Liang Liang¹ and Kate S. He²

¹Department of Geography, University of Kentucky, Lexington, Kentucky 40506, USA

²Department of Biological Sciences, Murray State University, Murray, Kentucky 42071, USA

Over the past few decades, phenology has been a focal point of monitoring biodiversity and ecosystem changes under climate change, species invasion, and other environmental stresses (Cleland et al. 2007, Calinger et al. 2013, Alp et al. 2016).  It has long been recognized that the closely coupled relationships exist between phenology of organisms and corresponding meteorological conditions, but the detailed patterns tied to genotypic complexity (in addition to climatic variation) within and among species are still poorly understood (Pau et al. 2011, Liang 2016).  In addition, recent studies have indicated that phenological shifts are taking place across ecosystems; yet, the magnitudes and impacts of these shifts have not been adequately studied or explained (Richardson et al. 2013, Friedl et al. 2014, Thackeray et al. 2016).

Although satellite remote sensing provides broad coverage and multi-temporal capability in observing land surface phenology on a regular basis, cross-scalar integration with in situ observations and ground-based optical measurements is still lacking for properly attributing measured changes to biophysical processes (Richardson et al. 2017).  While there has been some success to bridge multi-scale observations from an instrumental perspective, there remains a lack of understanding of the ecological processes underlying the observed phenological patterns at scales ranging from species to ecosystems (Liang et al. 2014, Melass et al. 2016).  Thus, the utility of phenology has been mostly constrained to being an indicator  of environmental change; and the pivotal role of phenology in the ecology and physiology of species and species interactions, though widely recognized, is limited in its potential to track ecosystem status and function for biological conservation (Enquist et al. 2014, Morellato et al. 2016).

To further the study of phenology for monitoring and conserving natural systems, efforts must be made on two fronts.  First, the means of phenological observations need to be expanded to include new techniques, which are capable of covering scales in-between traditional field-based observations and satellite remote sensing.  As the case for empirical sciences, more and richer data are necessary to depict a clearer picture of the phenomena that are under study.  In addition to synergizing different satellite sensor information through data fusion and broadening geographic coverage of field observations, more near-surface remote sensing techniques, such as IR-enabled digital photography, field spectroscopy, and drone-carried survey will further help clarify and sharpen our views of the processes of phenology and its ecological context.   Secondly, effort must be made to develop viable theories, conceptual frameworks, and operational models using existing data, by linking and integrating phenological knowledge that have been separately kept in various scientific disciplines, such as biometeorology, ecology, climatology, and biology.  It is especially crucial to identify the explicit mechanisms in which phenology is linked to broader ecological processes, such as exotic species invasion, trophic synchronization/mismatch, and biogeochemical cycles.  Ecological applications of phenology must be based on a thorough understanding of the relations and interactions between phenology and other ecological processes.  Certainly, besides collecting new data, there is still a great potential to gain new insight into the understanding of species phenology and shifts in phenology from existing remote sensing and field-based records through adopting novel analytical tools and new research angles.

In line with this research need, we invite high-quality contributions, which depict diverse patterns, trends, and ecological applications of phenology, to a special issue of Remote Sensing in Ecology and Conservation.  The aim is to bring together recent works demonstrating unique phenological patterns in different environments, as derived primarily from remote sensing measurements, enhanced by sensor fusion technology and data integrations.  We are particularly interested in studies that contribute to a better understanding of 1) spatiotemporal patterns of phenology that are tied to both climatic variability and species diversity and distribution; 2) the utilities of novel remote sensing technology, including high spatial and temporal resolution sensors and digital repeat photography in capturing land surface phenology and in situ phenology; and 3) explicit linkages between phenology and specific ecological applications in conservation effort.  Research demonstrating innovative approaches to monitoring and modeling phenology are also welcome.  The main objective of this special issue is to stress the need to illuminate the ecological context of phenological research and to identify better ways of using phenology for ecological monitoring and conservation.

Submission deadline: 31 October 2017

References

Alp, M., Cucherousset, J., Buoro, M. & Lecerf, A. (2016). Phenological response of a key ecosystem function to biological invasion. Ecology Letters,19: 519–527.

Calinger, K. M., Queenborough, S., & Curtis, P. S. (2014). Herbarium specimens reveal the footprint of climate change on flowering trends across north-central North America. Ecology Letters, 16(8),1037–1044.

Cleland, E.E., Chuine, I., Menzel, A., Mooney, H.A. & Schwartz, M.D. (2007). Shifting plant phenology in response to global change. Trends Ecol. Evol., 22, 357–365.

Enquist, C. A. F., J. L. Kellermann, K. L. Gerst & Miller-Rushing, A.J. (2014). Phenology research for natural resource management in the United States. International Journal of Biometeorology, 58, 579-589.

Friedl, M.A., J.M. Gray, E.K. Melaas, A.D. Richardson, K. Hufkens, T.F. Keenan, A. Bailey & O’Keefe, J. (2014). A tale of two springs: using recent climate anomalies to characterize the sensitivity of temperate forest phenology to climate change. Environmental Research. Letters. 9 054006 doi:10.1088/1748-9326/9/5/054006.

Liang, L. (2016) Beyond the Bioclimatic Law: geographic adaptation patterns of temperate plant phenology. Progress in Physical Geography, 40, 811-834.

Liang, L., M. D. Schwartz, Z. Wang, F. Gao, C. B. Schaaf, B. Tan, J. T. Morisette & X. Zhang (2014) A cross comparison of spatiotemporally enhanced springtime phenological measurements from satellites and ground in a northern U.S. mixed forest. Geoscience and Remote Sensing, IEEE Transactions on, 52, 7513-7526.

Melaas, E. K., M. A. Friedl & A. D. Richardson (2016) Multiscale modeling of spring phenology across Deciduous Forests in the Eastern United States. Global Change Biology, 22, 792-805.

Morellato, L. P. C., B. Alberton, S. T. Alvarado, B. Borges, E. Buisson, M. G. G. Camargo, L. F. Cancian, D. W. Carstensen, D. F. E. Escobar, P. T. P. Leite, I. Mendoza, N. M. W. B. Rocha, N. C. Soares, T. S. F. Silva, V. G. Staggemeier, A. S. Streher, B. C. Vargas & C. A. Peres (2016). Linking plant phenology to conservation biology. Biological Conservation, 195, 60-72.

Pau, S., E. M. Wolkovich, B. I. Cook, T. J. Davies, N. J. B. Kraft, K. Bolmgren, J. L. Betancourt & E. E. Cleland (2011). Predicting phenology by integrating ecology, evolution and climate science. Global Change Biology, 17, 3633-3643.

Richardson A D, Keenan T F, Migliavacca M, Ryu Y, Sonnentag O and Toomey M 2013 Climate change, phenology, and phenological control of vegetation feedbacks to the climate system Agric. Forest Meteorol. 169 156–73.

Richardson, A. D., J. Weltzin & J. T. Morisette (2017) Cross-scale phenological data integration to benefit resource management and monitoring. EOS, 98.

Thackeray, S.J., Henrys, P.A., Hemming, D., Bell, J.R., Botham, M.S., Burthe, S., Helaouet, P., Johns, D.G., Jones, I.D., Leech, D.I. and Mackay, E.B., 2016. Phenological sensitivity to climate across taxa and trophic levels. Nature, 535(7611), 241-245.