**Jette** **Reeg*,** Thorsten Schad ° , Jane Ta ng ° , T ilghman Hall ° , Thomas Preuss ° , Andreas Solga ° , **Florian Jeltsch** * 

# Modeling Population and Community Ef fects of Herbicide Drift - Xplicit - IBC

*University Potsdam, ° Bayer CropScience 

### EMPM Oct. 2014

# Problem Formulation  Risk assessment for Non - Ta rget Te rrestrial Plants (NTTP) (endangered or non - endangered) needs to account for :
• Agricultural activities ( eg , cropping, chemical use pattern) 

## • Prevailing environmental conditions and climate conditions 

## • I nter - and intra - specific competition with a local plant community

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### An integrated modeling approach wa s developed for NTTP risk assessment using • a local - scale plant Individual Based Community model (IBC) capable of simulating the dynamics and local ef fects of herbicides to NTTP species, and • a probabilistic model for estimating spatially and temporally explicit exposure and ef fect based landscape data ( Xplicit ) uni - giessen.de

# Xplicit - IBC Overview

- From Herbicide Use to Plant Community

• Fields (landscape) • Crop types • Chemical use pattern Applications • Drift model • Environmental conditions • Habitats (NTTP)  ibc patches Exposure • Dose - responses

(ecotoxicology)  individual - level effect by species and attribute Individual - level Effects • Empirical

distribution of effects over species by attribute Species Effect Distribution • Assign sensitivity to species • Species effect distribution sampling • Link attributes to model parameters IBC
**Plant Population**   ** and Community**   ** level Effects**

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### Xplicit IBC  individual - level effects in space and time

# Xplicit (Schad et al.)

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#  Xplicit is a probabilistic modelling approach for estimating spatially and temporally explicit exposure and ef fect based on landscape data
• Consider chemical applications, wi nd conditions, drift exposure, and ef fect data from standard ecotox. tests (vegetative vigor and seedling emergence) to predict plant individual - level ef fects
• Simulate a range of complexity levels ranging from simple edge - of - the - field to complex landscapes)
• Used in regulatory risk assessments in Europe

distance from field edge [m]

1 3 5 7 10 15 20 25 30 40 50 

### 3 m 2 

### patch Wind

# IBC Model

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### Individuals

Above - and belowground Zone Of Influence (ZOI) with overlapping zones* , **

* We iner et al. 2001 **May et al. 2009 Plant functional types (PFT) • Growth form • Plant height • Clonal reproduction • Ty pe of CSR - strategist * • Photosynthetic active area (~SLA) 

### Spatially explicit (local patch of 3 m2)

# IBC Model

- From Real - world to PFT Plant Communities

Page 6 **Species/taxa list of interest**

e.g. “Calthion “ **Tr ait Database (Eur**  **ope)** (e.g., BiolFlor

, LEDA , CloPla3)
selection of k ey functional traits, (plant siz e, growth form, resource response, seed mass, etc.) **Community (PFT**  **s) ‘Base' model PFT**  **community** IBC model initialization **‘A ctual' model PFT** 

**community** (dynamic) e.g.,Calthion ‘ (≈35 PFT

s) **Community (PFT**  **s) Ve**  **getation data from field**  **and lit**  **er ature (species lists,**  **vegetation surveys) Community**  **(species list)**



###  IBC has been validated in predicting plant community dy namics in research projects

# Example Community in IBC

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##  **Calthion grassland community**  • Common in Germany/Europe • Nutrient rich, moist meadow s • 2 cutting events/year • **Primula veris**  potentially endangered species included: moderate abundant PFT richness

year 17 plant (PFT) community initialization 

## Calthion Community Population PFT1 Ind 1 Ind 2 Ind i Population PFT 2 Ind 1 Ind 2 Ind j Population PFT 35 Ind 1 Ind 2 Ind k

# Configuration and Parameterization of IBC

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##  PFT sensitivity assigned randomly or by expert judgment  Species ef

fect function distribution sampling • Actual individual - level ef fect of PFT taken from Species - Ef fect Distribution 

