Publications

Below is a list of books, monographs and journal articles authored or co-authored 

Authored Books, Edited Books and Monographs (Published or In Press)

 

Ashton, M. S., & M. J. Kelty. 2018. The Practice of Silviculture: Applied Forest Ecology. 10th edition, Wiley & Sons, New York.

Hall, J. S., and M. S. Ashton. 2016. Reforestation Handbook for Native Species for Central America. Smithsonian Tropical Research Institute, Panama.

Hall, J. S., and M. S. Ashton. 2016. Guía de crecimiento y sobrevivencia temprana de 64 especies de árboles nativos de Pananmá y el Neotrópico. Instituto Smithsonian de Investigaciones Tropicales. 

Ashton, M. S., U. M. Goodale, K. S. Bawa, P. S. Ashton, and J. D. Neidel (Editors). 2014. Restoring Working Forests in Human Dominated Lands of Tropical South Asia: An Introduction. Forest Ecology and Management, Special Issue V. 329

Alcott, E., Ashton, M. S., and B. S. Gentry (Editors). 2013. Natural and Engineered Solutions for Drinking Water Supplies: Lesson from the Northeastern United States and Directions for Global Watershed Management. CRC Press, Boca Raton, FL. 290 p.

Ashton, M. S., Tyrrell, M. L., Spalding, D., & B. Gentry (Editors). 2012. Managing Forest Carbon in a Changing Climate. Springer Verlag, New York. 410p.

DuVal, A., Muruetagoiena, T., & M. S. Ashton (Editors).  2012. Multiple-Use Management of Protected Natural Areas: Integrating Conservation, Restoration and Recreation in the Spanish Basque country. Nova Publ., New York.

Hall, J. S., Ashton, M. S., & E. J. Garen (Editors). 2011. The Ecology and Ecosystem Services of Native Trees: Implications for Reforestation and Land Restoration in Mesoamerica. Forest Ecology and Management, Special Issue. V. 261.

Tyrrell, M. L., Ashton, M. S., Spalding, D., & B. Gentry (Editors). 2009. Forests and Carbon: A Synthesis of Science, Management, and Policy for Carbon Sequestration in Forests. FES Bulletin 23, 450 p.

Clark, T. W., Cherney, D. N., Ashton, M. S., Bond, A., & A. Johnson (Editors). (2009). Development and environmental challenges in Podocarpus National Park, Ecuador. Journal of Sustainable Forestry, Special Issue 28: 597-893.

Clark, T. W., Dixon, L., Ashton, M. S., & B. Petit (Editors). 2006. Innovation and Appraisal of Sustainability Efforts in La Amistad, Bocas del Toro, Panama and Talamanca, Costa Rica. Journal of Sustainable Forestry, Special Issue 22: 1-185.

Clark, T. W., Ashton, M. S., Zimmerman, K., & Q. Newcomer (Editors). 2004. Conservation and Development of the Condor Biosphere Reserve, Ecuador. Journal of Sustainable Forestry, Special Issue 18: 1-327.

Clark, T. W., Ashton, M. S. & J. Tuxill (Editors). 2003. Conservation or Development? The Case of the Amisconde Project, La Amistad Biosphere Reserve, Costa RicaJournal of Sustainable Forestry, Special Issue 16: 1-211.

Asbjornsen, H. A., & M. S. Ashton (Editors). 2002. Balancing Conservation with Development: A Comparison of Two Forest Communities in Oaxaca, MexicoJournal of Sustainable Forestry, Special Issue 15: 1-131.

M. S. Ashton, P. M., O’Hara, J. L., & Hauff, R. D. (1999). Protecting Watershed Areas Case of the Panama Canal. Taylor & Francis Group. http://public.eblib.com/choice/PublicFullRecord.aspx?p=6607642

Ashton, M. S. & F. Montagnini (Editors). 1999. The Silvicultural Basis for Agroforestry Systems. CRC Press, Boca Raton, Florida. 278 p.

Ashton, M. S., O’Hara, J.  & R. Hauff (Editors). 1998. Protecting Watershed Areas: Case of the Panama Canal. Haworth Press, Binghamton, New York. 214 p.

Ashton, M., Gunatilleke, S., de Zoysa, N., Gunatilleke. N., & S. Wijesundera. 1997. A Field Guide to the Common Trees and Shrubs of Sri Lanka. Wildlife Heritage Trust, Colombo. 432 p.


