Land surface phenology as indicator of global terrestrial ecosystem dynamics: A systematic review

Vegetation phenology is considered an important biological indicator in understanding the behaviour of ecosystems and how it responds to environmental cues. Changes in vegetation dynamics have been strongly linked to the variability of climate patterns and may have an important impact on the ecological processes of ecosystems, such as the land surface-atmosphere exchange of water and carbon, energy flows and interaction between different species. Land surface phenology (LSP) is the study of seasonal patterns in plant phenophases based on time series from vegetation indices (VI) or biophysical variables derived from satellite data, and has played an essential role in monitoring the response of terrestrial ecosystems to environmental changes from local to global scales. The goal of this systematic literature review is to provide a detailed synthesis of the main contributions of the global LSP research to the development of environmental knowledge and remote sensing science and technology, identifying possible gaps that could be addressed in the coming years. This systematic review found that the number of LSP studies has grown exponentially since the 1980s, although the analysis of phenological metrics or phenometrics derived from satellite data (i.e. proxies for the biological phenophases of plants) has focused specifically on ecosystems located in the mid- and high-altitude in the Northern Hemisphere (e.g. boreal forest/taiga, evergreen, deciduous or mixed temperate forest). LSP studies use different satellite dataset and methods to estimate phenometrics. These studies identified an advance in spring and a delay in autumn phenophases as general trends. Although these trends were associated mainly to changes in temperature and precipitation, phenological cycle dynamics might be related to other drivers, such as photoperiod, soil moisture or organic carbon content, among others. Therefore, this interaction between different climatic and non-climatic drivers make phenology modelling a difficult task. Hence, in the coming years, a greater integration of LSP data into ecological process modelling could provide a more complete overview on the terrestrial ecosystems functioning. Furthermore, different technical and methodological aspects (e.g. greater temporal coverage of recent high-spatial-resolution satellites, advances in remote-sensing technology or improved efficiency in the computational processing of geospatial data) may also contribute to improve our understanding of Earth's ecosystem dynamics and their environmental drivers.

Automated summary

Vegetation phenology serves as a key biological indicator for understanding ecosystem behavior and responses to environmental cues. Research shows a general trend of spring advancing and autumn delaying, although challenges arise from the complex interactions between various climatic and non-climatic factors, making phenology modeling a difficult task.