Saturday, November 27, 2010

Tree Hugger Gazette: Three Exclusive Pics of Latest Sightings

Ancient Treehugger Sighted
Near Indian Mound
Bit of more than he could hug!

Breaking News:
Treehugger Escapes on Vintage Scooter
Macon's Finest in Hot Pursuit!

Treehugger Expert Found:
Dazed and Bewildered in Deep Ditch
Psychiatrist: Expect Full Recovery; These Things Take Time

Thursday, November 25, 2010

Southern Pine Bark Beetle; It's a "Southern Thang"

Adult Southern Pine Bark Beetle
A:Egg, B:Larva, C:Pupa
    Southern pine bark beetles (Dendroctonus frontalis) like the one pictured above destroy millions of pine trees from Texas to Virginia every year.  Adult southern pine bark beetles (SPB) are reddish-brown to black and measure about 1/8 inch long.  Infestation typically begins in trees weakened by lightening strikes, storms, disease, or old age.  Once the beetles are established in a damaged host, they seem to have no trouble infesting healthy trees.  These insects go through four life stages.  Females burrow under the bark and lay their eggs along s-shaped channels that eventually girdle the tree and damage the phloem, the living layer of the tree that transports water and nutrients.  Beneath the bark, eggs hatch and the legless white larva or "grubs" rear their little reddish-brown heads and burrow into the tree trunk where they gorge themselves.  When they pupate, they remain white but take on a shape that closely mimics an adult.  The process takes about a month.  Given optimum conditions, SPB may raise seven or eight generations during their annual season from April to September.  When the host tree inevitably dies, adult beetles take to the wing to find a living host where they start the cycle again.
     SPB show a preference for particular species of pine.  They target the various yellow pine species, as well as loblolly, shortleaf, and Virginia pine.  They appear to avoid white, sand, slash, and longleaf species.  This preference may be related to a trees production of resin.  Pine trees respond to any damage by patching the wound with resin.  When SPB attack, resin oozes from the holes in the bark to produce pitch tubes.  Trees that produces a stronger response to attack appear to be less susceptible to infestation by SPB.  Research indicates that the trait is heritable. It may be practical to develop genetic lines of pines that have greater resin flow and more inherent resistance to SPB attack.
     Needles on trees that cannot repel an attack change color from yellow to red and finally to brown.  The images below show the damage caused by SPB and the pine tree's defensive response to attack.
     In an interesting footnote, SPB has a commensalistic (symbiotic) relationship with a fungus known as "bluestain".  The beetles introduce the fungi which then cause further damage to the conductive capacity of the trees phloem layer.   

Primary Direction of Infestation (bottom to top)
Defensive Response: Dozen of Pitch Tubes
Trunk Bearing "Bluestain" Fungi
An Adult Beetle and the Holes It Bores
Pitch Tubes Often Resemble Popcorn

Tuesday, November 23, 2010

Leaf Litter Decomposition

     Decomposition of leaf litter is a major means of recycling nutrients in forest ecosystems. The process is carried out by bacteria, fungi, and soil fauna.  It begins in earnest about 2 months after the leaves fall but decomposition may not be complete for up to 18 months.  As the fallen leaves are broken down by insects and microbes, their carbon, nitrogen, phosphorus and other nutrients become available for uptake by plants within the local environment.  Litter accumulates annually creating a layering effect with the most accessible nutrients underneath a layer of less decomposed material.  Precipitation washes organic nutrients into the soil layers below.  Decomposition is also a major pathway by which carbon, fixed during photosynthesis, is returned to the atmosphere.

Partially Decomposed Leaf Litter

     The primary influences on the rate of leaf litter decomposition have been shown to be temperature and water loss due to evaporation and transpiration.  Another important factor is litter quality, the ratio of carbon to nitrogen and nitrogen to phosphorus.  Surprisingly, precipitation is secondary.
     Understanding the processes and factors controlling leaf litter decomposition is important for studying nutrient cycles, developing carbon budgets and assessing it's role in global climate change.


