# Presentation: 472912

## Hydrological and Nutrient Controls on the Structure and Function of Southern African Savannas

- K.K. Caylor, Paolo D’Odorico,
- Christelle Hély, Greg Okin, S.A. Macko, Natalie Mladenov, Lydia Ries, Susan Ringrose, T.M. Scanlon, H.H. Shugart, R.J. Swap, Matt Therrell, Lixin Wang and Robert Washington-Allen

## Kalahari Transect

**Wet and dry season field campaigns for basic ecological process and detailed structural measurements of vegetation**

## Kalahari Transect

**Wet and dry season field campaigns for basic ecological process and detailed structural measurements of vegetation**
**Detailed soil characterizations**

## Kalahari Transect

**Wet and dry season field campaigns for basic ecological process and detailed structural measurements of vegetation**
**Detailed soil characterizations**
**Instrumented long-term physical data records**

## Kalahari Transect

**Wet and dry season field campaigns for basic ecological process and detailed structural measurements of vegetation**
**Detailed soil characterizations**
**Instrumented long-term physical data records**
**Field fertilization experiments with phosphorus and nitrogen and stable isotope analysis in experimental and spatially distributed contexts**

## IGBP Kalahari Transect

- Uniform sandy soils – ‘Kalahari sands’
- Heterogeneous vegetation; tree, shrub and grass in woodland, savanna, and shrubland mixtures.
- High net plant productivity, widespread biomass burning, high carbon turnover

**IGBP Kalahari Transect**

## Mean annual rainfall along the Kalahari Transect

## Kalahari Rainfall – 1901-1996  

**Kalahari Rainfall – 1901-1996  **

## Kalahari Rainfall – 1901-1996  

**Kalahari Rainfall – 1901-1996  **

## Kalahari Rainfall – 1901-1996  

**Kalahari Rainfall – 1901-1996  **

## Kalahari Rainfall – 1901-1996  

**Kalahari Rainfall – 1901-1996  **

## Kalahari Rainfall – 1901-1996  

**Kalahari Rainfall – 1901-1996  **

## Vegetation Patterns on the Kalahari Transect

**Vegetation Patterns on the Kalahari Transect**

## Spatial Variation in NDVI at Different Spatial Scales

## Pattern and Process

## Vegetation structural characteristics along the Kalahari Transect 

- Vegetation structural characteristics along the Kalahari Transect

## TRADE-OFFS

- Light

- Moisture

## TRADE-OFFS

## Dispersed

- Clumped

- Depends on the Prior History

## Slide 20

## A Landscape Vegetation Model

## UMD Tree Cover Data

**UMD Tree Cover Data**

## Live

- Non-woody

- Tree
- Leaves

- Dead
- Non-woody

- Dead
- Tree
- Leaves

## Could you tell me again where we’re going with all this?

## Slide 25

## Slide 26

## Along with wildfires, there are other significant sources of emissions to the atmosphere.

## We have some understanding of the contribution of these different sources.

## Regional Emissions

## Live

- Non-woody

- Tree
- Leaves

- Dead
- Non-woody

- Dead
- Tree
- Leaves

## Does this have any practical implications?

## Grazing Pressure across Southern Africa

***Grazing Pressure across Southern Africa***

## Grazing Impact across Southern Africa during a Wet Year.

***Grazing Impact across Southern Africa during a Wet Year.***

## Grazing Impact across Southern Africa in a Dry Year.

***Grazing Impact across Southern Africa in a Dry Year.***

## In wet versus dry years, the impact varies regionally 

- In wet *versus* dry years, the impact varies regionally*** ***

**Wet**

**Dry**

## Slide 36

## The End

## Slide 38

## Slide 39

## Slide 40