Макарова, О. А. Фенологический атлас растений / Н. В. Поликарпова, О. А. Макарова ; М-во природ. ресурсов и экологии Рос. Федерации, Федер. гос. бюджет. учреждение «Гос. природ. заповедник «Пасвик» ; [худож.: Хохлов В. А. ; пер.: Кислова О. С.]. - Рязань : Голос губернии, 2016.

198 A phenological atlas of plants Dry leaves cover paths in the end o f leaffa ll in birch turned to autumn colors. Tree and shrub crowns have become yellow, red or brown. The minor amounts of leaves remaining greenish are dis regarded. The inside of the crown in pine is all yellow, as if ‘scorched’. Alder and aspen may in some years drop all leaves virtually within one day or even several hours. Phenology observers should keep this fact in mind. On windy days leaf fall should be monitored more frequently not to miss its end. The end o f leaf fa ll date is defined as the day on which the tree or shrub crown became completely leafless. Minor amounts of leaves sometimes retained on the top of the crown are disregarded. The inside of the crown in pine has shed yellow needles and the crown is green again, but appearing sparser. Needle drop in spruce is observed starting November and may take quite a while. The fallen needles are distinctly visible on the snow cover, especially after windy days. If a phenologist monitors a substantial number of specimens of the same species, it would be beneficial for investigation of the poorly studied autumn phases in plants to record not only the beginning of a phase and its peak (50% of sampled plants have entered the phase), but also its end (leaves of the last specimen started changing color, have fully changed color or fully fallen). In our regions these observations are carried out for birch , aspen, willow, rowan. If frost happens early, some plant species would not shed brown leaves, retaining them through the winter. This situation should also be properly recorded.