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Short-term effect of Hurricane Irma and Maria in the population of Gesneria pauciflora (Gesneriaceae)

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The Caribbean was recently struck by two hurricanes (Irma and María) considered among the most powerful since 1928 in that region. !ese hurricanes brought intense and continuous rainfall, which likely impacted plants inhabiting riparian areas through flash floods and landslides. We conducted a post-hurricane assessment of Gesneria pauci!ora, an endemic riparian species of conservation concern in Puerto Rico, to determine the number of individuals of this species, their distribution and their response to the infuence of these natural phenomena across its distribution range; also, the assessment was an opportunity to survey additional sites within and outside of the Maricao Forest Reserve. A total of 79 colonies were surveyed during the study period (56 known colonies and 23 new records), yet seven of the known colonies were extirpated due to landslide or flood-driven habitat modifications. The survey yielded 7,853 plants distributed across three sub-watersheds with non-reproductive plants comprising 65.2% of the plants surveyed, followed by reproductive adults (25.3%) and seedlings (9.5%). Plants were found in a variety of habitats associated with riparian environments. Results from colonies that had pre-hurricane information suggest that plant mortality could have been as high as 89% with variation likely resulting from differences in their location within the riverine system (higher mortality for colonies in the main channel of the watershed). There was approximately an 11% reduction in estimated canopy cover at the site, and percent plant mortality showed a negative association with canopy cover after the hurricanes. While the number of individuals is higher than expected for a threatened species, the patchy distribution of its populations justifies the continuation of monitoring activities for the species at larger spatiotemporal scales to examine potential delayed responses to these hurricanes.
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Acta Científica · 32(1-3):12-22, 2021
12
Mervin E. Pérez, Elvia J. Meléndez-Ackerman, Liza García-Recinos, and Omar A. Monsegur-Rivera
ARTÍCULO
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45'!/'$-.+'.'6
Mervin E. Pérez1,5,
*, E lvi a J . M eléndez- Ac kerman1,2, Liza García-Recinos3, and
Omar A. Monsegur-Rivera4
1 Environment al Sciences Department, College of Natural Science, University of Puer to Rico, Río Piedras Campus. P.O. Box
70377, San Juan, PR 00936-8377
2 Center for Applied Tropical Ecology and Conservation, College of Natural Scienc e, Univers it y of Puerto Rico, Río Piedras
Campus. P.O. Box 23360 San Juan, PR, 00931
3 Biology Depar tmen t, College of Natur al Science, Universit y of Puer to Rico, Río Piedras Campus. P.O. Box 23360, San Juan,
PR 00931
4 Caribbean Ecological Service Field Ofce, Fish and Wildlife Service, P.O. Box 491 Boquerón, PR 00622
5 Curren t addres s: Depar tamento de Res tauración del Pais aje Forestal, Ins ti tuto Nacional de Bosques -INAB-, 7ma Avenida
6-80, Zona 13, Ciudad Guatemala, Guatemala
* Author for correspondence: ixmulej@gmail.com
.789:;<9
e Caribbean was recently struck by two hurricanes (Irma and María) considered among the
most powerful since 1928 in that region. ese hurricanes brought intense and continuous
rainfall, which likely impacted plants inhabiting riparian areas through ash oods and land-
slides. We conducted a post-hurricane assessment of Gesneria pauciora, an endemic riparian
species of conservation concern in Puerto Rico, to determine the number of individuals of
this species, their distribution and their response to the inuence of these natural phenomena
across its distribution range; also, the assessment was an opportunity to survey additional sites
within and outside of the Maricao Forest Reserve. A total of 79 colonies were surveyed during
the study period (56 known colonies and 23 new records), yet seven of the known colonies
were extirpated due to landslide or ood-driven habitat modications. e survey yielded
7,853 plants distributed across three sub-watersheds with non-reproductive plants comprising
65.2% of the plants surveyed, followed by reproductive adults (25.3%) and seedlings (9.5%).
