pterocarpus officinalis forested wetlands of puerto rico...
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Species composition and differences in diversity among the
Pterocarpus officinalis forested wetlands of Puerto Rico
Article · January 2013
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CaribbeanNaturalist
No. 4 2013
Species Composition and Differences in Diversity Among
the Pterocarpus officinalis Forested Wetlands of Puerto Rico
Rusty A. Feagin, Frances Toledo-Rodríguez, Ricardo J. Colón-Rivera, Fred Smeins, and Roel Lopez
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Cover Photograph: Traversing a tidal creek in the secondary Pterocarpus officinalis forest in la Reserva Natural de Humacao, Puerto Rico.. Photograph © Doel Delgado.
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CARIBBEAN NATURALIST
The Caribbean Naturalist (ISSN # 2326-7119) is published by the Eagle Hill Institute, PO Box 9, 59 Eagle Hill Road, Steuben, ME 04680-0009. Phone 207-546-2821, FAX 207-546-3042. E-mail: [email protected]. Webpage: www.eaglehill.us/cana. Copyright © 2013, all rights reserved. Periodical postage paid in Steuben, ME and additional mailing offices. Published quarterly. Special issue proposals are welcome. On-line secure subscription ordering: rate per year for Caribbean subscribers - $15 regular, $10 students, $60 organizations; for Non-Caribbean subscribers - $20 regular, $15 students, $80 organizations. Journal subscription exchanges are considered. Authors: submission guidelines are available at www.eaglehill.us/cana. Co-published journals: The Northeastern Natu-ralist (ISSN 1092-6194 [print], ISSN 1938-5307 [online]) and the Southeastern Naturalist (ISSN 1528-7092 [print], ISSN 1938-5412 [online]), journals with separate Boards of Editors. The Eagle Hill Institute is a tax exempt 501(c)(3) nonprofit corporation of the State of Maine (Federal ID # 010379899).
Board of EditorsJames D. Ackerman, Department of Biology, University of Puerto Rico at Río Piedras, USAAlfonso Aguilar-Perera, Department of Marine Biology, Universidad Autónoma de Yucatán, MexicoWayne J. Arendt, International Institute of Tropical Forestry, Luquillo, Puerto Rico, USARüdiger Bieler, Field Museum of Natural History, Chicago, IL, USALeo Douglas, Department of Geography/Geology, University of the West Indies, Mona, JamaicaRobert Erdman, Department of Biological Sciences, Florida Gulf Coast University, Fort Myers, FL,
USAKeith Goldfarb, Eagle Hill Institute, Steuben, ME, USA ... Editor-in-ChiefGrizelle González, International Institute of Tropical Forestry, San Juan, Puerto Rico, USAGary R. Graves, Department of Vertebrate Zoology, Smithsonian Institution, Washington, DC, USAS. Blair Hedges, Department of Biology, Pennsylvania State University, University Park, PA, USAJulia A. Horrocks, Dept. of Biological and Chemical Sciences, Univ. of the West Indies, Cave Hill
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FL, USACraig A. Layman, Department of Biological Sciences,Florida International University, North Miami,
FL, USAJohn Leavengood, Department of Entomology, University of Kentucky, Lexington, KY, USAAntonio A. Mignucci-Giannoni, Manatee Conservation Center, Inter American University, Bay-
amón, Puerto Rico, USAGregg Moore, Department of Biological Sciences, Jackson Estuarine Laboratory, University of New
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dad and TobagoDavid W. Steadman, Florida Museum of Natural History, Gainesville, FL, USAKathleen Sullivan Sealey, Department of Biology, University of Miami, Coral Gables, FL, USAJarrod M. Thaxton, Department of Biology, University of Puerto at Mayagüez, USAJason M. Townsend, Department of Wildlife, Fish and Conservation Biology, University of Califor-
nia-Davis, USA ... Managing EditorJill Weber, Eagle Hill Institute, Steuben, ME, USA ... Production EditorByron Wilson, Department of Life Sciences, University of the West Indies at Mona, Kingston,
JamaicaGraham A. J. Worthy, Department of Biology, University of Central Florida, Orlando, FL, USAJoseph M. Wunderle, International Institute of Tropical Forestry, University of Puerto Rico at Río
Píedras, USA
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R.A. Feagin, F. Toledo-Rodríguez, R.J. Colón-Rivera, F. Smeins, and R. Lopez2013 Caribbean Naturalist No. 4CARIBBEAN NATURALIST2013 No. 4:1–25
Species Composition and Differences in Diversity Among the Pterocarpus officinalis Forested Wetlands of Puerto Rico
Rusty A. Feagin1,*, Frances Toledo-Rodríguez2, Ricardo J. Colón-Rivera1, Fred Smeins1, and Roel Lopez3
Abstract - Pterocarpus officinalis (Dragonsblood Tree, known as Palo de Pollo in Puerto Rico)-dominated forests are a rare ecosystem, found only in fifteen locations in Puerto Rico, most of which are adjacent to the coast and are at risk from sea level rise, nutrient pollution, upstream hydrological modifications, and deforestation. Prior to this study, there was little information on the diversity of organisms inhabiting these forests. The central objectives of our study were to examine the diversity and species composition of three Pterocarpus forests in Puerto Rico located in Humacao, Patillas, and Dorado; compare and contrast diversity among the three forests; and identify possible differences caused by human influences or natural factors. Visual surveys, vegetation plots, pitfall traps, insect traps and nets, and audio recordings were carried out to collect records of birds, mammals, amphibians and reptiles, invertebrates (insects, crustaceans, mollusks), plants, and fungi. The Dorado Pterocarpus forest is only 2.4 ha in extent, but is the rich-est and most diverse; Humacao, the largest tract sampled at 150 ha (63% of the total Pterocarpus coverage in Puerto Rico), is the least rich and diverse. The most obvious factor influencing richness and diversity among the forests is the adjacent land cover and history of the sites. Saltwater intrusion (Humacao), freshwater inflow from watersheds (Humacao, Dorado), and emerging spring water sources (Patillas) may also be factors that alter richness and diversity. Our results will be useful to those planning the appropriate management of this ecosystem in the context of ongoing sea-level rise, climate change, nutrient pollution, upstream hydrological modifications, and deforestation.
Introduction
Tropical wetlands are considered among the most valuable (Costanza et al. 1989) and important ecosystems in the world because of the ecosystem services they provide (e.g., flood protection, wildlife habitat; Mitsch and Gosselink 2007). Forested wetlands, in particular, are a feature of low-lying coastal areas in the Ca-ribbean region (Bacon 1990). Rhizophora mangle L. (Red Mangrove) dominates most of these wetlands except for forested areas influenced by freshwater, where the leguminous tree Pterocarpus officinalis Jacq. (Dragonsblood Tree, known as Palo de Pollo in Puerto Rico) is the dominant species (Fig. 1; Weaver 1997). Adapted to flooded ecosystems, P. officinalis inhabits river floodplains, coastal basins, and subtropical rainforests (Alvarez-Lopez 1990). Due to human disturbance and land clearing, Pterocarpus wetlands are now limited to small, genetically isolated
1Department of Ecosystem Science and Management, Texas A&M University, College Station, TX , USA 77845. 2US Fish and Wildlife Service, Parker River National Wildlife Refuge, Newburyport, MA, USA 01950. 3Institute of Renewable Natural Resources, Texas A&M University, College Station, TX, USA 77843. *Corresponding author - [email protected].
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Figure 1. A Pterocarpus officinalis tree during the dry season in the secondary re-growth section of the Humacao Natural Reserve forest (H2 section of forest), in Humacao, PR, USA. Photograph © Doel Delgado.
