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<strong>Proceedings</strong> <strong>of</strong> <strong>the</strong> <strong>Third</strong> <strong>International</strong> <strong>Conference</strong> on Invasive SpartinaChapter 3: Ecosystem Effects <strong>of</strong> Invasive Spartina(e.g., mild temperature in summer) (Wang et al. 2008). Likenematodes, <strong>the</strong> relative abundance <strong>of</strong> major trophicfunctional groups <strong>of</strong> macrobenthic invertebrates was alsoaltered when S. mariqueter was replaced by S. alterniflora.Spartina alterniflora communities had a higher proportion <strong>of</strong>suspensivores but a lower proportion <strong>of</strong> herbivores anddetritivores than S. mariqueter communities (Chen et al.2005a).In addition, we compared <strong>the</strong> structure and diversity <strong>of</strong><strong>the</strong> bacterial communities in rhizosphere soils <strong>of</strong> S.alterniflora, P. australis and S. mariqueter throughconstructing 16S ribosomal DNA (rDNA) clone libraries.Our results showed that <strong>the</strong> shift <strong>of</strong> species composition <strong>of</strong>plant communities from native plants to S. alternifloracaused considerable changes in bacterial composition <strong>of</strong>rhizosphere soils in estuarine salt masrhes (Wang et al.2007).The above changes in soil biota caused by S.alterniflora invasions could have great effects on ecosystemprocesses in <strong>the</strong> soils that are associated with <strong>the</strong>seorganisms as decomposers.ARTHROPOD COMMUNITIESPlants serve as both food and habitats for manyarthropods, so subtle shifts in plant community compositionmay lead to considerable changes in <strong>the</strong> arthropodcommunity. In order to understand <strong>the</strong> possible effects <strong>of</strong> S.alterniflora invasions on arthropods, we examined <strong>the</strong>community structure and diets <strong>of</strong> arthropods in an estuarinesalt marsh previously dominated by native P. australis atChongming Dongtan through net sweeping and plantharvesting methods and stable isotope analysis (Wu et al.2009). We found that diversity indices were not significantlydifferent between exotic and native plant communities, but<strong>the</strong> total abundance <strong>of</strong> insects estimated through plantharvesting was found to be lower in S. alternifloramonocultures than that in P. australis monocultures.Community structure <strong>of</strong> insects in S. alternifloramonocultures was dissimilar to that in P. australismonocultures and P. australis–S. alterniflora mixtures.Moreover, stable isotope analysis showed that althoughsome native arthropods (perhaps generalists) shifted <strong>the</strong>irdiets, most native taxa did prefer P. australis to S.alterniflora even in S. alterniflora monocultures. Spartinaalterniflora invasions resulted in reduced abundances <strong>of</strong>some arthropds, and increased <strong>the</strong> dominance <strong>of</strong> o<strong>the</strong>rs thatfed preferentially on S. alterniflora. The experimentalevidence provided showed that invasive plants can change<strong>the</strong> community structure and diets <strong>of</strong> native arthropods,which will eventually alter arthropod food webs, and affect<strong>the</strong> integrity and functioning <strong>of</strong> native ecosystems within anature reserve that has been set aside for conserving <strong>the</strong>native biodiversity and maintaining <strong>the</strong> ecosystem integrity.BIRD COMMUNITIESThe conversion <strong>of</strong> mudflats to meadows resulting fromS. alterniflora invasions had significant impact on birds <strong>of</strong>Charadriidae and Scolopacidae, which might have beenattributable to <strong>the</strong> reduction in food resources and