Plants were found in a variety of habitats associated with riparian environments. Results from
colonies that had pre-hurricane information suggest that plant mortality could have been as
high as 89% with variation likely resulting from dierences in their location within the river-
ine system (higher mortality for colonies in the main channel of the watershed). ere was
approximately an 11% reduction in estimated canopy cover at the site, and percent plant mor-
tality showed a negative association with canopy cover aer the hurricanes. While the number
of individuals is higher than expected for a threatened species, the patchy distribution of its
populations justies the continuation of monitoring activities for the species at larger spatio-
temporal scales to examine potential delayed responses to these hurricanes.
=>?@A:B8 Caribbean, disturbance, endemics, plant conservation, riverine ecosystem.
$>8CD>E
El Caribe fue golpeado recientemente por dos huracanes (Irma y María) considerados en-
tre los más poderosos desde 1928 en esa región. Estos huracanes trajeron lluvias intensas y
continuas que probablemente impactaron en plantas que habitan áreas ribereñas a través
de inundaciones repentinas y eventos de deslizamientos de terreno. En este estudio,
ISSN: 1940-1148
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32(1-3):12-22, 2021 · Acta Científica
Gesneria pauciflora resilient to hurricanes
ARTÍCULO
realizamos una evaluación post-huracán del estado poblacional de Gesneria paucif lora,
una especie ribereña endémica de Puerto Rico y de interés de conservación, específica-
mente para determinar el número de individuos de esta especie, su distribución y la in-
fluencia de estos fenómenos naturales sobre los individuos en su área de distribución. Esta
evaluación representó además una oportunidad para explorar lugares adicionales dentro y
fuera de la Reserva Forestal de Maricao en búsqueda de poblaciones desconocidas al mo-
mento. Evaluamos 79 colonias durante el período de estudio (56 colonias conocidas y 23
nuevos registros), mas sin embargo, siete de las colonias conocidas f ueron extirpadas debi-
do a deslizamientos de tierra o modificaciones de hábitat generadas por inundaciones. La
evaluación resultó en 7,853 plantas distribuidas en tres subcuencas hidrográficas donde las
plantas no-reproductivas representaron el 65.2%, seguidas de adultos reproductivos
(25.3%) y plántulas (9.5%). Las plantas se encontraron en distintos microhábitats asociados
a ríos. Para las colonias con información previa al huracán, los resultados sugieren que la
mortalidad de plantas alcanzó hasta un máximo de 89% con variaciones entre colonias
dependiendo de la ubicación dentro del sistema f luvial (mayor mortalidad para las colo-
nias localizadas en el río principal de la cuenca hidrográfica). Hubo una reducción del 11%
en la cobertura estimada del dosel y el porcentaje de mortalidad de plantas mostró una
asociación negativa con la cobertura luego de los huracanes. Si bien el número de indivi-
duos aparenta ser relativamente alto para una especie considerada amenazada, la distribu-
ción geográfica restringida de sus colonias justifica el continuar los monitoreo de las
mismas a mayor escala espacio-temporal, para examinar posibles respuestas tardías de sus
individuos ante estos huracanes.
2;F;7:;8)<F;G> Caribe, conservación de plantas, disturbio, ecosistema riverino, endémico.
-/ %$#0,+%-#/
Caribbean forests frequently experience tropical
storms, which often become major natural phe-
nomena transforming their structure, composition,
and ecosystem function, and large-scale catastroph-
ic events to infrastructure (Boose et al. 1994; Lugo
2000; Van Bloem et al. 2003, 2005, 2006). Visible hur-
ricane eects include massive defoliation, snapped
and wind-thrown trees, large accumulation of debris,
landslides, debris ows, and altered stream channels,
among others (Lugo 2008)noticeable over the short-
term and relatively well documented in the literature.
Invisible eects are less understood as they require
well-focused research both in the short- and long-
term time scales. Even though these natural phe-
nomena might favor the survival and growth of some
species (i.e., Boucher and Mallona 1997), it may also
diminish the persistence of others either by direct
mechanical damage or changes in species interac-
tions. For example, hurricanes may promote imme-
diate or delayed mortality in trees through complete
defoliation and severe branch damage (Frangi and
Lugo 1998), facilitate the establishment of pioneer
and shade-intolerant species in disturbed sites within
the forest (Brokaw 1985, 1987), increase herbivory
rate (Hunter and Forkner 1999) and even help accel-
erate the spread of invasive plants (Bellingham et al.