##  Linking attributes of species ef fort to IBC
Ve getative vigor tests: biomass, shoot length, survival Seedling tests: Shoot length, biomass, survival, emergence Biomass gain (plants and seedlings) Mortality probability (plants and seedlings) Probability of establishment IBC
Direct transfer Species Ef

fect Distribution

# Assessment Endpoints (IBC output)

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# Plant Community Population PFT1
Ind 1 Ind 2 Ind i Population PFT 2
Ind 1 Ind 2 Ind j Population PFT N
Ind 1 Ind 2 Ind k • Biomass (total, above - and belowground) • Number of PFT

s • Number of individuals • Diversity indices (Shannon, Simpson, Evenness)

• Shootmass • Number of individuals (= population size) • Cover • Quasi extinction risk (extinction risk, if population size decreases below a certain threshold; here: conservative approach: 25% of mean population size in control)

# Case Study

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# 1: Xplicit a herbicide
• Soybean: 1 x 740 g/ha + 1 x 595 g/ha • Dose - responses • Wind tow ards NTTP • Drift predicted by AgDrift • edge of the field 

# 2: Species Ef fect Distribution Plant Community Te st Patches Field - edge distances: • 3 ft • 10 ft 

# 3: IBC Te st Plant Community ( Calthion ) • Tw o cutting events, low grazing intensity • Primula veris (PFT) as endangered species and assumed high sensitivity 

# To evaluate drift ef

fects on edge of the field NTTPPage 11 

### 1.0 0.5 1.5RelationTreatment/Control



### 30 years herbicide exposure 35 years recovery Relation T reatment/Control 

##  Reduction of biomass and the number of PFT s (PFT richness) 

# Community Level Ef

fects at Edge of Field ( 3 ft)Page 12RelationTreatment/Control 

### 1.5 1.0 0.5 35 years ‚recovery‘ Relation T reatment/Control 

##  Only temporary reduction of biomass, and no ef fect on PFT richness 

# Community Level Ef

fects at Edge of Field (10 ft)

30 years herbicide exposurePage 13 1.0

0.5 1.0 0.5 1.0 0.5RelationTreatment/Control

30 years herbicide exposure 35 years ‚recovery‘ 

### Inverse Simpson Eveness Shannon 

##  Dif ferent response of diversity indices  Interpretation of the dif ferent indices is ongoing 

# Community Level Ef

fects ( 3 ft)Page 14 

## Shootmass for selected PFT - types in community context PFT Carex panicea PFT Cirsium rivulare

PFT Lotus pedunculatus PFT Myosotis nemorosa

0 1 2 3 4 

### year 0 1 2 3 4 

### yearRelationTreatment/Control 

# Population Level Ef

fects ( 3 ft)

##  No ef fect on field boundary within a 10 ft distance

Page 15 3ft 3ft 3ft 

# Population Level Ef

fectsPage 16 

###  High extinction risks for Primula veris (assumed high sensitivity) at the field edge for isolated populations  Population recovers w hen degree of isolation is low  Low r isk for Primula veris populations at 10 ft distance

Degree of isolation High ( low seed input ) Medium Low (high seed input )

3ft 3ft 3ft *Quasi extinction risk : Extinction risk , if population size decreases below a certain threshold ; here , conservative setting of 25% of mean population size in control 

# Population Level Ef

fects - Primula veris

# Summary  Xplicit - IBC of

fers an integrated approach to analyze impacts of drift to individual plants (traits) at community and population levels at landscape scale. 

##  Scenarios with dif

ferent levels of complexity can be addressed, ranging from conservative edge - of - the - field to full landscape - scales 

## • representing real - world landscapes with specific agricultural and management practice and, 

## • spatial species occurrence with consideration of isolation of plant populations 

##  IBC has been validated in predicting plant community dynamics in research projects

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# Ongoing W ork  Additional scenario development based on the established framework 

## • Plant communities, landscape scenario, test patches, herbicide use, exposure model, plant species/community occurrence and isolation, etc . 

##  Va lidation of IBC - grass of predicted herbicidal ef fects at plant community and population level using field data 

##  Further evaluation of transferring measured individual - level ef fects of species to IBC traits 

##  Streamline model interface/runs for regulatory use

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# Thank you!