This article was downloaded by: [Texas A&M University] On: 10 June 2009 Access details: Access Details: [subscription number 784375697] Publisher Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Grana Publication details, including instructions for authors and subscription information: http://www.informaworld.com/smpp/title~content=t713648917 Palynological assessment of Holocene mangrove vegetation at the American Memorial Park, Saipan, Northern Mariana Islands David M. Jarzen a; David L. Dilcher a Florida Museum of Natural History, Paleobotany and Palynology Laboratory, Gainesville, Florida, USA a Online Publication Date: 01 June 2009 To cite this Article Jarzen, David M. and Dilcher, David L.(2009)'Palynological assessment of Holocene mangrove vegetation at the American Memorial Park, Saipan, Northern Mariana Islands',Grana,48:2,136 — 146 To link to this Article: DOI: 10.1080/00173130902797188 URL: http://dx.doi.org/10.1080/00173130902797188 PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdf This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, re-distribution, re-selling, loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. Grana, 2009; 48: 136–146 Palynological assessment of Holocene mangrove vegetation at the American Memorial Park, Saipan, Northern Mariana Islands SGRA DAVID M. JARZEN & DAVID L. DILCHER Palynology of the Holocene mangrove on Saipan, N. Mariana Is. Downloaded By: [Texas A&M University] At: 01:55 10 June 2009 Paleobotany and Palynology Laboratory, Florida Museum of Natural History, Gainesville, Florida, USA Abstract Pollen and spores recovered from three cores of Holocene to recent deposits from the island of Saipan indicate the presence of mangrove vegetation, including Bruguiera and Acrostichum, on the island previous to World War II. The occurrence of Casuarina equisetifolia Linneaus 1759, from cores elsewhere on the island of Saipan, at depths predating the arrival of humans to the island, suggest that this tree species is endemic to Saipan rather than a recent invasive species. These findings will assist in replanting native vegetation once destroyed through wartime activities on the island. Keywords: Fungal spores, pteridophytes, angiosperms, Bruguiera, Rhizophora, Acrostichum, Casuarina The American Memorial Park (15°12¢59” N 145°42¢52” E), located on the island of Saipan, Commonwealth of the Northern Mariana Islands (CNMI), was established in 1977 to honor American and Marianas people who gave their lives during the Marianas Campaign of World War II. As a “living memorial”, the park offers activities such as baseball, bicycling, tennis, picnicking, and swimming. Within the 133 acre boundary are beaches, sports fields, picnic sites, boat marinas, playgrounds, and a 30 acre wetland and mangrove forest. The United States National Park Service initiated an assessment of the ecological status and function of mangroves within the American Memorial Park boundaries. Mangrove communities are important ecosystems generally recognised as reducing the effects of land-based pollution on coral reef ecosystems and in providing nursery habitats for coral reef fishes and invertebrate organisms. Pollen analysis was incorporated within this assessment to determine the presence or absence of several mangrove associate species at or near the site of the AMP in the historical past. The aim of this study is to determine through pollen analysis of samples from three sediment cores the occurrence of Casuarina, and mangrove taxa at selected locations in or near the American Memorial Park (AMP). Pollen analysis may help in the determination of which mangrove tree species are native to the island, and which taxa have been introduced or lost due to the activities of humans, especially as a result of the military activities of World War II. In addition to the mangrove taxa (e.g. Bruguiera, Rhizophora, Acrostichum) the determination of the status of Casuarina as an introduction by humans, or as a native plant, will have important implications for managing mangrove communities at the AMP in the future. Geology and history of Saipan Saipan is the capital of the Commonwealth of the Northern Mariana Islands, located in the region of Micronesia in the western Pacific Ocean at 15°N and 146°E (Figure 1). It is about 1600 km south of Japan, 2400 km east of the Philippines, and 200 km north of the island of Guam. It is part of a string of 15 volcanic and raised coral islands forming a roughly north-south trending chain, most of which are uninhabited. Saipan is approximately 20 km long and 9 km wide. Correspondence: David M. Jarzen, Paleobotany & Palynology, Florida Museum of Natural History, University of Florida, Dickinson Hall, PO Box 117800, Gainesville, FL 32611-7800, USA. E-mail: dmj@flmnh.ufl.edu (Received 8 September 2008; accepted 4 February 2009) ISSN 0017-3134 print/ISSN 1651-2049 