean uplift account for almost half of the total Neotropical flora and are thus largely responsible for the excess floristic richness of the Neotropics. Closing of the Panamanian isthmus in the Pliocene led to 1) southward migration of some Laurasian taxa into the Andes where they have become ecologically dominant despite undergoing little speciation, at least in woody taxa, and 2) northward invasion of lowland Gondwanan taxa of canopy trees and lianas into Central America, leading to their ecological dominance in lowland tropical forests throughout the region, despite little significant speciation in Central America.-from Author
Plant formations adapted to dry climates extend in South America from tropical to temperate latitudes and from sea level to the highest mountain ranges, to constitute a significant proportion of the vegetation in this continent. Thirteen different dry formations are considered in this paper and thier overall floristic similarities are analysed on the basis of their woody flora at the generic level. Through the use of Sorensen's coefficient of similarity, the matrix of interformation floristic similarities was obtained, and these results then analysed by means of constellation diagrams and two-axis ordination. The same procedure was repeated utilizing only the genera of the single family Cactaceae. The comparisons show the various degrees of floristic affinity between the dry floras considered, with some formations scarcely related to the others. The data show the existence of different South American arid floras, pointing to a complex history of contacts and divergences. The major floristic discontinuity is located in the Peruvian Andes, and a possible explanation for this discontinuity is suggested.
  • L P De Queiroz
L. P. de Queiroz, in Neotropical Savannas and Seasonally Dry Forests: Plant Diversity, Biogeography, and Conservation, R. T. Pennington, G. P. Lewis, J. A. Ratter, Eds. (CRC Press, Boca Raton, FL 2006) pp. 121-157.