Composition Of Natural Regeneration Research Articles

Dynamics of natural regeneration after disturbance in a remnant of Mixed Ombrophilous Forest in southern Brazil

This study evaluated changes in the structure for remnant Mixed Ombrophilous Forest recovering from logging, which ceased over 40 years ago. Regarding the dynamics of the floristic composition of natural regeneration, 18 species remained (23.38% of the total) and 27 new species entered (35.06% of the total). The greatest increases were observed for Allophylus edulis, Myrsine umbellata, and Miconia cinerascens. When analyzing the dynamics of regeneration in ecological groups, it was observed that pioneer species had a similar value in both surveys (29.4% and 29.6%); secondary species decreased from 56.6% to 52.8%, and late-successional species increased from 0.2% to 6.0%. Therefore, the forest fragment studied is in a healing phase after disturbance, characterized by the increased regeneration of pioneer species as a result of sufficient light entering the interior of the forest.

Natural regeneration following wind disturbance increases the diversity of managed lowland forests in NE Poland

AbstractQuestionsAre there significant differences in the density and composition of natural regeneration among habitat types? Is the abundance of regeneration higher in patches more seriously damaged by a windstorm than in patches not affected by the wind? Is the species diversity of regeneration greater than the diversity of mature trees prior to disturbance?LocationSzast Protected Forest, NE Poland.MethodsThroughout the Szast P.F., 111 sample plots were distributed in a regular grid 13 years after a windstorm. In plots located in disturbed forests, we measured all the canopy trees and the 30 young individuals of each size class (seedlings, short saplings and tall saplings) closest to the plot centre. In non‐disturbed patches, we measured all trees within a plot of predefined radius. For statistical analyses of differences in the diversity between mature stands and young generation, we used the Kruskal–Wallis test followed by Dunn's multiple comparison test. The relationship between the canopy layer and the young generation of trees was analysed using Spearman's rank correlation and a classic negative binomial regression.ResultsNatural regeneration was more abundant in the coniferous and mixed coniferous habitat types than in the mixed deciduous type. The density of young trees was negatively correlated with the basal area of the trees that survived the windstorm and was positively correlated with canopy tree mortality. After the windstorm, Pinus sylvestris lost more trees than the other species; Picea abies and Betula pendula slightly increased their share; and the species that benefited most from the disturbance was Quercus robur. In the coniferous habitat type, the species diversity of the young generation of trees was higher than the diversity of the canopy trees prior to the windstorm.ConclusionsLeaving wind‐disturbed areas to natural regeneration could be a viable option for converting coniferous plantations into more diverse and species‐rich stands.

Seedling establishment and regeneration in a harvested Eucalyptus plantation at Maragamuwa, Naula, Sri Lanka

The first year of secondary succession in a harvested Eucalyptus camaldulensis plantation near Maragamuwa village, Naula, was examined to see the possible effect of distance from the adjacent relatively undisturbed mature forest on the form and composition of natural regeneration after removal of eucalypts. Composition, relative densities and absolute abundance were examined in cleared 40, 20 × 20 m 2 quadrats placed in eight 1 ha blocks in two types of locations: harvested eucalypt plantation away from the natural forest (MP) and harvested blocks next to the natural forest (MT), and compared with 20 similar sized quadrats sampled in the adjacent mature forest (NF). Relative density values for MT and MP were compared with the adjacent NF using Kruskal-Wallis and Mann-Whitney U tests. A total of 11,207 individuals from 77 species were recorded per hectare in MP, while 11,658 individuals/ha from 61 species were recorded from MT and 5,925 individuals/ha from 39 species in NF. Relative densities of seedlings in MP and MT were significantly different from NF ( p p>0.05 ). Most individuals in MP and MT were 1-100 cm tall. Species composition suggests the basis for seral succession, with the cleared and distant MP plots having most non-forest species, and a high abundance per species compared with the MT plots adjacent to the mature forest. Natural forest plots had fewer individuals in each family or species, and a far lower density of the lianas typical of the first stages of colonization. In the first year of succession, there were indications of a distance effect in blocks adjacent to forest sites.

Influence of partial harvesting and site factors on the abundance and composition of natural regeneration in the Acadian Forest of Maine, USA

Understanding the factors regulating the composition and abundance of natural regeneration in forest ecosystems is critical to sustainable management worldwide. Using a long-term silvicultural experiment in Maine, we partitioned the variation in natural regeneration and examined the contribution of overstory and understory vegetation (biotic factors), substrate and soil attributes (abiotic factors), and silvicultural treatment. We hypothesized that silvicultural treatment (single-tree selection with 5, 10, and 20-year cutting cycles and diameter-limit cutting) would be less influential than abiotic and biotic factors in structuring regeneration pattern. Overall, treatment and site (biotic and abiotic) factors accounted for 26% of the variation in regeneration species composition, highlighting stochasticity of the regeneration process. In support of our hypothesis, regeneration pattern that could be explained was primarily associated with local site factors; overstory and understory vegetation uniquely accounted for 16% of the variation in species composition. Substrate and soil attributes along with silvicultural treatment accounted for 4% of variation, and uniquely accounted for 2% and 4%, respectively. In support of earlier reports, shifts toward hardwood dominance were apparent at early stages of cohort development and were associated with high harvest intensities. Our findings suggested that overstory and understory vegetation exhibit greater control over regeneration patterns than substrate and soil attributes, or silvicultural treatment, in partially harvested Acadian Forest mixedwood stands, and also indicated the potential for composition control through selective overstory removal.

Natural colonisation of an open area by Quercus robur L. – From where did the vectors disperse the seed?

We quantified seed flow distances from seed trees of Quercus robur L. into areas with no forest cover based on a population of 147 trees growing next to an open heath land hosting many young oak seedlings. We sampled seedlings along four transects (6–700 m from the source population), and revealed likely parentage of seedlings by microsatellite genotyping data. We found seedlings that fitted the source population at distances up to 700 m, which was the furthest distance from the source population at which seedlings were sampled. However, we estimated that approximately half of the sampled seedlings did not originate from the source population, but must have been recruited from more distant oak populations, growing at least 500 m away. We conclude that the genetic origin and composition of natural regeneration of Q. robur are likely to originate from trees distributed at the landscape level rather than merely trees in the vicinity of the regenerated area. Implications for genetic management are discussed. The quantitative results fit well with qualitative reports of birds transporting acorns several hundred metres away from seed parents.

Effects of intensity and frequency of harvesting on abundance, stocking and composition of natural regeneration in the Acadian forest of eastern North America.

In a silviculture experiment in east-central Maine, USA, natural regeneration was sampled to measure the effects of: (1) a range of partial harvest intensities, and (2) repeated partial harvest at one intensity. Under the first objective, five treatments were compared with residual basal areas ranging from 15 to 24 m2 ha-1 for trees =1.3 cm diameter at breast height. For the second objective, regeneration was evaluated after four harvests at 5 year intervals. Prior to harvests, the overstory of all the treated stands was dominated by Tsuga canadensis (L.) Carr., Picea spp. A. Dietr., and Abies balsamea (L.) Mill. Eleven species or species groups were identified among the regeneration: A. balsamea, T. canadensis, Picea spp., Thuja occidentalis L., Pinus spp. L., Betula papyrifera Marsh., Acer rubrum L., Betula populifolia Marsh., Populus spp. L., Fagus grandifolia Ehrh. and Prunus serotina Ehrh.