online © 2009 Collegium Palynologicum Scandinavicum DOI: 10.1080/00173130902797188 Palynology of the Holocene mangrove on Saipan, N. Mariana Is. 137 Marianas in honor of Mariana of Austria, widow of Philip IV of Spain. The islands were sold by Spain to Germany in 1899 and so remained under the German flag until the start of World War I in 1914 when the Japanese moved against the German administration in the islands and forced them out. The Japanese occupied the island of Saipan from 1914 to 1944 when American forces gained control of the island in July, 1944 and began the construction of bases and airfields. In July, 1947 the area was recognised as a Trust Territory by the United Nations. The United States Navy, and later the Department of Interior, became the administrator under the Trusteeship Agreement with the United Nations Organization. Today the Northern Marianas are a selfgoverning Commonwealth of the United States. Downloaded By: [Texas A&M University] At: 01:55 10 June 2009 Material and methods Figure 1. Map of the island of Saipan showing the location of the American Memorial Park (AMP). Saipan is the second largest of the Mariana Islands (Guam is larger), with a land area of about 124 square kilometres. It consists of a volcanic core (Eocene?) surrounded by younger limestones (Cloud et al., 1956). In the area of the AMP, and including most of the west border of Saipan, the terrain is low and termed the Western Coastal Plain. This area is composed of loose and recently deposited calcium carbonate sands, and reworked volcanic materials. The surface rises landward to heights generally not exceeding six metres, but may reach elevations up to 30 metres. Parts of the Western Coastal Plain are marshy year round, while others are seasonally wet. The early history of Saipan and the Mariana Islands is uncertain; however, it is believed that the Islands were first settled around 3000 B.C. by an ancient seafaring prehistoric people who journeyed in outrigger canoes to various Pacific islands and eventually lost these navigational skills. Magellan sighted the islands in 1521 when he made his landfall at Guam during his voyage to establish a western route to the “Spice Islands” (http://net.saipan.com/cftemplates/humanities/index. cfm?pageID=2). He claimed the islands for Spain and christened the archipelago “Las Isles de las Velas Latinas” (The Islands of the Latine Sails) because the triangular shape of the sails used on native canoes were similar to those on Mediterranean vessels. In 1668 the name was changed to Las Three cores (Sadog, 0 to 40 cm depth; TR3, 0 to 60 cm depth and TR5, 0 to 50 cm depth) were collected by J. Starmer in 2005 (Figure 2), and stored at -82°C until thawed for palynological processing. The three cores were sampled at the Florida Museum of Natural History (FLMNH), by cutting discs from the core length at specified depths from the top of each core. Core sampling depths and lithology for the cores are given below. In each of the cores the deepest sample was taken at the limestone beach sand deposits at the base of the core. SADOG CORE: Total length of core 40 cm. Sampled at 5.0, 15.0, 25.0 and 35.0 cm. TR3 CORE: Total length of core 60 cm. Sampled at 5.0, 15.0, 25.0, 35.0, 45.0 and 55.0 cm. TR5 CORE: Total length of core 50 cm. Sampled at 5.0, 15.0, 25.0, 35.0, and 45.0 cm. Figure 2. Map of the American Memorial Park, showing the location of core TR3, and TR5. The Sadog core is located approximately 2 km to the north-east. Downloaded By: [Texas A&M University] At: 01:55 10 June 2009 138 D. M. Jarzen and D. L. Dilcher Cutting of the discs was done using a fine-toothed Delta™ band saw. Care was taken to clean the saw blade and table between each cutting interval, in order to avoid contamination from previous cuts. The cut discs were then dried in an oven, and sampled for approximately 2 cm3 and placed in 5% KOH and heated to near boiling. All samples were oxidised using 10% HNO3 followed by treatment in 5% NH4OH to remove humates. The samples were stained in safranin-O. Four slides were prepared from each sample, using glycerine jelly as a mounting medium, and sealed with clear nail polish. Slides, residues and unused portions of the samples are stored at the Paleobotany and Palynology Laboratory, Florida Museum of Natural History, Gainesville, Florida as locality UF 19093. Photography was done using a Nikon Coolpix 4500™ digital camera, mounted on a Leitz Dialux 20™ research microscope. Location of illustrated specimens is given by reference to the Florida Museum of Natural History, Paleobotany and Palynology Locality (UF number) followed by a specimen number, along with a slide number (PY1….PY…n). Stage coordinates are given as horizontal x vertical, followed by the England Finder Slide (EFS) location. Palynomorphs were identified using published pollen floras of the Pacific