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patches scattered throughout the Caribbean region (Muller et al. 2009, Rivera-Oca-sio et al. 2006). Although the floristic composition of these wetlands has been well described by Alvarez-Lopez (1990) and Imbert et al. (2000), these ecosystems have not received the same research attention as mangrove swamps or upland rainforests (Imbert et al. 2000). In the last century, Puerto Rico lost nearly all of its Pterocarpus forested wetland cover (Helmer 2004), due largely to clearing of the coastal plain for agricultural purposes, often to establish sugarcane plantations. Today, the total area of Ptero-carpus is estimated to cover only 261 ha in approximately 15 locations (Gould 2007). Furthermore, remnant Pterocarpus wetlands in Puerto Rico are restricted to the coast, abutting mangrove ecosystems (Cintrón 1983); the remaining stands now occur near their ecological limits in terms of salinity (Rivera-Ocasio et al. 2007). Though work has also been done on drought tolerance (Lopez and Kursar 2007) and nutrient depletion (Medina et al. 2008), sea-level rise and associated saltwater intrusion appear to be the most serious threats affecting the Pterocarpus ecosystem. Salinities above approximately 12% can kill populations of these trees (Rivera-Ocasio et al. 2007). Pterocarpus wetland forests sustain a unique set of fauna, mainly composed of reptiles, water birds, amphibians, crustaceans, and mollusks (Quiñones-Ramos et al. 1992). This wetland forest type is recognized as rare and limited in extent on the island by the Puerto Rico National Heritage Program (Schwartz 2004). The importance of Pterocarpus wetland forests rests on their rarity, high level of bio-logical productivity, and floral composition. These ecosystems are also of interest to science, and they have intrinsic social value (Figueroa et al. 1984) in terms of recreational and spiritual purposes. The biodiversity of these Puerto Rican wetlands is one factor that has resulted in their designation as a protected ecological resource (Commonwealth of Puerto Rico 2008). However, little is known about the differences in species composition among these forests in Puerto Rico, and the potential causes for these differences. Is there any variance in composition among sites? Is diversity highest in relatively natural areas, or in areas altered by humans? What are the most likely causes for any po-tential differences: temperature, precipitation, salinity, proximity to the coast, soil parameters, or land-use history? The central objective of this work was to examine the diversity and species com-position of three Pterocarpus forests in Puerto Rico (Humacao Natural Reserve, Dorado Pterocarpus Forest Natural Protected Area, and Punta Viento Wetland Natu-ral Reserve). We chose these three forests based on their relative sizes, locations, level of community interest in their preservation, and our ability to gain access to them (Fig. 2). The specific objectives of this project were to sample and list a wide range of plant and animal species, and then to compare and contrast the diversity among the three forests, and determine if differences are caused by human influ-ences or natural factors.
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Field Site Description
Humacao Natural Reserve The Humacao Natural Reserve (HNR), in Puerto Rico, contains the largest and best preserved Pterocarpus forest in the United States, yet the forested stand is only 150 ha in size (representing over half of Pterocarpus forest cover in the US; Alvarez-Lopez, 1990). Much of the original forest acreage was converted for sug-arcane production, and eventually into flooded lagoons (Fig. 2b, c). The reserve is currently managed by the Departamento de Recursos Naturales y Ambientales (DRNA). The community of Punta Santiago sits immediately adjacent to the forest, between the lagoons and the ocean. This low-income residential area flooded repeatedly after the 1970s, in part because there was reduced forest cover to absorb and reduce runoff. Subsequently, in 2000, the US Army Corps of Engineers modi-fied the Antón Ruiz River and several other drainages to open a connection between the lagoons and the ocean to allow floodwaters to flow into the ocean (Schwartz 2004). Unfortunately, this has also increased saltwater intrusion into the lagoons and the adjacent Pterocarpus forest (Ferrer 2007). The remnant Pterocarpus wet-lands are now threatened by saltwater intrusion due to rising global sea levels, a problem that may be exacerbated by climate change over the next decades.
Dorado Pterocarpus Forest Natural Protected Area (DPFNPA) The DPFNPA forest was donated to the Puerto Rico Conservation Trust in 1995 by the developers of a housing project, as required by the Planning Board (Junta de Planificación), and it is managed by the Fideicomiso de Conservación de Puerto Rico. The forest is located within the property of the Dorado Beach Hotel Corpo-ration, a luxury resort community (Fig. 2d, e). The forest is considered to be the best remaining example of a Pterocarpus forest community on the north coast of the island. The DPFNPA forest covers 2.4 ha. Endangered species like Peltophryne lemur Cope (Puerto Rican Crested Toad), Eleutherodactylus karlschmidti Grant (Web-Footed Coqui), Sabicea cinerea Aubl. (Largeflower Woodvine), and Epi-crates inornatus Reinhardt (Puerto Rican Boa) are known to occur in this forest (Figueroa et al. 1984, Quiñones-Ramos et al. 1992). In 1984, the USDA repeated a 1926 study (Gleason and Cook 1926) and found no change in composition of the climax swamp forest formed by Pterocarpus officinalis and six other tree species in the 54 years between studies (1926–1984). However, to-tal forested area was reduced by 30 percent over this time period. The primary cause of the forest cover loss was anthropogenic tree-cutting and hydrological modifica-tion. Construction of a golf course west of the study area altered drainage patterns, resulting in declines of both Pterocarpus and other secondary forest.
Punta Viento Wetland Natural Reserve in Patillas The Patillas forest is located on the south coast of Puerto Rico in El Bajo sector of the Municipality of Patillas (Fig. 2f, g). The forest covers an area of 4.6 ha and is enclosed within the Patillas Punta Viento Wetland Natural Reserve. The reserve
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Figure 2. (a) Pterocarpus forest study site locations across Puerto Rico; Humacao, (b) in 1977 and (c) 2006; Dorado, (d) in 1962 and (e) 2006; Patillas, (f) in 1967 and (g) 2006. Stars represent sampled forest sections in (b-g). Imagery courtesy of USGS (2013).
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contains more than 500 acres of wetlands. In 2008, a community-based organiza-tion, Frente Ambiental Amigos de la Naturaleza, Patillas, urged legislators to pass Act No. 92 (Commonwealth of Puerto Rico 2008), designating the wetlands of Punta Viento as an ecological reserve to be managed by the DRNA.
Methods
Sampling and identification of organisms We sampled a wide range of plant and animal species at the 3 different Ptero-carpus forests in Puerto Rico (Humacao, Patillas, and Dorado). The second author (F. Toledo-Rodríguez) identified organisms to the lowest taxonomic level possible in two sections of each forest. Taxonomy can be referenced in several databases by authority (Bird Life International 2013, Encylopedia of Life 2013, USDA 2013). The Dorado and Patillas forests were relatively small, and the sampled sec-tions were close together (approximately 67 m and 141 m between the sampled sections, respectively) and, thus, we assumed them to be similar. Subsequently, we grouped the section-level data to present a single list for each forest. In con-trast, the Humacao forest was relatively large and contained 2 different sections (approximately 1755 m apart). The Humacao 1 (H1) section was composed of primary forest that had not been cut since Pre-Columbian times, and had exclu-sively freshwater inputs, whereas the Humacao 2 (H2) section was composed of secondary re-growth following a tree harvest in the 1920s; it has both saltwater and freshwater inputs. We present the lists for each section of Humacao separately where applicable. We established two 100 m-long parallel transects in each section of forest. Each transect line had five points spaced 20 m apart (Fig. 3a). The first transect was used to survey birds, amphibians, reptiles, invertebrates, vegetation, and fun-gi, and the second was used to identify birds only. We chose this sampling scheme based on rapid-assessment techniques commonly used by US federal agencies. We collected or recorded all organisms during four 2–4 day sample sessions over a 2-year period, with at least 2 sessions in the rainy season and two in the dry season (Table 1). The driest months in Puerto Rico are December–April and the wettest months are May–November.
Table 1. Sampling dates for the forests, 2011–2012.