2005; Lynch et al. 2011; Bhattarai and Cronin 2014).
For species of conservation concern in the Caribbean,
understanding the eects of these natural events on
them is a priority in order to increase their chance of
recovery, with assisted rehabilitation, in response to
these events.
Puerto Rico receives hurricanes at a rate of one
every 21 years historically, but between 1852 and
Acta Científica · 32(1-3):12-22, 2021
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Mervin E. Pérez, Elvia J. Meléndez-Ackerman, Liza García-Recinos, and Omar A. Monsegur-Rivera
ARTÍCULO
1998 , that rate reduces to one ever y 11.2 years when
thirteen hurricanes affected the island including
Hurricane Georges, a category-3 hurricane in 1998
(Sc atena and Larsen 1991; Feng et al . 2018). In Septem-
ber 2017, however, Puerto Rico received the impact
of two higher-category hurricanes (Irma and María).
On 6 September 2017, the trajectory of Hurricane Ir-
ma (category-5) crossed about 85 km East-Northeast
from San Juan, with maximum-sustained-winds of
295 km/h. Even though the eye of Hurricane Irma
was away from the U.S. Virgin Islands (it struck the
British Virgin Islands and moved upwards into the
Atlantic Ocean), tropical storm and hurricane con-
ditions were reported for Puerto Rico (Cangialosi et
al. 2018). On 20 September 2017, the eye of Hurri-
cane María made landfall near Yabucoa, southeast
coast of Puerto Rico, as a top category-4 storm with
maximum-sustained-winds of 250 km/h (Pasch et al.
2018). Hurricane María crossed the island exiting it
from the north coast between the municipalities of
Camuy and Quebradillas at around 1800 h (Pasch et
al. 2018). As Hurricane María made landfall on the
island, damage to infrastructure and natural areas
was evident (Hu and Smith 2018). It is estimated that
Hurricane María may have killed or damaged more
than 20 million trees (Feng et al. 2018) with massive
wind-driven defoliation leading to the browning of
forests throughout the landscape (Burnett 2017).
During hurricane events, rainfall may become ex-
treme, increasing the number and intensity of flash
floods and landslides (Scatena and Larsen 1991;
Larsen and Torres Sanchez 1992). Species associated
with riparian ecosystems might be especially vul-
nerable to the action of flashflood events and land-
slides, possibly experiencing extirpation following
these events when extreme. If the number and in-
tensity of hurricanes in the Caribbean increase as
predicted by models (Emanuel 2005), species en-
demic to riparian areas and of conservation concern
could face a much more complicated scenario in the
near future. Gesneria pauciflora (Gesneriaceae) is
the only one of five endemic Gesneriaceae species
to Puerto Rico (Skog 1976) (Figure 1), classified as
Threatened under the Endangered Species Act (U.S.
Fish and Wildlife Service 1995). This riparian spe-
cies was listed due to its narrow distribution restrict-
ed to serpentine soils in the western part of Puerto
Rico (i.e., Maricao Forest Reserve boundaries), and
the potential for population extirpation due to the
threats from large-scale natural phenomena (i.e.,
hurricanes, landslides, flooding) and from human
activities (i.e., modifications in the river hydrol-
ogy due to water extraction; U.S. Fish and Wildlife
Service 1995). Populations of G. pauciflora at the
reserve inhabit riverine environments and are estab-
lished on wet rocks near to the river flow. Some of
Figure 1. , an endemic species from Puerto Rico.
Photo by O. Monsegur-Rivera.
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32(1-3):12-22, 2021 · Acta Científica
Gesneria pauciflora resilient to hurricanes
ARTÍCULO
these populations have been monitored since 2013,
and we expected that populations might have expe-
rienced consequences of intense and prolonged du-
ration because of hurricanes Irma and María. One
hypothesis is that colonies (i.e., patch level) with
more individuals were more susceptible to plant
mortality or extirpation. Likewise, flooding events
may lead to differential mortality across plant stages
if, for example, different plant stages were to be dif-
ferentially impacted by the incoming water during
flash flood events, and small individuals may be
more likely to be washed than juveniles or adults.
