BOTANY WITH BASICS OF HYDROBOTANY (AQUATIC PLANTS OF UKRAINE) - B.Ye. Yakubenko - 2011

XIV. INSTRUMENTATION AND METHODS FOR THE STUDY OF AQUATIC VEGETATION

Studying the Patterns of Overgrowth and Vegetation Distribution

To study the patterns of overgrowth and vegetation distribution, cartographic Materials or Water body plans (preferably with depth marks) are required. Based on these, a preliminary regionalization can be carried out and overgrowth diagrams can be compiled, taking into account primarily morphometric features. A detailed study of vegetation is conducted in selected areas directly on the water body. When working on large water bodies, aerial visual

observations from small, maneuverable, low-speed aircraft (such as Yak-12 or Po-2) or helicopters [2] are helpful. Large-scale (1:5000, 1:10000) aerial photographs taken during the growing season can also be utilized. If funds are available, it is advisable to use spectrozonal satellite imagery and a software package for Image Processing. Aerial Methods are indispensable not only for reconnaissance; they can also be used to determine the distribution pattern of emergent and floating-leaved vegetation (and sometimes submerged vegetation) across the water body, define the contours and Structure of Plant communities, and calculate overgrowth areas. Subsequently, the images must be deciphered, and cartographic diagrams of overgrowth should be compiled based on visual observations.

Image interpretation is carried out directly at the water body. The type of plant community can sometimes be identified by the Location, shape, structure, and photographic tone of the contour. For example, stands of cattail and reed appear on images as patches of various sizes with distinct contour coloration intensities. The bulrush and flowering rush can be recognized by their contour configurations. Floating vegetation is characterized by light, almost white contours, the configuration of which varies depending on the species COMPOSITION OF THE stand. Submerged vegetation appears on images as grainy, blurred gray patches.

When compiling cartographic diagrams, the boundaries of overgrowth are determined using prominent landmarks on the shore or within the water body itself. Ecological profiles, as well as linear or strip transects, are then laid out in selected key areas to describe and study the vegetation. When The Nature of the overgrowth changes, environmental factors (such as depth, water Temperature, and bottom sediment characteristics) are typically taken into account; water and bottom sediment samples are collected for subsequent analysis, and water transparency is measured within submerged plant beds to establish the dimensions of vegetation zones or belts. When studying the regularities of vegetation distribution, profiles are laid out taking into account the direction of environmental gradients. The number of profiles needed across a water body to establish distribution patterns depends on its size, the Nature of the overgrowth, and the research objectives. In water bodies with a low number of biotopes and relatively uniform vegetation, 1–2 profiles or transects are sufficient. In large water bodies and watercourses with complex shoreline topography and high biotope diversity, profiles or transects are laid out in the most representative areas.

Ecological profiles are usually laid out using a non-stretching measuring cord (preferably with floats), stretched at a right angle to the shoreline. The direction of the profile is set using a compass. When studying vegetation, It is important to determine the depth limit of overgrowth, its distribution, and species composition. This is accomplished during surveys using a rake with 4–5 Teeth (preferably curved) on a long (2.5–3 m) handle, or various grappling hooks. Dredges and vegetation samplers described by V. M. Katanska [36] and I. M. Raspopov and A. P. Belavskaya [76] can also be used.

Most submerged plants typically reach depths of 2.5–3 m. The depth of their distribution largely depends on water transparency and the pigment composition of the plants. Sometimes aquatic moss, elodea, quillwort, water lobelia, and hornwort descend to depths of 8–12 m, and charophyte Algae down to 30 m. Floating-leaved plants are distributed down to 1–4 m (usually up to 2 m), while emergent plants typically occur from the waterline down to an average of 1–2 m. To better examine plant clusters on the bottom, especially when the water surface is choppy, a viewing tube can be used; its construction is described by I. M. Raspopov and A. P. Belavskaya [76]. Such a tube doubles the observation efficiency compared to the unaided eye.

The most accurate description of submerged vegetation distribution, its quantitative indicators, Ecological features of species, and the composition of phytocoenoses can be obtained only by using diving equipment [73, 75]. During a single dive (1 hour 10 minutes) in light diving gear, approximately 2000 m² of vegetation can typically be visually surveyed.

Based on the research data, cartographic diagrams of vegetation distribution across the water body are compiled. It is also advisable to draw an ecological depth profile. On these diagrams, different ecological groups of vegetation are indicated by hatching, or the distribution of each species is marked with conventional symbols [79].

Using the cartographic diagrams, measurements are taken of the areas (m², ha, km²) of various overgrowth types, the species forming them, specific plant formations (or orders and alliances), as well as the total overgrowth area. Cartographic diagrams and ecological profiles compiled from observations across different years make it possible to describe Changes in the overgrowth dynamics of a water body over specific periods of time.