Session I Session II Session III Session IV
Humacao Natural Reserve 13, 17 Nov 15, 16 March 23, 24 Dec 1, 2 May 11, 12 Jan 6, 7 May
Dorado Pterocarpus Forest 28, 29 Nov 22, 23 March 20 Dec 15, 16 April Natural Protected Area 19, 20 Jan 17, 18 April 8, 9 Jan
Punta Viento Wetland Natural 18, 19 Nov 20, 21 March 17, 18 Jan 11, 12 AprilReserve, Patillas 13, 14 April
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We conducted bird surveys from 7:00–7:30 AM (UTC-4). We recorded all birds seen and heard during a 5-minute period, within a 5-m radius around each point on the transect (Bibby et al. 1998, Hill et al. 2005). We placed audio recording equip-ment (Olympus, Olympus Linear Recorder, LS-11) in the deepest part of the forest (last point on the transect lines) and left it overnight to record both amphibian and bird vocalizations. We identified organisms to the lowest taxonomic level pos-sible by listening to the audio recording for 10 minutes at intervals of every hour throughout the duration of the recording. Additionally, we surveyed for reptiles and amphibians from 9:00–9:30 AM through visual observation and traps. We placed pitfall traps (1.5 gallons) with an opening of 27.75 cm at each transect point and recovered them 24 hours later (Corn and Bury 1990, Hill et al. 2005, Lambert 2002). The overnight recordings described above were particularly useful for our identifications of the endemic coquís. To collect insects, we placed 16-ounce pitfall traps at each transect point and recovered them 24 hours later (Grootaert et al. 2010, Raghavendra et al. 1990). Additionally, we placed baited hanging traps and ground-level traps at the deepest part of the forest transect for a 24-hour period, after which we retrieved them and identified trapped organisms. We sampled vegetation at each point along all transects (Fig. 3b). To estimate the understory cover, we established a 10-m transect perpendicular to the primary transect at each point and recorded the percent cover by species within ten 1-m2 quadrats (Fidelibus and MacAller 1993, Hill et al. 2005). We defined understory
Figure 3. Within each forest section, (a) sampling points and traps were placed along two parallel transects, (b) with vegetation sampling centered on a transect point.
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as the vegetation at the lower level in the forest, below 1.3 m in height. We also recorded the percentage of the ground that was covered by woody Pterocarpus of-ficinalis roots in these quadrats. For tree samples, we used circular plots with a 5-m radius centered around each point and divided the plots into four quadrants. For each quadrant, we identified all tree species present and measured the diameter at breast height (dbh) of the 5 largest trees. We measured dbh 1.3 m from the ground and included the buttress root width, which can be relatively large on Pterocarpus trees. We quantified the percent cover of the upper forest canopy using a spherical crown densiometer and recorded canopy cover for the largest single tree at every quadrant, for a total of 4 trees per point. We measured canopy cover for each tree at the 4 cardinal directions (north, east, south, and west) and recorded the average of these values as the canopy cover for each tree. We then averaged the single-tree canopy cover values to estimate the canopy cover in the transect area. For reference, we used LIDAR data from another unpublished study (William Gould, International Institute of Tropical Forestry, US Forest Service, San Juan, Puerto Rico, USA, unpubl. data) (in H1) to estimate the canopy height, which was ≈30 m for the largest trees, though height varies greatly by forest location and section. Fungi and fishes were also surveyed when we encountered them along the tran-sects (Backiel 1980, BCME 1997, Hill et al. 2005, Schieck and Stambaugh 2006). We then compared species composition and variety among the different forests, and we categorized each species as endemic, native, common resident, visitor, or in-troduced. We calculated Shannon’s diversity index as the total of all species within an organismal group, and for all species together, for a particular forest. Shannon’s diversity index (H') was calculated for each forest using the following formula: s H' = ∑ -(Pi * ln Pi), i = 1where S is the species count and Pi is the relative abundance of each species (i.e., the to-tal number of observations of the species divided by the total number of observations).
Soil, land cover, and environmental factors We sought to identify the environmental differences among the three forests that were related to human influences or natural factors. We used NOAA-NCDC (2013) temperature and precipitation records from 1980–2010 recorded at nearby stations. The station name is Dorado 2 WnW PR for the Dorado Forest data, Patillas PR US and Guayama 2E, PR US for the Patillas forest, and Roosevelt Roads for the forest in Humacao. We collected soil samples from each forest, beginning at the surface and taking samples at every 10 cm to a depth of 40 cm. We immediately placed samples in bags and sent them to Servi-Tech Laboratories to determine percent nitrate-nitrogen, phosphorus, potassium, sulfur, calcium, magnesium, sodium, organic matter, soil pH, buffer pH, soluble salts, cation exchange capacity, and base saturation. We used GIS to digitize and map the land cover that surrounded each forest. Land cover classes included Pterocarpus forest, agricultural or human-managed,
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non-Pterocarpus forest, pasture, forest and pasture mix, mangrove forest, marsh, open water, palm forest, and urban. We then measured the distance from each for-est to the following closest features: house, street, ocean, agricultural land, and human-managed area. We used cover classes and distances to determine the pos-sible human influence on the forest.
Results
Sampling and identification of organisms Among all Pterocarpus officinalis forests, we found 39 species of birds (Table 2). Dorado, Patillas, and Humacao had 33, 23, and 21 species, respectively. The primary section of forest in Humacao (H1) had 11 bird species and the sec-ondary section (H2) had 19 species. After visiting each forest 6 times, the number of newly-identified organisms slowed for nearly all organisms except for birds (Fig. 4). It appeared that the sampling effort had not yet detected all birds at Do-rado or Patillas, though the numbers at Humacao had begun to level out (Fig. 4c). These species sampling-effort curves demonstrate that, because we generally did not detect new species beyond the fifth visit, our sampling effort proved adequate for most organisms. Among all forests, we found 17 species of amphibians and reptiles. Dorado, Pa-tillas, and Humacao had 15, 10, and 11 species, respectively (Table 3). The primary section of forest in Humacao (H1) had 10 species, while the secondary section (H2) had 11.
Figure 4. Species-sampling effort curves for birds, amphibians and reptiles, and inverte-brates for Dorado (a), Patillas (b), and Humacao (c).
-
R.A. Feagin, F. Toledo-Rodríguez, R.J. Colón-Rivera, F. Smeins, and R. Lopez2013 Caribbean Naturalist No. 4
10
Tabl
e 2.
Bird
s su
rvey
ed in
the
fore
sts.
D =
Dor
ado
fore
st, P
= P
atill
as fo
rest
. H1
= H
umac
ao p
rimar
y fo
rest
, H2
= H
umac
ao s
econ
dary
fore
st.
Scie
ntifi
c na
me
Sp
anis
h co
mm
on n
ame
Engl
ish
com
mon
nam
e St
atus
D
P
H1
H2
Amm
odra
mus
sav
anna
rum
Gm
elin
G
orrió
n C
hich
ara
Gra
ssho
pper
Spa
rrow
C
omm
on re
side
nt
√
Anth
raco
thor
ax d
omin
icus
L.
Zum
bado
r Dor
ado
A
ntill
ean
Man
go
Com
mon
resi
dent
√
√
√An
thra
coth
orax
vir
idis
Aud
eber
t & V
ieill
ot
Zum
bado
r Ver
de d
e Pu
erto
Ric
o G
reen
Man
go
Ende
mic
√
Ar
dea
alba
L.
Gar
za R
eal
Gre
at E
gret
C
omm
on re
side
nt
√ √
√
Arde
a H
erod
ias
L.
Gar
zon
Cen
izo
G
reat
Blu
e H
eron
V
isito
r
√ √
√Br
otog
eris
ver
sico
luru
s M
ülle
r Pe
rico
Ali-
Am
arill
o W
hite
-win
ged
Para
keet
In
trodu
ced,
191
2 √
Bu
teo
jam
aice
nsis
. Gm
elin
G
uara
guao
R
ed-ta
iled
Haw
k C
omm
on re
side
nt
√ √
Buto
ride
s vi
resc
ens
L.
Mar
tinet
e G
reen
Her
on
Nat
ive
√ √
√
Coc
cyzu
s m
inor
Gm
elin
B
obo
Men
or
Man
grov
e C
ucko
o C
omm
on re
side
nt
√ √
√ √
Coe
reba
flav
eola
L.