In this study, we took advantage of ongoing stud-
ies to assess the post-hurricane condition of 11
colonies of G. pauciflora for which there were plant
counts before the hurricane events of 2017. We took
the opportunity to visit all known colonies distrib-
uted in the Maricao Forest Reserve to conduct a full
count of plants for this species. Also, we surveyed
other watersheds outside of the reserve to evaluate
the potential of occurrence of additional popula-
tions and provide more updated information on
the distribution, general habitat, and the number
of plants for this species. This information expands
previous knowledge from other studies and allows
us to make recommendations on the best practices
to conserve and restore the population of this en-
demic and threatened species.
('%" #0!
!"#$%&!'"(
The Maricao State Forest Reserve (4,150 ha; Fig-
ure 2) is located at the western end of Puerto Rico
within the municipalities of Maricao, Sabana
Grande, and San Gern (Anadon-Irizarry 2006).
The protected area’s topography is dominated by
rugged mountains and is characterized by serpen-
tine soils. This particular geological soil type dis-
tinguishes the Maricao Reserve as an important
A
B
C
ecological area due to a high number of associated
endemic species (Ricart Pujals and Padrón Vélez
2010). The mean temperature and rainfall at Mari-
cao are 21.7°C and 2,326 mm, respectively (Tossas
2006). A seasonal trend in rainfall in the Maricao re-
serve is suggested, with a wet season from August to
November and a dry season from January to April
(Fogarty and Vilella 2002). Data from a period of 32
years (1985-2016; https://waterdata.usgs.gov) indi-
cate highly variable streamf low in the Maricao River
with the lowest monthly mean discharge reported in
February (0.54 m3/s) and the highest in October (3.1
m3/s). The maximum discharge values for this river
were reported in 1998, in September (8.7 m3/s) and
October (204.8 m3/s), which were associated with
Hurricane Georges. In 2017, rainfall associated to
Hurricane María, between 19 to 21 September, was
estimated within a range between 254 mm and 381
mm (Pasch et al. 2018), and the maximum daily
mean discharge recorded for Maricao River was
about 14.2 m3/s, also in September; there is no data
on the maximum discharge of the Maricao River as-
sociated to Hurricane Maa, however, because most
of the sensors were damaged. Nonetheless, f lood-
ing and landslides associated with Hurricane Maa
caused unprecedented damage to the infrastructure
and the Maricao River watershed (current and for-
mer staff from the Maricao Fish Hatchery, Depart-
ment of Natural and Environmental Resources
[DNER], p ers onal c ommun ica tion).
)'(*$&+,-'",.'-/
Fifty-six previously known colonies of G. pauciflo-
ra were visited from March to April of 2018 (between
five and six months after María impacted the island).
At each colony, we counted the number of plants and
classified individual plants in one of three categories
or life-history stages using the classification scheme
of Pérez et al. (2019): seedlings, non-reproductive,
and reproductive. Individuals were considered
Acta Científica · 32(1-3):12-22, 2021
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Mervin E. Pérez, Elvia J. Meléndez-Ackerman, Liza García-Recinos, and Omar A. Monsegur-Rivera
ARTÍCULO
seedlings if they were small plantlets with a hyaline
stem with two or four leaves (approximately less than
0.4 mm in high). Non-reproductive plants were those
greater than 0.4 mm and smaller than 15 cm. Re-
productive plants were those larger than 15 cm, but
if plants smaller than 15 cm were flowering or had
remnants of inflorescences, they were also catego-
rized as reproductive individuals. For each plant, we
recorded the length of the largest branch, the number
of inf lorescences, f lowers, and fruits (when present),
and the frequency of floral herbivory. To character-
ize the habitat of each colony after the hurricane, we
collected the following information: habitat type (i.e.,
cascade, rock wall, step, and pool), the surface area
occupied by the species, percentage of area avail-
able for reintroduction (unoccupied space within
Figure 2. Distribution of the 79 colonies of  distributed in the Maricao Reserve. (A) All of the colonies combined; (B–D) distri-
bution of the 29 colonies located outside the limits of the Maricao Reserve. (B) Four colonies located at Quebrada Santa Rita and three in the
Maricao River; (C) twenty colonies established along the Rio Lajas around the Salto Curet touristic place and Indiera Alta; (D) two colonies along
the Rio Grande.
