Tundra Ch. 7

Plants with a dense covering of clear epidermal hairs may also make use of

A "greenhouse effect"

Perennials can survive without reproducing each year, requiring

A net production that is sufficient for initial growth the following spring

Periodic growth

A plants development is stopped at a particular stage in late summer, regardless of weather conditions

Producing roots late in the winter allows plants to

Absorb melt water on the surface of the still frozen soil

Blue-green algae are often _______ on nitrogen-deficient soil because

Abundant, they're capable of nitrogen fixation

There are a wide variety of soils in the Alpine tundra, but

All are young with a high-rock content

Epidermal hairs are more common on

Alpine plants than arctic plants

Drought is much more likely in the

Alpine zone

High arctic has much drier mineral soil known as

Arctic desert soil

The short stature of tundra plants can be considered an adaption, since

Carbohydrates are not used up in nonessential growth but are conserved

Alpine ecotypes have a lower

Chlorophyll count than arctic ecotypes

Many plants of open alpine areas can reduce transpiration by

Closing their stomates

Layering is common in

Cushion plants and prostrate shrubs

The greatest change in the alpine tundra has been the

Destruction of vegetation cover and erosion brought about by the grazing of domestic lifestyle

Ecotypes

Ecological races of the same species

Tundra plants have to continually be

Frost-hardy and able to recover very quickly

Nutrient levels in arctic tundra soils are

Generally low

Low chlorophyll count results in

Greater light reflectance by alpine plants- a factor that helps maintain proper leaf-heat balance

Both mosses and lichens are well suited for periodic drought, since their

Growth is opportunistic

Structure of the tundra is dominated by

Herbs and shrubs

Dark (night measured) respiration rates are ______ for arctic individuals than for alpine individuals of the same species

Higher

Respiration rates for tundra plants are ________ than for others kept at the same temperature

Higher

Plant communities of the Alpine tundra of North America are

Highly varied

The tundra can be said to have evolved without

Human influence

The purpose for the short/dwarf stature of most tundra plants is to

Increase the likelihood that they will be at least partially covered with snow

Wind causes desiccation by

Increased transpiration at a time when water cannot be absorbed from the frozen soil

Semi-evergreen plants have basal parts if the

Inner leaves remain green throughout the winter and are pushed above the protecting old leaves with the first growth in the spring

The evolutionary disadvantage of little genetic variation __________ important in the tundra as it is elsewhere

Is not as

Asexual reproduction in tundra plants can be beneficial because

It has the advantage that individual gene combinations, which are adaptive to the environment, are not lost through out-crossing

Arctic plants have leaf areas that are _______ for the overall size of the plants, an adaption to

Large, weak light intensities

Tundra plants are physiologically adapted to carry on their metabolic activities at

Low temperatures

The low arctic is floristically and vegetationally ____________ than the high arctic

More diverse

Asexual reproduction is thought to be evolutionary disadvantageous because

No genetic recombination takes place, and with little genetic variation, environmental change can result in the local extinction of a species

Solifluction , although accelerated by steeper relief, is less widespread because

Of the dry, shallow, rocky character of the soil and the lack of permafrost

The climate of the alpine tundra is different from the arctic tundra because

Of the smaller variation in day lengths at lower latitudes

Aperiodic growth

Opportunistically use as much of the growing season as possible, not ending their growth season at any particular stage of development, continuing growth until the weather changes in the fall and then resume the following spring

Plants growing in dry alpine sites are known to be able to

Photosynthesize at lower water-content levels than plants growing in wet sites

The arctic tundra receives relatively low

Precipitation

Dense radiation-absorbing epidermal hairs, anthocyanin pigments, and several layers of leaf photosynthetic tissue provide

Protection from high light intensities

Relatively low temperatures during the growing season usually ______ rates of metabolic activity

Reduce

Epidermal hairs could also be important in

Reducing heat loss at night in alpine species

Snowbank species do not

Respond and develop high winter hardiness levels

Permafrost limits

Root growth

Must tundra plants are capable of _________________, unlike most temperate plants

Self-pollination

_____ growing seasons, ____ temperatures, and ____ winds

Short, low, strong

Wind speed is ______ close to the ground

Slower

The greatest cover occurs around

Snow drifts where melting snow provides soil moisture and adjacent to rocks where animals perch and enrich the soil

Species are able to be drought resistant by the conversion of

Stored starch to soluble sugar

Persistent dead leaves and stems are adaptive, since they

Take the brunt of wind abrasion, slow wind flow, and create eddies that cause blowing snow/ice particles to drop and build up around the plant

Phenotypic plasticity

The ability of individuals to adjust to new or changing enviroments

Winter winds aid in

The dispersal of tundra plants, a factor of importance since tundra plants generally lack the varied dispersal mechanisms of temperate plants

Solifluction

The downslope sliding of water-saturated soil

Melt water, increasing day lengths, rising soil and air temperatures, and completion of a lengthy cold period are triggers for

The end of dormancy

The greater the water content of the soil, the greater

The expansion

The melting of permafrost due to the disturbance of vegetation can cause

The forming a depression which becomes a site for water runoff and erosion

When the vegetation is disturbed, part of

The insulation for the permafrost is lost

Shortening day lengths, decreasing soil and air temperatures, increasing drought, and accumulating carbohydrate reserves are a cue for

The onset of dormancy

Layering is

The rooting of plants where branches touch the ground

Both aperiodic and periodic perennials typically have a spurt of growth immediately after

The snow melts

Some herbaceous tundra perennials transfer organic compounds from

Their aerial portions to their storage organs before winter; therefore, little more than cellulose cellulose cell walls are lost when the aerial parts die

Epidermal hairs reduce

Transpiration by absorbing and reflecting light and by decreasing wind flow near stomates

The low arctic has wet peat soils in which gleization forms what may be called

Tundra glei soil

A major characteristic of arctic tundra soil is that they are

Unstable

The nature and extent of the damage done to the tundra greatly depends on the

Vegetation and soil

Net primary productivity in tundra vegetation tends to be ________ because

Very low, it is influenced by factors such as cool temperatures, low soil-nutrient levels, and short growing season

Short height also enable plants to metabolize in a microenvironment that is

Warmed by the radiation of energy absorbed by the soil surface

Permafrost blocks

Water drainage

Individual tundra species frequently have a

Wide distribution over a range of somewhat different environments

Wind causes abrasion by

Wind-borne snow and ice crystals

The alpine tundra has

higher precipitation than the arctic tundra

Plant temperatures may be ___________ by pigments- the

increased, darker the color, the more sunlight is absorbed

The tundra environment is such that the vegetation has _______ impact on it, than say a forest has on its environment

less