ELEVATION AND VEGETATION: THE THIN TREE LINE

ELLA - JACK - GRAHAM

THE BIG PICTURE

• How do plants respond to changes in the environment?

• We were interested in seeing how abiotic factors could affect plant growth.

WHAT FACTORS CAUSE VEGETATION COVERAGE TO CHANGE WITH ELEVATION?

RESEARCH QUESTION

OUR HYPOTHESIS WE HYPOTHESIZED THAT SOIL NUTRIENT LEVELS AND RELATIVE AIR HUMIDITY WOULD DECREASE AT HIGHER ELEVATIONS WHILE WIND EXPOSURE INCREASED, RESULTING IN LESS VEGETATION COVERAGE.

THE TESTS WE CONDUCTED• Percent Foliage Coverage (Est.)

• Wind Speed (M/S)

• Relative Humidity (%)

• Soil Temperature

• soil pH

• Nitrate

• Phosphate

• Potassium

VAN NORDEN MEADOW: 6715 FEET (5 PM)

SITE A

• 90-99% Vegetation Cover• Mostly Dry Grass• Avg. Relative Humidity: 42%

SLOPES BELOW CLAIR TAPPAAN 6938 FEET (1 PM)

SITE B

• 50-70% Cover• Humidity: 36% • Small Shrubs

DONNER SKI RANCH7070 FEET (10:30 AM)

SITE C

HUMIDITY 48%COVER 30-65%

GRASSES AND SMALL BUSHES

DONNER SKI RANCH SUMMIT7437 FT. (11:30)

SITE D

• Cover 5-15%• Humidity: 28.7%

• Rocky Terrain

AS ELEVATION INCREASED VEGETATION COVERAGE DECREASED

Strong Correlation: .855

NO RELIABLE CORRELATION BETWEEN SOIL NUTRIENT LEVELS AND ELEVATION CHANGE

CONCLUSIONS

• no apparent relationship between soil nutrient levels, elevation or vegetation coverage

• Exposure is the main factor in elevation and vegetation coverage

• exposure hard to measure, complexity, many factors

CONCLUSIONS

• Soil Nutrient Hypothesis was inconclusive

• Wind exposure hypothesis supported.

• Vegetation hypothesis strongly supported

FOR NEXT TIME…

• Soil nutrients are not universally identical

• More tests in various locations

• Testing the biomass

FURTHER QUESTIONS

• What other factors could we have measured?

• Would our conclusion change if we could test wind speeds year round?