ALPINE RESTORATION

Chambers, J.C. 1997. Restoring alpine ecosystems in the western United States: environmental constraints, disturbance characteristics and restoration success. Ch. 9 in K. Urbanska, N. Webb and P. Edwards, (eds.) Restoration Ecology and Sustainable Development. Cambridge University Press, Cambridge, 397 p.

I. Extent and damage

A. Extent

About 8% of the total U.S. land area is alpine.

Value: critical watersheds, wildlife habitat, mineral resources, livestock forage, recreational areas.

B. Damage

Around 12% is damaged according to 1978 study.

trails

mining: acid runoff; high concentration of heavy metals

C. Restoration prognosis: difficult

1. Extreme and variable temperature and precipitation

2. Unpredictable environment

3. Small number of adapted species are available

4. Seedling establishment is episodic.

5. Rates of recovery depend on disturbance severity (low after severe disturbance).

 

II. Alpine environment

A. Climate and microenvironment

1. Temperature may drop below freezing any time during growing season

2. Growing season lasts 60-90 days.

3. High intensity solar radiation common (including ultraviolet)

4. High and persistent winds (that desiccate and cool plants)

5. Aspect differences are extreme

B. Soils

1. Young, cold, weakly developed, heterogeneous, may be shallow

2. Ridge soils have low OM; cold, saturation produce high OM in places

3. Acid soils

4. NH4, NO3 and PO4 tend to be low; nitrification low so NH4 common

C. Vegetation

1. Plant growth

Alpine tundra plants have growth rates like temperate plants but short growing season.

Leaf and flower production may be prolonged over several seasons.

Annuals are rare.

Floras small (several hundred spp. on a whole mountain range)

Low growing cushion and rosette plants, forbs, graminoids, deciduous and evergreen shrubs.

2. Succession not very apparent

Small floras of low stature

Early seral species usually Poaceae or Asteraceae

Some colonizers facilitate later ones

If you get anything to establish, it looks like late seral state

III. Disturbance and restoration

A. Gradient of alpine disturbances

1. Topsoil left in place, organic soil (least severe)

Caused by grazing, trails, campsites

2. Topsoil left in place, mineral soil

Caused by grazing, trails, campsites

3. Topsoil removed

Caused by roads, mining

4. Soils altered (most severe)

Caused by mining, resulting in exposure of pyritic materials, sulfide oxidation, low pH, availability of heavy metals.

B. Restoration

1. Goals

On severely disturbed sites, surface stabilization

Eventually, on any site, re-establishment of ecosystem

2. Soils

In cases with soil loss, replacement of topsoil is best way to get good growth medium.

Fertilizers generally not necessary and effects are temporary.

After a disturbance, OM slow to recover.

-straw, peat or manure may be added

-N may be added to facilitate microbial decomposition

3. Plant species

Desirable spp. have broad ecological amplitude.

Will colonize various disturbances.

Most are graminoids.

Graminoids produce high numbers of easily harvestable seeds.

Respond to nutrient addition and grow fast.

Cover and stabilize ground quickly.

Nit-fixers may be used in low-N sites (Astragalus, Lupinus, Trifolium).

4. Restoration approach

Sites with intact topsoil usually have seeds and rhizomes for regeneration.

Vegetative regeneration may equal or exceed that from seed.

Seed production at a restored site likely to be highly variable.

Availability of alpine seeds from commercial sources is limited.

Usually several years of collection needed to produce enough seed for a restoration project.

Container plant survival generally high.

Sods may be collected from salvage sites.

5. Restoring by seeding

Seedling growth is slow, prone to drought-kill and subject to frost-heave and needle-ice damage.

Organic mulches often improve seedling survival.

Mulches are applied, then secured using netting or tackifier.

6. Ecosystem development

Systems that are fertilized will develop high biomass, which will decrease when fertilizing is stopped.

Mycorrhizal re-establishment is slow. (only 1 out of 11 local mycorrhizal spp. were found in a Beartooth Mtn, Montana restoration site after three years.)

Initial establishment of graminoids may suppress or delay eventual development of diversity.

Extreme sites or extreme disturbance result in slowest recovery.