region including especially Cranwell (1953), Huang (1981), Moar (1993), Selling (1946, 1947), and the Modern Pollen and Spore Reference Collection of 7100 slides at the Paleobotany and Palynology Laboratory, Florida Museum of Natural History, Gainesville, Florida. Measurements of palynomorphs are taken from the specimens recovered from the cores. Results Tables I – III provide absolute counts for the taxa recovered, including algae, fungal, pteridophyte spores and angiosperm pollen. For the most part, Cores TR3 and TR5 contain similar pollen and spore taxa, while the Sadog Core is less diverse. Appendix 1 lists the identified taxa recovered from each of the three cores. Descriptions and remarks are provided for the pteridophyte spores and angiosperm pollen forms identified to genus and in some cases to species. Many other spores and angiosperm pollen remain unidentified and will be the subject of further research. Figure 3 illustrates the palynomorphs described in this report, as well as some that are yet to be described, and some selected fungal elements. Pteridophyte spores Genus Acrostichum Linneaus 1753. – Acrostichum aureum Linneaus (Figure 3A). Table I. Sadog core relative abundance of palynomorphs. Taxa arranged alphabetically. Depth in centimetres Taxon 5.0 15.0 25.0 35.0 Acrostichum aureum Amaranthaceae Bruguiera gymnorrhiza Carya sp. Casuarina cf. C. equisetifolia Cocos nucifera Compositae Cyathea sp. 1 Cyathea sp. 2 Cyperus sp. Poaceae (Gramineae) Hibiscus tiliaceus Inaperturate thin walled Lycopodiella cernua Pandanus sp. Polypodiaceae Tricolpites sp. 1 Tricolpites sp. 2 Tricolpites sp. 3 Tricolporites sp. 1 Tricolporites sp. 2 Tricolporites sp. 3 Triporate P3 Trilete Unidentified 6 — — — — 1 1 2 — 2 1 — 149 — 9 — 1 — — — — — 1 1 6 1 — — 1 — — 39 — 1 3 — 40 3 1 1 1 — — 1 — 3 2 6 — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — Sub-total Algal Fungal spores & hyphae Insect egg case? Scolecodont Foram test Dinoflagellate 174 14 475 11 — 10 — 109 35 128 11 — 2 1 — — — — — — — — — — — — Sub-total 510 177 TOTAL COUNT 684 286 P – present in sample but not encountered in counts. Description. – Spore trilete, amb rounded triangular, lasurae extending 2/3 or slightly more of the distance to the amb; surface granulate, with granules near lasurae somewhat larger; spore wall 2 – 3 mm thick, diameter of amb 42 (51) 61 mm (13 spores measured). Remarks. – These spores are often folded or split making identification difficult. Acrostichum is a genus of three species of marsh ferns distributed throughout the tropics, often associated with mangrove communities and opportunistic in disturbed estuarine areas (Tomlinson, 1986). In the Northern Marianas Acrostichum occurs in moist ravines and on wet banks and swampy places, especially near mangrove communities (Fosberg et al., 1975). Acrostichum aureum Palynology of the Holocene mangrove on Saipan, N. Mariana Is. Table II. Core TR3 Relative abundance of palynomorphs. Taxa arranged alphabetically. Table III. Core TR5 relative abundance of palynomorphs. Taxa arranged alphabetically. Depth in centimetres Depth in centimetres Downloaded By: [Texas A&M University] At: 01:55 10 June 2009 Taxon 139 5.0 15.0 25.0 35.0 45.0 55.0 Taxon 5.0 15.0 25.0 35.0 45.0 Acrostichum aureum Amaranthaceae Bruguiera gymnorrhiza Carya sp. Casuarina cf. C. equisetifolia Cocos nucifera Compositae Cyathea sp. 1 Cyathea sp. 2 Cyperus sp. Poaceae (Gramineae) Hibiscus tiliaceus Inaperturate thin walled Lycopodiella cernua Pandanus sp. Polypodiaceae Tricolpites sp. 1 Tricolpites sp. 2 Tricolpites sp. 3 Tricolporites sp. 1 Tricolporites sp. 2 Tricolporites sp. 3 Triporate P3 Trilete Unidentified P P — 16 64 — 2 11 P P 2 P 73 — 1 3 1 — 1 — — P 146 1 — 1 7 — P 2 1 25 — 2 3 — 42 1 1 2 2 — — — — — 10 1 3 — 12 P 3 4 — 3 — P 1 1 62 5 P 3 1 — — — 2 1 4 4 — 1 — 1 — 13 — — — — 2 — 78 — 3 6 — — — 1 — — 3 2 — — — — — — — — — — — — — — — — — — — — — — — — Acrostichum aureum 145 Amaranthaceae P Bruguiera gymnorrhiza — Carya sp. P Casuarina cf. C. equisetifolia — Cocos nucifera 2 Compositae 12 Cyathea sp. 1 27 Cyathea sp. 2 — Cyperus sp. 2 Poaceae (Gramineae) 5 Hibiscus tiliaceus — Inaperturate thin walled 11 Lycopodiella cernua — Pandanus sp. 6 Polypodiaceae 5 Tricolpites sp. 1 1 Tricolpites sp. 2 P Tricolpites sp. 3 — Tricolporites sp. 1 — Tricolporites sp. 2 — Tricolporites sp. 3 — Triporate P3 51 Trilete Unidentified 3 348 P — P P P 2 16 — — — — 5 — — 3 — — — — — — 9 1 203 16 30 — 1 — — 17 — 2 — — 16 1 — 12 2 — — 1 1 1 10 3 97 11 4 — 3 10 — 25 — 4 1 — 49 — 1 17 — — — — — 1 4 4 — — — — — 11 — — — 113 3 — 76 1 P — — — — — — — — 1 1 0 2 — 6 14 — — — 2 2 — 60 — 2 5 1 — — — — — 2 3 Sub-total Algal Fungal spores & hyphae Insect egg case? Scolecodont Foram test Dinoflagellate 270 7 22 — — — 1 384 1 11 P — — — 316 90 98 3 — — — 231 91 124 9 4 — — 205 300 65 1 2 — — 100 300 30 9 — — — Sub-total Algal Fungal