Geology topics

Daniel B. Botkin

Publications and source records attributed to Daniel B. Botkin.

4 recordsLinked to original sources

USGS2017

Modeling the long-term effects of introduced herbivores on the spread of an invasive tree

Context Melaleuca quinquenervia (Cav.) Blake (hereafter melaleuca) is an invasive tree from Australia that has spread over the freshwater ecosystems of southern Florida, displacing native vegetation, thus threatening native biodiversity. Suppression of melaleuca appears to be progressing through the introduction of insect species, the weevil, Oxiops vitiosa , and the psyllid, Boreioglycaspis melaleucae . Objective To improve understanding of the possible effects of herbivory on the landscape dynamics of melaleuca in native southern Florida plant communities. Methods We projected likely future changes in plant communities using the individual based modeling platform, JABOWA-II, by simulating successional processes occurring in two types of southern Florida habitat, cypress swamp and bay swamp, occupied by native species and melaleuca, with the impact of insect herbivores. Results Computer simulations show melaleuca invasion leads to decreases in density and basal area of native species, but herbivory would effectively control melaleuca to low levels, resulting in a recovery of native species. When herbivory was modeled on pure melaleuca stands, it was more effective in stands with initially larger-sized melaleuca. Although the simulated herbivory did not eliminate melaleuca, it decreased its presence dramatically in all cases, supporting the long-term effectiveness of herbivory in controlling melaleuca invasion. Conclusions The results provide three conclusions relevant to management: (1) The introduction of insect herbivory that has been applied to melaleuca appears sufficient to suppress melaleuca over the long term, (2) dominant native species may recover in about 50 years, and (3) regrowth of native species will further suppress melaleuca through competition.

Landscape Ecology↗

USGS2017

The practice of prediction: What can ecologists learn from applied, ecology-related fields?

The pervasive influence of human induced global environmental change affects biodiversity across the globe, and there is great uncertainty as to how the biosphere will react on short and longer time scales. To adapt to what the future holds and to manage the impacts of global change, scientists need to predict the expected effects with some confidence and communicate these predictions to policy makers. However, recent reviews found that we currently lack a clear understanding of how predictable ecology is, with views seeing it as mostly unpredictable to potentially predictable, at least over short time frames. However, in applied, ecology-related fields predictions are more commonly formulated and reported, as well as evaluated in hindsight, potentially allowing one to define baselines of predictive proficiency in these fields. We searched the literature for representative case studies in these fields and collected information about modeling approaches, target variables of prediction, predictive proficiency achieved, as well as the availability of data to parameterize predictive models. We find that some fields such as epidemiology achieve high predictive proficiency, but even in the more predictive fields proficiency is evaluated in different ways. Both phenomenological and mechanistic approaches are used in most fields, but differences are often small, with no clear superiority of one approach over the other. Data availability is limiting in most fields, with long-term studies being rare and detailed data for parameterizing mechanistic models being in short supply. We suggest that ecologists adopt a more rigorous approach to report and assess predictive proficiency, and embrace the challenges of real world decision making to strengthen the practice of prediction in ecology.

Ecological Complexity↗

USGS2015

Carbon exchange between the atmosphere and subtropical forested cypress and pine wetlands

Carbon dioxide exchange between the atmosphere and forested subtropical wetlands is largely unknown. Here we report a first step in characterizing this atmospheric–ecosystem carbon (C) exchange, for cypress strands and pine forests in the Greater Everglades of Florida as measured with eddy covariance methods at three locations (Cypress Swamp, Dwarf Cypress and Pine Upland) for 2 years. Links between water and C cycles are also examined at these three sites, as are methane emission measured only at the Dwarf Cypress site. Each forested wetland showed net C uptake from the atmosphere both monthly and annually, as indicated by the net ecosystem exchange (NEE) of carbon dioxide (CO 2 ). For this study, NEE is the difference between photosynthesis and respiration, with negative values representing uptake from the atmosphere that is retained in the ecosystem or transported laterally via overland flow (unmeasured for this study). Atmospheric C uptake (NEE) was greatest at the Cypress Swampp (−900 to −1000 g C m 2 yr −1 ), moderate at the Pine Upland (−650 to −700 g C m 2 yr −1 ) and least at the Dwarf Cypress (−400 to −450 g C m 2 yr −1 ). Changes in NEE were clearly a function of seasonality in solar insolation, air temperature and flooding, which suppressed heterotrophic soil respiration. We also note that changes in the satellite-derived enhanced vegetation index (EVI) served as a useful surrogate for changes in NEE at these forested wetland sites.

Florida↗

USGS2004

Ten suggestions to strengthen the science of ecology

There are few well-documented, general ecological principles that can be applied to pressing environmental issues. When they discuss them at all, ecologists often disagree about the relative importance of different aspects of the science's original and still important issues. It may be that the sum of ecological science is not open to universal statements because of the wide range of organizational, spatial, and temporal phenomena, as well as the sheer number of possible interactions. We believe, however, that the search for general principles has been inadequate to establish the extent to which generalities are possible. We suggest that ecologists may need to reconsider how we view our science. This article lists 10 suggestions for ecology, recognizing the many impediments to finding generalizations in this field, imposed in part by the complexity of the subject and in part by limits to funding for the study of ecology.

Conference Paper↗