Julie Denslow

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Julie Sloan Denslow (born November 29, 1942, Coral Gables, Florida) is an American botanist, ecologist and biologist. She grew up in South Florida, and always loved nature. She graduated from Coral Gables Senior High School in 1960. [1] She has contributed to the field of ecology through her work with and research of tropical ecosystems. Earlier in her career, she spent significant time in the field in tropical locations such as Costa Rica and Panama, as well as in temperate locations in Louisiana. and later on in her career she worked more in the office and classroom, but still spent the occasional day in the field. She has focused on research involving the ecology of exotic invasive plant species, and on ecosystem reactions and recovery following disturbances. Denslow is also a strong supporter of gender equality in the natural sciences, pushing for equal representation of women involved in tropical research and leadership during a 2007 Gender Committee Meeting within the Association for Tropical Biology and Conservation (ATBC). [2] Her most notable contribution to tropical research is her paper "Gap Partitioning among Tropical Rainforest Trees", published in 1980. [3]

Contents

Early life and education

Influences in early life

Denslow was influenced by the natural world from an early age. Growing up in South Florida, her family spent plenty of time outdoors. She grew up fishing and swimming with her parents and her cousins in the Everglades and the Florida Keys. Throughout her high school and college years, she assisted graduate students at the Virginia UM Marine Laboratory. While Denslow was studying at Oberlin College, Rachel Carson published Silent Spring, bringing to light the negative impacts that humans can have on the environment. She grew up knowing that she wanted to have a career focused on nature and conservation, but it was a pivotal experience during a 2-month field course on the fundamentals of tropical ecology in Costa Rica with the Organization for Tropical Studies that she found her passion for tropical ecosystems, and felt she could positively impact this field. [1]

Education [4]

1964 A.B. Zoology, Oberlin College, Oberlin, Ohio

1969 M.S. Biology, University of Miami, Coral Gables, Florida.

1978 Ph.D. Botany, University of Wisconsin, Madison, Wisconsin

Career

Field work in Invasive Species Unit

Denslow worked for the United States Department of Agriculture Forest Service at the Institute for Pacific Islands Forestry as a research ecologist and team leader of the Invasive Species Unit from 1999 to 2007. While working there, she and a team of other scientists studied impacts on native forests in Hawaii, and other Pacific islands when exotic invasive plants were introduced, and used their findings to help advise land managers as well as the public on the effects that non-native plants can have on native ecosystems. [1]

Publications

Papers

Gap Partitioning among Tropical Rainforest Trees [3]

Her long career as a scientist and educator allowed her to publish many papers, with the journal Biotropica containing 11 of her works. These 11 papers alone have been cited widely by other researchers, with over 700 citations in other papers. Her paper "Gap Partitioning among Tropical Rainforest Trees" alone accounts for a large percentage of these, and had been cited over 450 times as of 2016—making it the most cited paper in Biotropica's history. [5] However, her paper on gap partitioning among tropical rainforest trees is her most notable contribution to the field of tropical ecology. It was published in 1980 in the journal Biotropica. This study focused on the gaps created in tropical rainforests when trees fall, and sought to answer how so many different species of trees can have reproductive success within these gaps. Denslow considered that depending on the severity of the tree fall, the gaps would be made larger or smaller. She suggested that rainforest trees adapted strategies to improve reproductive success by evolving specific traits that increase the rate of seedling success and recruitment in tree fall gaps of certain size ranges—some species may exploit smaller gaps, while others may exploit larger gaps. The size of the gaps affects many other factors in seedling success, such as the amount of light, humidity, and temperature. This 'partitioning' of the tree fall clearings encourages diversity and coexistence of rainforest tree species, because each species is best adapted to a specific microclimate.