Rei
nita
B
anan
aqui
t C
omm
on re
side
nt
√ √
√ √
Cro
toph
aga
ani L
. Ju
dío
Gar
rapa
tero
Sm
ooth
-bill
ed A
ni
Com
mon
resi
dent
√
√D
endr
oica
ade
laid
ae B
aird
R
eini
ta M
arip
oser
a A
dela
ide'
s W
arbl
er
Ende
mic
√
√
D
endr
oica
dis
colo
r V
ieill
ot
Rei
nita
Gal
ana
Prai
rie W
arbl
er
Vis
itor
√
Gal
linul
a ch
loro
pus
L.
Gal
lare
ta C
omún
C
omm
on M
oorh
en
Perm
anen
t res
iden
t √
Ic
teru
s do
min
icen
sis
L.
Cal
andr
ia
Puer
to R
ican
Orio
le
Com
mon
resi
dent
√
M
arga
rops
fusc
atus
Vie
illot
Zo
rzal
Par
do
Pear
ly-e
yed
Thra
sher
C
omm
on re
side
nt
√ √
Meg
asco
ps n
udip
es D
audi
n M
ucar
o C
omún
/ M
ucar
ito
Puer
to R
ican
Scr
eech
-Ow
l En
dem
ic
√ √
Mel
aner
pes
port
oric
enci
s D
audi
n C
arpi
nter
o de
Pue
rto R
ico
Pu
erto
Ric
an W
oodp
ecke
r En
dem
ic
√ √
√ √
Mim
us p
olyg
lotto
s L.
R
uise
ñor
Nor
ther
n M
ocki
ngbi
rd
Com
mon
resi
dent
√
√M
olot
hrus
bon
arie
nsis
To
rdo
Lust
roso
Sh
iny
Cow
bird
In
vasi
ve, 1
955
√
√
M
yair
chus
ant
illar
um G
mel
in
Juí J
uí d
e Pu
erto
Ric
o
Puer
to R
ican
Fly
catc
her
Ende
mic
√
√ √
√M
yiop
sitta
mon
achu
s B
odda
ert
Peric
o M
onje
M
onk
Para
keet
In
trodu
ced,
197
0 √
N
ycta
nass
a vi
olac
ea L
. Ya
boa
Com
ún
Yello
w-c
row
ned
Nig
ht-H
eron
C
omm
on re
side
nt
√ √
√ √
Oxy
ura
jam
aice
nsis
Gm
elin
Pa
to C
horiz
o
Rud
dy D
uck
Rar
e vi
sito
r
√
Pa
rula
am
eric
ana
L.
Rei
nita
Pec
hido
rada
N
orth
ern
Paru
la
Vis
itor
√
Pata
gioe
nas
leuc
ocep
hala
L.
Palo
ma
Cab
ecib
lanc
a W
hite
-cro
wne
d Pi
geon
C
omm
on re
side
nt,
√ √
n
ear t
hrea
tene
dPa
ndio
n ha
liaet
us L
. Á
guila
de
Mar
O
spre
y M
igra
nt
√
Pata
gioe
nas
squa
mos
al B
onna
terr
e Pa
lom
a Tu
rca
Scal
y-na
ped
Pige
on
Com
mon
resi
dent
√
√ √
√Pr
ogne
dom
inic
ensi
s G
mel
in
Gol
ondr
ina
Car
ibeñ
a C
arib
bean
Mar
tin
Nat
ive
√
Qui
scal
us n
iger
Bod
daer
t M
ozam
biqu
e, C
hang
o
Gre
ater
Ant
illea
n G
rack
le
Nat
ive
√
√
-
11
R.A. Feagin, F. Toledo-Rodríguez, R.J. Colón-Rivera, F. Smeins, and R. Lopez2013 Caribbean Naturalist No. 4
Tabl
e 3.
Am
phib
ians
and
rept
iles
surv
eyed
in th
e fo
rest
s. D
= D
orad
o fo
rest
, P =
Pat
illas
fore
st. H
1 =
Hum
acao
prim
ary
fore
st, H
2 =
Hum
acao
sec
onda
ry
fore
st.
Scie
ntifi
c na
me
Sp
anis
h co
mm
on n
ame
Engl
ish
com
mon
nam
e St
atus
D
P
H1
H2
Amei
va e
xsul
Cop
e Si
guan
a C
omún
C
omm
on S
igua
na
Nat
ive
√
Anol
is c
rist
atel
lus
Dum
éril
& B
ibro
n La
garti
jo C
omún
Pu
erto
Ric
an C
rest
ed A
nole
En
dem
ic
√ √
√ √
Anol
is e
verm
anni
Ste
jneg
er
Laga
rtijo
Ver
de
Emer
ald
Ano
le
Ende
mic
√
An
olis
gun
ladc
hi P
eter
s La
garti
jo B
arba
Am
arill
a Ye
llow
-Bea
rded
Ano
le
Ende
mic
√
An
olis
pul
chel
lus
Dum
éril
& B
ibro
n La
garti
jo J
ardi
nero
C
omm
on G
rass
Ano
le
Ende
mic
√
√
√An
nolis
str
atul
us C
ope
Laga
rtijo
Man
chad
o B
arre
d A
nole
En
dem
ic
√ √
Bufo
mar
inus
L.
Sapo
Mar
ino
Can
e To
ad
Intro
duce
d, 1
920
√ √
√ √
Eleu
ther
odac
tylu
s an
tille
nsis
Rei
nhar
dt &
Lüt
ken
Coq
uí C
hurr
í Fi
eld
Coq
ui
Ende
mic
√
√ √
√El
euth
erod
acty
lus
britt
oni S
chm
idt
Coq
uí d
e la
s H
ierb
as
Gra
ss C
oqui
En
dem
ic
√ √
√ √
Eleu
ther
odac
tylu
s co
chra
nae
Gra
nt
Coq
uí P
itito
W
hist
ling
Frog
En
dem
ic
√ √
√ √
Eleu
ther
odac
tylu
s co
qui T
hom
as
Coq
uí C
omún
C
oqui
En
dem
ic
√ √
√ √
Igua
na ig
uana
L.
Gal
lina
de P
alo
Gre
en Ig
uana
In
trodu
ced,
197
0
√
√Le
ptod
acty
lus
albi
labr
is G
ünth
er
Ran
ita d
e La
bio
Bla
nco
Whi
te-li
pped
Fro
g N
ativ
e √
√ √
√Ra
na c
ates
beia
na S
haw
R
ana
Toro
A
mer
ican
Bul
lfrog
In
trodu
ced
√
√ √
Rana
gry
lio S
tejn
eger
R
ana
Cer
do
Pig
Frog
In
trodu
ced,
199
8
√
√Sp
haer
odac
tylu
s m
acr o
lepi
s G
ünth
er
Sala
man
quita
Com
ún
Com
mon
Dw
arf G
ecko
N
ativ
e √
√
Tabl
e 2,
con
tinue
d.
Scie
ntifi
c na
me
Sp
anis
h co
mm
on n
ame
Engl
ish
com
mon
nam
e St
atus
D
P
H1
H2
Seiu
rus
mot
acill
a G
mel
in
Pizp
ita d
e M
angl
e
Nor
ther
n W
ater
thru
sh
Com
mon
resi
dent
√
√ √
√Sp
inda
lis p
orto
rice
nsis
Bry
ant
Rei
na M
ora
Puer
to R
ican
Spi
ndal
is
Ende
mic
√
√ √
Ti
aris
bic
olor
L.
Gor
rión
Neg
ro
Bla
ck-f
aced
Gra
ssqu
it C
omm
on re
side
nt
√
Tur d
us p
lum
beus
L.