Wild Ginger

Wild Ginger in Bloom
     Wild ginger (Asarum canadense) is a herba- ceous plant native to the deciduous forests of eastern North America.  It grows as far north as southeastern Canada but here along the fall line, we are at the southern edge of it's range.  Wild Ginger's long rhizomes smell and taste similar to ginger root but the two are not closely related.  The plants grow in small clumps that put down shallow roots and bear kidney-shaped leaves and tan to purplish flowers.
     Native Americans used the plant for medicinal purposes ranging from headache and cold remedy to the treatment of tuberculosis and venereal disease.  The use of wild ginger in medicines and cooking is inadvisable, however, because we know it contains an undetermined concentration of carcinogenic aristolochic acid.

Monday, November 22, 2010

Pick-a-Parasite: The Candiru

     The candiru or "toothpick fish" is parasitic freshwater catfish native to the Amazon and is especially prevalent in and around the confluence of the Rio Negro and Rio Blanco rivers.  The term "candiru" is sometimes used in reference to any number of members of the family Trichomycteridae but Vandellia cirrhosa is the most interesting.  Candiru habitually target the gills of larger fish to acquire their obligatory feast of blood.  Reports of these tiny catfish entering the human body through the urethra date back more than 100 years but the only documented case was in 1997.  The man was attacked as he urinated thigh-deep in the river.  He required two hours of urological surgery to rid him of the little horned parasite.  Ouch!  Scientist suspect that the candiru swam up the stream of urine while the urethra was expanded and that the fish would not normally enter the otherwise closed orifice.  This little prick could really piss  a fellow off!

Monday, November 8, 2010

A Wide Array of Aquatic Organisms

Bioluminescent Phytoplankton
Phytoplankton - The bioluminescent dinoflagellate Noctiluca scintillans is widely distributed throughout the world.  It is found in estuaries and shallow places on the continental shelf where there is plenty of light.  Noctiluca thrive by eating plankton, other phytoplankton like diatoms, other dinoflagalettes, and small fish eggs.  They are capable of enormous blooms and their light shows can be spectacular!

The Copepod Macrocyclops albidus
Zooplankton - The copepod Macrocyclops albidus is a tiny crustacean that feeds on mosquito larvae.  Field testing indicates that an adequate population of these voracious little creatures can consume up to 90% of the mosquito larvae that hatch in their environment.  With a fifth leg and hairy antennule that have 17 segments, their appearance is truly alien!

Aquatic Macrophyte - Hydrilla verticillata is an rapid-growing invasive species native to Asia and Africa.  This rooted, submerged plant produces long stems with short leaves that are capable of filling the entire water column to a depth of about 10 feet.  It chokes the channels and boat docks of slow-moving waterways throughout the U.S.  Hydrilla is prolific and is spread easily when careless boaters fail to clean the strands of Hydrilla from their motors.

Grass Carp
Fish - Grass carp (Ctenophyrynogodon idella) are herbivorous fish native to Asian rivers and lakes.  They were introduced into the U.S. in 1963 for aquatic weed control because they EAT up to THREE TIMES THEIR BODY WEIGHT DAILY!  Grass carp grow rapidly, reaching lengths of 3 ft. 9 in. and weighing as much as 40 lbs.  They are available to private land owners for use in their ponds. The Army Corp of Engineers still releases grass carp into public waterways to control aquatic vegetation in reservoirs like Lake Seminole, Ga. but the Corps only releases triploid (artificially sterilized) carp.  They have not been very successful in Lake Seminole.

A Blue Crab
Crustaceans - Blue crabs (Callinectes sapidus) are denizens of many coastal salt and brackish water environs.  They are omnivores, eating some plants but preferring animal protein including other blue crabs and carrion.  They molt, shedding their hard shells and producing a new, soft one in order to grow.  Blue crabs in this "soft-shelled" state are best when lightly battered and fried whole.

Mammal -Narwhal (or narwahls; either can be plural) are Arctic whales that bear the scientific name Monodon monoceros.  They are the so-called "Unicorns of the Sea" because of a single enlarged "tooth" that grows from the left side of their jaw.  All males and some females have this over-sized incisor.  Males may stretch to 18 ft. and sport a tusk up to 10 ft. long.  There is no consensus about what the tusk is used for but some researchers speculate that it may be simply for show!  Do you think maybe these fantastic animals are really just the "Peacocks of the Sea"?