spores & hyphae Insect egg case? Scolecodont Foram test Dinoflagellate 321 24 241 4 1 — — 100 156 185 10 — — — 109 172 135 4 — 3 P 110 56 63 1 — — 5 — — — — — — — 30 12 191 228 368 339 Sub-total 270 351 314 125 — 300 396 507 459 573 439 TOTAL COUNT 591 451 423 235 — Sub-total TOTAL COUNT P – present in sample but not encountered in counts. The sample at 45.0 cm is dominated by algal cells. Counts were made of the algal and fungal, etc., separately. P – present in sample but not encountered in counts. The barren sample at 45.0 cm is a sandy sample near the bottom of the core. occurs today in the American Memorial Park (Raulerson & Rinehart, 1989). In core TR3, Acrostichum spores are the dominant form, accounting for up to 90% of the total palynomorph sum (Table II). The high frequency of Acrostichum is suggestive of a wetland or pond environment. 씮 Figure 3. Selected Holocene palynomorphs from the Saipan cores. A. Acrostichum aureum UF 19093-TR3A-2, PY01A, 23.6 ´ 95.3, EFS U23/4. B. Cyathea sp. 1. UF 19093-TR3A-2, PY01A, 27.2 ´ 93.1, EFS ´27. C. Cyathea sp. 2. UF 19093-TR5, PY01A, 5.0 cm, 26.1 ´ 111.4, EFS D26/1. D. Lycopodiella cernua UF 19093-TR3A-2, PY01A, 22.3 ´ 109.2, EFS F22. E. Cyperus sp. UF 19093-TR5, PY01A, 5.0 cm, 27.5 ´ 93.1, EFS W27/4. F. Cocos nucifera UF 19093-TR3A-2, PY01A, 16.3 ´ 98.3, EFS R16/3. G. Pandanus sp. UF 19093TR3A-3, PY01A, 28.0 ´ 93.0, EFS W28. H. Bruguiera sp. UF 19093-TR3, PY01A, 35 cm, 33.2 ´ 109.3, EFS F33. I. Bruguiera sp. UF 19093-TR5, PY01A, 15.0 cm, 34.4 ´ 106.0, EFS J34/4. J. Carya sp. UF 19093-TR5, PY01A, 5.0 cm, 25.5 ´ 107.0, EFS H25/4. K. Casuarina equisetifolia UF 19093-TR3A-1, PY02, 31.5 ´ 95.7, EFS U31/2. L. Hibiscus sp. UF 19093-TR5, PY01A, 5.0 cm, 30.9 ´ 107.7 EFS H31. M. Hibiscus tiliaceus UF 19093-TR5, PY01A, 5.0 cm, 43.0 ´ 101.4, EFS O43/2. N. Poaceae (Gramineae) UF 19093TR3, PY01A, 45 cm, 20.8 ´ 94.1, EFS V20/4. O. Tricolporites sp.1 UF 19093-TR3A-2, PY02A, 20.9 ´ 106.1, EFS J20/4. P. Triporicellaesporites sp. UF 19093-TR3A-1, PY03A, 25.3 ´ 99.1, EFS Q25/4. Q. Dictyosporites sp. UF 19093-TR3A-1, PY03A, 24.2 ´ 103.6, EFS M24. R. Phragmothyrites sp. UF 19093-TR3A-1, PY01A, 42.0 ´ 112.3, EFS C42/2. S. Mediaverrunites sp. UF 19093-TR3A-1, PY01A, 34.2 ´ 99.2, EFS Q34/4. T. Palaeocirrenalia sp. UF 19093-TR5, PY01A, 25 cm, 41.4 ´ 109.4, EFS F41/2. U. Frasnacritetrus sp. UF 19093-TR5, PY01, 15.0 cm, 22.3 ´ 110.4, EFS E22. Scale bars – 30mm (A, B, D–F, H–K, O and S–U); 50 mm (C, L); 25 mm (G); 6 mm (M); 20 mm (P); 75 mm (R). Downloaded By: [Texas A&M University] At: 01:55 10 June 2009 140 D. M. Jarzen and D. L. Dilcher Palynology of the Holocene mangrove on Saipan, N. Mariana Is. Genus Cyathea Smith 1793. – (Figure 3B). Cyathea sp. 1. Downloaded By: [Texas A&M University] At: 01:55 10 June 2009 Description. – Spore trilete, amb rounded triangular, lasurae extending half to 2/3 the distance to amb; surface psilate; spore wall about 2 mm thick; diameter of amb 30 (40) 57 mm (8 spores measured). Remarks. – Variations of spore size may indicate the presence of more than one species. Cyathea spores occur commonly in the core samples. In the Sadog core, Cyathea sp. 1 spores account for 35% of the pollen and spores recovered. About 620 species of Cyathea occur in tropical and warm regions of the world. The Northern Mariana Islands endemic, Cyathea aramaganensis Kanehira, is a common treefern on high open volcanic slopes above the forest limit. Cyathea has not been reported within the AMP Boundaries (Raulerson & Rinehart, 1989). Genus Cyathea Smith 1793. – Cyathea (Figure 3C). sp. 141 Monocotyledon pollen Genus. – Cyperus Linneaus 1735. cf. Cyperus sp. (Figure 3E). Description. – Pollen grains free, rounded to tetrahedral in shape; four-aperturate, apertures poorly defined thinned areas in the exine, with ragged or torn margins; three apertures lateral with one aperture basal; exine thin, about 1.0 mm; longest dimension 31 (37.6) 57 mm (10 grains measured). Remarks. – The 300 species of the genus Cyperus are found throughout tropical and warm temperate regions of the world associated with marine and freshwater habitats. Cf. Cyperus pollen occurs in all cores, reaching a maximum abundance of 55% in core TR3 at 45.0 cm (Table II). Genus. – Cocos Linneaus 1753. Cocos nucifera Linneaus 1753 (Figure 3F). 