physicalalterations <strong>of</strong> habitats for birds (Li et al. 2009). Never<strong>the</strong>less,S. alterniflora may also provide habitat for certain landbirds.Recent bird surveys indicated that <strong>the</strong> Japanese marshwarbler Megalurus pryeri, a newly-recorded species in <strong>the</strong>Yangtze River estuary, nested exclusively in S. alternifloracommunities (Gan et al. 2006). This might be because <strong>the</strong>dense vegetation benefits <strong>the</strong> construction <strong>of</strong> nests. Inaddition, M. pryeri largely fed on <strong>the</strong> invertebrates in S.alterniflora communities (Gan 2009). It is likely that <strong>the</strong>rapid population increase <strong>of</strong> <strong>the</strong> Japanese marsh warbler wasrelated to <strong>the</strong> rapid spread <strong>of</strong> S. alterniflora in <strong>the</strong> YangtzeRiver estuary. However, <strong>the</strong> effects <strong>of</strong> S. alterniflora onlocal landbird communities still remain largely unexplored,and fur<strong>the</strong>r studies are needed.CARBON AND NITROGEN CYCLESS. alterniflora had great productive potential in <strong>the</strong>marshlands in <strong>the</strong> Yangtze River estuary. The results weobtained in Jiuduansha marshlands showed that exotic S.alterniflora had much greater primary productivity thannatives S. mariqueter and P. australis (Liao et al. 2007)because <strong>the</strong> exotic had greater leaf area index (LAI) and alonger photosyn<strong>the</strong>tic season than <strong>the</strong> native species (Jianget al. 2009). At <strong>the</strong> same time, decomposition rates <strong>of</strong> S.alterniflora litter, particularly <strong>the</strong> belowground litter, werelower than those <strong>of</strong> S. mariqueter and P. australis litter dueto <strong>the</strong> lower litter quality <strong>of</strong> S. alterniflora (Liao et al. 2008).Therefore, larger stocks <strong>of</strong> carbon and nitrogen were foundin <strong>the</strong> ecosystems dominated by S. alterniflora than in thosedominated by S. mariqueter and P. australis. Our fur<strong>the</strong>ranalysis <strong>of</strong> stable carbon isotopes also confirmed that <strong>the</strong>replacement <strong>of</strong> S. mariqueter by S. alterniflora significantlyincreased soil organic carbon and total soil nitrogen (Chenget al. 2006), especially soil labile carbon, recalcitrant carbon,and soil recalcitrant nitrogen contents in <strong>the</strong> upper soil layers(0–60 cm) (Cheng et al. 2008). The ecosystem carbon andnitrogen cycles altered by S. alterniflora invasions might be<strong>of</strong> limited significance on a large scale in relation to <strong>the</strong>range <strong>of</strong> S. alterniflora in <strong>the</strong> Yangtze River estuary, butmight have potentially far-reaching impact on <strong>the</strong> adjacentecosystems. In fact, S. alterniflora functioned as <strong>the</strong> primaryenergy source for certain nektons in <strong>the</strong> marshlands in <strong>the</strong>Yangtze River estuary (Quan et al. 2007). Potentialcascading effects on estuarine food webs <strong>of</strong> increasedecosystem productivity due to S. alterniflora invasions needsfur<strong>the</strong>r exploration.- 149 -