Zors
al d
e Pa
tas
Col
orad
as
Red
-legg
ed T
hrus
h C
omm
on re
side
nt
√ √
Tyra
nnus
cau
difa
scia
tus
d’O
rbig
ny
Clé
rigo
Logg
erhe
ad K
ingb
ird
Com
mon
resi
dent
√Ty
rann
us d
omin
icen
sis
Gm
elin
Pi
tirre
G
ray
Kin
gbird
C
omm
on re
side
nt
√
√
Vire
o al
tiloq
uus
Vie
illot
Ju
lian
Chi
ví
Bla
ck-w
hisk
ered
Vire
o C
omm
on re
side
nt
√ √
Vire
o la
timer
i Bai
rd
Bie
n-te
-veo
Pu
erto
Ric
an v
ireo
En
dem
ic
√ √
√
Zena
ida
auri
ta T
emm
inck
Tó
rtola
Car
dosa
nter
a Ze
naid
a D
ove
Com
mon
resi
dent
√
√
√
-
R.A. Feagin, F. Toledo-Rodríguez, R.J. Colón-Rivera, F. Smeins, and R. Lopez2013 Caribbean Naturalist No. 4
12
We found relatively few invertebrates overall. Our sampling methods were re-stricted to two types of hanging traps and a single type of land trap, and thus the survey did not capture the full range of insect niche habitats; for example we did not sample habitats within decaying plant materials. Moreover, both flying and crawl-ing insects were subject to frequent precipitation events and flooding of the forest floor. On one of our sampling dates, our results were affected by flooding of the traps themselves, though that effort was repeated on a subsequent date. For these reasons, we present here the list of organisms found in our surveys but we did not include them into our calculations of Shannon’s diversity index, nor in our further discussion of the forests. We found 15 species of insects, 6 species of arachnids, 2 species of myriapods, 2 species of mollusks, 3 species of crustaceans, and 2 additional animals (Table 4). All forests had nearly the same number of insect species—Dorado had 8, Patillas had 6, H1 had 8, and H2 had 7. We detected mollusks only at Dorado and Patil-las. Patillas had the most crustaceans, and H2 had the least. In terms of additional animals, only H1 had fish, probably because this section of forest receives direct freshwater inflow from a nearby creek. Among all forests, we found 56 species of plants and 6 species of fungi (Table 5). Dorado had 47 plant species, Patillas had 16, and Humacao had only 6. H1 had the largest trees, followed by Patillas; Dorado and H2 had much smaller trees (Fig. 5a). The canopy cover percentage was similar among all forests, except
Figure 5. (a) Average DBH, (b) canopy coverage percentage, (c) understory coverage per-centage and coverage of Pterocarpus officinalis roots for Dorado, Patillas, Humacao 1 and Humacao 2.
-
13
R.A. Feagin, F. Toledo-Rodríguez, R.J. Colón-Rivera, F. Smeins, and R. Lopez2013 Caribbean Naturalist No. 4
Tabl
e 4.
Inv
erte
brat
es a
nd o
ther
ani
mal
s su
rvey
ed in
the
fore
sts.
D =
Dor
ado
fore
st, P
= P
atill
as f
ores
t. H
1 =
Hum
acao
prim
ary
fore
st, H
2 =
Hum
acao
se
cond
ary
fore
st.
Scie
ntifi
c na
me
Sp
anis
h co
mm
on n
ame
Engl
ish
com
mon
nam
e D
P
H1
H2
Inse
cts
Odo
ntom
achu
s ha
emat
odus
L.
Ber
raco
/ H
orm
iga
Fier
cely
Biti
ng B
lack
Ant
/ Tr
ap-J
aw A
nt
√ √
√ √
Sub
fam
ily E
mes
inae
sp.
C
hinc
he D
epre
dado
r Th
read
-legg
ed A
ssas
sin
Bug
√
S
capt
eris
cus
bore
llii G
iglio
-Tos
G
rillo
Top
o So
uthe
rn M
ole
Cric
ket
√ √
√ √
Oro
char
is s
p.
Gril
lo d
e A
rbus
to
Loud
-sin
ging
Bus
h C
ricke
t √
√ √
√ S
uper
fam
ily F
ulgo
roid
ea
Salta
Hoj
as /
Salta
Pla
ntas
Pl
anth
oppe
r √
F
amily
Ter
mito
idae
sp.
C
omej
én
Dry
Woo
d Te
rmite
√
√ √
√ D
oldi
na in
terj
unge
ns B
ergr
oth
Chi
nche
Dep
reda
dor
Ass
assi
n B
ug
√
Api
s sp
. A
beja
Dom
éstic
a, A
veja
Afr
ican
izad
a D
omes
tic H
oney
bee,
Afr
ican
ized
Hon
ey B
ee
√
Dys
derc
us a
ndre
ae L
. B
ombe
ritos
Lo
ve B
ug, P
yrrh
ocor
id B
ug
√
√
Bat
tus
poly
dam
as L
. O
ruga
de
Mar
ipos
a Pa
pilio
C
ater
pilla
r of G
old
Rim
Sw
allo
wta
il
√
O
rder
Hem
ipte
ra
Inse
cto,
no
iden
tifica
dos
mas
Tr
ue B
ug, n
ot id
entifi
ed fu
rther
√
O
rder
Hem
ipte
ra
Inse
cto,
no
iden
tifica
dos
mas
Tr
ue B
ug, n
ot id
entifi
ed fu
rther
√
O
rder
Hem
ipte
ra
Esca
raba
jo R
ojo
True
Bug
, not
iden
tified
furth
er
√ √
Tet
ragn
atha
sp.
A
raña
Ext
ensa
St
retc
h Sp
ider
√
Mol
lusk
s P
olyd
onte
s lim
a Fé
russ
ac
Car
acol
Ásp
ero
o R
aspa
do
Ras
ping
Nip
ple
Snai
l √
C
arac
ullu
s m
argi
nella
C
arac
ol d
e B
anda
s B
ande
d C
arac
ol
√ √
Cru
stac
eans
Uca
lept
odac
tyla
Rat
hbun
C
angr
ejo
Vio
linis
ta
Fidd
ler C
rab
√ √
√ √
Car
diso
ma
guan
hum
i Lat
reill
e Ju
ey C
omún
B
lue
Land
Cra
b √
√
U
cide
s co
rdat
us L
. Ju
ey P
elú
Zam
buco
M
angr
ove
Land
Cra
b
√ √
-
R.A. Feagin, F. Toledo-Rodríguez, R.J. Colón-Rivera, F. Smeins, and R. Lopez2013 Caribbean Naturalist No. 4
14
Tabl
e 4,
con
tinue
d.
Scie
ntifi
c na
me
Sp
anis
h co
mm
on n
ame
Engl
ish
com
mon
nam
e D
P
H1
H2
Ara
chni
ds F
amily
Pho
lcid
ae s
p.
Ara
ña d
e Pa
tas
Larg
as
Dad
dy-lo
ngle
gs /
Cel
lar s
pide
r √
√
F
amily
Lyc
osid
ae s
p.
Ara
ña L
obo
Wol
f Spi
der
√ √
√
Ord
er O
pilio
nes
sp.
Opi
lión
Har
vest
men
√
C
oryt
halia
ban
ski R
oew
er
Ara
ña S
alta
dora
Ju
mpi
ng S
pide
r √
√ S
elen
ops
insu
lari
s K
eyse
rling
A
raña
Pla
na
Flat
Spi
der
√
Leu
caug
e re
gnyi
Sim
on
Ara
ña T
ejed
ora
Orc
hard
Spi
der
√ √
√ √
Fam
ily B
uthi
dae
sp.
Esco
rpió
n Sc
orpi
on
√ √
Myr
iapo
ds S
colo
pend
ra a
ltern
ans
Leac
h C
ienp
iés
Cen
tiped
e
√ √
F
amily
Jul
idae
sp.
M
ilpié
s M
illip
ede
√
Oth
er a
nim
als
pres
ent
Cla
ss A
ctin
opte
rygi
i sp.
Pe
z, n
o id
entifi
cado
Fi
sh, n
ot id
entifi
ed fu
rther
√
Est
here
lla s
p.
Lom
briz
de
Tier
ra
Earth
wor
m
√ √
√ √
-
15
R.A. Feagin, F. Toledo-Rodríguez, R.J. Colón-Rivera, F. Smeins, and R. Lopez2013 Caribbean Naturalist No. 4
Tabl
e 5.
Pla
nts
and
fung
i sur
veye
d in
the
fore
sts.