2 Description. – Spore trilete, amb rounded triangular, lasurae extending half to 2/3 the distance to amb; proximal surface psilate, distal surface variously rugulate; spore wall about 2 mm thick; diameter of amb 76 (82) 87 mm (6 spores measured). Remarks. – This form of Cyathea is very similar to Cyathea sp. 1 but differs in the rugulate distal face and is larger in size. One or two specimens are very similar to the extant fern genus Cheilanthes Swartz 1806. Cyathea sp. 2 occurs in core TR5 at 5.0 cm (Table III). Lycophyte spore Genus. – Lycopodiella Holub 1964. Lycopodiella cf. L. cernua (Linneaus) Pichi Sermolli 1968 (Figure 3D). Synonym. – Lycopodium cernuum Linneaus 1753. Description. – Spore trilete, amb rounded triangular, lasurae extending 2/3 or more of the distance to amb; proximal surface psilate, distal surface rugulate; spore wall about 1.4 mm thick; diameter of amb 26 (32) 38 mm (7 spores measured). Remarks. – Lycopodiella is a genus of 40 species of clubmosses (Lycophyta) distributed throughout moist temperate and tropical environments. Lycopodium cernuum occurs on the Northern Mariana Islands often on lava or ash in open places (Fosberg et al., 1975). Spores of Lycopodiella are infrequent to rare in all cores. Description. – Pollen grains free, monosulcate, sulcus extending nearly the full length of the long axis of the grain, sulcus margin thickened and sinuous; surface scabrate to granulate; exine two-layered 2.5 mm thick; longest dimension 49 (73.3) 106 mm (11 grains measured). Remarks. – The large size and nature of the aperture margins are comparable with pollen of Cocos nucifera Linneaus 1753. The coconut palm is nearly ubiquitous throughout tropical coastlines of the world. Cocos pollen occurs in nearly all samples in cores TR3 and TR5. It is rare to absent in the Sadog core. Genus. – Pandanus S. Parkinson 1773. Pandanus sp. (Figure 3G). Description. – Pollen grain free, spherical; monoporate, pore small often difficult to distinguish, circular; surface echinate, spines small 1.0 mm or less in height; exine thin, about 1.5 mm thick; size 19 (25.5) 34 mm (15 grains measured). Remarks. – Pollen of Pandanus is very distinctive and is not easily confused with other monoporate, echinate grains (Jarzen, 1983). Pandanus is a large genus of 700 or possibly more species distributed throughout the Old World tropics (Mabberley, 1997). Pandanus tectorius Parkinson ex J. P. du Roi 1774 (Screw Pine) occurs on all islands in the Northern Marianas (Fosberg et al., 1975) and within the park boundaries of the AMP (Raulerson & Rinehart, 1989). The trees are usually insect pollinated; however, Cox (1990) considers P. tectorius, a coastal pandan, to be wind 142 D. M. Jarzen and D. L. Dilcher pollinated, with the male inflorescences producing copious amounts of dry pollen that are easily transported through frequent coastal air movements. Pandanus pollen occurs in low numbers, infrequently in nearly all Saipan core samples. Dicotyledon pollen Genus. – Bruguiera Savatier 1798. Bruguiera sp. (Figure 3H,I). Downloaded By: [Texas A&M University] At: 01:55 10 June 2009 Description. – Pollen grains free, tricolporate, colpi short extending only half the distance to the poles; surface psilate to very finely scabrate; exine about 1.0 mm thick; diameter in polar view 15 (19) 23 mm (10 grains measured). Remarks. – Bruguiera (family Rhizophoraceae) comprises six species distributed in east Africa and the Pacific. B. gymnorrhiza (Linnaeus) Savatier 1798, the mangle lahi, is a mangrove tree abundant within the park boundaries of the AMP (Raulerson & Rinehart, 1989), but is rare or does not occur on the smaller islands to the north of Saipan (Fosberg et al., 1975). Bruguiera pollen occurs in cores TR5 and TR3, where it accounts for 9.5% of the relative abundance of all pollen and spores (Table II). Genus. – Carya Nuttall 1818. Carya sp. (Figure 3J). Description. – Pollen grains free, outline more or less circular to subcircular; triporate, pores circular and situated off the equator onto one hemisphere only, pore diameter 2.0 – 2.5 mm, about 5.0 mm inside of the equator; surface psilate to finely granulate, some specimens show a thinning of the exine in the polar regions; exine of uniform thickness, 1.5 – 2.0 mm; 34 (42) 49 mm. Remarks. – It is odd that Carya pollen should occur in the Saipan core samples; however, the trees of Carya may have been or are still present today on the island as an introduced cultivated species (R. M. Bourke pers. comm., 30 September 2006). There is a possibility of contamination during processing of the samples; however, this is unlikely as this pollen occurs in several samples from both TR3 and TR5 cores, processed on separate occasions. Carya reaches a relative abundance of 5% in sample 5.0 cm of core TR5 (Table III). Pecan nut [Carya illinoinensis (Wangenh) K. Koch] has been introduced to Papua New Guinea and several fruit-bearing trees have been noted growing at 1400 – 1600 m on a plantation and a research station (Aiyura) in Eastern Highlands Province (Bourke, in press). Genus. – Casuarina Linneaus 1759. Casuarina equisetifolia Linneaus 1759 (Figure 3K). Description. – Pollen grains free, shape in polar view circular to rounded triangular; triporate, pores somewhat protruding, 2.5 – 3.5 mm diameter; surface psilate; exine two-layered, 2.0 – 2.5 mm thick; size 23 (26.6) 34 mm (13 grains measured). Remarks. – The 17 species of the genus Casuarina