On 12 Dec. 2018, Ph.D. candidate Jie Wei and her supervisor Yali Si published a study onEcological Indicators, entitled “A new satellite-based indicator to identify spatiotemporal foraging areas for herbivorous waterfowl”. Qinchuan Xin from Sun Yat-Sen University, Luyan Ji and Peng Gong from the department of Earth System Science (DESS) are the co-authors.

The distribution of food resources is a key factor in habitat selection. Herbivorous waterfowl prefer early-stage growing plants (from the onset of plant growth to the peak in nutrient biomass) as these offer higher energy intake rates. This plant development stage is not fully captured by commonly used satellite-derived vegetation indicators, which focus on plant biomass (e.g., Enhanced Vegetation Index, EVI) or active plant growth (e.g., the differential EVI between current and a previous date, diffEVI). To improve mapping suitable grazing areas for herbivorous waterfowl, we propose a new satellite-based plant growth indicator of early-stage plant growth (ESPG). We hypothesize that herbivorous waterfowl prefer plants at an early development stage during the growing season and select plants with a relatively later end of ESPG during the non-growing season. We use satellite tracking data of 20 greater white-fronted geese (Anser albifrons) wintering in the Yangtze River floodplain to validate our predictions. We build generalized linear models for goose distributions during the growing and non-growing seasons and compare the performance of ESPG to commonly used plant growth indictors (EVI and diffEVI).

This study found that during the growing season, ESPG can explain 53% of variation in the goose distribution, outperforming EVI (27%) and diffEVI (34%). During the non-growing season, only the end of ESPG significantly influences goose distribution, explaining 25% of the variance (ESPG: AUC=0.78; EVI: AUC=0.58; diffEVI: AUC=0.58). The newly-developed plant growth indicator ESPG could be used to improve models of herbivorous waterfowl distributions and hence support efforts toward waterfowl conservation and wetland management.

Fig. 1. Herbivorous waterfowl prefer plants at early-stage plant growth (ESPG). Utilizing the new plant growth indicator ESPG, we could generate the spatiotemporal distribution of suitable foraging areas for herbivorous waterfowl. The site is Dongting Lake in the middle and lower Yangtze River floodplain.

Ph.D. candidate Jie Wei is in her third year. Her research is focused on bird migration ecology and bird conservation under the global changing.

Article link:

Wei, J., Xin, Q., Ji, L., Gong, P. & Si, Y. (2019). A new satellite-based indicator to identify spatiotemporal foraging areas for herbivorous waterfowl. Ecological indicators 99: 83-90.

https://www.sciencedirect.com/science/article/pii/S1470160X1830949X?via%3Dihub