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.

Nature's calendars 193 on the ground surface, or by the presence of hoar frost on the ground. First autumn ground frost. Determined in the same way. First autumn airfrost. Determined in the same way as the last air frost. Specify the damage to farmed crops. First snow. The date when it first snowed or the date of wet snow mixed with rain. First snow to cover the ground. The date on which snow covered the ground, at least for several hours. Final soil freezing, ice formation on waterbodies, and their complete freeze-up do net require further comments. Snow cover establishment. The date on which snow fe ll to persist over the winter. For uncommon weather events, such as storms, hurricanes, heavy hail storms and others, not only the date but also the hours should be recorded, and the damage inflicted should be described. 2. Trees and shrubs in spring and summer The first step for an observer just beginning to do phenological obser vations is to find out which of the trees and shrubs listed in the programme do grow in the area and compile their checklists for each plant community. To make the records scientifically usable one should rigorously stick to the same method in choosing site and objects, the same indicators of phases, the same frequency and accuracy of plant inspection. For a species that occurs frequently, grows in clumps or large stands (forests, field shelterbelts, gardens, parks, tree nurseries, etc.) permanent sampling groups of plants should be chosen for each species and mapped on the locality sketch map. If a species is represented by isolated individual plants growing ran domly, one should choose several (say, five) plants and put down their locations or mark them off with conspicuous labels. The plants of choice must be healthy and growing normally, but not positioned in exclusive habitats atypical of the species. The plants situated in the immediate vicinity of buildings or fences, or on steep slope are unsuitable as ob jects for observations (for compilation of the local nature’s calendar and geographical study of seasonal events in a large territory) because the