Peer-Reviewed Journal Research Papers/Reviews  (Published or In Press)

2021

Borden, C.G., Duguid, M.C., Ashton, M.S. (2021). The legacy of fire: long-term changes to the forest understory from periodic burns in a New England oak-hickory forest, Fire Ecology, 17 (1), 1-17. https://doi.org/10.1186/s42408-021-00115-2

Carpenter, R., Ward, E.B., Wikle, J., Duguid, M.C., Bradford, M.A., Ashton, M.S. (2021). Soil nutrient recovery after shelterwood timber harvesting in a temperate oak hardwood forest: Insights using a twenty-five year chronosequence, Forest Ecology and Management, 499, 119604. https://doi.org/10.1016/j.foreco.2021.119604

Martin, M.P., Woodbury, D.J., Doroski, D.A., Nagele, E., Storace, M., Cook-Patton, S.C., Pasternack, R., Ashton, M.S. (2021). People plant trees for utility more often than for biodiversity or carbon, Biological Conservation, 261, 109224. https://doi.org/10.106/j.biocon.2021.109224

Martin, M., Woodbury, D., Glogower, Y., Duguid, M., Frey, B., & Ashton, M. S. (2021). Within-gap position shapes fifty years of forest dynamics in a temperate hardwood forest in Connecticut, USA. Forest Ecology and Management, 494, 119311. https://doi.org/10.1016/j.foreco.2021.119311

Piotto, D., Magnago, L. F. S., Montagnini, F., Ashton, M. S., Oliver, C., & Thomas, W. W. (2021). Nearby mature forest distance and regenerating forest age influence tree species composition in the Atlantic forest of Southern Bahia, Brazil. Biodiversity and Conservation, 30(7), 2165–2180. https://doi.org/10.1007/s10531-021-02192-w

Martin, M. P., Peters, C. M., Asbjornsen, H., & Ashton, M. S. (2021). Diversity and niche differentiation of a mixed pine–oak forest in the Sierra Norte, Oaxaca, Mexico. Ecosphere, 12(4). https://doi.org/10.1002/ecs2.3475

Miller, E. F., Doolittle, A. A., Cerutti, P. O., Naimark, J., Rufino, M. C., Ashton, M. S., & Mwangi, E. (2021). Spatial distribution and perceived drivers of provisioning service values across an East African montane forest landscape. Landscape and Urban Planning, 207, 103995. https://doi.org/10.1016/j.landurbplan.2020.103995

Hanle, J., Singhakumara, B. M. P., & Ashton, M. S. (2021). Complex Small-Holder Agriculture in Rainforest Buffer Zone, Sri Lanka, Supports Endemic Birds. Frontiers in Ecology and Evolution, 9, 608434. https://doi.org/10.3389/fevo.2021.608434

Scanlan, C., Doroski, D., Murphy-Dunning, C., & Ashton, M. S. (2021). Urban Resources Initiative: A University Model for Clinical Urban Forestry Education. Arboriculture & Urban Forestry, 47(1), 34–50. https://doi.org/10.48044/jauf.2021.004

Doroski, D. A., Duguid, M. C., & Ashton, M. S. (2021). Forest patch size predicts seed bank composition in urban areas. Applied Vegetation Science, 24(1). https://doi.org/10.1111/avsc.12534

2020

Doroski, D. A., Ashton, M. S., & Duguid, M. C. (2020). The future urban forest – A survey of tree planting programs in the Northeastern United States. Urban Forestry & Urban Greening, 55, 126816. https://doi.org/10.1016/j.ufug.2020.126816

Piotto, D., Flesher, K., Nunes, A. C. P., Rolim, S., Ashton, M., & Montagnini, F. (2020). Restoration plantings of non-pioneer tree species in open fields, young secondary forests, and rubber plantations in Bahia, Brazil. Forest Ecology and Management, 474, 118389. https://doi.org/10.1016/j.foreco.2020.118389

Hooper, E. R., & Ashton, M. S. (2020). Fragmentation reduces community‐wide taxonomic and functional diversity of dispersed tree seeds in the Central Amazon. Ecological Applications, 30(5). 