Other Significant Research [6]

  • 1985 Denslow, J. S. Disturbance-mediated coexistence of species. pp. 307–323 In: S.T.A. Pickett and P. S. White (eds.) Ecology of Natural Disturbance and Patch Dynamics. Academic Press, Orlando, Florida.
  • 1987 Denslow, J. S. Tropical Treefall Gaps and Tree Species Diversity. Ann. Rev. Ecol. Syst. 18: 431–451.
  • 1990 Denslow, J. S., J. Schultz, P. M. Vitousek, B. Strain. Growth responses of tropical shrubs to treefall gap environments. Ecology 71:165-179.
  • 1990 J. S. Denslow and A. E. Gomez D. Seed rain to treefall gaps in a neotropical rain forest. Can. J. Forest Research 20:642-648.
  • 1996 Chazdon, R. L., R. K. Colwell, J. S. Denslow, and M. Guariguata. Statistical methods for estimating species richness in primary and secondary rain forests of NE Costa Rica. In: Measuring and Monitoring Forest Biological Diversity: The International Network of Biodiversity Plots, Smithsonian Institution Press, In press.

Thesis

1978 J. S. Denslow. Secondary succession in a Colombian rainforest: Strategies of species response across a disturbance gradient. Ph.D. Thesis, University of Wisconsin-Madison [7]

Book

1988 J. S. Denslow and C. Padoch (eds.) People of the Tropical Rain Forest. U. of California Press, Berkeley and Los Angeles, 225 pp.

Recognitions

Julie S. Denslow Prize

The tropical ecology journal Biotropica has recognized Denslow's research contributions to the field by enstating the Julie S. Denslow Prize in 2015. Previously called the Award for Excellence in Tropical Biology and Conservation, since 2000 it has been awarded each year to a researcher who has published an outstanding paper in the journal during the previous calendar year. Recipients are determined based on papers that are presented clearly, with a well thought out design, that allow for new insights into factors influencing the various processes in tropical ecosystems. [5]

Related Research Articles

<span class="mw-page-title-main">Rainforest</span> Type of forest with high rainfall

Rainforests are forests characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropical rainforests or temperate rainforests, but other types have been described.

<span class="mw-page-title-main">Tropical forest</span> Generic forest in the tropics

Tropical forests are forested landscapes in tropical regions: i.e. land areas approximately bounded by the tropic of Cancer and Capricorn, but possibly affected by other factors such as prevailing winds.

<span class="mw-page-title-main">Liana</span> Type of vine

A liana is a long-stemmed, herbaceous or woody vine that is rooted in the soil at ground level and uses trees, as well as other means of vertical support, to climb up to the canopy in search of direct sunlight. The word liana does not refer to a taxonomic grouping, but rather a habit of plant growth – much like tree or shrub. It comes from standard French liane, itself from an Antilles French dialect word meaning to sheave.

<span class="mw-page-title-main">Tropical rainforest</span> Forest in areas with heavy rainfall in the tropics

Tropical rainforests are dense and warm rainforests that occur in tropical rainforest climate where there is no dry season – all months have an average precipitation of at least 60 mm. True rainforests are typically found between 10 degrees north and south of the equator ; they are a subset of the tropical forest biome that occurs roughly within the 28-degree latitudes. Tropical rainforests are a type of tropical moist broadleaf forest, that includes the more extensive seasonal tropical forests.

<span class="mw-page-title-main">Old-growth forest</span> Forest that has developed over a long period of time without disturbance

An old-growth forest is a forest that has developed over a long period of time without disturbance. Due to this, old-growth forests exhibit unique ecological features. The Food and Agriculture Organization of the United Nations defines primary forests as naturally regenerated forests of native tree species where there are no clearly visible indications of human activity and the ecological processes are not significantly disturbed. One-third of the world's forests are primary forests. Old-growth features include diverse tree-related structures that provide diverse wildlife habitats that increases the biodiversity of the forested ecosystem. Virgin or first-growth forests are old-growth forests that have never been logged. The concept of diverse tree structure includes multi-layered canopies and canopy gaps, greatly varying tree heights and diameters, and diverse tree species and classes and sizes of woody debris.

<span class="mw-page-title-main">Windthrow</span> Trees uprooted by wind

In forestry, windthrow refers to trees uprooted by wind. Breakage of the tree bole (trunk) instead of uprooting is called windsnap. Blowdown refers to both windthrow and windsnap.