D =
Dor
ado
fore
st, P
= P
atill
as fo
rest
. H =
Hum
acao
fore
st.
Scie
ntifi
c na
me
Sp
anis
h co
mm
on n
ame
Engl
ish
com
mon
nam
e St
atus
D
P
H
Plan
ts A
cros
tichu
m a
ureu
m L
. H
elec
ho d
e M
angl
e
Gol
den
Leat
her F
ern
Nat
ive
√ √
√ A
ndir
a in
erm
is W
right
M
oca
Cab
bage
-bar
k Tr
ee
Nat
ive
√
A
nnon
a gl
abra
L.
Cay
ur
Pond
App
le
Nat
ive
√ √
A
nona
cea
sp.
Ann
onac
eae
Cus
tard
App
le F
amily
√
D
esco
noci
da
Ant
huri
um c
rena
tum
Kun
th
Leng
ua d
e Va
ca
Scal
lope
d La
ce L
eaf
Nat
ive
√ √
√ A
rdic
ea s
p.
Ard
icia
spp
A
rdic
ea
√
Ard
isia
elli
ptic
a Th
unb.
M
amey
uelo
Sh
oe B
utto
n A
rdis
ia
Intro
duce
d √
Buc
ida
buce
ras
(L.)
Wrig
ht
Uca
r G
rego
ry W
ood
Nat
ive
√
B
urse
ra s
imar
uba
(L.)
Sarg
. A
lmac
igo
Gum
bo L
imbo
N
ativ
e √
Cal
ophy
llum
cal
aba
Brit
ton
Mar
ía
Sant
a-M
aria
N
ativ
e √
√
Cas
eari
a gu
iane
nsis
(Aub
l.) U
rb.
Palo
Bla
nco
G
uyan
ese
Wild
Cof
fee
Nat
ive
√
C
asea
ria
sylv
estr
is S
w.
Laur
el E
spad
a C
rack
Ope
n N
ativ
e √
Clu
sia
rose
a Ja
cq.
Cup
ey
Wild
-mam
ee
Nat
ive
√
C
occo
loba
div
ersi
folia
Jac
q.
Uva
de
Sier
ra
Tie
Tong
ue
Nat
ive
√
D
idym
opan
ax m
orot
oton
i (A
ubl.)
Mag
uire
, Ste
yerm
. & F
rodi
n Ya
grum
o M
acho
M
atch
woo
d N
ativ
e √
Eug
enia
jam
bos
(L.)
Als
ton
Pom
arro
sa
Mal
abar
Plu
m
Intro
duce
d √
Eug
enia
pse
udop
sidi
um J
acq.
G
uaya
ba S
ilves
tre
Chr
istm
as C
herr
y N
ativ
e √
Fab
acea
e sp
. # 1
Fa
bace
ae
Faba
ceae
√
P
elto
phor
um p
tero
carp
um (D
C.)
Bac
ker e
x K
. Hey
ne
Flam
boya
n A
mar
illo
Gol
den
Flam
boya
nt
√
Far
amea
occ
iden
talis
(L.)
A. R
ich.
C
afec
illo
Fals
e C
offe
e N
ativ
e √
Fic
us c
itrifo
lia M
ill.
Jagü
ey B
lanc
o W
ild B
anya
n Tr
ee
Nat
ive
√
F
icus
sp.
Fi
cus
Fic
us
√
G
enip
a am
eric
ana
L.
Jagu
a Ja
gua
Nat
ive
√
G
uapi
ra fr
agra
ns (D
um. C
ours
.) Li
ttle
Cor
cho
Bla
ck M
ampo
o N
ativ
e √
Hoh
enbe
rgia
ant
illan
a M
ez
Bro
mel
ia
Ant
illes
Lac
ebar
k N
ativ
e √
Hyl
ocer
eus
trig
onus
(Haw
.) Sa
ff.
Cac
tus
Pita
haya
W
ild S
traw
berr
y N
ativ
e √
√
Hym
enae
a co
urba
ril L
. A
lgar
robo
St
inki
ng T
oe
Nat
ive
√
I
nga
laur
ina
(Sw
.) W
illd.
G
uam
a Sa
cky
Sac
Bea
n N
ativ
e √
Lau
race
a sp
. La
urac
ea
Laur
acea
√
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R.A. Feagin, F. Toledo-Rodríguez, R.J. Colón-Rivera, F. Smeins, and R. Lopez2013 Caribbean Naturalist No. 4
16
Tabl
e 5,
con
tinue
d.
Scie
ntifi
c na
me
Sp
anis
h co
mm
on n
ame
Engl
ish
com
mon
nam
e St
atus
D
P
H
Lic
aria
par
vifo
lia (L
am.)
Kos
term
. C
anel
illa
Puer
to R
ico
Cin
nam
on
Nat
ive
√
M
anilk
ara
bide
ntat
a (A
.DC
.) A
. Che
v A
usub
o B
ulle
t Woo
d N
ativ
e √
√
Mas
ticho
dend
ron
foet
idis
sim
um J
acq.
To
rtugo
Am
arill
o
Fals
e M
astic
N
ativ
e √
Mor
inda
citr
ifolia
L.
Non
i In
dian
Mul
berr
y In
trodu
ced
√
M
orus
nig
ra L
. M
oral
B
lack
Mul
berr
y In
trodu
ced
√
O
rmos
ia k
rugi
i Urb
. Pa
lo d
e M
atos
Pe
roni
a N
ativ
e √
Pau
llini
a pi
nnat
a L.
B
ejuc
o de
Cos
tilla
B
read
and
Che
ese
Nat
ive
√
√ P
hleb
odiu
m a
ureu
m (L
.) J.
Sm
. H
elec
ho E
spad
a G
olde
n Se
rpen
t Fer
n N
ativ
e √
√
Pip
er a
mal
ago
L.
Hig
uillo
de
Lim
ón
Rou
gh-le
aved
Pep
per
Nat
ive
√
P
runu
s du
lcis
(Mill
.) D
.A. W
ebb
Alm
endr
o
Swee
t Alm
ond
Nat
ive
√
P
silo
tum
nud
um (L
.) P.
Bea
uv.
Hel
echo
Esc
oba
Whi
sk F
ern
Nat
ive
√ √
P
sych
otri
a br
achi
ate
Sw.
Palo
de
Cac
him
bo
Palo
de
Cac
him
bo
Nat
ive
√
P
tero
carp
us o
ffici
nalis
Jac
q.
Palo
de
Pollo
D
rago
n B
lood
woo
d T r
ee
Nat
ive
√ √
√ R
andi
a ac
ulea
te L
. Ti
ntill
o W
hite
Indi
go B
erry
N
ativ
e √
Roy
ston
ea b
orin
quen
a O
.F. C
ook
Pa
lma
Rea
l R
oyal
Pal
m
Nat
ive
√ √
√ T
abeb
uia
hete
roph
ylla
(DC
.) B
ritto
n R
oble
Bla
nco
Whi
te C
edar
N
ativ
e √
Till
ands
ia fa
scic
ulat
e Sw
. B
rom
elia
G
iant
Airp
lant
N
ativ
e √
Unk
now
n #
1
√
U
nkno
wn
# 2
√
√
Unk
now
n #
3
√
U
nkno
wn
# 4
√
Van
illa
clav
icul
ata
(W.W
right
) Sw
. O
rqui
dea
Vain
illa
Gre
en W
ithe
Nat
ive
√
Fung
i C
hlor
ophy
llum
mol
ybdi
tes
(G. M
ey.)
Mas
see
Hon
go S
ombr
illa
Verd
e G
reen
Par
asol
√
C
ooke
ina
tric
holo
ma
(Mon
t.) K
ount
ze
Cop
itas
Red
Cup
Fun
gus
√
Gan
oder
ma
appl
anat
um (P
ers.
) Pat
. O
reja
de
Palo
A
rtist
's C
onk
√
√ P
helli
nus
igni
ariu
s (L
.) Q
uél.
