Managing Grasslands Ecosystems in a Changing Climate: opportunities for mitigation and adaptation (UNDP presentation)
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Grasslands are important ecosystems that cover a quarter of the world's land area and support livelihoods through livestock production. They store a significant amount of the world's carbon and are vulnerable to climate change impacts like increased temperatures and altered precipitation patterns. Grasslands are also threatened by overgrazing, agriculture conversion, invasive species, and unnatural fire regimes. Conservation strategies aim to maintain native biodiversity and ecological processes through measures like expanding protected areas, improving connectivity, and sustainable grazing management. Restoration efforts and adapting natural disturbance regimes can increase grasslands' resilience to climate change.
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Managing Grasslands Ecosystems in a Changing Climate: opportunities for mitigation and adaptation (UNDP presentation)
- 1. Managing Grasslands Ecosystems in a Changing Climate: opportunities for mitigation and adaptation Adriana Dinu, Regional Practice Leader, Environment and Energy, Europe and CIS © 2010 UNDP. All Rights Reserved Worldwide. Proprietary and Confidential. Not For Distribution Without Prior Written Permission.
- 2. Grasslands are important to livelihoods.... 20% converted to crops 25% of milk production 23% of beef production Livestock industry – 1 billion poorest people; 1/3 of global protein intake 3.5 billion ha 26% of the world land area 70% of the world agricultural area 20% of the world’s carbon stocks
- 3. Grasslands are vulnerable to .... Climate change - most of any terrestrial ecosystem (Sala et al., 2000; IPCC, 2001a). Invasive species - especially following disturbance, due to low-stature of vegetation conferring high light availability – natural vulnerability Vegetation change - if the changes to temperatures and precipitation are sufficient to alter biomass and fire frequency
- 4. World’s Temperate Grasslands – most threatened, least protected Only 5% protected!
- 5. Geographical coverage of steppe ecosystems Steppe PAs Kazakhstan Steppe PAs Russia Working with oil sector Uzbekistan Macin NP Romania Steppe PAs Turkey
- 6. Threats to Grasslands: Livestock grazing Major land use of the world’s remaining grasslands (IPCC, 2001a) Compacts soils, reduces infiltration and soil water capacity, dries out surface soils, increasing vulnerability to drought and accelerate desertification. Erosion, topsoil loss and destroys biological soil crusts critical for soil fertility Degrades riparian habitats - hot spots of native biodiversity; connectivity between grassland patches; Localized increases in soil fertility in areas of concentration - vegetation in nutrient hot spots is dominated by IS : foci for further invasion СО2emissions: 0.3-0.9 t/ha
- 7. Grasslands exposed to over-grazing Original state High biodiversity Native grass Grass dominated system High economic value Altered state Low biodiversity Invasive species – weeds Shrub dominate system Low economic value Even when grazing pressure is relaxed, there may be little change in composition, because of the advantage of woody vegetation over grass when the woody is dominant
- 8. Threats to Grasslands: Agriculture conversion Turning into croplands: 1 Million ha after 2007 in Russia Isolation leaves grassland species little room to migrate in response to CC; Changes in the level of surface water evaporation alters regional climate influencing plant community composition Decline in soil carbon stocks by 60%
- 9. Threats to Grasslands: Alterations of fire regimes 78-84% world’s springtime black carbon,nationwide 30 million ha burning annually in Russia Shortening of the fire return interval due to invasions has favored fire-tolerant plant species, resulting in the loss of fire-intolerant bunchgrasses, shrubs, and wildlife Accelerated nutrient losses through volatilization and mortality of biological crust organisms; Fuel breaks created to suppress fire may act as conduits for the spread of invasive species
- 10. Increases of atmospheric CO2 impact on grasslands: Depends on: The mix of C3 vs. C4 species: Plants with the C3 photosynthetic pathway (e.g., Stipaspp.) may increase photosynthetic rates and show enhanced growth rates as CO2 concentrations increase. Location: ecotonal habitats -most likely to experience vegetation changes
- 11. Increases of atmospheric CO2 impact on grasslands: Leads to: An increase of water use efficiency of plants: reduced time needed to have stomata open for CO2 uptake; Increase soil moisture, may negatively impact grasslands where conditions favor invasive species Large scale vegetation change: as the current species composition in most grasslands often includes introduced species
- 12. Managing Grasslands for Resilience to Climate Change .... what we need to know? Vigorous stands of native vegetation: roots have access to deeper soil moisture and are better able to compete with invasive species Healthy plant cover intercepts rainfall, maximizing infiltration and soil water supply, reducing overland flow, and preventing nutrient losses due to erosion Healthy level of soil organic matter: important for soil aggregate formation, fertility, stability, water movement and holding capacity, Abundance and relative composition of plant species depend on ecological processes such as herbivory and fire.
