Anticipating climate Change
Grasslands currently store approximately 34% of the worlds terrestrial carbon, making these ecosystems important carbon sinks and play a critical role in climate change mitigation (Contant, 2010). Carbon sequestration is achieved by grassland vegetation holding organic carbon within their roots, therefore higher sequestration is found in less disturbed grasslands with long lived perennial grasses that develop dense root systems (Acharya et al ., 2012). This suggests that long term management of grasslands will likely provide greater climate regulation. Carbon sequestration has been observed to improve with good management techniques, particularly the addition of nitrogen fixing plants (De Deyn et al ., 2011), addition of fertilizers and lime (Acharya et al ., 2012) and withholding excessive grazing (Ezeet al ., 2018). Further, grasslands are essential for human food security and provide an income for approximately 1.3 billion people around the world (Suttie et al ., 2005). Livestock grazing utilizes 80% of the total agricultural land and contributes to 40% of global agricultural production (Suttie et al ., 2005). It is predicted that demands for animal-based proteins and dairy are only going to increase as a result of projected population growth (O’Mara, 2012), making functioning grasslands critical for providing adequate nutritional resources.
Accelerated climate change adds a further element of complexity for managing restoration projects into the future. It is expected that for every 1OC increase in air temperature, there will be a 1.5OC increase in soil temperature (Ooi et al ., 2011), which may also cause disruptions to the seedbanks of many plant species. Temperature has proven to be an important environmental factor for breaking seed dormancy and these increased temperatures could influence these important physiological processes (Ooi, 2012; Prosottoet al ., 2014). Further, atmospheric CO2 has steadily risen from 325ppm recorded in 1970 to 405ppm in 2017 (Lindsay, 2018), and this is expected to approximately double by the end of this century (IPCC, 2019). Enhanced atmospheric CO2 can result in higher saturation of CO2, potentially reducing photorespiration in C3 plants, even under a warmer climate. This increased physiological efficiency has been demonstrated to alter dynamics between C3 and C4plants (Dukes, 2000). As a result of these physiological improvements, such as increased water-use efficiency (Varga et al ., 2015), plants can allocate more resources to growth and fecundity and these changes have also been observed to be more pronounce in weeds than natives or crops (Marble et al ., 2015). Changes in extreme weather patterns is expected to increase as a result of human induced climate change. Compared to pre-industrial data, changes in the intensity and pattern of rainfall events are already being noticed (Power et al ., 2017). Changes in rainfall have direct consequences on the intensity and frequency of fire, drought and flood events (Ooi, 2012). As these factors play an important role in shaping the vegetation of ecosystems and agroecosystems, new challenges for managing native and weed competition dynamics can be expected.