Threads

By Dr Robert Thomas and Dr. Aimée Thomas:

THREADS STRESSED AND FOLLOWED IN OUR WORKSHOPS (help us identify more)

1. Journaling for and by naturalists.  Keeping a journal is fundamental to making observations, interpreting, and reminiscing about your time in nature.  Those who keep journals can easily revisit their nature experiences.  A trait of a good naturalist is to keep notes, including observations, thoughts, sketches, maps, data, concepts, and much more.  Choose your preferred techniques of journaling:  a notebook/journal, recordings, photos, note apps – whatever works best for you.
Naturalists may just have “one” journal (numbering them as they fill over time), but many keep their principal journal and may begin a new one if they make a special prolonged trip such as a visit to the Galápagos or Africa.
Bottomline:  journaling will enhance your learning and will become an important reference as you expand your knowledge.

2. Characters that define taxa and taxonomic groups.  Most taxa (taxonomic groupings such as species, genera, etc.) have one or more characters on which we depend to identify them.  You will become accustomed to hearing us share these taxonomic characters and you will soon be asking us to share them.

3. Adaptive strategies – why things happen the way they do.  This term helps us understand why things happen the way they do.  All organisms have strategies for successful living.  Most of our discussions will touch on adaptive strategies, even if we don’t use those words. 

4. Plant succession.  All plant communities, if left alone in their uniform environment, will continue to change until they reach what we call a climax (final) stage.  The process of moving in that direction is called succession, and any snapshot during that process is called a seral stage.  Next time you see someone clear a piece of land, check it out periodically and you will see obvious changes in the vegetation over time – ranging from plant-free soils to either the climax seral stage (this will take decades, so you will have to be patient!) or something like a shopping center.  If you visit once a month, each visit you will view a seral stage in plant succession.  In the Greater New Orleans area, the natural climax stage will be a live oak dominated forest – once that is in place, there will be few changes.  In a healthy Louisiana swamp, the climax vegetation is dominated by Bald Cypress and Tupelo Gum.  In our coastal wetlands, climax stages will be grasslands whose species composition will vary depending on salinity and elevation.

5. Resource partitioning.  How do living things divvy up resources in the environment?  If a green anole (lizard) feeds on small insects, how does it co-exist/partition those resources with a Mediterranean gecko?  It does so by being active in daylight, while the gecko is active at night – using insects that are also active at night.  In order for plants and animals to live together, they must use adaptive strategies to partition necessary resources.

6. Plant/animal intelligence/awareness.  We will often discuss intelligence and perceptiveness in plants and animals.  Most people don’t give this much thought, but animals are quite aware of their surroundings.  And, their senses may be acute.  Plants also perceive and respond to environmental cues.

7. Plant/animal communication.  When you walk through a forest or grassland, the plants around you are in constant communication, and the same is true for animals.  Not quite as in Disney, but very sophisticated.  There is now clear evidence that older trees in forests actually nurture younger trees, enabling enhanced community health.

8. Habitats – how are they characterized?  We will consistently discuss habitats, their relation to one another, how they operate, and their indicator species.

9. Importance of salinity & edaphic features of the habitat.  The basic chemistry of habitats are prime determinants of the forms of life supported by those habitats.  This is especially true in coastal Louisiana where there is plenty of water and salinities range from fresh (basically with no salt) to the Gulf of Mexico where salinities are 35 parts per thousand.  As you will find, some species have a narrow range of tolerance to salt, while others have a wide range of tolerance.
Edaphic factors include physical, chemical, and biological properties of soil.  The range of edaphic factors are determinants of patterns of diversity we encounter in ecosystems.

10.  Indicator, keystone, flagship, foundation species, & apex predators.

a.     Indicator species – there are two uses of this term – the first is the one we most commonly use in LMNGNO:

§  Species whose presence defines a certain habitat.  Example: (swamps in Louisiana have cypress and tupelo gum as indicator species; bottom-land hardwoods may be diagnosed by the presence of dwarf palmetto).

§  A species whose presence or change in density may suggest the change of quality of a habitat.  Example:  A rapid invasion of a species often suggests major changes in an ecosystem, such as when Salvinia arrived in the 1980s.

b.     Keystone species – A species that lives in a place and its presence/activities contribute to the existence of that habitat (oysters, since they build reefs that are used by myriad other species; crocodilians in the Amazon are key to the health of that ecosystem due to the electrolytes they constantly emit into the water)

c.     Flagship species – Charismatic species that gain broad public interest and support in conservation.  One of the best examples in the last few decades is the Red-eyed Treefrog – its beauty and combination of colors (very red eyes) mobilized global support to save rainforests in Central and South America.

d.     Foundation species – Species that are extremely common in a habitat.  Example:  Spartina patens in brackish marsh; Spartina alterniflora in salt marsh.

e.     Apex predators – Top predators in any food web (jaguars, alligators, bald eagles, humans)

11.  Native vs. non-native species and their terminology.  After your first few nature walks, you may wonder if we have any native species.  Non-native species are abundant in most developed areas due to human introduction, both purposeful and accidental.  When there is a story to tell, we will share how the species got here, why, and its impact on the native environment.  See the words and definitions we adopted for LMNGNO (posted under the City Park workshop and in the Primer on Natural History).