Chapter 3: Ecosystem Effects <strong>of</strong> Invasive Spartina<strong>Proceedings</strong> <strong>of</strong> <strong>the</strong> <strong>Third</strong> <strong>International</strong> <strong>Conference</strong> on Invasive SpartinaCONCLUSIONSThe invasion history <strong>of</strong> S. alterniflora in <strong>the</strong> YangtzeRiver estuary is relatively short, but this invasive plant hasbeen found to cause considerable impact on structure andfunctioning <strong>of</strong> native ecosystems although it might havepositive effects on certain species. However, <strong>the</strong> responses<strong>of</strong> native ecosystems to plant invasions may be <strong>of</strong> longerduration than a few decades, thus long-term monitoring isneeded to understand <strong>the</strong> ecosystem changes in response toS. alterniflora invasions. In <strong>the</strong> meantime, most <strong>of</strong> ourstudies have examined <strong>the</strong> effects <strong>of</strong> S. alterniflora invasionson biodiversity and processes <strong>of</strong> native ecosystems.Therefore, future studies are clearly needed to examine how<strong>the</strong> change <strong>of</strong> one ecosystem component affects or isaffected by those <strong>of</strong> o<strong>the</strong>r components, as examined byLevin et al. (2006) in San Francisco Bay (USA), and to link<strong>the</strong> changes <strong>of</strong> biodiversity caused by S. alterniflorainvasions to <strong>the</strong> alterations <strong>of</strong> ecosystem processes. Finally,considering that most <strong>of</strong> <strong>the</strong> marshlands invaded by S.alterniflora that we studied are protected for conserving <strong>the</strong>native biodiversity and maintaining <strong>the</strong> ecosystem integrityin <strong>the</strong> Yangtze River estuary, S. alterniflora invasions needto be managed appropriately.ACKNOWLEDGMENTSWe thank <strong>the</strong> students at <strong>the</strong> Ecology Lab <strong>of</strong> BiologicalInvasions at Fudan University who <strong>of</strong>fered assistance in <strong>the</strong>filed. The entire work described here was financiallysupported by National Basic Research Program <strong>of</strong> China(Grant no.: 2006CB403305), Natural Science Foundation <strong>of</strong>China (Grant No.: 30670330 and 30370235), <strong>the</strong> Ministry <strong>of</strong>Education <strong>of</strong> China (Grant No.: 105063), and <strong>the</strong> Scienceand Technology Department <strong>of</strong> Shanghai (Grant No.:04DZ19304) to Bo Li.REFERENCESChen, H.L., Li B., Fang C.M., Chen J.K., and Wu J.H. 2007a. Exoticplant influences soil nematode communities through litterinput. Soil Biology and Biochemistry 39: 1782-1793.Chen, H.L., Li B., Hu J.B., Chen J.K., and Wu J.H. 2007b. Effects<strong>of</strong> Spartina alterniflora invasion on benthic nematode communitiesin <strong>the</strong> Yangtze Estuary. Marine Ecology-Progress Series336: 99-110.Chen, J.K., Ma Z.J. and Li B. (ed). 2003. Comprehensive Surveyson Shanghai Jiuduansha Wetland Nature Reserve, <strong>the</strong> YangtzeRiver Estuary. Beijing: Science Press.Chen, Z.Y., Li B., Zhong Y., and Chen J.K. 2004. Local competitiveeffects <strong>of</strong> introduced Spartina alterniflora on Scirpus mariqueterat Dongtan <strong>of</strong> Chongming Island, <strong>the</strong> Yangtze River estuaryand <strong>the</strong>ir potential ecological consequences. Hydrobiologia528: 99-106.Chen, Z.Y., Fu C.Z., Wang H.Y., Li B., Wu J.H., and Chen J.K.2005a. Effects <strong>of</strong> Spartina alterniflora invasions on <strong>the</strong> macrobenthicinvertebrate community in saltmarshes at ChongmingDongtan , <strong>the</strong> Yangtze River Estuary. Wetland Science, 3: 1-7.Chen, Z.Y., Li B. and Chen J.K. 2005b. Growth-related traits andrelative competitive ability <strong>of</strong> invasive Spartian alterniflora andnative Scirpus mariqueter. Biodiversity Science 13: 130-136.Cheng, X.L., Luo Y.Q., Chen J.Q., Lin G.H., Chen J.K. and Li B.2006. Short-term C 4 plant Spartina alterniflora invasions change<strong>the</strong> soil carbon in C 3 plant-dominated tidal wetlands on a growingestuarine island. Soil Biology and Biochemistry 38: 3380–3386.Cheng, X.L., Chen J.Q., Luo Y.Q., Henderson R., Zhang Q.F.,Chen J.K. and Li B. 2008. Assessing <strong>the</strong> effects <strong>of</strong> short-termSpartina