occur from southeast Asia through the western Pacific islands. Casuarina equisetifolia has been introduced to many tropical and subtropical coasts throughout the world. Determination of its indigenous range is often very difficult to discern. Pollen of Casuarina equisetifolia occurs with varying frequency in all cores. It is most frequent in core TR5 at 5.0 cm. where it reaches a relative abundance of 20% (Table III). The pollen is distinctive and not easily confused with other Saipan pollen forms. Genus. – Hibiscus Linneaus 1737. Hibiscus sp. Linneaus 1753 (Figure 3L,M). Description. – Pollen grains free, spherical, multiaperturate; apertures are pores, distributed evenly over surface of grain, 9 – 10 mm diameter; surface echinate, spines 10 – 12 mm high; diameter 114 (148) 171 mm (3 grains measured). Remarks. – The 300 species of Hibiscus are distributed throughout the tropical to warm temperate regions of the world. The pollen recovered from the Saipan samples is comparable to H. tiliaceus, a small tree common along edges of freshwater swamps and channels. Hibiscus tiliaceus is a pantropical species (Moore et al., 1977). Pollen of Hibiscus sp. occurs rarely and only in core TR5 at the 5.0 and 25.0 cm levels (Table III). Discussion The presence of Acrostichum spores, often in very high relative numbers, indicates a bog or marsh conditions (Athens & Ward, 1998). The ferns are understorey plants common in mangrove communities and other wetland forests. The fronds of Acrostichum aureum are long, measuring 1.2 – 1.8 metres in height and are as broad as they are tall. The sporangia are borne on the underside of the fertile fronds and often cover the surface completely. Considering the size and height of the fronds, the spores of Acrostichum are probably carried for some distance from the parent plant. The abundance of Acrostichum spores in some of the core samples, especially TR3 at 15.0 and 25.0 cm, may reach as high as Downloaded By: [Texas A&M University] At: 01:55 10 June 2009 Palynology of the Holocene mangrove on Saipan, N. Mariana Is. 90% relative frequency, indicating that those samples may represent an Acrostichum-dense environment. The ferns are aggressive and tend to become weedy in disturbed sites. In Vietnam this fern has suppressed the regrowth of mangrove tree species that were destroyed by military activity (Tomlinson, 1986, p. 314). Athens and Ward (2004) note that although Acrostichum is today common along some shorelines on Saipan, it was not recorded in their pollen counts of the modern flora, suggesting a much degraded landscape from that represented in older sediments which contain abundant Acrostichum spores. Two distinctly different spore forms referable to the extant genus Cyathea were recovered from many of the samples. Cyathea sp.1 has a smooth spore wall and is typical of several species of Cyathea. The second species referable to Cyathea has a regulate sculpture on the distal face of the spore, and frequently measures somewhat larger than Cyathea sp. 1. The 620 species of Cyathea are tree ferns growing to heights of 20 m or more, and distributed throughout the tropics and warm regions of the world (Mabberley, 1997). C. aramaganensis Kanehira 1934 occurs in the Northern Mariana Islands, but not on Saipan (Fosberg et al., 1975). Athens and Ward (2005) reported Cyathea pollen in low numbers from only a few samples in the core material from Lake Susupe. Cyathea tree ferns were not reported in the extant flora from Saipan as recorded by Moore et al. (1977). The presence of Cyathea pollen in relative frequencies from 1% to 35% in the cores from the AMP is interesting in that it shows an earlier presence of the genus, but provides little ecological information other than supporting a tropical climate. Palm pollen occurs in all samples from the cores. Cocos nucifera, the Coconut palm, has distinctive, rather large monosulcate pollen that is easily recognizable. Cocos nucifera pollen was recovered by Athens and Ward (2005) from core samples taken from Lake Susupe, in sediments dated at 7800 years BP. This occurrence suggests that Cocos nucifera is native to Saipan and not introduced by humans who first came to the islands in 4800 BP (Athens & Ward, 2005). Pandanus pollen is identified by its monoporate, densely spinate (echinate) surface. Pandanus occurs in a variety of habitats from near sea level to montane environments. Although never abundant, it occurs in all cores. Most pandans are insect pollinated and as such the pollen recovered from the cores may not reflect the abundance of the parent plants. The pollen of Casuarina occurs in varying frequency in all three cores collected from Saipan. In the core TR5, at the 5.0 cm level, it is one of the most frequent palynomorph encountered (Table III). Casuarina equisetifolia, the Australian Pine, is an angiosperm tree 143 with