A global-scale assessment of water resources and vegetation cover dynamics in relation with the earth climate gradient

Authors: Sohoulande, Clement; AWOYE, HERVE - University Of Calgary; Nouwakpo, Sayjro; DOGAN, SELIM - Konya Technical University; Szogi, Ariel; Stone, Kenneth; Martin, Jerry

Submitted to: Remote Sensing in Earth Systems Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/30/2021
Publication Date: 1/7/2022
Citation: Sohoulande Djebou, D.C., Awoye, H., Nouwakpo, S.K., Dogan, S., Szogi, A.A., Stone, K.C., Martin, J.H. 2022. A global-scale assessment of water resources and vegetation cover dynamics in relation with the earth climate gradient. Remote Sensing in Earth Systems Sciences. https://doi.org/10.1007/s41976-021-00063-0.
DOI: https://doi.org/10.1007/s41976-021-00063-0

Interpretive Summary: Changes in the climate and the rapid growth of the world population cause pressures on water resources and natural vegetation covers. This situation is a threat to the survival of both human communities and natural ecosystems. In many regions of the planet, natural vegetation disappeared and water resources are scarce. As the situation is getting worse, it is critical to plan strategies to preserve vegetations and freshwater resources. Yet, these strategies could only be effective if they consider the full extent of the ongoing changes in the climate and vegetation covers. In an effort of contributing to the understanding of these changes, our study investigated these changes in relation with the climate gradient of the earth. Especially, climate aridity indices were calculated and used to highlight climate classes. A trend analysis showed different signals depending on the earth latitude bands. For instance, results show that 36.54% of the continental lands experienced a decrease of water resources and these areas do not necessarily encompass regions with decreasing vegetation covers. However, statistics indicated a significant connection between climate classes, vegetation cover changes, and water resources changes. The results suggest that the overall changes in vegetation cover and water resources across the earth are regulated by the earth’s climate gradients.

Technical Abstract: Changes in the terrestrial climate and the rapid growth of the world population cause pressures on water resources and natural vegetation covers. This situation is a threat to the survival of both human communities and the terrestrial ecosystems. Already, in many regions of the globe, natural vegetation disappeared, and water resources are scarce. As the situation is getting worse, it is critical to envision strategies for preserving vegetations and freshwater resources. Yet, these strategies could only be effective if they consider the full extent of the ongoing changes in the terrestrial water resources and vegetation covers. In an effort of contributing to the understanding of these changes, the present study investigated the actual patterns in the terrestrial land water masses and vegetation covers in relation with the climate gradient of the globe. Especially, climate aridity indices were estimated and used to highlight climate classes. A trend analysis of 15 years monthly 0.5° gridded leaf area index and land water storage anomalies showed different signals depending on the earth latitude bands. For instance, results show that 36.54% of the continental lands experienced a decrease of water resources and these areas do not necessarily encompass regions with decreasing trends of vegetation covers. However, Chi-square statistics indicated a significant connection between climate classes and vegetation cover trends as well as climate classes and land water mass trends. The results suggest complex connections between vegetation cover and land water resources anomalies, but the earth’s climate gradients marginally regulate the overall patterns.