- 13. Climate Change Adaptation Options in Grasslands Include all grassland types across environmental gradients in protected areas:as we do not know precisely which grassland types will be most sensitive to CC Protect relict and native-dominated communities: as models for habitat restoration and help in understanding how grasslands altered vs. unaltered are affected by CC. Improved Connectivity: to facilitate the migration of species in response to CC - where it is critical for maintaining gene flow among populations of rare species Minimize fragmentation by land use changes and roads: protect core grassland habitats distant from roads and human disturbances as they are often refuges for native species; time road maintenance to avoid spread of invasives; monitor roadside vegetation. Low-intensity, sustainable grazing practices: where native species are adapted to it; Reduce/remove grazing from sites where the predominant native species lack a long evolutionary history of grazing by large hooved herbivores; Maintain heterogeneity of management at the landscape and mimic grazing patterns of native herbivores;
- 14. Climate Change Adaptation Options in Grasslands Prevent and control the spread of invasive species: Focus on the causes of invasion - seed sources and disturbances that increase vulnerability to invasion.
- 15. Climate Change Adaptation Options in Grasslands Restoration:including reintroductions of native species, IAS control, inoculations with soil biota important to native plant vigor, nutrient cycling and restoration of native disturbance regimes
- 16. Maintenance of natural fire regimes: as it is influencing the health and heterogeneity of grassland vegetation Climate Change Adaptation Options in Grasslands
- 17. Climate Change Adaptation Options in Grasslands Provide buffer zones: provide suitable conditions for shifting of populations to lands bordering reserves as conditions inside reserves become unsuitable; act as barriers to the spread of new invaders away from roads.
- 18. Climate Change Adaptation Options in Grasslands Identify and protect functional groups and keystone species: increased tolerance to environmental extremes and recovery potential as native species richness or cover increases.
- 19. Climate Change Adaptation Options in Grasslands Protect climatic refugia at multiple scales: identify past climatic refugia and focus conservation efforts on these areas so they can again function as refugia during present and future CC
- 20. Carbon sequestration in Grasslands Disturbance through removing of biomass, changing vegetation – is an integral part of traditional grassland management system Disturbance through overgrazing, fire, invasivescan deplete grasslands of carbon stocks Biomass : herbaceous; TRANSIENT CARBON POOL Soils: DOMINANT CARBON pool Much of Carbon lost from agricultural land soil and biomass pools can be recovered with changes in management practices that increase carbon inputs, stabilize carbon within the system or reduce carbon losses.
- 22. Most of the potential sequestration Sowing Improved species: better adapted to local climate, resilient to grazing, resistant to drought Restoring degraded lands: enhances production in areas with low productivity , increasing carbon inputs and sequestering carbon Including Grass in the rotation cycle – have the largest impact on soil carbon
- 23. THANK YOU!
Editor's Notes
- Competition between grasses and woody vegetation in a semiarid environment. Suppose that either the grass or the woody vegetation has an advantage when at high densities relative to the other. In such a case, the system has stable equilibria that correspond to high levels of grass and woody vegetation, respectively. The competition is also influenced by the stocking rate of cattle, which consume grass but not woody vegetation. We shall regard the two plant forms as the dynamic state variables, and the stocking rate as a slowly varying parameter. Imagine starting with high levels of grass and low levels of woody vegetation. At low levels of stocking, there is only a small difference from the ungrazed system: if the system starts out with grass dominant, grass will continue to dominate. As stocking increases, the competition may favor woody vegetation. Eventually, there may be a collapse of the grass, and woody vegetation will dominate. Thus, the effect of grazing is to move the system from a state in which grass dominates to one in which woody vegetation dominates. Even when grazing pressure is relaxed, there may be little change in composition, because of the advantage enjoyed by woody vegetation over grass when the former is dominant. The effect of grazing is to move the system into the domain of attraction of woody vegetation for the ungrazed system. If one plots grass density vs. the stocking level, the behavior may appear to be inexplicable: the grass level declines as grazing increases, but does not return to former levels when grazing returns to its former level. The apparent paradox is resolved if we realize that the density of grass depends not only on the stocking level, but also on competition with woody vegetation.