A
C
B
D
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32(1-3):12-22, 2021 · Acta Científica
Gesneria pauciflora resilient to hurricanes
ARTÍCULO
the colony, or available space with
similar microhabitat conditions),
canopy cover (estimated using a
densitometer), and the presence
of landslides. If new colonies were
found, these were georeferenced,
and we collected all parameters de-
scribed above.
0#..'12-(&3+421"5
We have pre-hurricane count data (number of
plants per life-history stage) for a subset of 11 colonies
(out of the 56 previously known colonies), located in
the Rio Maricao watershed. For these 11 colonies,
we used post-hurricane counts of plants to estimate
percent mortality (i.e., {[number of plants in 2017 –
plants in 2018]/[number of plants in 2017]} *[100]) for
the whole colony and by stage. We analyzed changes
in the number of plants per colony before (June 2017)
and aer (April 2018) these hurricanes and tested if
the dierence between the pre- and post-hurricane
count of plants was signicantly dierent among
plant stages using a Negative Binomial General Linear
Model (NBGLM) and a post hoc analysis using the
“emeans” package in R (R Core Team 2018). At each
colony, we also estimated changes in canopy cover af-
ter Hurricanes Irma and María by taking hemispheri-
cal photographs (using a Nikon Coolpix 8400 camera
and sh-eye lens FC-E9) before (October 2016) and
aer the hurricanes (April 2018). e percent of
canopy cover at each colony was estimated from the
images with the soware ImageJ (Rasband 2014) us-
ing Hemispherical 2.0 macro (Beckschäfer 2015). We
conducted a paired t-test to determine if the dier-
ence in the percentage of canopy cover before and af-
ter hurricanes was signicant. e relationship of the
percentage of plant mortality with canopy cover and
initial population size was analyzed using regression
analysis. All statistical analyses were conducted using
R (R Core Team 2018).
$'!,3%!
e overall survey resulted in 79 colonies (23 new
ones), which expanded the inventory of G. pauciora
colonies; 29 colonies were located outside the Maricao
Forest Reserve limits (Figure 2). Also, 46 colonies were
in a third-order stream, 30 in a second-order, and 3
in a fourth-order stream. Aer the hurricanes, seven
colonies were extirpated. ese were mostly located
in second- and third-order streams in the lower part
of the basin; ve of these colonies were extirpated be-
cause of landslides. For the 72 extant colonies among
the three sub-watersheds, colony size varied from 4
to 476 individuals with larger colonies concentrated
in the upstream within the watershed. Among all
colonies, we found 7,853 individuals quantied and
classied as follows: 8.5% seedlings, 65.2% non-repro-
ductive, and 26.3% reproductive plants (Table 1). Most
of the colonies had at least one individual classied
as a reproductive adult (> 15 cm in length), and only
397 (5.1%) out of the 7853 individuals had reproduc-
tive structures. At the time of the survey, reproductive
adults were developing 105 inorescences (average =
1.61/plant, ± 0.22 [standard error of the mean]), and
produced 375 ower buds (2.27/plant ± 0.13), 76 open
owers (1.18/plant ± 0.06), and 1914 fruits (3.59/plant
± 0.19). Overall, oral herbivory was minimal (2.9% of
the plants presented damages), and the level of dam-
age from herbivory varied between 0% and 25% per
colony. Colonies of Gesneria were distributed across
Table 1. P opul atio n structure a nd habi tat char acte riza tion of  colonies.
Life history stage: Seed = seedlings; NRP = non-reproductive plants; RP = reproductive plants.
Habitat characteristics: R = rock-wall; C = cascade; S = step; P = pool; CC = canopy cover;
AfR = area for restoration. * = grand mean of all sites.
