Distribution of Dioecious Eastern Red Cedar (Juniperus virginiana) along an Environmental Gradient in Ogallala, NE.

Abstract The purpose of this research was to study the sex distribution and energy allocation of dioecious Eastern Red Cedars (Juniperus virginiana) along an environmental resource gradient. The trees surveyed were growing in a canyon located at the University of Nebraska’s Cedar Point Biological Research Station in Ogallala, Nebraska. Due to the geography of this canyon, environmental factors necessary for plant growth should vary depending on the tree’s location within the canyon. These factors include water availability, sun exposure, ground slope, and soil nitrogen content, all of which are necessary for carbon acquisition. Juniperus virginiana is a dioecious conifer. Dioecious plants maintain male and female reproductive structures on separate individuals. Therefore, proximal spatial location is essential for pollination and successful reproduction. Typically female reproductive structures are more costly and require a greater investment of carbon and nitrogen. For this reason, growth, survival and successful reproduction are more likely to be limited by environmental resources for females than for male individuals. If this is true for Juniperus virginiana, females should be located in more nutrient and water rich areas than males. This also assumes that females can not be reproductively successful in areas of poor environmental quality. Therefore, reproductive males should be more likely to inhabit environments with relatively lower resource availability than females. Whether the environment affects sexual determination or just limits survival of different sexes is still relatively unknown. In order to view distribution trends along the environmental gradient, the position of the tree in the canyon transect was compared to its sex. Any trend in sex should correspond with varying environmental factors in the canyon, ie: sunlight availability, aspect, and ground slope. The individuals’ allocation to growth and reproduction was quantified first by comparing trunk diameter at six inches above ground to sex and location of the tree. The feature of energy allocation was further substantiated by comparing carbon and nitrogen content in tree leaf tissue and soil to location and sex of each individual. Carbon and nitrogen in soil indicate essential nutrient availability to the individual, while C and N in leaf tissue indicate nutrient limitation experienced by the tree. At the conclusion of this experiment, there is modest support that survival and fecundity of females demands environments relatively richer in nutrients, than needed by males to survive and be reproductively active. Side of the canyon appeared to have an influence on diameter of trees, frequency of sex and carbon and nitrogen leaf content. While this information indicated possible trends in the relation of sex to nutrient availability, most of the environmental variables presumed responsible for the sex distribution bias differed minutely and may not have been biologically significant to tree growth.

Online Dictionary of Invertebrate Zoology: T

tabula tabular tachyauxesis tachyblastic tachygen tachygenesis tachytelic tactic tactile tactoreceptors taenia taeniate taenidium taenioglossate tagma tagmata tagmosis tail tailfan Takakura's talon talus tandem tangent tangoreceptor tanylobous tapetal tapetum tapinoma-odor Tardigrada tardigrades tarsal tarsation tarsite tarsomere tarsungulus tarsus taste tautonomy tautonym taxa taxes taxis taxis taxodont taxometrics taxon taxonomic taxonomist taxonomy tectiform tectostracum tectum teeth teges tegillum tegmen tegmentum tegula tegular tegulum tegumen tegument tegumentary tela telaform telamon telegonic teleiochrysalis telenchium teleoconch teleodont teleology teleotrocha telepod telescope telescopic teletrophic telioderma teliophan telmophage telocentric telodendria telofemur telogonic telolecithal telomitic telophase telophragma telopod telopodite telorhabdions telosonic telostome telosynapsis telosyndesis telotarsus telotaxis telotroch telson template temporal tenacipeds tenaculum tenent teneral tensor tentacle tentacular tentaculocyst tentaculozooid tentilla tentorial tentorium tenuous teratocyte teratogen teratogenesis teratogyne teratology terebella terebra terebrant terebrate teres terete terga tergal tergite tergolateral tergopleural tergopore tergum tergum termen terminal terminalia termitarium termitophile terranes terrestrial terricolous territory tertiary tertibrach tertibrachial tessellate test testaceology testaceous test-cross testes testis testisac testudinate tetanus tetany tetractinal tetractine tetrad tetradelphic tetramerous tetramorphic tetraploid tetrapod tetrapterous tetrasomic tetrathyridial tetrathyridium tetraxon tetraxonid thalassophilous thallus thamnophilous thanatocoenosis thanatosis theca thecae thecal thecate thelycum thelygenesis thelygenous thelyotokous thelyotoky theory thermocline thermophile thermophobe thermoreceptor thermotaxis thickness thigmotactic thigmotaxis thigmotropism third-form thoraces thoracic thoracomere thoracopod(ite) thorax thoraxes thread thylacium thylacogen thyridial thyridium thyroid thysanuriform tibia tibial tibiotarsal tibiotarsus Tiedemann's tiled timbal tinctorial tine tissue tissue titilla titillae titillator tocopherol tocospermal tocospermia tocostome tokostome tomentose tomentum Tomosvary tone tonic tonofibrillae tonus topochemical topogamodeme topomorph topomorphic toponym topotype tori torma tormogen tornote tornus torose torpid torqueate torsion tortuose torulose torus totipotent totomount toxa toxicognath toxicology toxin toxinosis toxoglossate toxoid trabecula trabeculate trabeculated trachea tracheae tracheal tracheate tracheoblast tracheolar tracheoles trachychromatic tract Tragardh's tragus transad transcoxa transcurrent transect transection transformation transient transitional translocation translucent transmission transposed transscutal transstadial transtilla transverse trapeziform trapezium trapezoid trema tremata Trematoda trenchant trepan triact triactinal triad triaene triage triangle triangular triangulate triaulic triaxial triaxon tribe tribocytic trichite trichobothrium trichobranchia trichobranchiate trichocerous trichodes trichodeum trichodragmata trichogen trichoid trichomes trichophore trichopore trichosors trichostichal trichotomous trichroism tricolumella tricomes tricostate tricrepid tricuspid tricuspidate tridactyl trident tridentate trifid trifurcate triglycerides trignathan trigonal trigoneutism trilabiate trilateral trilobate trilocular trimorphic trimorphism Trinominal triordinal tripartite tripectinate triplet triploblastic triploid triquetral triquetrous triradiate triradiates tritocerebral tritocerebrum tritocerebrum tritonymph tritosternum triturate triungulin triungulinid trivial trivium trivoltine trixenic troch trochal trochalopodous trochantellus trochanter trochanteral trochantin trochi trochiform trochlea trocholophous trochophore trochosphere trochus troglobiont troglodytic troglophile trogloxene tropeic trophal trophallactic trophallaxis trophamnion trophi trophic trophidium trophobiont trophobiont trophobiosis trophobiotic trophocytes trophodisc trophogeny trophoporic trophorhinium trophosome trophotaxis trophothylax trophozooid trophus tropis tropism tropotaxis trumpet truncate truncation trunk trypsin tryptic tryptophan tryptophane T-tubule tube tube-feet tubercle tubercula tuberculate tuberculose tuberiferous tubicolous tubifacient tubule tubulus tubus tuft Tullgren tumefaction tumescence tumid tumulus tunic tunica tunicary tunicate turbinate turgid turreted turriculate tychoparthenogenesis tylasters tylenchoid tyli tyloid tyloides tylosis tylostyle tylote tylus tymbal tympanal tympanal tympanic tympanum Tyndall type typhlosole typologist typolysis typostasis