Subalpine, Aspen, and Montane Meadows Ecology

Flashcards covering the vocabulary and ecological concepts of subalpine environments, including 5-needle pine species, aspen biology, and montane meadow threats.

Subalpine woodland

An open tree stand with approximately $20\%$ canopy cover characterized by cold temperatures where $75-90\%$ of precipitation falls as snow.

Krummholz

A term meaning 'crooked wood' that describes wind-sculpting of trees occurring at the upper limit of tree growth.

Whitebark pine (Pinus albicaulis)

A 5-needle pine growing up to $10\,m$ tall that received federal threatened status in 2023.

Western white pine (Pinus monticola)

A 5-needle pine reaching $30-40\,m$ tall that often forms stands on exposed, rocky slopes with a pinemat manzanita understory.

Limber pine (Pinus flexilis)

A 5-needle pine with flexible young stems, distributed primarily in the drier Eastern Sierra and migrating to higher elevations faster than other species.

Mountain hemlock (Tsuga mertensiana)

A shade-tolerant tree species with droopy tops that grows on north-facing or protected slopes with deep snowpack.

Sierra juniper (Juniperus grandis)

A species that can form enormous twisted trunks and colonize small fractures in granite domes that other species cannot support.

Bristlecone pine (Pinus longaeva)

A 5-needle pine famous for its extreme longevity, reaching ages up to $5000$ years, mainly found in the White Mountains of California.

Foxtail pine (Pinus balfouriana)

A 5-needle pine with a disjunct distribution in the Klamath Mountains and southern Sierra that does not form krummholz but has highly resinous wood.

White pine blister rust (Cronartium ribicola)

An invasive fungus that kills the cambium of 5-needle pines, requiring Ribes species as an alternate host.

Quaking aspen (Populus tremuloides)

The only broadleaf canopy species that grows higher than $2000\,m$ ($6000\,ft$), often found in drainages and moist slopes.

Aspen paradox

The occurrence of aspens primarily on the drier east side of the Sierras due to wet-site seeps, summer rainfall, and rhizomatous growth.

Quaking

The movement of aspen leaves caused by a flattened petiole perpendicular to the plane of the leaf blade.

Stem photosynthesis

A process in aspens where photosynthetic bark can account for up to $40\%$ of the tree's photosynthesis.

Pando

A male clonal stand of Populus tremuloides in Utah that covers $43\,hectares$ ($107\,acres$) and is estimated to be $14,000$ years old.

Dioecious

A biological term for species like aspen where male and female flowers are on different individual trees or clones; describes only $10\%$ of the world’s tree species.

Sudden aspen decline

A threat to aspen populations driven by a combination of drought and heat.

Montane meadow

A community consisting of a single herbaceous layer of sedges (Carex spp.), grasses (Deschampsia caespitosa), and flowering herbs.

Incision

The erosional cutting down into a meadow that results in the drying of wet meadows.

Headcut

An erosional feature in a meadow, often caused by excessive livestock, that leads to a drop in the water table and drier conditions.