12.  Phenology, periodicity and cycles.

a.     Phenology – The study of plant and animal life cycle events and how they vary with annual and trending changes in climate and other environmental events.  Such studies are adding to the biological evidence of the effects of climate change over time.  This is very clear to people who live a long life in nature!

b.     Periodicity – Patterns we see in nature that repeat in regularly-spaced periods of time (daily – so-called diel rhythms; seasonally, annually, and the like).  We have a full moon every 29.5 days.  Periodic cicadas appear every 17 years, and many of our local cicadas appear every 3 years.  We have three species of frogs that breed each winter. Discussed in phonological studies, but it has been foundational in our understanding of ecology.

c.     Cycles – One cannot discuss life histories of living organisms without being aware of the impact of recurring cycles over time, and cycles of life events in daily terms as well as seasonality.

13.  Ecological equivalents.  Different habitats and geographic regions usually have critters, totally unrelated, living with the same adaptive strategies.  A study of desert frogs around the world found that there were frogs from different families that converged in their life histories in order to live in an arid, non-froggy environment.  They all shared being pudgy, having rather rough and dry skin, during dry periods they burrow beneath the surface and become inactive, have the ability to secrete slime that hardens and encapsulates them while inactive underground so as to conserve water, are stimulated to move to the surface immediately during heavy rains, lay thousands of eggs that hatch quickly in temporary desert puddles, and all share a very rapid tadpole development period in order to metamorphose before puddles dry.  Another prime example is small, insect eating birds.  North America has lots of warblers, South America has antbirds, Australia has fairy wrens, and more – all being ecological equivalents.  All these birds are small, hop around in trees and shrubs feeding on invertebrates, and nest in these habitats – thus they fit the definition of ecological equivalents.

14.  Meanings and uses of words in natural history.  Every field has its language, and naturalists certainly have ours.  We will share many words that help us better communicate.

15.  Effect of latitude and elevation on ecological activity (temperature, humidity, etc.).  As one moves north and south from the tropics, there are latitudinal changes in biomes:  tropical rainforest, temperate forest, taiga, tundra, polar ice.  Each of these biomes is a response to temperature cycles and associated factors.  The same pattern is observed as one moves up mountains:  in the Andes of South America (and Rockies of North America), one finds the same biomes with altitude changes.  Of course, the lowest biomes vary with the mountain’s latitudinal location.  A rule-of-thumb is that for every 1000 m one ascends in elevation, average temperatures drop 6°C.

16.  Connecting the dots – interconnectedness.  Nature is a complex system of interconnections, and we will often discuss this fact.  Coastal wetlands capture sunlight to make organic matter, they die and feed the estuaries & Gulf with organic matter, zooplankton feed on this material, small things eat zooplankton, menhaden/pogy (a fish) are filter feeders that enjoy plankton, pogy are harvested for their fish meal and oils; fish meal is necessary to support the chicken and catfish industries, and we eat chicken constantly.  Lose the coastal marshes and we lose chicken as an abundant protein source.

17.  Anachronistic characters.  These are characteristics that evolved for specific reasons that may no longer have a stimulus; this makes their presence enigmatic, often perplexing.  Once the driving force is gone, the characters may gradually disappear over prolonged periods of time.  The example we use is the very large thorns on the trunks of honey locust trees.  They developed when the trees were heavily predated upon by mastodons, which were capable of chewing the bark off the trees.  Via natural selection, the thorns appeared and enlarged (were “selected for”) to thwart this behavior.  Several thousand years ago, mastodons became extinct, and the thorns on honey locust have not yet disappeared.  They seem to have no purpose in spite of the enormous energy the tree expends growing them.  These are anachronistic characters.

18.  Ecological impacts by climate change.  It is clear that Louisiana is among the most vulnerable places in the U.S. with regard to ecological changes that may occur due to climate change.  We are very susceptible to sea level rise, increasing storm damage, negative impacts on offshore fisheries, and delays in shipping and energy movements.  Therefore, LMNGNO is concerned about effects on the flora, fauna, and funga in our coastal wetland habitats.

19.  Impacts of human activity on natural environments.  In addition to anthropogenic elements of climate change listed above, human life impacts natural environments in many ways.  We do many things to protect and conserve natural habitats, but the historical assumption (particularly in European cultures) that nature exists to be exploited for human use has often led to the degradation of the environment:  we have clearcut forests, poorly managed agricultural production, overly relied on oil & gas extraction and production, dumped plastics into our waterways and oceans, and much more.  One conundrum is that our noble efforts to save the coastal marshes have been tainted time and again by poor selection of practices that have been deleterious to populations and species!

20.  Importance of Traditional Ecological Knowledge (TEK).  We will often discuss the obvious role of science in our acquisition of knowledge, but we must honor knowledge that has accumulated throughout the history of humanity.  Indigenous peoples, folks who live “off the land” or “by the seasons,” fishers, oystermen, trappers, and hunters have vast knowledge of how nature works, and it is mostly observational and gathered over time.  Seasoned scientists improve their science by including TEK in their analyses.

-end-