Plant interactions and limitations to growth

GROWING TOGETHER DRY SOIL MESIC SOIL VIRGINIA PINETULIP POPLAR

HeightHeight DryWet Mesic

Modified from Ellenberg, 1963

Niche Theory Fundamental Niche Realized Niche

HeightHeight DryWet Mesic

Site Sensitive / Site Insensitive No tree ‘likes’ a bad site Where you see a tree is where it reproduced and survived Many examples of trees in the ‘wrong’ place

Communities Mutualism –Animals – plants- plants and animals Competition –Primary model for this course Facilitation –Focus of much current research

Mutualism Organisms depend on each other Communities become a ‘reproducing’ entity Common in animals –Food pyramid –Plants don’t eat each other

Competition Survival of the fittest Gene – environment interaction Probabilities Ultimately natural selection

Facilitation One plant ‘helps’ another with no detriment to itself Interaction must be close to selective neutral for ‘helper’ Role of mycorrhizae

Climax theory Historic role of ‘superorganism’ –No way for natural selection to work –Many examples showing this does not hold –Has greatly (negatively) impacted forest management

Growth Factors Light Water Nutrients Others?

Photosynthesis Chlorophyl in the foliage Chloroplasts Sun foliage/shade foliage

Photosynthesis 6 CO H 2 OC 6 H 12 O O 2 SUNLIGHT

Photosynthate C 6 H 12 O 6 “Stuff” Energy

Respiration C 6 H 12 O 6 + O 2 CO 2 + H 2 O (Not balanced) ENERGY

Light PAR –P hotosynthetical A ctive R adiation Sun foliage/ shade foliage Shade tolerance

20% LIGHT 0% Ps Sun foliage Shade foliage

20% LIGHT 0% Ps Sun foliage Shade foliage

Shade Tolerance Ps Light Shade tolerant Shade intolerant

Water Input Soil Stomates

Percent Soil Water Heaviness of Texture Field Capacity Available Water Unavailable Water From Brady, 1974

AET PET Precipitation Water Input

Rainfall Consistent

Cold Hot

Stomatal Behaviour Internal moisture stress –Drought avoiders –Drought endurers

Nutrients

Law of the Minimum Growth is limited by whatever factor is most need

Nitrogen Potential Growth Actual Growth

Law of Compensation The addition of one factor can increase the efficiency that a tree uses another factor

Law of Compensation With P Amount of N Growth Rate

Rule of Efficacy Diminishing returns Growth Amount of “X”

Nutrient Cycling Availability CEC Weathering Mineralization C:N Nutrient capital Translocation

Nutrients Nitrogen fixers Mycorrhizae

Temperature

Growing Space Sunlight Water Nutrients Physical space

Total growing space Available growing space

Total growing space Depends on time and place –Macro and Micro conditions

Available Growing Space Grow Regeneration

Thinned Unthinned

Latewood Earlywood

No Available Growing Space Repartition Competition

Priorities for Photosynthate 1.Respiration 2.Foliage – Fine Roots 3.{Reproduction} 4.Primary Growth 5.Secondary Growth – Secondary Compounds

Photosynthesis > Respiration ? –GROW Photosynthesis < Respiration ? –DIE Photosynthesis = Respiration ? –NOT A LONG TERM CHOICE

Volume Wood formation (total volume) is: [ (Photosynthesis-Respiration)] - Allocation

Where Does It Go? Respiration Increment Dominant Tree26% 42% Co-dominant Tree29% 41% Suppressed Tree50% 8% [ash stand in Denmark]