Nature's Air Conditioners: How Trees Regulate Land Surface Temperatures

As our planet continues to warm, it's crucial to seek natural solutions to keep our spaces comfortable. Picture yourself walking under the relentless sun, desperately searching for a shady refuge. It feels like paradise when you finally discover a tree with a broad canopy and lush leaves, providing a cooling place to rest. This instinctive knowledge is something we all share. While you may appreciate the cool breeze of mid-spring, residents of Chauk town in the Magway Region of Myanmar's Central Dry Zone endure extremely high temperatures. In April 2024, a heatwave hit this region, with temperatures soaring to 48.2 degrees Celsius (118.76 degrees Fahrenheit) - a reminder of our urgent need for natural cooling solutions.

I’m thrilled to share my recent research, which reveals a significant relationship between the Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) in the Magway Region. You might be wondering, "What are NDVI and LST?" Simply put, NDVI measures vegetation health and coverage, which indicates how lush and green an area is. Meanwhile, LST measures the temperature of the earth's surface. Understanding these concepts is essential, as they provide valuable insights into environmental conditions that can significantly impact land management and our responses to climate change, like heatwaves.

My study specifically examined how trees and other vegetation can mitigate the intensity of land surface temperatures. This research quantifies the problem and leads us toward a nature-based solution by demonstrating how vegetation can transform our landscapes into more comfortable, sustainable environments, even in challenging areas like Myanmar’s Central Dry Zone.

Landsat 8 satellite imagery was used to calculate NDVI and LST using Google Earth Engine. The relationships between vegetation (NDVI), land surface temperature (LST), and proximity to water bodies were investigated using ArcGIS Pro and R. Over 860,000 observing points were analyzed to explore how these elements influence land surface temperatures. Furthermore, through spatial autocorrelation testing with Moran's I and Geary's C, and models like multiple regression and the Casetti Expansion Model (which accounts for spatial autocorrelation), this study explored the impacts of vegetation on land temperatures, paving the way for further research.

The findings were crystal clear. Areas with more vegetation generally have cooler surface temperatures, as indicated by the correlation between NDVI and LST at -0.77. To quantify the impact of vegetation, I employed a multiple linear regression model, revealing an adjusted R-squared value of 0.59. This value indicates this is an acceptable model. After identifying strong spatial autocorrelation with Moran’s I and Geary’s C, I refined the model using the Casetti Expansion Model, which improved the adjusted R-squared to 0.65. These results underscore the necessity of accounting for spatial autocorrelation when estimating the impact of vegetation on mitigating elevated land surface temperatures.

To sum up, trees play a crucial role in cooling the land, as evidenced by the negative correlation between NDVI and land surface temperature (LST) of -0.77, demonstrating that areas with more vegetation tend to have cooler surface temperatures. These findings highlight the importance of strategic vegetation (trees, including forests) management in mitigating the effects of heat and enhancing climate resilience across diverse landscapes.