<span class="mw-page-title-main">Forest dynamics</span> Biotic and abiotic ecosystem influences

Forest dynamics describes the underlying physical and biological forces that shape and change a forest ecosystem. The continuous state of change in forests can be summarized with two basic elements: disturbance and succession.

<span class="mw-page-title-main">Intermediate disturbance hypothesis</span> Model proposing regional biodiversity is increased by a moderate level of ecological disturbance

The intermediate disturbance hypothesis (IDH) suggests that local species diversity is maximized when ecological disturbance is neither too rare nor too frequent. At low levels of disturbance, more competitive organisms will push subordinate species to extinction and dominate the ecosystem. At high levels of disturbance, due to frequent forest fires or human impacts like deforestation, all species are at risk of going extinct. According to IDH theory, at intermediate levels of disturbance, diversity is thus maximized because species that thrive at both early and late successional stages can coexist. IDH is a nonequilibrium model used to describe the relationship between disturbance and species diversity. IDH is based on the following premises: First, ecological disturbances have major effects on species richness within the area of disturbance. Second, interspecific competition results in one species driving a competitor to extinction and becoming dominant in the ecosystem. Third, moderate ecological scale disturbances prevent interspecific competition.

<span class="mw-page-title-main">Canopy (biology)</span> Aboveground portion of a plant community or crop

In biology, the canopy is the aboveground portion of a plant cropping or crop, formed by the collection of individual plant crowns. In forest ecology, canopy refers to the upper layer or habitat zone, formed by mature tree crowns and including other biological organisms. The communities that inhabit the canopy layer are thought to be involved in maintaining forest diversity, resilience, and functioning. Shade trees normally have a dense canopy that blocks light from lower growing plants.

<span class="mw-page-title-main">Treefall gap</span> Ecological feature

A treefall gap is a distinguishable hole in the canopy of a forest with vertical sides extending through all levels down to an average height of 2 m (6.6 ft) above ground. These holes occur as result of a fallen tree or large limb. The ecologist who developed this definition used two meters because he believed that "a regrowth height of 2 m was sufficient" for a gap to be considered closed, but not all scientists agree. For example, Runkle believed that regrowth should be 10–20 m (33–66 ft) above the ground. Alternatively, a treefall gap is "the smallest gap [that must] be readily distinguishable amid the complexity of forest structure."

Cocha Cashu Biological Station is a tropical biological research station located at 11° 54'S and 71° 22'W in Manú National Park, Peru. It was established in 1969-70, predating the founding of its containing national park. Though only 10 km2 in area, the site has provided valuable research. The station is situated on the shore of an oxbow lake, from which it takes its name. "Qucha" is the Quechua word for lake. "Cashu" is derived from the English word "cashew" and refers to the shape of the lake.

Tropical ecology is the study of the relationships between the biotic and abiotic components of the tropics, or the area of the Earth that lies between the Tropic of Cancer and the Tropic of Capricorn. The tropical climate experiences hot, humid weather and rainfall year-round. While many might associate the region solely with the rainforests, the tropics are home to a wide variety of ecosystems that boast a great wealth of biodiversity, from exotic animal species to seldom-found flora. Tropical ecology began with the work of early English naturalists and eventually saw the establishment of research stations throughout the tropics devoted to exploring and documenting these exotic landscapes. The burgeoning ecological study of the tropics has led to increased conservation education and programs devoted to the climate. Tropical ecology provides a wealth of natural resources to humans, this includes contributing to the carbon cycle, with the ability to store 50% of carbon emissions as well as turnover 40% of global oxygen. However, despite the natural services provided by tropical ecology, deforestation is a threat of tropical rainforests. Any plant of interest can be exploited for commercial reasons and extraction of these specific plant species can be at a rapid rate without time for healthy regeneration. Most of the global plant biodiversity is hosted in tropical areas, however studies in this area is mostly covered by scientist from Northern countries. Inclusion of scientist from countries where rainforest is present is heavily encouraged because it extends global knowledge and research which advances scientific contributions, benefiting tropical ecology.

