Abstract We examined the seasonal variation in totalnon-structural carbohydrate (TNC) concentrations inbranch, trunk, and root tissues of Anacardium excelsum,Luehea seemannii, Cecropia longipes, and Urera caracas-ana growing in a seasonally dry forest in Panama. Ourmain goals were: (1) to determine the main sites of carbo-hydrate storage, and (2) to determine if seasonal patternsof carbohydrate storage are related to seasonal asynchro-nies in carbon supply and demand. We expected asynchro-nies to be related to seasonal variation in water and lightavailability and to foliar and reproductive phenology.Cecropia and Urera are fully drought-deciduous and sowe expected them to exhibit the most dramatic seasonalvariation in TNC concentrations. We predicted that maxi-mum carbon supply would occur when canopies were attheir fullest and that maximum carbon demand would oc-cur when leaves, flowers, and fruits were produced. Theconcentration of total non-structural carbohydrates was as-sessed monthly in wood tissue of roots and in wood andbark tissue of terminal branches. Trunk tissue was sam-pled bimonthly. All tissues sampled served as storage sitesfor carbohydrates. As predicted, TNC concentrations var-ied most dramatically in branches of Cecropia and Urera:a 4-fold difference was observed between dry season max-ima and wet season minima in branch wood tissue. Peakconcentrations exceeded 25% in Urera and 30% in Cecr-opia. Less dramatic but significant seasonal variation wasobserved in Anacardium and Luehea. In all species, mini-mum branch TNC concentrations were measured duringcanopy rebuilding. In Anacardium, maximum branchTNC concentrations occurred when canopies were at theirfullest. In Cecro-pia, Urera, and Luehea, TNC concentra-tions continued to increase even as canopies thinned in theearly dry season. The greater photosynthetic capacity ofleaves produced at the beginning of the dry season and thepotential for the export of carbohydrates from senescingleaves may explain this pattern. In all species, the phenol-ogy of carbon gain was more important than the phenolo-gy of reproduction in influencing seasonal carbohydratepatterns. The combination of high TNC concentrationsand the large biomass of branches, trunks, and roots indi-cates these species are storing and moving large quantitiesof carbohydrates.Keywords Total non-structural carbohydrates · Anacardium excelsum · Cecropia longipes · Lueheaseemannii · Urera caracasanaIntroductionWhile temperatures in tropical forests are generally con-ducive to plant growth year-round, seasonal variation inthe availability of water, light, and nutrients has the po-tential to limit plant productivity. For example, photo-synthetic rates may be limited by low light intensitiesduring rainy seasons when water is plentiful or bydrought during dry seasons when light intensities are attheir highest (Wright and Van Schaik 1994; Mulkey et al.1996). The great variety of leaf longevity and patterns ofleaf production observed in tropical trees may result inpart from this contrasting seasonality of water and lightavailability (Wright 1996). Plants may also adapt to thisseasonal variation in resource availability at the level ofleaf morphology and physiology. There is evidence thatsome species produce seasonal leaf phenotypes withcharacteristics that optimize the allocation of resourcesfor carbon gain during different seasons (Kitajima et al.1997). Another response to temporal variation in re-source availability is to acquire a resource when it isplentiful and then store it until it is required.E.A. Newell (✉)Department of Biology, Hobart and William Smith Colleges, Geneva, NY 14456, USAe-mail: [email protected].: +1-315-7813590, Fax: +1-315-7813860S.S. MulkeyDepartment of Botany, University of Florida, Gainesville, FL 32611, USAS.J. WrightSmithsonian Tropical Research Institute, Apartado 2072, Balboa,Ancon, PanamaOecologia (2002) 131:333–342DOI 10.1007/s00442-002-0888-6ECOPHYSIOLOGYElizabeth A. Newell · Stephen S. MulkeyS. Joseph WrightSeasonal patterns of carbohydrate storage in four tropical tree speciesReceived: 3 July 2001 / Accepted: 3 January 2002 / Published online: 14 March 2002© Springer-Verlag 2002Whenever species experience seasonal asynchroniesin resource supply and demand, we should expect storedreserves to play an important role in the plant’s resourcebudget (Chapin et al. 1990). Tropical deciduous speciesshould be no different from temperate species in accu-mulating carbon when leaf canopies are full and drawingfrom stored carbohydrates while leafless for respiratorycosts and for the flushing of new leaves. Three speciesfrom Neotropical forests were found to follow this pat-tern, whether they were leafless during the dry season(Jacaratia mexicana, Spondias purpurea; Bullock 1992)or during the rainy season (Jacquinia pungens; Janzenand Wilson 1974). While seasonal variation in carbongain may be less common for evergreen species in tropi-cal forests than in temperate forests, there still may beperiods when demand for carbon does not match supply.For example, in three understory Psychotria shrub spe-cies, the costs of leaf production are paid in part by non-structural carbohydrates stored in shoot tissues (Tissueand Wright 1995). In Piper arieianum, an understoryshrub of wet tropical forests, the costs of reproductionrequire the use of stored reserves in addition to currentphotosynthate (Marquis et al. 1997).The importance of carbohydrate storage in temperatetrees has been well-documented (Kramer and Kozlowski1979), but we know little about its role in the productivi-ty and reproduction of tropical trees. Most studies on theseasonal patterns of carbohydrate storage in tropicaltrees have measured carbohydrate concentrations in oneorgan or another (e.g. canopy branches: Bhatt and Appukuttan 1986; trunk tissue: Olofinboba 1969; Newell1994), but rarely has storage been examined in multipleorgans simultaneously. When branch and trunk tissueshave been sampled together (e.g. Bullock 1992), a limit-ed number of sampling dates made a detailed descriptionof annual patterns difficult.This study addresses the following questions for trop-ical trees: (1) What are the main sites of carbohydratestorage? and (2) Are seasonal patterns in carbohydrateconcentrations related to predictable seasonal asynchro-nies in carbon supply and demand? Although the mainconducting cells in wood (secondary xylem) lack protop-lasts, living parenchyma cells