Yesc
a Ph
ellin
us F
ungu
s
√
P
silo
cybe
sp
Hon
gos
Mág
icos
M
agic
Mus
hroo
ms
√
Tra
met
es g
ibbo
sa
Yesq
uero
Bla
nco
Lum
py B
rack
et
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17
R.A. Feagin, F. Toledo-Rodríguez, R.J. Colón-Rivera, F. Smeins, and R. Lopez2013 Caribbean Naturalist No. 4
H2, where cover values were lower (Fig. 5b). Understory cover was highest at Do-rado and lowest at H2. Patillas had the most visible root coverage on the ground surface (Fig. 5c). In summary, Dorado had the highest faunal abundance (48 organisms, excluding invertebrates) and the highest faunal Shannon’s diversity value (H' = 3.40 [exclud-ing invertebrates]; Table 6). Dorado had the greatest number of native or endemic species—birds, 7; amphibians/reptiles, 12; and plants, 43. However, Dorado also had the most invasive or exotic bird and plant species, 3 and 4, respectively. For plants and fungi, Dorado had the highest plant and fungal diversity (H' = 2.87). Patillas was second in richness for both fauna (H' = 2.89) and plants/fungi (H' = 1.27). H2 was the least rich in fauna (11 organisms, excluding invertebrates) and least diverse (H' = 1.56). Humacao had the most invasive amphibian/reptile spe-cies, 4. All of the plants in both Patillas and Humacao were native or endemic.
Soil, land cover, and environmental factors The Dorado area has an average temperature of 25.1 °C (77.2 °F), a mean an-nual maximum temperature of 28.3 °C (83.0 °F), and a mean annual minimum
Table 6. Shannon’s diversity index values for each forest. H1 = Humacao primary forest, H2 = Hu-macao secondary forest.
Dorado Patillas H 1 H 2
Birds 3.08 2.40 1.94 2.21Amphibians and reptiles 2.14 2.00 1.85 1.89Fauna (excluding invertebrates) 3.40 2.89 2.59 1.56Plants and fungi 2.88 1.27 0.73
Table 7. Temperature and precipitation averages for the forests from 1980 to 2010.
Rainfall Avg min temp Average temp Avg max tempForest (station)/period mm (in) °C (°F) °C (°F) °C (°F)
Dorado (Dorado 2 WnW PR US) Annual 1637.0 (64.5) 21.3 (70.4) 25.1 (77.2) 28.3 (83.9) Winter (DJF) 388.4 (15.3) 19.4 (67) 24.1 (73.5) 26.6 (80) Spring (MAM) 349.8 (13.8) 20.7 (69.4) 24.7 (76.6) 28.7 (83.7) Summer (JJA) 404.9 (15.9) 22.8 (73.1) 26.6 (79.9) 30.4 (86.8) Fall (SON) 494.0 (19.5) 22.2 (71.9) 25.8 (78.6) 29.5 (85.2)Patillas (Guayama 2 E PR US) Annual 1386.1 (54.6) 23.5 (74.4) 27.1 (80.9) 30.7 (87.4) Winter (DJF) 182.9 (7.2) 22.2 (72) 25.9 (78.7) 29.6 (85.4) Spring (MAM) 247.9 (9.7) 23.1 (73.5) 26.7 (80.1) 30.3 (86.6) Summer (JJA) 421.1(16.6) 24.8 (76.7) 28.3 (83) 31.7 (89.2) Fall (SON) 534.2 (21.0) 24.1 (75.3) 27.7 (81.9) 31.3 (88.4)Humacao (Roosevelt Roads) Annual 1329.4 (52.3) 23.8 (75) 27.1 (80.8) 30.2 (86.5) Winter (DJF) 242.1 (9.5) 22.3 (72.2) 25.5 (78) 28.7 (83.7) Spring (MAM) 281.4 (11.1) 23.4 (74.1) 26.6 (79.9) 29.7 (85.6) Summer (JJA) 333.0 (13.1) 25.4 (77.8) 28.5 (83.3) 31.5 (88.8) Fall (SON) 472.9 (18.6) 24.4 (75.9) 27.6 (81.8) 31.0 (87.8)
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R.A. Feagin, F. Toledo-Rodríguez, R.J. Colón-Rivera, F. Smeins, and R. Lopez2013 Caribbean Naturalist No. 4
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temperature of 21.3 °C (70.4 °F) (Table 7). The average annual precipitation is 1637.0 mm (64.5 in). At Patillas, the average temperature is 27.1 °C (80.9 °F), the mean annual maximum temperature is 30.7 °C (87.3 °F), and the mean annual mini-mum temperature is 23.5 °C (74.3 °F). On average, Patillas receives 1386.1 mm (54.6 in) of precipitation annually. The average temperature for the Humacao area is 27.1 °C (80.8°F), with a mean annual maximum temperature of 30.2 °C (86.4 °F) and a mean annual minimum temperature of 23.8 °C (74.3 °F); Average annual precipitation is 1329.4 mm (52.3 in). For the soil samples, we present here only nitrate, percent organic matter, soluble salts, sulfur, and calcium. Nitrate was highest in the Dorado samples, but
Figure 6. Soil components for Dorado, Patillas, Humacao 1 and Humacao 2 forest: (a) ni-trate, (b) organic matter %, (c) soluble salts, (d) sulfur, and (e) calcium.
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19
R.A. Feagin, F. Toledo-Rodríguez, R.J. Colón-Rivera, F. Smeins, and R. Lopez2013 Caribbean Naturalist No. 4
was low in those from Patillas, H1, and H2 (Fig. 6a). Organic matter values were lowest in samples from H1 followed by H2; higher values were recorded for the Patillas and Dorado soils (Fig. 6b). Soluble salts were highest at H2, but low in H1 and Dorado (Fig. 6c). Sulfur values were highest in H2 soils; Dorado and H1 had the lowest values (Fig. 6d). Calcium was the lowest in Dorado, H1, and H2; the highest value was recorded at Patillas (Fig. 6e). The Dorado forest (Fig. 7a) is located within lands owned by the Dorado Beach Hotel Corporation, which is a luxury resort community. To the north of the Ptero-carpus forest, there is an additional non-Pterocarpus forested area that is managed by the Puerto Rico Conservation Trust. To the east, the Dorado forest is separated from a large area of urban development by only a small patch of trees. A remain-ing small patch of forest adjacent to another well-developed urban area lies to the south, and there is a large golf course to the west. The Patillas forest (Fig. 7b) occurs within the Punta Viento Natural Reserve. A large pasture abuts the forest on the north and mangrove forests occur to the east, south, and west. The Humacao forest (Fig. 7c) is the only one of the forests we sampled that has direct connections to open water through channels or lagoons connected to the ocean. Agricultural lands are adjacent to the northern part of the forest. Urban areas are immediately across the lagoon, to the southwest. The Dorado forest was the closest to roads, houses, human-managed ecosys-tems, and the ocean (Table 8). In contrast, H1 had the greatest distances to roads,
Figure 7. Land-use/land-cover maps, for (a) Dorado, (b), Patillas, and (c) Humacao.
-
R.A. Feagin, F. Toledo-Rodríguez, R.J. Colón-Rivera, F. Smeins, and R. Lopez2013 Caribbean Naturalist No. 4
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houses, and the ocean. Patillas was the closest to an agricultural area, and H2 was the farthest from an agricultural area.