<span class="mw-page-title-main">La Suerte Biological Field School</span>

La Suerte Biological Field School, located in Northeastern Costa Rica, is one of two field schools operated by the Maderas Rainforest Conservancy. The site is situated in a tropical rainforest basin. It houses courses in primatology, ecology, botany, and other courses related to the flora and fauna of Northeastern Costa Rica.

Monodominance is an ecological condition in which more than 60% of the tree canopy comprises a single species of tree. Monodominant forests are quite common under conditions of extra-tropical climate types. Although monodominance is studied across different regions, most research focuses on the many prominent species in tropical forests. Connel and Lowman, originally called it single-dominance. Conventional explanations of biodiversity in tropical forests in the decades prior to Connel and Lowman's work either ignored monodominance entirely or predicted that it would not exist.

Phyllis Dewing Coley is a Biology professor currently teaching at the University of Utah. In 1996 she received the University's Distinguished Research Award. She has been a research associate at the Smithsonian Tropical Research Institute since 1995. In 2023, she was elected to the National Academy of Sciences.

<span class="mw-page-title-main">Light gap</span> Ecological terminology

In ecology, a light gap is a break in forest canopy or similar barrier that allows young plants to grow where they would be otherwise inhibited by the lack of light reaching the seedbed. Light gaps form predominantly when a tree falls, and thus produces an opening in the forest canopy. Light gaps are important for maintaining diversity in species-rich ecosystems.

Katherine Carter Ewel is a Professor Emeritus at the University of Florida's School of Forest Resources and Conservation. She is an ecosystem, forest, and wetlands ecologist who has worked in Florida for much of her career, focusing much of it on cypress swamps, pine plantations, and mangrove forests in the Pacific. Ewel served as the vice-president of the Society of Wetland Scientists in 2003, becoming president in 2004 and now since 2005, a past president. She has now retired and lives near Gainesville, Florida.

<span class="mw-page-title-main">North American inland temperate rainforest</span>

The North American inland temperate rainforest is a 7 million hectare disjunct temperate rainforest spreading over parts of British Columbia in Canada as well as Washington, Idaho and Montana on the US side. Its patches are located on the windward slopes of the Rocky Mountains and the Columbia Mountains, extending roughly over 1000km from 54° North to 45° North. It is one of the largest inland temperate rainforests in the world.

John Massa Kasenene is a botanical and environmental ecologist, academic, scientist and academic administrator in Uganda. From 4 October 2022, he serves as the substantive Deputy Vice Chancellor of the Mountains of the Moon University (MMU), at that time, the tenth public university in the country.

<span class="mw-page-title-main">Tropical Wet Forests (US and Mexico)</span>

The Tropical Wet Forests are a Level I ecoregion of North America designated by the Commission for Environmental Cooperation (CEC) in its North American Environmental Atlas. As the CEC consists only of Mexico, the United States, and Canada, the defined ecoregion does not extend outside these countries to Central America nor the Caribbean.

References

  1. 1 2 3 "Julie Denslow". hilo.hawaii.edu. Retrieved 2018-10-26.
  2. "Gender Committee Meeting 2007". tropicalbiology.org. Retrieved 2018-10-26.
  3. 1 2 Denslow, Julie Sloan (1980). "Gap Partitioning among Tropical Rainforest Trees". Biotropica. 12 (2): 47–55. doi:10.2307/2388156. JSTOR   2388156.
  4. "Julie Denslow| Pacific Southwest Research Station". 2012-10-30. Archived from the original on 2012-10-30. Retrieved 2018-11-20.
  5. 1 2 "Biotropica renames its "Outstanding Paper" awards for two pioneering scientists". Biotropica Editor's Blog. 2016-09-12. Retrieved 2018-10-26.
  6. Denslow, Julie. "JULIE SLOAN DENSLOW" . Retrieved 2018-11-20.
  7. Denslow, Julie S. (1996), "Functional Group Diversity and Responses to Disturbance", Biodiversity and Ecosystem Processes in Tropical Forests, Ecological Studies, vol. 122, Springer Berlin Heidelberg, pp. 127–151, doi:10.1007/978-3-642-79755-2_7, ISBN   9783642797576