Hall, J. S., Harris, D. J., Saltonstall, K., Medjibe, V. de P., Ashton, M. S., & Turner, B. L. (2020). Resource acquisition strategies facilitate Gilbertiodendron dewevrei monodominance in African lowland forests. Journal of Ecology, 108(2), 433–448. 

Woodbury, D. J., & Yassir, I. (2020). Filling a void: Analysis of early tropical soil and vegetative recovery under leguminous, post‐coal mine reforestation plantations in East Kalimantan, Indonesia. Land Degradation & Development.

Ediriweera, S., Bandara, C., Woodbury, D. J., Mi, X., Gunatilleke, I. A. U. N., Gunatilleke, C. V. S., & Ashton, M. S. (2020). Changes in tree structure, composition, and diversity of a mixed-dipterocarp rainforest over a 40-year period. Forest Ecology and Management, 458, 117764. 

Hanle, J., Duguid, M. C., & Ashton, M. S. (2020). Legacy forest structure increases bird diversity and abundance in aging young forests. Ecology and Evolution.

2019

Piotto D, Craven D, Montagnini F, Ashton M, Oliver C, Thomas WW (2019) Successional, spatial, and seasonal changes in seed rain in the Atlantic forest of southern Bahia, Brazil. PLoS ONE 14(12): e0226474. 

Wikle, J., M. Duguid, and M. S. Ashton. 2019. Legacy forest structures in irregular shelterwoods differentially affect regeneration in a temperate hardwood forest. Forest Ecology and Management, 454, 117650.

Hall, J. S., D. J. Harris, K. Saltonstall, V. P. Medjibe, M. S. Ashton, and B. L. Turner. 2019. Resource acquisition strategies facilitate Gilbertiodendron dewevrei monodominance in African lowland forests. Journal of Ecology.

Singer, J. A., R. Turnbull, M. Foster, C. Bettigole, B. R. Frey, M. C. Downey, K. R. Covey, and M. S. Ashton. 2019. Sudden Aspen Decline: A review of pattern and process in a changing climate. Forests, 10, 671.

Mossman, A., M. R. Lambert, M. S. Ashton, J. Wikle, and M. C. Duguid. 2019. Two salamander species respond differently to regeneration timber harvest across time. Peer J.

Ostrowsky, L. R., M. S. Ashton. 2019. Untangling the red maple paradox: Regeneration and morphological plasticity of Acer rubrum. 2019 ESA Annual Meeting (August 11-16). 

Martin, M., K. L. Geiger, B. M. P. Singhakumara and M. S. Ashton. 2018. Quantitatively characterizing the floristics and structure of a traditional homegarden in a village landscape, Sri Lanka. Agroforestry Systems, 93 (4), 1439-1454. 

Pregitzer, C. C., M. S. Ashton, S. Charlop-Powers, A. W. D’Amato, B. R. Frey, B. Gunther, R. A. Hallett, K. S. Pregitzer, K. W. Woodall, and M. A. Bradford. 2019. Defining and assessing urban forests to inform forest management and policy. Environmental Research Letters, Open Access. 

Prats, K. R., C. R. Brodersen, and M. S. Ashton. 2019. Influence of climate seasonality on Quercus suber L., leaf traits in the Iberian Peninsula. American Journal of Botany 106: 656-666. 

Fenichel, E. P., W. L. Adamowicz, M. S. Ashton, and J. S. Hall. 2019. Incentive systems for forest-based ecosystem services with missing financial service markets. Journal of the Association of Environmental and Resource Economists 6: 319-347.

Weerasinghe, M., M. S. Ashton, E. R. Hooper, and B. M. P. Singhakumara. 2018. Floristics of soil seed banks on agricultural and disturbed land cleared of tropical forests. Restoration Ecology, 27 (1), 138-147.
 

2018

Rutenbeck, N. E., B. R. Frey, K. R. Covey, G. P. Berlyn, O. J. Schmitz, B. C. Larson, and M. S. Ashton. 2018. Influence of gap position and competition control on the leaf physiology of planted Picea glauca and natural regeneration of Populus tremuloides. Forest Ecology and Management, 424, 228-235.

Frey, B. R., and M. S. Ashton. 2018. Growth, survival, and sunfleck response of underplanted red oaks (Quercus section Erythrobalanus) along a topographical gradient in southern New England. Forest Ecology and Management 419, 179-186.

