From uncertainty to an exact number: Developing a method to estimate the fitness of a clonal species with polyvariant ontogeny

Potential-Growth Indicators Revisited: More Merits of Indication

“…Reed grasses of the Calamagrostis genus are perennial herbaceous polycarpic graminoids growing in a wide range of ecological conditions, mainly in forests and meadows, a traditional research object in the Russian school of population botany. Their ontogenies are well studied including that of Calamagrostis epigeios [17,19], where the ontogenetic stages of individual plants are detectable from the morphology of the above-ground parts. Moreover, the chronological age (in years) of the plant can also be determined from the annual increments in its tillering zone [19].…”

“…As a pioneer species of plant succession, C. epigeios invades open plant communities, such as spruce clear-cut areas, due to extensive population growth by means of vegetative propagation. However, the mosaic of its colonies (systems of clonal plants) has not yet formed a continuous cover by the initial years of colonization, so that the colonies have distinguishable boundaries [21]. Annual observations (late August, when the herbs complete their development) show that different plants spend different numbers of years at the same stage of ontogeny, i.e., there are individuals of different ages among the plants at the same stage.…”

“…These graphs are constructed on a two-dimensional integer-valued "lattice" of all possible states that an individual plant may have in terms of age-stage. Botanists call this diversity polyvariant ontogeny and consider it as a major mechanism of plant adaptation to the environment [22,17,19,23]. The numerical values of ontogenetic transition rates assigned to the solid arrows in Figure 2 were obtained from the data of "identified individuals" type [1, p. 134], while the reproduction rates are shown on the dashed arcs of the LCG as symbolic parameters to be calibrated rather as a tribute to the tradition of reproductive uncertainty, i.e., inability to detect the status of parents for each recruited plant, hence inability to calibrate the status-specific reproduction rates in a unque way [24,19].…”

“…In fact, the 2017 project was aimed to get rid of the reproductive uncertainty inherent in the analysis of aboveground vegetation [ibidem], and for this purpose the whole reed colony (two of them in fact) was digged up, with preserving the entire system of rhizome parent-offspring links. The fragments of the linkage system related to each parent plant (Figure 2 in [21]) were analyzed and summerized over the colony, thus resulting in a total picture of paret-offspring links in a colony.…”

“…We expose this algorithm in Section 2. Section 3 reports on a case study of Calamagrostis epigeios, a perennial herbaceous graminoid, a traditional object to study in the Russian botanical school [17], with the PPMs beyond the class of rank-1 F. "More Merits of Indication" by PGIs are thereafter discussed in Section 4.…”