Life history stage Habitat characteristics
Locality
Seed NRP RP Patch surface CC
(mean %)
AfR
(m2)
Total % Total % Total % R C S P
Bonelli — — — — — — 0 1 0 0
Lajas 0 0 953 65.3 506 34.7 10 6 4 6 70.8 89.7
Maricao 447 8.7 3,419 66.3 1,288 25.0 8 16 10 10 79.7 158.3
Prieto 217 17.5 749 60.4 274 22.1 3 1 6 0 71.4 30.3
Total 664 8.5 51 21 65.2 2,068 26.3 21 24 20 16 76.5* 278.3
Acta Científica · 32(1-3):12-22, 2021
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Mervin E. Pérez, Elvia J. Meléndez-Ackerman, Liza García-Recinos, and Omar A. Monsegur-Rivera
ARTÍCULO
Figure 3. Difference in the number of individuals before and after the
hurricane events as a function of plant stage (adults, juvenile, and
seedlings). The full model (see text) was expressed as the difference =


among groups.
Table 2. N umbe r of plants (n) an d re prod ucti ve individuals (R epro d.),
before and after hurricanes Irma and María, and percent mortality per
colony in each of two riverine localities. ext. = extirpated.
Pre-hurricane Post-hurricane
Locality Colony n Reprod. nReprod. Mortality (%)
Main Channel 1 16 1 5 1 68.8
2251 14 44 2 82.5
3 40 3 5 0 87.5
414 1 ext. —
5573 45 63 5 89.0
6 225 29 42 3 81.3
Tributary 7 36 5 13 1 63.9
8 1 0 ext. —
921 5 5 2 76.2
10 219 17 129 6 41 .1
11 241 8174 4 26.1
(NBGLM: X2 = 10.52, p = 0.03). Colonies 5 and 6 (see
Figure 2b) had the greatest number of reproductive
plants before the hurricanes, but also scored the high-
est reduction (Table 2). e percent of canopy cover
ranged between 79.4% and 98.7% (average = 93.8 %
± 1.6) before the hurricanes, and between 71.6% and
93.6% (average = 82.9% ± 2.3) aer the hurricanes (NB-
GLM: X2 = -5.94, df = 10, p = 0.0001). Percent mortality
of plants per colony was negatively related with canopy
cover aer hurricanes (Estimate ± standard error of
the mean = -2.6 ± 0.51, F1,9 = 25.85, p = 0.0006) (Figure
4a) and a positive relationship with the percent canopy
cover change (Estimate ± standard error of the mean =
2.3 ± 0.94, F1,9 = 6.1, p = 0.0350) (Figure 4b) and these
models explained 71.3% and 40.4% of the total varia-
tion in plant mortality, respectively. Initial population
four types of microhabitats (in decreasing percentage):
cascades (29.6%), rockwalls (25%), steps (24.6%), and
pools (19.8%) (Table 1). On average, the area occupied
by colonies was 20.2 m2 (± 4.4), and the average canopy
cover was 76.5% (± 1.73). e average available space for
reintroduction within a colony was 4.5 m2 (± 0.9); the
total area available for reintroduction among the three
watersheds was approximately 278.3 m2.
Out of eleven colonies monitored for reproduc-
tion and mortality before hurricanes Irma and María,
two were extirpated: one was in the main channel and
another in a tributary of the Maricao River. e two
extirpated colonies had the lowest number of plants
before the hurricanes (Table 2). Colonies located in the
main channel exhibited an average rate of mortality of
81.2%, while colonies in the tributary had an average
rate of 51.8% (Table 2). e average number of plants
per colony was signicantly lower six months aer the
hurricanes: it changed from 148.8 plants (± 52.9) to 44
plants (± 17.8) (NBGLM: X2 = 3.86, p = 0.049) (Table 2).
Changes in the number of plants were related to plant
stage, but changes were larger for seedling than for ju-
veniles when compared with adults (Figure 3).
Overall, survivorship was higher in the juvenile and
adult size-categories with 48.5% and 56.7%, respective-
ly (Table 2). e average number of reproductive indi-
viduals changed from 11.6 (± 4.25) per colony to about
2.7 (± 0.7) before and aer the hurricanes, respectively
19
32(1-3):12-22, 2021 · Acta Científica
Gesneria pauciflora resilient to hurricanes
ARTÍCULO
size did not explain the percent mortality of plants per
colony (F1,9 = 0.21, p = 0.6600).
