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Home , Bush encroachment

Tropical grassy : definitions, threats & challenges

Kate Parr, University of Liverpool

Caroline Lehmann, Macquarie University William Bond, University of Cape Town Bill Hoffmann, North Carolina State University Alan Andersen, CSIRO Why care about tropical grassy biomes?

• = 30% of terrestrial NPP • 20% of the terrestrial surface • Respond rapidly to fluctuations in climate • 85% of average annual burnt area on earth • Massive impact global carbon and energy cycles • Most of the world’s remaining megafauna • Support 1/5th of the worlds population – 1.5 billion!! • Ecosystem services • Unique adapted to harsh climate conditions What makes TGBs different? How do we define them? How are they threatened? DYNAMIC and VARIABLE

TGBs vary hugely in woody cover

5 – 80% cover Pretoriuskop, KNP 13 % 66 %

Sankaran et al. 2005, Nature TGBs vs.

• Grass – C4, shade intolerant • Grass – C3, shade tolerant • High light • Low light • Fire is frequent • Fire is rare • Relatively shorter trees • Relatively tall trees • Thick bark • Thin bark • Lower specific leaf area • Higher specific leaf area

• Shade intolerant • Shade tolerant • Fire resilient • Fire sensitive

Ratnam et al. 2011, Global Ecol. & Biogeog.

Classification problems

TGBs classified as other types

Classification problems

Thailand/ // Mozambique

Dry Miombo Dry deciduous forest Moist deciduous forest Seasonal dry forest Seasonal dry forest Classification problems

Secondary successional stage?

India Degraded lands?

Gabon Anthropogenic artefacts? Threats

Land management for C-sequestration

Increase & maintain C-stocks for C-sequestration

Clean Development Mechanism (CDM): enhancement of C-stocks through & Creating plantations

• Eligible activities Developing • May include agroforestry agroforestry • Land without forest since at least 31 December 1989

Reducing Land management for C-sequestration • Tropical deforestation = 17.4% emissions • Not included in any other agreement such as the CDM REDD (Reduction of Emissions from Deforestation and forest Degradation)

• REDD+ • Reduce emissions from deforestation and forest degradation • Forest conservation, sustainable forest management, enhancement of forest carbon sinks (biodiversity & livelihoods) Land management for C-sequestration

Increase & maintain C-stocks

Afforestation Clean Development Mechanism Reforestation

Deforestation REDD+ Degradation

Gaining trees = ✓ Losing trees = ✗ Land management for C-sequestration Definitions of forest

Land spanning more than 0.5 hectares with trees >5 metres and a canopy cover of >10% or trees able to reach these thresholds in situ

FAO, 2010

An area of >0.05-1ha with >10-30% cover of plants >2-5m tall at maturity UNFCCC, 2001

44% of African projects listed on ‘CIFOR Global database of REDD+ and Other Forest Carbon Projects’ are in TGBs TGB Forest Total cover (%) 33.5 11.4 % of continent with min. 10% tree cover 17.3 9.7 % of continent with min. 30% tree cover 6.5 7.8

TGB extent: Lehmann et al. 2011, New Phytologist

Land management for C-sequestration

1. Defining baseline vegetation state Land management for C-sequestration

Site 1 – 1400 yrs

Site 2 – 5000 yrs

Gillson & Duffin 2007, Phil. Trans. R. Soc. Lon. B Land management for C-sequestration

1. Defining baseline vegetation state 2. Quantification of degradation Land management for C-sequestration

1. Defining baseline vegetation state 2. Quantification of degradation 3. Degraded/ anthropogenic classification Uchindile-Mapanda afforestation: ‘Degraded ’