Discussion
Richness and diversity among the forests, and possible causes for differences Of the forests we sampled, the Dorado Pterocarpus forest is the most rich and diverse in terms of organisms and has the greatest number of native and endemic species, while the Humacao Pterocarpus forest is the least rich and diverse. How-ever, Dorado is the smallest forest, covering only 2.4 ha, while Humacao is the largest, with an area of 150 ha, which comprises 63% of the total Pterocarpus cov-erage in Puerto Rico. The temperature and precipitation differences among the forests do not likely explain the difference in richness or diversity. The average annual precipitation is 1637.0 mm (64.5 in) in Dorado Forest and 1329.4 mm (52.3 in) in Humacoa, a dif-ference of only ≈1/5 the total (NOAA 2013). The average temperatures are 25.1 °C (77.1 °F) and 27.1 °C (80.8 °F) for Dorado and Humacao, respectively, a difference of only 2 °C (3.7 °F) (Table 7; NOAA 2013). One potential explanation for the differences in species richness and diversity can be found in results of our soil sampling. Dorado soil samples were high in ni-trate, a component of many commercial fertilizers. It is also produced by fixation of nitrogen by soil bacteria as part of the nitrogen cycle, as well as through the decay of organic matter in the soil. The relatively high level of nitrate may be due, in part, to inputs from human activity: Dorado is surrounded by human-managed areas, including a golf course and urban areas. Dorado soils also had the highest organic matter percentage, likely because of the large amount of plant material deposited due to high understory cover and low overstory canopy cover. In contrast, H1 has soils with nitrate below detectable limits, and low impact from human disturbance. The mature trees in H1 have the largest average dbh and, due to the large dense canopy, there is low understory coverage and a low amount of organic matter. Ad-ditionally, the low organic matter in H1 forest soils could be explained by inflow that washes the material downstream during frequent rain events. Inflow and water sources may also be factors that alter richness and diversity. The amount of soluble salts and sulfur in the forests’ soils are likely related to saltwater intrusion, as they were highest at the H2 forest, followed by the Patillas forest. Hydrogen sulfide often results from anaerobic digestion or reduction, the
Table 8. Distance of forest to selected features.
Distance (m)
Features Dorado Patillas H 1 H 2
Road 173.43 542.19 1455.42 734.58House 107.57 640.61 1253.19 723.00Agricultural area 1764.99 620.92 1443.95 2509.16Ocean 477.77 495.61 2514.75 1106.54Human managed 118.62 578.52 1170.34 1326.03
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R.A. Feagin, F. Toledo-Rodríguez, R.J. Colón-Rivera, F. Smeins, and R. Lopez2013 Caribbean Naturalist No. 4
bacterial breakdown of organic matter in the absence of oxygen, which commonly occurs in swamps. The subsequent oxidation of hydrogen sulfide produces sulfur. Interestingly, Patillas soils had the highest calcium levels, reaching almost 4000 ppm. Patillas differs from the other sites because spring water enters the forested wetland’s surface waters from underlying karst limestone through the Pozo Encan-tado or Enchanted Well. The most evident factor influencing richness and diversity among the forests is the adjacent land-use history of the sites. As mentioned earlier, the Dorado forest is the smallest as well as the most fragmented one, in terms of its interspersion with other land-cover types. Dorado also has the highest number of endemic and native plant species, as well as invasive plant species. Increased plant diversity provides increased animal habitat, and explains, in part, the higher richness of fauna. The forest’s perimeter-to-area ratio is high and it is surrounded by urban homes, infra-structure, and a golf course. Patillas is the second smallest forest, but it is entirely enclosed within a natural reserve. It consistently ranks in the middle of the three forests sampled, in terms of richness and diversity, proximity to human disturbance, and average dbh. It also has the highest Pterocarpus root-cover percentage, likely because it is drier than Huma-cao, though it is still influenced to a small degree by salt, rain, and spring water. H1 is the best example of a large, mature, historically undisturbed, primary Ptero-carpus forest in Puerto Rico. Its trees have a large dbh and canopy coverage, and its soils are low in nutrients, organic matter, and have limited saltwater influence. H2 is the youngest forest of the sites we sampled, and is composed of second-ary re-growth established in the 1950s. It has the lowest dbh and overstory canopy cover among all of our study sites. It is strongly affected by saltwater intrusion, with channels crossing it that connect directly to the ocean. It is also necessary to mention that our methodology excluded some habitats where we likely would have recorded additional species. For example, we would undoubtedly have detected additional invertebrates utilizing habitat niches such as dead wood, live tree interiors, and the upper canopy of the forest.
Primary versus secondary Pterocarpus forests At Humacao, the primary and secondary forests have been exposed to different human disturbances. Humans have altered the water flowing into the forests in both sections of forest, though the primary forest has been more affected by altered up-stream inflow through digging of irrigation channels for sugarcane production. The secondary forest, while also affected by changes in water flow, was cut and cleared in the 1950s. Subsequently, abandonment of this section resulted in re-growth. In 2000, the US Army Corps of Engineers attempted to reduce flooding in the nearby urban community of Punta Santiago, and their creation of a canal introduced saltwater to the Humacao secondary forest. The number of bird, amphibian and reptile species is lower in the primary forest (total 21) than the secondary forest (total 30). Moreover, the soil in the primary forest had the lowest organic matter values and low nutrient values, including nitrate, while also showing signs of saltwater inundation.
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R.A. Feagin, F. Toledo-Rodríguez, R.J. Colón-Rivera, F. Smeins, and R. Lopez2013 Caribbean Naturalist No. 4
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Our results suggest that mature Pterocarpus officinalis-dominated forests are largely vegetatively monospecific (as also found by Alvarez-López 1990), low in number of dependent species, and have nutrient-poor soils. The fragmentation of these forests, alteration of hydrology, and conversion of adjacent environments has only increased their floristic and faunal diversity.
Conclusion Human influences on these forests have been significant across Puerto Rico and the Caribbean region. Our analysis points out that fragmentation and changes in the surrounding land used by humans increased both richness and diversity in these for-ests. This increase in the diversity of species comes from both native and endemic Puerto Rican species that have become established in the fragmented forest and small remnants, but also from exotic and invasive species. Still, all Pterocarpus forests provide a natural environment to sustain organisms, and there are likely organisms that thrive particularly in conjunction with Pterocar-pus. For example, although we did not identify any species endemic to Pterocarpus forests, we did find small, as yet unidentified fish in only the most undisturbed por-tions of the primary forest in Humacao. Because the remaining areas covered by the Pterocarpus forest are so limited in extent, protection and management of this forest type are necessary. Ptero-carpus forests are known to support a number of native and endemic species (Cintrón 1983), specifically amphibians, which are reported to be imperiled worldwide. Our results should be useful to those who manage areas that support Pterocarpus forests, not only in a broad sense, but also more specifically to the managers of the forests included in this research. This work will assist those who manage this limited resource in the context of ongoing sea level rise, climate change, nutrient pollution, human interaction, upstream hydrological modifica-tions, and deforestation. We suggest that future management should focus on two distinct preservation efforts. Maintenance of high diversity and use of beneficial habitat should be the goals for Dorado and Patillas, the smaller forests. One problem with this strategy is that Pterocarpus trees may not be able to replace themselves over multiple genera-tions, as other flora may be able to outcompete Pterocarpus seedlings in areas with lower amounts of upper canopy cover and higher sun exposure, particularly con-sidering the low number of trees from which to recruit propagules. If management is undertaken to favor Pterocarpus growth, this might negatively affect several species of concern present at the site. Whether these forests will eventually lose their Pterocarpus trees or revert back to a forest with more complete Pterocarpus dominance is unknown, but future studies on tree age structure and recruitment suc-cess could help to answer this question. Conversely, for the remaining large forest (Humacao), the maintenance of low diversity as a semblance of the Pre-Columbian state should be the goal because this forest is the remaining exemplar of the natural state of the Pterocarpus forest ecosystem in Puerto Rico.
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R.A. Feagin, F. Toledo-Rodríguez, R.J. Colón-Rivera, F. Smeins, and R. Lopez2013 Caribbean Naturalist No. 4
Acknowledgments
This research was funded in part by the Hispanic Leaders in Agriculture and the Envi-ronment Fellowship Program, and the College of Agriculture and Life Sciences at Texas A&M University. We would like to thank Dr. Manuel Piña and Dr. Dave Reed for mentor-ship and support. We would like to thank Doel Delgado for his photography skills. This research would not have been possible without the assistance of Ana Pagan, Luis Baergas, Maño Corbet, Cynthia Morales Otero, Omar Monzon Carmona, Frank Cosme Arroyo, Ray Rodriguez Colon, Noel Rivera Gómez, Carlos Zayas, Alejandro Maldonado, Natalia López-Figueroa, and Denny Fernández del Viso.
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