Brief summary of the paper: Photographic methods of environmental monitoring have grown in popularity and now represent one of the main ways in which habitat and biodiversity are monitored for change through time. However, efficacy and efficiency of this technique compared with traditional approaches to environmental monitoring (direct count or observation) are lacking.
This study compares the results and time-efficiency of manual versus photographic monitoring of floral abundance in low-growing flowering plants in a relatively open herbfield. Specifically, we compared 1) manual flower counting of individual plants for four species, followed by data entry in the laboratory, with 2) taking photographic images of each plant and quantifying flower counts in the laboratory.
Photographic monitoring underestimated flower counts by an average of 7.5%. Manual counting was more time consuming in the field, but less time consuming in post-processing than photographic monitoring. Overall, photographic monitoring took almost twice as long as manual counting (81.5% longer in duration), which was attributed to the much longer post-processing associated with photographic monitoring.
This suggests that perhaps the main benefit of photographic monitoring is a permanent record of the sampling frame rather than any cost savings or enhanced data accuracy, at least in the systems investigated in this study.