AUTHOR=Katal Negin , Rzanny Michael , Mäder Patrick , Wäldchen Jana TITLE=Deep Learning in Plant Phenological Research: A Systematic Literature Review JOURNAL=Frontiers in Plant Science VOLUME=Volume 13 - 2022 YEAR=2022 URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.805738 DOI=10.3389/fpls.2022.805738 ISSN=1664-462X ABSTRACT= 2 ABSTRACT 3 Climate change represents one of the most critical threats to biodiversity with far-reaching 4 consequences for species interactions, the functioning of ecosystems, or the assembly of 5 biotic communities. Plant phenology research has gained increasing attention as the timing 6 of periodic events in plants is strongly affected by seasonal and interannual climate variation. 7 Recent technological development allowed us to gather invaluable data at a variety of spatial 8 and ecological scales. The feasibility of phenological monitoring today and in the future depends 9 heavily on developing tools capable of efficiently analyzing these enormous amounts of data. 10 Deep Neural Networks learn representations from data with impressive accuracy and lead to 11 significant breakthroughs in, e.g., image processing. This paper is the first systematic literature 12 review aiming to thoroughly analyze all primary studies on deep learning approaches in plant 13 phenology research. In a multi-stage process, we selected 24 peer-reviewed studies published in 14 the last five years (2016–2021). After carefully analyzing these studies, we describe the applied 15 methods categorized according to the studied phenological stages, vegetation type, spatial scale, 16 data acquisition- and deep learning methods. Furthermore, we identify and discuss research 17 trends and highlight promising future directions. We present a systematic overview of previously 18 applied methods on different tasks that can guide this emerging complex research field.