PLSC 381 Module 3 (mixed evergreen forest to deserts) & 4/Plant List 5-6

trees found in mixed evergreen coniferous forests

Pacific madrone, black oak, big-leaf maple

where are montane coniferous forests found?

high elevations → Sierra Nevada, Cascade Mountains

• begins >4000’ in Northern CA, >7000’ in Southern CA

what species dominate in montane coniferous forests?

Pinaceae & Cupressaceae

climate of montane coniferous forests

• mainly Mediterranean highlands climate

• short growing season, prolonged freezing during the winter

• melting snowpack important source of water for trees

characteristics and climate of closed cone coniferous forests

• occurs inland from the immediate coast, sporadically distributed

• winters & summers are temperate, frosts are rare

• rainfall varies 20”-60”/yr + fog drip

• soil low in nutrients

• produces serotinus seed cones

trees found in closed cone coniferous forests

Pinus radiata, Pinus muricata

serotinus seed cones

stay unopened on branches for years, resins need to melt for cones to open (heat & fire)

following a fire, seedlings grow quickly, even-aged stand develops

where do deserts of the world occur?

30 degrees latitude, high pressure atmospheric cells, cool nearby offshore ocean currants, rain shadows

how to cold nearby ocean currents affect deserts?

• cool offshore ocean currents reduce the amount of moisture in the air that blows inland from the ocean

• cold water suppressed evaporation

• the air warmed as it move inland can hold more moisture & that prevents any moisture from the ocean from condensing and forming precipitation

hadley cells

• massive, tropical atmospheric circulation pattern

• warm air rises near the equator, moves poleward at high altitudes, cools, and sinks near 30 deg latitude in both hemispheres

• this mechanism transports heat/moisture, drives trade winds, and creates tropical rain belts and subtropical deserts

• cold air sinks in the subtropics creating high-pressure, arid environments

deserts of CA

• represents 38% of the state

• four deserts in North America, 3 in CA

  • Great Basin Desert (smallest area in CA)

  • Mojave Desert

  • Colorado/Sonoran Desert

• Chihuahuan Desert

characteristics of the Great Basin Desert

• occupies most of NV, UT, & parts of adjacent states

• located in the rain shadow of Cascade Range and Sierra Nevada

• large parts occupy an interior drainage basin with no outlet to the sea (streams drain in valleys, salt accumulation)

climate of Great Basin Desert

• elevations 5000-7000’

  • warm summers, cold winters with prolonged freezing temps

  • snow in winter, rain occasionally in the summer

vegetation in Great Basin Desert

dominated by desert scrub, saltbush scrub, alkali sink scrub

Mojave desert location & characteristics

• located in S NV, SW UT, NW AZ, SE CA

• located in rain shadow of S Sierra Nevada and Transverse Mountain ranges

• Western part has interior drainage, eastern part is drained by the CO river

climate in Mojave desert

• hot summers, cool winters (frost but no prolonged freezing temps)

• rain and occasional snow winter

• sometimes summer thunderstorms

vegetation in Mojave desert

• desert scrub & desert woodlands

• unique winter display of annual plants

Sonoran Desert location & characteristics

• SE CA, SW AZ, Baja CA

• rain shadow of Transverse and Peninsular ranges

• parts of region drained by CO River

Sonoran Desert climate

• driest region in North America, lowest elevation

• rarely experiences freezing temp

• rain is strongly bi-seasonal

• PET is extremely high

desert riparian areas

stream courses that enter or cross the desert regions of CA, may be bordered by a band of riparian vegetation

• largest was the CO River, now altered by dam construction

lots of flow is subsurface except during floods

small desert riparian communities exist

why were many invasive species introduced?

introduced as ornamentals

CA-IPC

California-Invasive Plant Council (2002)

educate community about invasive plants

how do invasive species impact “habitat value”

as natives are replaced by non-natives, “habitat value” (ability for an area to support the natural variety of plant and animal species) decreases

what are invasive species?

plants that can move rapidly into and dominate or disrupt native communities

why do invasives thrive in non-native lands?

they are free from vast and complex array of natural controls present in their native lands (competition, herbivores, parasites, diseases)

• may experience rapid and unrestricted growth in new environments

invasiveness is characterized by:

• strong vegetative growth

• abundant seed production

• high seed germination rate

• long-lived seeds

• rapid maturation to a sexually reproductive stage or ability to quickly reproduce vegetatively

how did invasives get to CA?

mid-1800s: exotic weeds began arriving with immigrants from overseas

many were intentionally brought to CA by settlers for use as garden/ornamental plants or for profit through agriculture/timber harvesting

many introduced unintentionally in our highly mobile society

how do exotic pest plants have a negative impact on native ecosystems?

• disturbing a community’s natural equilibrium

• displace native flora/fauna by competition and monopolization of resources

• use allelopathy (chemical defenses to inhibit growth) like eucalyptus and ice plant

Asclepias speciosa

showy milkweed

• 4-6’ tall, 4’ wide

• winter deciduous

• eye-catching furry pale pink/purple-ish flowers arranged in thick umbels

• spreads by underground rhizomes

• popular with the Monarch Butterfly

Eriogonum grande var. rubescens

red flower buckwheat

• perennial herb to subshrub

• evergreen

• 0.7-1.5’ tall, 3’ wide

• showy flowers in spring, summer, and fall

Ribes speciosum

fuchsia flower gooseberry

• beautiful fuchsia red flowers hanging down

• 6-10’ tall, 3-8’ wide

• deciduous

• grow in full/nearly full shade in slightly moister spots

• gooseberries have spines, currants do not

Arbutus menziesii

Pacific madrone