Lefland, A. B., M. C. Duguid, R. S. Morin, M. S. Ashton. 2018. The demographics and regeneration dynamic of hickory in second-growth temperate forest. Forest Ecology and Management, 419, 187-196

Craven, D., J. S. Hall, M. S. Ashton, and G. P. Berlyn. 2018. Environmental filtering limits functional diversity during succession in a seasonally wet tropical secondary forest. Journal of Vegetation Science, 29, 511-520.

Ashton, M. S., E. R. Hooper, B. Singhakumara, and S. Ediriweera. 2018. Regeneration recruitment and survival in an Asian tropical rain forest: Implications for sustainable management. Ecosphere, 9 (2).

Montes, I., F. Montagnini, and M. S. Ashton. 2018. Allometric relationships and reforestation guidelines for Maclura tinctoria, an Important multi-purpose timber tree of Latin America . New Forests, 49, 249-263.

Doroski, D. A., A. J. Felson, M. A. Bradford, M. S. Ashton, E. E. Oldfield, R. A. Hallet and S. E. Kuebbing. 2018. Factors driving natural regeneration beneath an urban tree plantation . Urban Forestry and Urban Greening, 29, 238-247

2017

Umunay, P., T. G. Gregoire and M. S. Ashton. 2017. Estimating biomass and carbon for Gilbertiodendron dewevrei (De Wild) Leonard, a dominant canopy tree of African tropical rainforest: Implications for policies on forest carbon. Forest Ecology and Management, 404: 31-44.

Sinacore, K., Hall, J. S., Potvin, C., Royo, A. A., Ducey, M. J. and M. S. Ashton. 2017. Unearthing the hidden world of roots: root biomass and architecture differs among species within the same guild. PloS one 12:(10) e0185934

Fernandez-Vega, J., K. R. Covey, and M. S. Ashton. 2017. Tamm Review: Large-scale disturbances and their role in regenerating shade-intolerant tree species in Mesoamerican rainforests: Implications for sustainable forest management. Forest Ecology and Management 395: 48-68.

Sohng, J., B. M. P. Singhakumara and M. S. Ashton. 2017. Effects on soil chemistry of tropical deforestation for agriculture and subsequent reforestation with special reference to changes in carbon and nitrogen. Forest Ecology and Management 389: 331-340.

Delavaux, C. S., T. Camenzind, J. Homeier, R. Jiménez-Paz, M. S. Ashton, and Simon A. Queenborough. 2017. Nutrient enrichment effects on mycorrhizal fungi in an Andean tropical montane forest. Mycorrhiza, 27 (4): 311-319.

2016

T. T. Caughlin, S. J. Graves, G. P. Asner, M. van Breugel, J. S. Hall, R. E. Martin, M. S. Ashton, S. A. Bohlman. 2016. A hyperspectral image can predict tropical tree growth rates in single‐species standsEcological Applications, 26 (8), 2369-2375.

K. R. Covey, C. P. Bueno de Mesquita, B. Oberle, D. S. Maynard, C. Bettigole, T. W. Crowther, M. C. Duguid, B. Steven, A. E. Zanne, M. Lapin, M. S. Ashton, C. D. Oliver, X. Lee, and M. A. Bradford. 2016. Greenhouse tace gases in deadwood. Biogeochemistry, 130 (3), 215-226.

Duguid, M. C., E. H. Morrell, E. Goodale, & M. S. Ashton (2016). Changes in breeding bird abundance and species composition over a 20-year chronosequence following shelterwood harvests in oak-hardwood forests. Forest Ecology and Management, 376, 221-230.

Martin, M. P., C. Simmons, and M. S. Ashton (2016). Survival is not enough: The effects of microclimate on the growth and health of three common urban tree species in San Francisco, California. Urban Forestry & Urban Greening, 19, 1-6.

Lu, Z., C. Peters, M. S. Ashton, J. Feng, and D. Xue. 2016. The effect of forest tenure on forest composition in a Miao Area of Guizhou, China. Mountain Research and Development, 36 (2), 193-203.

Bare, M. C., and M. S. Ashton. Growth of native tree species planted in montane reforestation projects in the Colombian and Ecuadorian Andes differs among site and species. New Forests, 47 (3), 1-23.

