Plant Heat Stress Equals Veld Fires

Article: Matshediso Motshabi

In the last ten years, Botswana has seen an increase in heat waves with global record highs; this is thought to be a result of climate change. With severe repercussions for both people and animals as well as plants, heat waves are happening more frequently, getting warmer, and lasting longer. It appears that heat stress weakens ecosystems, negatively impacts plants in their natural habitats, drastically reduces crop yields, and this endangers our ability to feed ourselves. In 2016, Botswana recorded the highest temperature of 44 °C in the north-west district, according to meteorological data that has been made available from various sources. Since then, warm temperatures have fluctuated. There is a specific temperature range in which various crops thrive. 20–24°C is the ideal range for most horticultural crops, and 30–34°C is the ideal range for arable cereals. The majority of crop cultivars altered their molecular response to deal with heat stress so as to adapt to fluctuating warm temperatures experienced in our country.

To survive heat, plant cells activate a molecular defence mechanism for heat stress protection known as heat-shock response (common to all organisms). This mechanism guards against proteotoxic stress, which prevents cells from damaging themselves during an episode of heat stress. Such stress can result from over exposure to certain toxins, UV light, or salinity of the soil in addition to heat stress. The production of so-called heat-shock proteins, which act as molecular shields to protect proteins by preventing misfolding, is one of the ways the heat shock response defends cells. The production of Brassinosteroids (BRs), a class of steroid hormones that are crucial for plant growth and development as well as a defence mechanism which increases the plant’s resistance to heat stress, is another molecular mechanism by which plants defend themselves against extreme heat. Physiological traits like leaf rolling, thick cuticle wax, thorny or spikey leaves, wilting, dry leaf edges, bolting, sun scalding, and fruit dropping are physical signs resulted from the response of heat shock response and BR for plants to cope with intense heat. Farmers are also known to provide mulch, humidity, net shade, plant heat-resistant crops, and do other things to help their crops survive the heat.

However, some plants, such as wild grass, have BR hormones that are unable to express mechanisms of heat tolerance, so they end up drying to deal with the heat. Somehow in this intense weather, and with the ploughing season approaching, wild grass catches fire which eventually turns into a veld- fire. We can reduce the risk of veld fires spreading into our farms by building internal firebreaks measuring 2.5 meters as well as external fire breaks surrounding the farm that are at least 5 meters in length. Make sure that you have the right tools for putting out fires, such as grass fire beaters and safety gears, and educate your staff on how to put out fire within the farm safely. Refrain from spitting cigarette ashes on the ground. Install solar-powered fire alert systems, such as drums, bells, and whistles, and Keep up with weather-related news to stay informed of veld fire outbreaks and be ready.

The typical season for veld fires in Botswana is between August and October, though this can extend into January during protracted drought periods, according to a research paper written by Dube in 2007. Additionally, a publication by Maabong and Mphale from 2021 included comprehensive data on wildfire occurrences from 1994 to 2019. Their research showed that the year 2015 had the highest number of veldfire outbreaks, which were caused by a prolonged drought and enough biomass, which were ideal conditions to spark wildfires. Additionally, according to data released by the Department of Forestry and Range Resources (DFRR), the Central district had the most wildfires (385), followed by Chobe and Ghanzi (226 and 185) respectively, from 2006 to 2017. Legislative frameworks have been established to reduce the risk of veld fires. The first is the Herbage Preservation Act of 1977, which advocates for the creation and upkeep of firebreaks; the second is the Forest Policy of 2011, which offers an integrated bushfire management approach that will improve the capacity for managing fires, promote biodiversity and ecosystem integrity, improve human health and safety, as well as promote social, cultural, and economic benefits; and the National Disaster Risk Management Plan of 2009, which serves as the country of Botswana’s main disaster risk management strategy. It provides a framework for sector Disaster Management Plans to be created by all Ministries and Organizations, as well as backup plans for hazard-specific preparedness plans to be created at the national, district, and village levels.

Please don’t move or do anything if wildfires damage your farm’s property. Leave the property in its current condition and get in touch with your local DFRR and agricultural offices so they can come and inspect your damaged property, ascertain the origin of the wildfire, and assess the extent of the damage so you can be compensated appropriately.