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ŠUMARSKI LIST 9-10/2022 str. 28     <-- 28 -->        PDF

Each plot is at least 50 m apart so that they have different ecological conditions. Therefore, plots could be served as single observations.In each plot of cypress forests, the team investigated the regeneration characteristics, stand factors (biological factors) and environmental factors (abiotic factors). The recorded characteristics of natural regeneration mainly included species, quantities, and tree heights of regeneration plants; stand factors of records mainly include adult cypress density, tree canopy density, tree density, shrub coverage, shrub density, herb coverage, herb density, and moss coverage; environmental factors of records mainly include long and short axis length of forest gap, altitude, geographical coordinates, slope, slope direction, rock exposure rate, and soil stone content.
Establishment of a model for influence factor of NR of cypress plantation – Utvrđivanje modela za utjecaj čimbenika prirodne obnove (NR) na plantaži obične azijske tuje
According to the principles of objectivity, representativeness, systematicness, and measurability, and based on the investigation analysis, our study constructed an influence factor model of NR of cypress plantation, which was composed of stand factors and environmental factors, as shown in Figure 2.
The desired position of Figure 2.
Division standard of regeneration seedlings – Distribucija pomlatka prema visinskim klasama
An age structure is an important characteristic of population dynamics. The height level of seedlings can be used to replace an age structure in seedling research. In this study, cypress seedlings were divided into four grades based on plant height level (Table 1).
The desired position of Table 1.
Data analysis – Analiza podataka
The data of characteristics stand factors and environmental factors of regeneration seedling in the sample plots were pre-processed. Slope direction management: In each plot of cypress forest, the fixed slope direction is 0° to the north and the slope direction gradually increases clockwise, thereby 0 ~ 45° and 315° ~ 360° are shady slopes; 45° ~ 135° is semi shady slope; 135° ~ 225° is sunny slope; 225° ~ 315° is semi sunny slope.
Gap measurement: In each plot of cypress forest, gap area was calculated by the elliptic area formula: S = π AB / 4 (where S was the forest gap area, A was the long axis length and B was the short axis length).
Statistical analysis: All data analysis was completed by GraphPad Prism v9 software. Data were subjected to a nonparametric test using Kruskal-Wallis.Pearson and Spearmanrank correlation test was used for correlation analysis. Multiple stepwise regression analysis was used to explore which stand factors and environmental factors had an impact on regeneration. P < 0.05 was considered statistically significant.
Results
Rezultati
Density structure of regeneration seedlings – Gustoća sklopa pomlatka
he study plots were located in pure cypress forest or mixed forest, with the characteristics of altitude of 149 – 348 m. The community structure of survey area was complete with arbor, shrub and grass, and plant species was abundant. See Table 2 for the main types of trees and shrubs and all types of regeneration seedlings in the survey area.
The desired position of Table 2.
In 42 investigated plots, the distribution of cypress regeneration seedlings and plants was extremely uneven. The regeneration density of one plot (No.8 plot) was up to 48000 ~ 49000 individuals / hm2, and we also found that the moss coverage of this sample plot was very high and the forest gap area was large. The density of regeneration seedlings in other sample plots was concentrated at 1–8000 individuals / hm2, as shown in Table 2. However, plant density of regenerated seedlings in 20 sample plots was 0 individuals / hm2, meaning no regeneration phenomenon. Additionally, the average regeneration density of 22 sample plots with cypress seedlings was calculated, as 5018 individuals / hm2. In general, the number of regenerations of cypress in some sample plots was large and small in some sample plots, and the density and regeneration frequency of cypress plantation in the survey plots still have room for improvement.
The desired position of Table 3.