T. W. Crowther, H. B. Glick, K. R. Covey, C. Bettigole, D. S. Maynard, S. M. Thomas, J. R. Smith, G. Hintler, M. C. Duguid, G. Amatulli, M. N. Tuanmu, W. Jetz, C. Salas, C. Stam, D. Piotto, R. Tavani, S. Green, G. Bruce, S. J. Williams, S. K. Wiser, M. O. Huber, G. M. Hengeveld, G. J. Nabuurs, E. Tikhonova, P. Borchardt, C. F. Li, L. W. Powrie, M. Fischer, A. Hemp, J. Homeier, P. Cho, A. C. Vibrans, P. M. Umunay, S. L. Piao, C. W. Rowe, M. S. Ashton, P. R. Crane, M. A. Bradford. 2016. Corrigendum: Mapping tree density at a global scale. Nature, 532 (7598), 268.

2015

C. Barker, M. S. Ashton, P. A. Ashton. 2015. Segregation of Tilia cordata and T. platyphyllos (Malvaceae) along environmental gradients. New Journal of Botany, 5 (3): 157-163.

T. W. Crowther, H. B. Glick, K. R. Covey, C. Bettigole, D. S. Maynard, S. M. Thomas, J. R. Smith, G. Hintler, M. C. Duguid, G. Amatulli, M. N. Tuanmu, W. Jetz, C. Salas, C. Stam, D. Piotto, R. Tavani, S. Green, G. Bruce, S. J. Williams, S. K. Wiser, M. O. Huber, G. M. Hengeveld, G. J. Nabuurs, E. Tikhonova, P. Borchardt, C. F. Li, L. W. Powrie, M. Fischer, A. Hemp, J. Homeier, P. Cho, A. C. Vibrans, P. M. Umunay, S. L. Piao, C. W. Rowe, M. S. Ashton, P. R. Crane, M. A. Bradford. 2016. Mapping tree density at a global scale. Nature, 525, 201-205.

Oldfield, E., A. J. Felson, N. Auyeung, T. W. Crowther, N. Falxa-Raymond, Y. Harada, D. S. Maynard, N. W. Sokol, R. I. Warren, R. J., Hallett, M. S. Ashton & M. A. Bradford. Growing the urban forest: tree performance in response to biotic and abiotic land management. Restoration Ecology (In press).

Craven, D., M. van Breugel, J. S. Hall, M. S. Ashton and G. P. Berlyn. 2015. Changing gears during succession: shifting ecological strategies in young tropical secondary forests. Oecologia, 179 (1): 293-305.

K. R. Covey, A. L. Barrett, and M. S. Ashton. 2015. Ice storms as a successional pathway for Fagus grandifolia advancement in Quercus rubra dominated forests of southern New England. Canadian Journal of Forest Research, 45 (11): 1628-1635.

Covey, K., C. J. W. Carroll, M. C. Duguid, K. Dorji, T. Dorji, S. Tashi & M. S. Ashton. 2015. Developmental dynamics following selective logging of evergreen oak forest in the Eastern Himalaya, Bhutan: Structure, composition and spatial pattern. Forest Ecology and Management, 336: 235-243.

Ashton, M. S., M. C. Duguid, A. L. Barrett, & K. Covey. 2015. Yale School Forests, New England, United States of America. In: “Forest Plans of North America”, Siry, J. P., Bettinger, P., Merry, K., Grebner, D. L., Boston, K., & C. Cieszewski. Academic Press, New York, NY. 253-364 pp.

2014

Ashton, M. S., U. M. Goodale, K. S. Bawa, P. S. Ashton, and J. D. Neidel (Editors). 2014. Restoring Working Forests in Human Dominated Forest in Tropical South Asia: An Introduction. Forest Ecology and Management, Special Issue V. 329

Martin, M. P., Peters, C. M., and M. S. Ashton. 2014. Revisiting camu-camu (Myrciaria dubia): Twenty-seven years of fruit collection and flooding at an ox-bow lake in Peruvian Amazonia. Economic Botany

Warren, K. L. and M. S. Ashton. 2014. Change in soil and forest floor carbon after shelterwood harvests in a New England oak-hardwood forest, USA. International Journal of Forest Research.

Ashton, M. S., I. A. U. N. Gunatilleke, C. V. S. Gunatilleke, K. Tennakoon, and P. S. Ashton (2014). The use and cultivation of plants that yield products other than timber from South Asian forests, and their potential in forest restoration. Forest Ecology and Management.