elongate needle-like leaves, and cone-like fruiting structures. These characters suggested to some botanists that the tree resembled those of the pine family. Casuarina trees are found on nearly all tropical and subtropical coastlines around the world. Casuarina is native to south-east Asia and many islands of the western Pacific Ocean (Mabberley, 1997). The pollen of Casuarina equisetifolia is triporate, psilate (smooth) or very finely granulate and shows a thickening around the pore margins providing a protruding appearance of the pores. The pollen is present in most samples of the cores from the AMP. These cores, however, do not provide sediment dated as far back as the first arrival of humans. The work of Athens and Ward (2004) from cored sediments does provide the necessary depth and age control to conclude that the pollen of Casuarina extends back at least to 8000 years BP, predating the arrival of humans at 4300 years BP. The arrival of Casuarina to Saipan and possibly other islands of the South Pacific is probably the result of bird transport (D. W. Steadman, pers. comm., 2008). Mangroves play an important role in the ecology of tropical islands. These communities comprise a variety of taxa, dependent upon their location in the new world or old world tropics. Species of Rhizophora are often associated with tropical coastlines; and indeed the Northern Mariana Islands, including Saipan, once were home to species of Rhizophora trees (Athens & Ward, 1998, 2004, 2005). Rhizophora no longer occurs on Saipan; instead it has been replaced by Bruguiera gymnorrhiza, another member of the mangrove family Rhizophoraceae (Moore et al., 1977). Bruguiera gymnorrhiza trees are evergreen, reach a height of 30 m, and display buttressing of the trunk (Tomlinson, 1986). Mangrove trees are nearly exclusively animal pollinated, although there is some evidence of wind pollination in Rhizophora (Tomlinson, 1986). In Bruguiera gymnorrhiza, the flowers are conspicuous and recurved back toward the main axis of the tree, facilitating pollination by birds (Davey, 1975), recently identified as two species of honeyeaters (Kondo et al., 1991). Through the activity of perching birds, the pollen is literally thrown onto the head of the visiting bird, and carried to another flower (Tomlinson, 1986). This efficient method of pollination probably leaves little pollen to be incorporated into the mangrove sediments. The highest relative frequency of Bruguiera pollen recovered from the Saipan cores is from core TR3, sample 25.0 cm, where it reaches 9.5% (Table II), and may be explained through pollen “outwashing” (Graham, 1976), or the entry of normally zoophillous pollen in sediments due to the action of heavy rainfall in tropical environments. Downloaded By: [Texas A&M University] At: 01:55 10 June 2009 144 D. M. Jarzen and D. L. Dilcher Hibiscus tiliaceous, the Pago or Sea-Hibiscus, is a small tree, with smooth grey bark, and long petioled leaves. It is a member of the family Malvaceae, the cotton family. The pantropical species is common along the edges of freshwater swamps and river channels (Moore et al., 1977). Pollen of the Malvaceae is usually large and ornamented with large spines or echinae. Pollen comparable to Hibiscus tiliaceous occurs rarely in core TR5, at depths of 5.0 and 25.0 cm. Pollen of the Poaceae (Gramineae) occur in all cores in varying amounts (Tables I – III). The pollen is characteristically spherical, psilate, and with a single annulate pore (Figure 3N). The pollen of most grasses is wind borne, making ecological interpretations difficult. Several angiosperm pollen grains, as yet not formally described, were recovered from the cores (see Tables I – III). A tricolporate, finely reticulate undescribed form is illustrated in Figure 3O. Fungal elements including spores, fructifications and mycelia are present in all core samples. In addition to the common fungal elements recovered, algal cysts, insect eggs, scolecodonts, microforaminifer tests and dinoflagellate cysts were also identified and counted. These components often account for the majority of palynomorphs present. See for example core TR3 samples at 45.0 and 55.0 cm levels where the algae alone account for 52 to 89% of all palynomorphs encountered in the counts. These high percentages are probably due to specific circumstances of deposition that favoured the accumulation of algal or fungal spores or mycelia, etc. The diversity of the fungal element (Figure 3P–U) requires further investigation and may prove helpful in elucidating environmental conditions at the time of sedimentation. Such investigations are beyond the purpose of this study. Conclusions Future work must include the identification of the angiosperm pollen forms described here as morphotypes (e.g. Tricolpites, Tricolporites), or those described only to family level (e.g., Poaceae, etc.). Often