Spatiotemporal Structure Features of a Pine Stand on the South Slope of the Eastern Sayan Mountain

Due to relatively long development and long life of forest-forming species most of the conclusions on stand dynamics are based on the data collected by indirect methods of comparative research and analysis of cenosis forming theoretically temporal and spatial succession sequences and need to be verified and clarified. The most reliable results on the stand dynamics can be received on stationary objects such as permanent sample areas. The article presents the analysis results of long-term monitoring (1968–2012) of a pine (Pinus sylvestris L.) stand in low-mountain Eastern Sayan on the south slope with a steepness of 7–8º. The intermittent test of morphometric indicators of trees mapped on the permanent sample area was used. It is shown that the sum of tree trunk cross-section areas at breast height (1.3 m) varied by no more than 10 % with timber reserves on the lower, central and upper equal sites of the sample area during the entire observation period. At the same time heterogeneity of ecological conditions, taking place even on a small section of a smooth slope, influences the plantation self-thinning intensity. In the 42-year-old stand density ratio at lower, central and upper sites was 1:1.5:2.1. Stand density difference along the slope had been decreasing gradually over time, although it remained around 30 % at the time of the last observation. Over the years of observation, 53, 47, and 32 % of pines on the lower, central, and upper sites, respectively, have survived. The calculated average age of the died trees showed that in all groups of natural diameter classes, there was an earlier die-off of pines at the bottom of the slope with an increase in dying age up to the slope. Trees with larger trunk diameter (first telling) died later. All this led to a rearrangement of the horizontal structure of the plantation, a decrease in the average diameter and average volume of trees up to the slope. Typical for mountain forests clinal tree distribution, which affects their morphological indicators, is important to consider when studying and modeling forest ecosystems, as well as when implementing forest management measures. For citation: Ovchinnikova N.F. Spatiotemporal Structure Features of a Pine Stand on the South Slope of the Eastern Sayan Mountains. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 5, pp. 34–47. DOI: 10.37482/0536-1036-2021-5-34-47