18 000 ha unused grassland being planted with alien, invasive tree species

http://www.carbonneutral.com/ Land management for C-sequestration

1. Defining baseline vegetation state 2. Quantification of degradation 3. Degraded/ anthropogenic classification 4. Inappropriate management compromises ecosystem functioning CONSEQUENCES ACTIONS Ecosystem functioning Biodiversity Human livelihoods (ecosystem goods & services) Change in • Bush encroachment/ • Loss of TGB • Loss of productive dominant woody thickening. biodiversity. lands. system drivers • Change in system state • Loss of savanna (i.e., ( switch). products. suppression of • Alter ecosystem • Reduction in fire & processes. water flow. herbivory) Alter way system • Dynamic nature of • Invasive plants • Fire seen as ‘bad’. perceived to system is suppressed. gain foothold. function • Fire seen as undesirable. Reforestation/ • Alter ecosystem • TGB biodiversity • Loss of productive afforestation processes. decline with lands. plantations. • Loss of savanna • Potential spread & products. negative effects of • Reduction in . water flow. Woinarski et al. 2004, Aust. Ecol. CONSEQUENCES ACTIONS Ecosystem functioning Biodiversity Human livelihoods (ecosystem goods & services) Change in • Bush encroachment/ • Loss of TGB • Loss of productive dominant woody thickening. biodiversity. lands. system drivers • Change in system state • Loss of savanna (i.e., (biome switch). products. suppression of • Alter ecosystem • Reduction in fire & processes. water flow. herbivory) Alter way system • Dynamic nature of • Invasive plants • Fire seen as ‘bad’. perceived to system is suppressed. gain foothold. function • Fire seen as undesirable. Reforestation/ • Alter ecosystem • TGB biodiversity • Loss of productive afforestation processes. decline with lands. plantations. • Loss of savanna • Potential spread & products. negative effects of • Reduction in invasive species. water flow. Biodiversity consequences

Highly biodiverse – though not always visible

Large number of forbs

Geophytes present in Brazilian & campos/ African grassland-

Biodiversity consequences

Pretoriuskop, KNP 13 % 66 % ANOSIM, R = 0.630

7 spp. characteristic of open savanna plots

1 spp. characteristic of closed plot CONSEQUENCES ACTIONS Ecosystem functioning Biodiversity Human livelihoods (ecosystem goods & services) Change in • Bush encroachment/ • Loss of TGB • Loss of productive dominant woody thickening. biodiversity. lands. system drivers • Change in system state • Loss of savanna (i.e., (biome switch). products. suppression of • Alter ecosystem • Reduction in fire & processes. water flow. herbivory) Alter way system • Dynamic nature of • Invasive plants • Fire seen as ‘bad’. perceived to system is suppressed. gain foothold. function • Fire seen as undesirable. Reforestation/ • Alter ecosystem • TGB biodiversity • Loss of productive afforestation processes. decline with lands. plantations. • Loss of savanna • Potential spread & products. negative effects of • Reduction in invasive species. water flow. CONSEQUENCES ACTIONS Ecosystem functioning Biodiversity Human livelihoods (ecosystem goods & services) Change in • Bush encroachment/ • Loss of TGB • Loss of productive dominant woody thickening. biodiversity. lands. system drivers • Change in system state • Loss of savanna (i.e., suppression of (biome switch). products. fire & herbivory) • Alter ecosystem • Reduction in processes. water flow. Alter way • Dynamic nature of • Invasive plants • Fire seen as ‘bad’. system system is suppressed. gain foothold. perceived to • Fire seen as function undesirable. Reforestation/ • Alter ecosystem • TGB biodiversity • Loss of productive afforestation processes. decline with lands. plantations. • Loss of savanna • Potential spread & products. negative effects of • Reduction in invasive species. water flow. CONSEQUENCES ACTIONS Ecosystem functioning Biodiversity Human livelihoods (ecosystem goods & services) Change in • Bush encroachment/ • Loss of TGB • Loss of productive dominant woody thickening. biodiversity. lands. system drivers • Change in system state • Loss of savanna (i.e., suppression of (biome switch). products. fire & herbivory) • Alter ecosystem • Reduction in processes. water flow. Alter way system • Dynamic nature of • Invasive plants • Fire seen as ‘bad’. perceived to system is suppressed. gain foothold. function • Fire seen as undesirable. Reforestation/ • Alter ecosystem • TGB biodiversity • Loss of productive afforestation processes. decline with lands. plantations. • Loss of savanna • Potential spread products. & negative effects • Reduction in of invasive water flow. species. The Future of Tropical Grassy Biomes

Accurate identification of TGBs

Restoration is very challenging

Interaction with increasing [CO2]a