identification to an extant genus is possible through the careful microscopic comparison with a reference pollen collection made from the plants living within a specific geographic region. In this case a reference collection of pollen from plants growing today on the Northern Mariana Islands and specifically on Saipan would provide adequate material for future identifications. A survey of the vascular plants growing today at the AMP lists 128 species, 10% of which are ferns, with no gymnosperms present (Raulerson & Rinehart, 1989). Even a small reference collection of these 128 species of angiosperms and ferns would form the basis for a modest comparative collection. The reference collection of the Paleobotany and Palynology Laboratory at the Florida Museum of Natural History comprises about 7100 prepared slides of pollen or spores of plants from around the world. The species in the collection are predominately tropical, especially from southeast Asia and Australasia. Representation of pollen and spores from plants of the Pacific islands is not strong, and that from the Marianas is nearly wanting. Regardless of these limitations, pollen and spores of the major common forms were available for comparison and identification. The palynomorphs recovered and identified from cores taken from the American Memorial Park, Saipan, Northern Marianas, represent a part of the terrestrial vegetation cover at and surrounding the core sites from the Holocene to the present. The occurrence of Casuarina equisetifolia (Australian Pine) at depths predating the arrival of humans (Athens & Ward, 2004) to the island suggest that this tree species is endemic to Saipan. Rhizophora pollen was not recovered from the cores; however, Bruguiera gymnorrhiza pollen and the fern Acrostichum aureum, were identified, and indicate the presence of mangrove vegetation at the core sites during the Holocene. Future work must consider the identification of several additional angiosperm pollen taxa that may prove helpful in an elucidation of the paleoenvironment of the island during the last several millennia. Acknowledgements Appreciation is expressed to John Starmer for the collection of surface and core samples from Saipan. We thank the United States National Park Service for financial support of the project. Susan Jarzen helped with manuscript preparation and some laboratory preparation. Nathan Bruce and Pat Bennett of the FLMNH are thanked for their expertise and courtesy in cutting samples from the frozen core material. Lisa Wade and Harry Luther of Marie Selby Botanical Gardens (Sarasota, Florida) allowed me to collect fresh pollen of Cocos nucifera, and Scott Zona at the Fairchild Tropical Gardens (Miami, Florida) provided information and pollen of Cocos nucifera. We thank Owen Davis (University of Arizona, Tucson, Arizona) and Mark Brenner (University of Florida) for valuable advice on sampling and processing procedures of Holocene material. Rona IkeharaQuebral, International Archaeological Research Institute, Inc., Honolulu, HI, assisted in obtaining United States Navy Reports on Saipan. We especially thank J. Stephen Athens (International Archaeological Research Institute, Inc.) for Palynology of the Holocene mangrove on Saipan, N. Mariana Is. supplying important papers and reports regarding the paleoenvironment of Saipan. Mike Bourke provided comments on the status of pecan on Saipan. We thank Vaughn Bryant Jr. and an anonymous reviewer for their improvements to the manuscript. We especially thank David Cantrill for his careful editorial skills and advice. Tricolporate sp. 3 Amaranthaceae Hibiscus tiliaceus Sadog Core Fungal Frasnacritetrus sp. Fusiformisporites sp. Mediaverrunites sp. Palaeocirrenalia sp. Palaeomycites sp. Appendix 1. Palynomorph composition for Saipan cores Core TR3 Spores Acrosticum aureum Cyathea sp. Lycopodiella cernua Polypodiaceae Downloaded By: [Texas A&M University] At: 01:55 10 June 2009 Fungal Frasnacritetrus sp. Fusiformisporites sp. Mediaverrunites sp. Palaeocirrenalia sp. Palaeomycites sp. Phragmothyrites sp. Scoleosporites sp. Spores Acrostichum aureum Cyathea sp. Lycopodiella cernua Polypodiaceae Pollen Inaperturate thin-walled Cyperus sp. Poaceae (Gramineae) Pandanus sp. Cocos nucifera Triporate unidentified Carya sp. Casuarina sp. cf. C. equisetifolia Bruguiera gymnorrhiza Asteraceae (Compositae) Tricolporate sp.2 Amaranthaceae Core TR5 Fungal Frasnacritetrus sp. Fusiformisporites sp. Palaeocirrenalia sp. Palaeomycites sp. Spores Cyathea sp. Lycopodiella cernua Pollen Inaperturate thin-walled Cyperus sp. Poaceae (Gramineae) Pandanus sp. Cocos nucifera Triporate unidentified Carya sp. Casuarina sp. cf. C. equisetifolia Tricolpites sp. 3 Bruguiera gymnorrhiza Compositae 145 Pollen Inaperturate thin-walled Poaceae (Gramineae) Pandanus sp. 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