Ashton, M. S., C. V. S. Gunatilleke, I. A. U. N. Gunatillke, B. M. P. Singhakumara, S. Gamage, C. Tomimura and T. Shibayama. (2014). Restoration of rain forest beneath pine plantations: A relay floristics model with special application to tropical South AsiaForest Ecology and Management.

Grogan, J., Landis, R. M., Free, C. M., Schulze, M. D., Lentini, M., Ashton, M. S. (2014). Big-leaf mahogany Swietenia macrophylla population dynamics and implications for sustainable managementJournal of Applied Ecology. doi: 10.1111/1365-2664.12210

Goodale, U. M., Berlyn, G. P., Gregoire, T. G. , Tennakoon, K. U. and Ashton, M. S. (2014). Differences in Survival and Growth Among Tropical Rain Forest Pioneer Tree Seedlings in Relation to Canopy Openness and HerbivoryBiotropica, 46: 183–193. doi: 10.1111/btp.12088

Tyrrell, M., Fried, M., Ashton, M., & R. Campbell. 2014. The Quiet Corner Initiative at the Yale School of Forestry and Environmental Studies. In: “Conservation catalysts: The academy as nature’s agent”.  Levitt, J.N. (Editor), Lincoln Institute of Land Policy, Cambridge, MA. 151-170 pp.

2013

Schneider, T., Ashton, M. S., Montagnini, F., and P. P. Milan. 2013. Growth performance of sixty tree species in smallholder reforestation trials on Leyte, Philippines. New Forests. 45(1): 83-96; doi 10.1007/s11056-013-9393-5

Jack-scott, E., Piana, M., Troxel, B., Murphy-dunning, C., & Ashton, M. S. 2013. Stewardship Success: How Community Group Dynamics Affect Urban Street Tree Survival and Growth. Journal of Arboriculture and Urban Forestry, 39;189-196.

Duguid, M. C., & M. S. Ashton. 2013. A meta-analysis of the effect of forest management for timber on understory plant species diversity in temperate forests. Forest Ecology and Management. 303, 81-90.

Duguid, M. C., Frey, B. R., Ellum, D. S., Kelty, M. & M. S. Ashton. 2013. The influence of ground disturbance and gap position on understory plant diversity in upland forests of southern New England. Forest Ecology and Management. 303, 148-159.

Alcott, E, Ashton, M. S., and B. S. Gentry (Editors). 2013. Natural and Engineered Solutions for Drinking Water Supplies: Lesson from the Northeastern United States and Directions for Global Watershed Management. CRC Press, Boca Raton, FL. 290 p. 

Troxel, B., Piana, M., Ashton, M. S., Murphy-Dunning, C., 2013. Relationships between bole and crown size for young urban trees in the northeastern USA. Urban Forestry & Urban Greening. 12:144-153.

2012

Craven, D., Hall, J. S., Ashton, M. S., and G. P. Berlyn. 2012. Water-use efficiency and whole-plant performance of nine tropical tree species at two sites with contrasting water availability in Panama. Trees: Structure and Function

Goodale, U. M., Ashton, M. S., Berlyn, G. P., Gregoire, T. G., Singhakumara, B. M. P., & K. U. Tennakoon. 2012. Disturbance and tropical pioneer species: Patterns of association across life history stages. Forest Ecology and Management 277: 54-66.

Laurance, W. F., et al., 2012. Averting biodiversity collapse in tropical forest protected areas. Nature 489: 290-294. 

Tomimura, C., Singhakumara, B. M. P., & M. S. Ashton. 2012. Pattern and composition of secondary succession beneath Caribbean pine plantations of southwest Sri Lanka. Journal of Sustainable Forestry 31: 818-834. 

Ashton, M. S., Tyrrell, M.L., Spalding, D., & B. Gentry (Editors). 2012. Managing Forest Carbon in a Changing Climate. Springer Verlag, New York. 410p.

DuVal, A., Muruetagoiena, T., & M. S. Ashton (Editors).  2012. Multiple-Use Management of Protected Natural Areas: Integrating Conservation, Restoration and Recreation in the Spanish Basque country. Nova Publ., New York.

Protecting Watershed AreasCase of the Panama Canal
Protecting Watershed AreasCase of the Panama Canal