In November 2018, the sample plot survey method was used to analyze the population characteristics of Lithocarpus polystachyus in the natural secondary forest with different disturbance intensity in Jianning, Fujian Province, and compile its population static life table. The results showed that the number of individuals in the population was small, but it was clustered. With the increase of interference intensity, the first and second age seedlings and young trees decreased. The population types affected by human disturbance are all lacking level V trees, and the population type belongs to primary population (N₁); The undisturbed population lacks level I and II seedlings and young trees, but there are level V trees, and the population type belongs to medium decline population (S₂). In general, all populations of L. polystachyus are unstable and belong to the transitional type. In the static life table, the mortality of level I and II seedlings and young trees is high, the survival rate has a small peak in level III and IV, and then the survival rate decreases rapidly, and the average life expectation of level II is the highest. It shows that artificial conservation measures and appropriate space re-lease are needed to maintain the stability of the population.

Every year, hundreds of fires occur in the forests and rangelands across the world and damage thousands hectare of trees, shrubs, and plants which cause environmental and economic damages. This study aims to establish a real time forest fire alert system for better forest management and monitoring in Golestan Province. In this study, in order to prepare fire hazard maps, the required layers were produced based on fire data in Golestan forests and MODIS sensor data. At first, the natural fire data was divided into two categories of training and test samples randomly. Then, the vegetation moisture stresses and greenness were considered using six indexes of NDVI, MSI, WDVI, OSAVI, GVMI and NDWI in natural fire area of training category on the day before fire occurrence and a long period of 15 years, and the risk threshold of the parameters was considered in addition to selecting the best spectral index of vegetation. Finally, the model output was validated for fire occurrences of the test category. The results showed the possibility of prediction of fire site before occurrence of fire with more than 80 percent accuracy.

Tropical dry forests are complex and fragile ecosystems with high anthropogenic intervention and restricted reproductive cycles. They harbor unique richness, structural, physiological and phenological diversity. This research was carried out in the upper Magdalena valley, in four forest fragments with different successional stages. In each fragment, four permanent plots of 0.25 ha were established and the light habitat associated with species richness, relative abundance and rarity was evaluated, as well as the forest dynamics that included mortality, recruitment and diameter growth for a period of 5.25 years. In mature riparian forest, species richness was found to be higher than that reported in other studies for similar areas in the Cauca Valley and the Atlantic coast. Values of species richness, heterogeneity and rarity are higher than those found in drier areas of Tolima. Forest structure, diversity and dynamics were correlated with light habitat, showing differences in canopy architecture and its role in the capture and absorption of radiation. The utilization rate of photosynthetic effective radiation in the forest underlayer with high canopy density is low, which is related to the low species richness, while the underlayer under light is more abundant and heterogeneous.

A topic of current interest in forestry science concerns the regeneration of degraded forests and areas. Within this topic, an important aspect refers to the time that different forests take to recover their original levels of diversity and other characteristics that are key to resume their functioning as ecosystems. The present work focuses on the premontane rainforests of the central Peruvian rainforest, in the Chanchamayo valley, Junín, between 1,000 and 1,500 masl. A total of 19 Gentry Transects of 2 × 500 m, including all woody plants ≥2.5 cm diameter at breast height were established in areas of mature forests, and forests of different ages after clear-cutting without burning. Five forest ages were considered, 5-10, 20, 30, 40 and ≥50 years. The alpha-diversity and composition of the tree flora under each of these conditions was compared and analyzed. It was observed that, from 40 years of age, Fisher’s alpha-diversity index becomes quite similar to that characterizing mature forests; from 30 years of age, the taxonomic composition by species reached a similarity of 69–73%, like those occurring in mature forests. The characteristic botanical families, genera and species at each of the ages were compared, specifying that as the age of the forest increases, there are fewer shared species with a high number of individuals. Early forests, up to 20 years of age, are characterized by the presence of Piperaceae; after 30 years of age, they are characterized by the Moraceae family.

[Objective] To understand the relationship between species diversity and tree growth in natural secondary forests in Northeast China, to determine the reasonable size of species diversity, and to carry out appropriate nurturing harvesting and artificial replanting, so as to provide a scientific and theoretical basis for secondary forest management and management. [Methods] A total of 123 sample plots were set up in the Xiaoxinganling (XXAL), Zhangguangcailing (ZGCL), Laojialing (LYL), Changbai Mountain (CBS), Hadaling (HDL) and Longgang Mountain (LGS) areas in Northeast China, they were used to investigate the species composition, importance value, diversity and tree growth in each area. [Results] A total of 48 species belonging to 17 families and 31 genera were investigated in all the sample plots, among which the sample plots in Longgang Mountain contained the largest number of families, genera and species, followed by Hada Ling, Changbai Mountain, Laoyaling, Zhangguangcai Mountain and Xiaoxinganling. The α-diversity index of species in the sample sites was the largest in Changbai Mountain and the smallest in Xiaoxinganling, and the difference between them was significant (P < 0.05), while the richness index was the largest in Longgang Mountain and the smallest in Xiaoxinganling. The difference between them was significant (P < 0.05), while the greater the difference in latitude between the regions, the more obvious the difference in β-diversity index of species in the sample sites, and the fewer species shared between the two regions. The higher the rate of community succession, the higher the average diameter at breast height and the average tree height in each region were CBS > LYL > LGS > ZGCL > HDL > XXAL. The largest breast tree species in each region was Mongolian oak in Changbai Mountain with a diameter at breast height of 64.8 cm, and the smallest breast tree species in each region was Tyrannus sylvestris in Longgang Mountain with a diameter at breast height of 4.0 cm. The highest tree species in each region was Liriodendron sylvestris in Longgang Mountain with a height of 28.9 m, and the smallest species is yellow pineapple with a height of 1.3 m in Longgang Mountain. [Conclusion] Within a certain range, species diversity has a facilitating effect on the average diameter at breast height and average tree height of species within a stand. Therefore, during the management of secondary forests, appropriate nurturing harvesting and artificial replanting should be adopted to ensure reasonable species diversity in the stands and provide optimal space for the growth of natural secondary forests.

Taking the 13 years pure artificial forest Phoebe chekiangensis and heterogeneous mixed forests in Tiantong mountain, Zhejiang Province as the research object, the characteristics of stand development, tree competition differentiation, tree height/breast diameter ratio and dominant wood growth were compared and analyzed from the perspective of ecology. The results show that compared with pure forests, the growth advantages of heterogeneous mixed-age forests were significant. Average breast diameter growth of stand increased 1.8%; the growth of single plant wood accumulation increased 7.4%. The relationship between tree height and diameter showed that the high growth of Phoebe chekiangensis individuals in the heterogeneous mixed forest was significantly promoted, and the high growth of the tree was 8.4% higher than that of pure forest. 1–5 grade wood scale sizes Phoebe chekiangensis in heterogeneous mixed forests and pure forests are ranked grade 3 (43.7%) > grade 2 (26.5%) > grade 4 (15.7%) > grade 1 (12.9%) > grade 5 (1.2%); grade 3 (34.7%) > level 2 (25.6%) > level 4 (20.0%) > level 1 (18.2%) > level 5 (1.2%); the straight-diameter structure shows a normal distribution, and the degree of differentiation of pure forests is greater than that of heterogeneous forests. The dominant trees of Phoebe chekiangensis pure forest and heterogeneous forest accounted for 18.2% and 12.9% of the total number of plants respectively, providing a reserve of 51.1% and 35.4% respectively, reflecting the contribution of dominant trees caused by the self-thinning effect.