From Population to Landscape Ecology:

Ecological Basis for Management of Weeds In Agroecosystems

University of Rosario

September 11: Lecture 9 – 12:30: Weed population dynamics

Lecture document: Life History Models.doc  and in Castellano Historias de vida y modelos - Avena fatua.pdf

1.      Weed population demographics

2.      Stage transition models and estimating population growth rates

3.      Density dependence

4.      Stochastic variability

5.      Spatial dynamics

Readings: Chapter 1 from R. Cousens and M. Mortimer. 1995. Dynamics of Weed Populations. Pp.1-20. Cambridge University Press Chapter 5 from R. Cousens and M. Mortimer. 1995. Dynamics of Weed Populations. Pp.135-168. Cambridge University Press

Menges 2000

Exercise: (2 to 6 pm)

Read: General Approaches to Modelling. pdf

Develop a stage transition model for a weed species in Excel. Calculate population growth rates. Include density dependence and stochasticity into the model. Download: Life History Models.pdf and popdemo0.xls

Demonstrate simple spatial models (cellular automata). 

September 12: Lecture 9 – 12:30: Weed Populations and Decision To Manage

Lecture document: Weed Populations and Decision To Manage.doc and in Castellano Competencia Interspecifica. Leyes.pdf

1.      The weed threshold concept

2.      Quantify the impact of weeds on crop production and/or quality

a.       Experimental design

b.      Data assessment

3.      Calculating the Economic Injury Level (EIL)

4.      Applying the threshold concept

5.      Other factors that need to be taken into account (e.g. crop density)

Reading: Maxwell, B.D. and J. T. O’Donovan. 2007. Understanding weed-crop interactions to manage weed problems. Pp.  In M.K. Upadhyaya and R.E. Blackshaw (Eds) Non-chemical Weed Management. CAB International. (In press)

Maxwell & ODonovan 2007.pdf

 Exercise:

Learn calculation of Economic Injury Level and optimum weed management approach using simple transition difference equation models. Download: Lab5_Threshold Calculation 06.doc and Lab5_Threshold.xls 

September 13: Lecture 9 – 12:30: Distribution of Weeds Across Scales

Lecture Document: Weed Distribution.doc

1.      World scale distribution processes

a.       Early discovery and rapid response management approach

2.      Regional scale dispersal vectors and distribution

a.       Corridors of dispersal

3.      Local scale distribution, dispersal processes and relative habitat quality

a.       Species traits

b.      Dispersal patterns

c.       Habitat quality

                                                                           i.      Abiotic constraints

                                                                         ii.      Biotic constraints

                                                                        iii.      Genotypic and phenotypic variability

Reading: Chapter 2 from R. Cousens and M. Mortimer. 1995. Dynamics of Weed Populations. Pp.21-54. Cambridge University Press

Exercise:

Use a model to investigate resultant local (within field) spatial patterns given assumptions about habitat distribution, dispersal characteristics, competitive interactions and management. Download: Lab4_LinkingSpatialTemporal.doc and PopDyn_spatial_1.0.xls

September 14: Lecture 9 – 12:30: Site-Specific Management of Agricultural Inputs

Lecture Document: Site_Specific_EcoBased Argentina.ppt

a)      Are weeds patchy?

b)      Are crop yields variable across fields?

c)      What factors best explains variability in crop yield?

d)      Economic rationale for site-specific weed management.

e)      Weed density thresholds for management and optimization of inputs.

Readings: Maxwell, B.D. and L.C. Luschei. 2005. Ecological justification for site-specific weed management. Weed Science 53:221-227. Maxwell_Luschei 2005.pdf

Exercise:

Adding the spatial aspects of weed population dynamics and subsequent calculation of optimum input management using on-farm experiments. SiteSpecific Input Management Lab.doc and SAIO.xls

Seminar 1: Weed Ecology: Will It Have An Impact On Weed Management? (September 17)  Ecologically Based Agriculture Arg.ppt

Seminar 2: Linking Spatial and Temporal Plant Population Dynamics, Forecasting and Informing Management Through The Use of Models (September 18) Linking Spatial and Temporal Argentina.ppt

Seminar 3: Models Suggest Regional Regulations To Delay Herbicide Resistance Spread (September 19) RSpread_Maxwell et al Argentina.ppt