Presentation on

Competition for space, light and nutrient in forest stand

Presented by:Shanta kaphleM. Sc. First Year First SemesterRoll no 2IoF, Pokhara

Outlines of Presentation

• Introduction• Methodologies• Results and

discussion• Conclusion• Recommendation

Introduction

Definition and concept:• the process by which two or more individuals differentially capture a potentially common, limiting resource supply.• Plants compete for Nutrients, Water, Light, space, CO2• Types: Inter-specific vs Intra-specific

Introduction...

Competition may be • symmetric : limited resources are evenly shared or received in same amount of

resources irrespective of competitors' size ; • asymmetric :receives different amounts of

resources (loser and winner exist)• In forest stand, generally asymmetric

competition pronounced (individuals grow disproportionately)

Introduction...

Growth of forest stand also affected by competitive factors (nutrients, space and light)

can be measured as competition index (distance dependant and distance independent)

Methodology

Three methodologies have been reviewed:• Detail gap inventory on transect belt for

assessing regeneration status in tropical Sal forest of Nepal (Shapkota and Ode'n ,2009) .

• Plot design and planting cottonwoods using space variable searching for seedling survival and its biomass (Bhattacharjee et al 2011 ).

• Use of historical data of growth and precipitation from Sitka spruce forest of Denmark for analysis (Wichmann 2001).

Result

• Relative densities of seedling of Terminalia alata is correlated with gap size created due to tree fall where as it is negatively correlated with Sal, Eugenia operculata and Syzigium cumini seedling (Shapkota and Ode'n ,2009) .

• Seedlings were shorter when the neighbor distance was 5 cm

• Mean number of leaves was the lowest at neighborhood distances of 5 and 25 cm (Bhattacharjee et al 2011 ).

Result..

• Seedlings of cottonwood accumulated greatest biomass when the distance between neighbors was 15 cm but it reduces when it apart at 25 or 35 cm (Bhattacharjee et al 2011) .

Result..

• From the analysis of the size-increment relationship for diameter, it is evident that there is a positive effect of precipitation on the increment (Wichmann 2001).

Discussion

• the overall expression of competition is a mixture of asymmetric and symmetric competition.

• Competition for light is intrinsically asymmetric, while competition for water and nutrients is symmetric (Wichmann L. 2001).

discussion..

• Understanding the mechanisms of competition reveals how competition has influenced the evolution of plant species.

• For example, nutrient competition plants have maintained higher root length and light competition plants are taller, with flatter canopies (Craine and Dybzinski, 2013 ).

Conclusion

• two or more individuals acquire resources from a potentially common, limiting supply.

• The effects of of resource competition alter species survival, its growth and productivity.

• Above ground competition for light is of asymmetric , while below ground competition is symmetric in nature

Recommendation

• Understanding the mechanisms of competition helps to harmonize compatible species in their temporal and spacial arrangement. So, detail study and research is suggested for.

Thank you for your patience .