- Plants that survive solely on C3 fixation (C3 plants) tend to thrive in areas where sunlight intensity is moderate, temperatures are moderate, carbon dioxide concentrations are around 200 ppm or higher, and ground water is plentiful. The C3 plants, originating during Mesozoic and Paleozoic eras, predate the C4 plants and still represent approximately 95% of Earth's plant biomass. C3 plants lose 97% of the water taken up through their roots to transpiration.[1] Examples include rice and barley.C3 plants cannot grow in hot areas because RuBisCO incorporates more oxygen into RuBP as temperatures increase. This leads to photorespiration, which leads to a net loss of carbon and nitrogen from the plant and can, therefore, limit growth. In dry areas, C3 plants shut their stomata to reduce water loss, but this stops CO2 from entering the leaves and, therefore, reduces the concentration of CO2 in the leaves. This lowers the CO2:O2 ratio and, therefore, also increases photorespiration. C4 and CAM plants have adaptations that allow them to survive in hot and dry areas, and they can, therefore, outcompete C3 plants.C4 plants have a competitive advantage over plants possessing the more common C3 carbon fixation pathway under conditions of drought, high temperatures, and nitrogen or CO2 limitation. When grown in the same environment, at 30°C, C3 grasses lose approximately 833 molecules of water per CO2 molecule that is fixed, whereas C4 grasses lose only 277 water molecules per CO2 molecule fixed. This increased water use efficiency of C4 grasses means that soil moisture is conserved, allowing them to grow for longer in arid environments.[7]C4 carbon fixation has evolved on up to 40 independent occasions in different families of plants, making it a prime example of convergent evolution.[8] C4 plants arose around 25 to 32 million years ago[8] during the Oligocene (precisely when is difficult to determine) and did not become ecologically significant until around 6 to 7 million years ago, in the Miocene Period.[8] C4 metabolism originated when grasses migrated from the shady forest undercanopy to more open environments,[9] where the high sunlight gave it an advantage over the C3 pathway.[10] Drought was not necessary for its innovation; rather, the increased resistance to water stress was a by-product of the pathway and allowed C4 plants to more readily colonise arid environments.[10]Today, C4 plants represent about 5% of Earth's plant biomass and 1% of its known plant species.[11] Despite this scarcity, they account for about 30% of terrestrial carbon fixation.[8] Increasing the proportion of C4 plants on earth could assist biosequestration of CO2 and represent an important climate change avoidance strategy. Present-day C4 plants are concentrated in the tropics (below latitudes of 45°) where the high air temperature contributes to higher possible levels of oxygenase activity by rubisco, which increases rates of photorespiration in C3 plants.
- Plants that survive solely on C3 fixation (C3 plants) tend to thrive in areas where sunlight intensity is moderate, temperatures are moderate, carbon dioxide concentrations are around 200 ppm or higher, and ground water is plentiful. The C3 plants, originating during Mesozoic and Paleozoic eras, predate the C4 plants and still represent approximately 95% of Earth's plant biomass. C3 plants lose 97% of the water taken up through their roots to transpiration.[1] Examples include rice and barley.C3 plants cannot grow in hot areas because RuBisCO incorporates more oxygen into RuBP as temperatures increase. This leads to photorespiration, which leads to a net loss of carbon and nitrogen from the plant and can, therefore, limit growth. In dry areas, C3 plants shut their stomata to reduce water loss, but this stops CO2 from entering the leaves and, therefore, reduces the concentration of CO2 in the leaves. This lowers the CO2:O2 ratio and, therefore, also increases photorespiration. C4 and CAM plants have adaptations that allow them to survive in hot and dry areas, and they can, therefore, outcompete C3 plants.C4 plants have a competitive advantage over plants possessing the more common C3 carbon fixation pathway under conditions of drought, high temperatures, and nitrogen or CO2 limitation. When grown in the same environment, at 30°C, C3 grasses lose approximately 833 molecules of water per CO2 molecule that is fixed, whereas C4 grasses lose only 277 water molecules per CO2 molecule fixed. This increased water use efficiency of C4 grasses means that soil moisture is conserved, allowing them to grow for longer in arid environments.[7]C4 carbon fixation has evolved on up to 40 independent occasions in different families of plants, making it a prime example of convergent evolution.[8] C4 plants arose around 25 to 32 million years ago[8] during the Oligocene (precisely when is difficult to determine) and did not become ecologically significant until around 6 to 7 million years ago, in the Miocene Period.[8] C4 metabolism originated when grasses migrated from the shady forest undercanopy to more open environments,[9] where the high sunlight gave it an advantage over the C3 pathway.[10] Drought was not necessary for its innovation; rather, the increased resistance to water stress was a by-product of the pathway and allowed C4 plants to more readily colonise arid environments.[10]Today, C4 plants represent about 5% of Earth's plant biomass and 1% of its known plant species.[11] Despite this scarcity, they account for about 30% of terrestrial carbon fixation.[8] Increasing the proportion of C4 plants on earth could assist biosequestration of CO2 and represent an important climate change avoidance strategy. Present-day C4 plants are concentrated in the tropics (below latitudes of 45°) where the high air temperature contributes to higher possible levels of oxygenase activity by rubisco, which increases rates of photorespiration in C3 plants.