0-!+,!!-#/
As expected, hurricanes Irma and María induced
higher plant mortality rates, which is partly consis-
tent with theory. For example, theory predicts that
small populations are usually more vulnerable to
environmental stochasticity (Colling and Matthies
2006). In fact, our results showed that 1) changes in
canopy cover (higher mortality occurred in areas
with less cover); 2) the location within the riverine
system (main channel vs. a tributary); 3) and stochas-
tic events (landslide extirpating some of the colonies)
were factors that explained most of the variation in
plant mortality and population persistence. eory
also predicts that populations with less than six plants
are more likely to be extirpated (or extinct in the case
of whole species) (Matthies et al. 2004; Öckinger and
Nilsson 2010). Contrary to theory, however, our re-
sults showed that few colonies were extirpated and
that the initial number of individuals in a colony was
not a signicant factor explaining plant mortality af-
ter these hurricanes. Most likely, environmental vari-
ation may play a greater role in plant mortality than
frequently acknowledged (see next).
Colonies of Gesneria pauciora appear to be asso-
ciated with shaded environments (Pérez et al. 2018).
Hurricane María defoliated most forests across Puerto
Rico massively (Miller et al. 2019). Canopy cover and
changes in it were signicantly associated with percent
mortality of plants among colonies, with higher mor-
tality in colonies located in more-open forest areas or
where the reduction in the percent canopy cover was
highest. Also, plant mortality seemed to be highest
in seedlings relative to juveniles and adults follow-
ing these hurricanes. Several hypotheses may explain
these results. First, evapotranspiration rates of plants
increases in an opened canopy, and these increases are
higher in seedlings relative to other plant stages by vir-
tue of having a higher surface to volume ratios (Zotz
et al. 2001) Also, and in the case of seedlings, they may
have a less developed root system relative to juveniles
and adults and thus, are less able to access groundwater,
which makes them more susceptible to drought stress
due to an open canopy. In addition, our observations
frequently revealed plants slightly detached from the
substrate and showed drying symptoms, which sug-
gest that seedlings may be more susceptible than other
stages of plant development to mechanical forces from
water currents.
Overall, the rate of plant mortality ranged from
68% to 89% in the main channel, while in the tribu-
tary, it was between 26% and 76%. Colonies along the
main channel were likely to be subjected to greater
volumes of water and sediment that scraped the veg-
etation along river margins due to the ooding events
Figure 4. Relationship between percent plant mortality of Gesneria
 among colonies as a function of (A) percent canopy cover
and (B) percent canopy cover change after the 2017 hurricane events
at the Maricao Forest Reserve in Maricao, Puerto Rico.
Acta Científica · 32(1-3):12-22, 2021
20
Mervin E. Pérez, Elvia J. Meléndez-Ackerman, Liza García-Recinos, and Omar A. Monsegur-Rivera
ARTÍCULO
associated with hurricanes Irma and María. Prior de-
mographic studies of G. pauciora suggest that plants
in dierent locations along the river system may ex-
hibit life-history trade-os that are consistent with dif-
ferent disturbance regimes along the river (Pérez et al.
2019). Although we did not have data to quantify and
compare the discharge in the main channel and the
tributary, structural damage of the forest was higher
along the main channel where more landslides and
greater accumulation of rocks and sediments were evi-
dent (M. Pérez, personal observation).
Plants documented in this study are distributed
among 79 local patches in the forest, and only 63.2% of
patches are currently protected, and at least 29 colonies
are located outside areas managed for conservation.
Also, even when the number of plants detected for the
species could be considered high (> 7,000 individu-
als), and that 11 “new” colonies were added to previous
surveys, only a quarter of plants sampled were ow-
ering and capable of sexual reproduction. Even when
this species is capable of some autogamy (i.e., autono-
mous pollination), fruit production is oen pollination
limited (Pérez et al. 2018). Pollen limitation on sexual
reproduction may be even stronger if these natural
phenomena also aected populations of pollinators
like hummingbirds, which are the main visitor to indi-
viduals of G. pauciora (Pérez et al. 2018).
