ВЛИЯНИЕ КОНКУРЕНЦИИ ДРЕВОСТОЯ НА ВОЗОБНОВЛЕНИЕ И РОСТ ПОДРОСТА КЕДРА СИБИРСКОГО В БЕРЕЗНЯКЕ
Authors: Танцырев Н.В. , Андреев Г.В. 
Published: February 2025

Рассмотрено влияние конкуренции древостоя березняка ягодниково-зеленомошного, пройденного выборочной рубкой ухода, на возобновление и развитие подроста кедра сибирского под его пологом на Среднем Урале. При относительно ежегодном разной интенсивности возобновлении кедра до рубки после её проведения наблюдается спад и через несколько лет прекращение появления его всходов. Основным фактором, определяющим дальнейший рост и развитие подроста кедра, является уровень перехвата пологом древостоя фотосинтетически активной радиации (световая конкуренция). Видимая связь с корневой конкуренцией берёзового древостоя за почвенное питание не выражена, что предполагает определённую адаптацию подроста кедра к ней.

Introduction. The abundance of Siberian cedar undergrowth (Pinus sibirica Du Tour.) under the canopy of secondary small-leaved stands is observed throughout its range. This undergrowth is considered to be a potential cedar stand. At that, the influence of competition of small-leaved stands on the regeneration and development of cedar undergrowth under their canopy has not been sufficiently studied. The goal of this study is to analyze the competition of the Vaccinium pleurocarpous moss birch stand with the Siberian cedar undergrowth. Material and methods. The research was carried out on the basis of a microecosystem approach, using a previously proposed and tested complex of indices of light, root and integral competition of a stand under the canopy of a 70-year-old foothill Vaccinium pleurocarpous moss birch stand in the northern part of the eastern macroslope of the Middle Urals, which was selectively felled. The record of parameters of the stand, environment, and undergrowth of cedar was taken in 80 circular sites with a radius of 7 m. The age of the undergrowth is calculated with an accuracy of one year by the number of annual increment of the terminal shoot. The dynamics of annual generations of one-year-old seedlings is reconstructed by the age structure of undergrowth and the empirical coefficients of its survival curve. Results. With almost annual cedar regeneration with different intensity (up to 0.7 thousand trees/ha) under the canopy of birch forest, a reduction in the number of generations is observed after the tending cuttings. In 5-7 years, there is a complete cessation of the emergence of cedar seedlings. In 26 years after cutting, the values of the average for the past five years vertical growth of terminal shoots of 23-35 years old cedar undergrowth, growing on the borders of former technological corridors (skidding tracks) and on the site of felled individual trees (in the" windows " of the stand), are 8 times higher than they are in the areas under the closed canopy, where the trees were not cut down. At that, they are closely negatively related (R2 = 0.83) to the light competition of the stand ( level of interception of photosynthetically active radiation by its canopy). The relationship with its root competition for soil nutrition is not expressed. As a result, the closeness and reliability of the negative relationship (R2 = 0.67) of mean increment of terminal shoots with the complex index of integral competition of the stand, which characterizes the joint influence of these factors, is 20% lower than the relationship with the particular index of light competition. Conclusion.Hence after the selective felling, the emergence of cedar seedlings under the canopy of birch forest ceases. But it contributes to the intensive growth of existing cedar undergrowth, reducing, first of all, light competition of the stand, which is a determining factor in its development. No clear root competition supposes adaptation of cedar undergrowth to the conditions of the birch grove.