alterniflora invasion on labile and recalcitrant C and Npools by means <strong>of</strong> soil fractionation and stable C and N isotopes.Geoderma 145: 177-184.Cohen, A.N. and Carlton J.T. 1998. Accelerating invasion rate in ahighly invaded estuary. Science 279: 555-558.Gan, X.J. 2009. Habitat selection <strong>of</strong> saltmarsh birds at ChongmingDongtan in <strong>the</strong> Yangtze River Estuary as influenced by Spartinaalterniflora invasions. Ph.D. dissertation, Fudan University,Shanghai, China.Gan, X.J., Zhang K.J., Tang S.M., Li B. and Ma Z.J. 2006. Threenew records <strong>of</strong> birds in Shanghai: Locustella pleskei (Pleske’swarbler), Megalurus pryeri (Japanese swamp warbler) and Acrocephalusconcinens (blunt-winged paddyfield warbler). Journal<strong>of</strong> Fudan University (Natural Science) 45: 417–419.Grosholz, E. 2002. Ecological and evolutionary consequences <strong>of</strong>coastal invasions. Trends in Ecology and Evolution 17: 22-27.Jiang, L.F., Luo Y.Q., Chen J.K. and Li B. 2009. Ecophysiologicalcharacteristics <strong>of</strong> invasive Spartina alterniflora and native speciesin salt marshes <strong>of</strong> Yangtze River estuary, China. Estuarine,Coastal and Shelf Science 81:74-82.Levin, L.A, Neira C., and Grosholz E.D. 2006. Invasive cordgrassmodifies wetland trophic function. Ecology 87: 419-432.Li B., Liao C.Z., Zhang X.D., Chen H.L, Wang Q., Chen Z.Y., GanX.J., Wu J.H., Zhao B., Ma Z.J., Cheng X.L., Jiang L.F. andChen J.K. 2009. Spartina alterniflora invasions in <strong>the</strong> YangtzeRiver estuary, China: an overview <strong>of</strong> current status and ecosystemeffects. Ecological Engineering 35:511-520.Liao, C.Z., Luo Y.Q., Jiang L.F., Zhou X.H., Wu X.W., Fang C.M.,Chen J.K. and Li B. 2007. Invasion <strong>of</strong> Spartina alterniflora enhancedecosystem carbon and nitrogen stocks in <strong>the</strong> Yangtze Estuary,China. Ecosystems 10: 1351-1361.Liao, C.Z., Luo Y.Q., Fang C.M., Chen J.K. and Li B. 2008. Litterpool sizes, decomposition, and nitrogen dynamics in Spartina alterniflora-invadedand native coastal marshlands <strong>of</strong> <strong>the</strong> YangtzeEstuary. Oecologia 156: 589-600.Ma, Z.J., Li B., Jing K., Tang S.M. and Chen J.K. 2004. Are artificialwetlands good alternatives to natural wetlands for waterbirds?-A case study on Chongming Island, China. Biodiversityand Conservation 13: 333-350.Ma, Z.J., Wang Y., Gan X.J., Li B., Cai Y.T. and Chen J.K. 2009.Waterbird population changes in <strong>the</strong> wetlands at ChongmingDongtan in <strong>the</strong> Yangtze River estuary, China. EnvironmentalManagement 43:1187-1200.Quan, W.M., Fu C.Z., Jin B.S., Luo Y.Q., Li B., Chen J.K. and WuJ.H. 2007. Tidal marshes as energy sources for commerciallyimportant nektonic organisms: stable isotope analysis. MarineEcology-Progress Series 352: 89–99.Wang, J.Q., Zhang X.D., Nie M., Fu C.Z., Chen J.K. and Li B.(2008) Exotic Spartina alterniflora provides compatible habitatsfor native estuarine crab Sesarma dehaani in <strong>the</strong> Yangtze Riverestuary. Ecological Engineering 34: 57-64.Wang, M., Chen J.K. and Li B. 2007. Characterization <strong>of</strong> bacterialcommunity structure and diversity in rhizosphere soils <strong>of</strong> threeplants in rapidly changing salt marshes using 16S rDNA. Pedosphere17: 545-556.- 150 -
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FORWARD & ACKNOWLEDGEMENTSThe <stro
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TABLE OF CONTENTSForward & Acknowle
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Community Spartina Education and St
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CHAPTER ONESpartina Biology
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Chapter 1: Spartina Biology
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