In this study, we did not measure plant damage
nor reductions in plant size, which likely occurred
during the hurricane-driven ood events as plants
can be broken easily. Plant damage following hur-
ricanes, however, may lead to delayed mortality and
decrease reproduction and recruitment in the long
term. For example, the reproductive eort of two epi-
phyte orchid species did not return to pre-hurricane
condition, and one of them, Dendrophylax lindenii,
showed a decline in the population growth rate that
continued eight years aer Hurricane Ivan struck
Cuba in 2004 (Mújica et al. 2013; Raventós et al. 2015).
Similarly, over a period of nine years, values of the
population growth rate of the cactus Mammillaria
gaumeri were lower than unity and were associated
with the ooding period that occurred in the Yuca-
tán Península due to the Hurricane Isidore in 2002
(Ferrer-Cervantes et al. 2012).erefore, although it
was beyond the scope of our study, we need to con-
tinuously monitor colonies of G. pauciora to assess
its long-term response to the inuence of these hur-
ricanes, particularly the survival, growth, and fecun-
dity of its individuals at a larger spatio-temporal scale.
62-2/(+(-"&7(1,++(-$2"',-5
We provide recommendations based on the quan-
titative and qualitative information herein discussed.
Aer the hurricanes, there were plants slightly de-
tached from the rock or hanging from their roots. us,
we recommend that following a hurricane, plants un-
der such conditions (detached from the rock) should be
glued to the rock (based on preliminary experiments
we recommend using Loctite® marine adhesive seal-
ant) or relocated in microhabitats with environmental
conditions similar to those of pre-hurricane condi-
tions and mostly undisturbed. e species can gener-
ate roots from vegetative material within a period of
two or three months (Pérez et al., unpublished data).
Relocation of large plants (i.e., adult plants) aer a hur-
ricane seems to provide an acceptable management
strategy for some epiphyte orchids aer hurricane
events (Tremblay 2003; Raventós et al. 2015). erefore,
relocating adult plants of G. pauciora also might be
a plausible strategy, at the population level, to increase
their probability of survival.
e spatial location and microsite conditions where
the establishment of plants is most successful should
be known before relocating plants or establishing
new colonies (Tremblay 2003; Tremblay and Castro
2009; Vale et al. 2013). Colonies distributed in the
second- and third-order streams may be more vul-
nerable than the ones in the upper part of the basin
(rst-order streams) during extreme natural events
because they showed higher mortality of plants aer
21
32(1-3):12-22, 2021 · Acta Científica
Gesneria pauciflora resilient to hurricanes
ARTÍCULO
these hurricanes. Fortunately, our surveys within
the Maricao Forest Reserve revealed available space
for reintroduction, either in sites in which colonies
were extirpated, in sites were colonies were reduced
in number, or in new microhabitats that share eco-
logical features similar to pre-hurricane conditions.
erefore, these new microhabitats may represent
adequate options for future relocations if deemed
necessary. Also, we recommend monitoring all colo-
nies documented here, at least once a year, to detect
signs of delayed mortality before it reaches unsustain-
able levels. Likewise, we need to study the reproduc-
tive activity because recent population models of G.
pauciora suggest that populations are declining in
numbers across the main watershed examined here
(Pérez et al. 2019). Finally, we recommend executing
eorts to educate and integrate surrounding commu-
nities and private stakeholders in conservation eorts
for this species, given that recent surveys suggest that
36.7% of colonies lie outside the Maricao Forest Re-
serve boundaries.
Acknowledgements
is study was nanced by the U.S. Fish and Wild-
life Service under the Endangered Species Conser-
vation Recovery Implementation Funds Program
(CFDA15.675) in compliance with amended agree-
ment F16AC00894 to the University of Puerto Rico,
Río Piedras campus. We thank the Puerto Rico De-
partment of Natural and Environmental Resources
(PRDNER) the logistic support during eld activities.
We further acknowledge the collaboration from Jesús
M. Rios-Cruz (USFWS) and Jong Piel Banchs-Plaza
(PRDNER) for identifying new potential localities and
populations extending to private lands. e ndings
and conclusions in this article are those of the authors
and do not necessarily represent the views of the U.S.
Fish and Wildlife Service. e use of trade names in
this article does not imply endorsement by the United
States government.
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