scholarly journals Modeling Tree Species Count Data in the Understory and Canopy Layer of Two Mixed Old-Growth Forests in the Dinaric Region

Forests ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 531
Author(s):  
Srđan Keren
Keyword(s):  
Count Data ◽  
Tree Species ◽  
Negative Binomial ◽  
Continuous Variable ◽  
Silver Fir ◽  
Dispersion Index ◽  
Canopy Layer ◽  
Old Growth ◽  
Area Of Interest ◽  
Old Growth Forest

The distribution of tree species has traditionally been analyzed based on tree diameter (DBH) as a continuous variable. However, this approach does not usually provide information on how species are distributed across the area of interest. In this study, an inverse approach was applied to investigate tree distribution patterns in two Dinaric old-growth forest stands composed primarily of European beech, silver fir, and Norway spruce. Specifically, the variance-to-mean relationship of tree counts based on 80 plots (40 in each old-growth stand) were evaluated by using a dispersion index. Understory trees exhibited clumped and random patterns, whereas canopy trees were mostly distributed in a random manner. A regular pattern was only determined for beech and all trees in the canopy layer (two cases out of ten). The observed discrete variables were further compared with three theoretical distributions. It was found that a Poisson, binomial, and negative binomial model best fitted the observed count data, which, based on the dispersion index, exhibited a random, regular, and clumped pattern, respectively. The frequency of plots with low species presence and complete absence of species was also revealed. Consequently, the analysis and modeling of tree counts can be of practical use for species conservation purposes.

Tekstura drzewostanów naturalnych w polskich parkach narodowych na tle teorii dynamiki lasu

2021 ◽  
Author(s):  
Leszek Bartkowicz ◽  
Keyword(s):  
Tree Species ◽  
Stand Structure ◽  
Basal Area ◽  
Site Conditions ◽  
Gap Dynamics ◽  
Old Growth ◽  
Mosaic Pattern ◽  
Spruce Forests ◽  
Old Growth Forest ◽  
Patch Mosaic

The aim of the study was to compare a patch-mosaic pattern in the old-growth forest stands developed in various climate and soil conditions occurring in different regions of Poland. Based on the assumption, that the patch-mosaic pattern in the forest reflect the dynamic processes taking place in it, and that each type of forest ecosystem is characterized by a specific regime of natural disturbances, the following hypotheses were formulated: (i) the patches with a complex structure in stands composed of latesuccessional, shade-tolerant tree species are more common than those composed of early-successional, light-demanding ones, (ii) the patch-mosaic pattern is more heterogeneous in optimal forest site conditions than in extreme ones, (iii) in similar site conditions differentiation of the stand structure in distinguished patches is determined by the successional status of the tree species forming a given patch, (iv) the successional trends leading to changes of species composition foster diversification of the patch structure, (v) differentiation of the stand structure is negatively related to their local basal area, especially in patches with a high level of its accumulation. Among the best-preserved old-growth forest remaining under strict protection in the Polish national parks, nineteen research plots of around 10 ha each were selected. In each plot, a grid (50 × 50 m) of circular sample subplots (with radius 12,62 m) was established. In the sample subplots, species and diameter at breast height of living trees (dbh ≥ 7 cm) were determined. Subsequently, for each sample subplot, several numerical indices were calculated: local basal area (G), dbh structure differentiation index (STR), climax index (CL) and successional index (MS). Statistical tests of Kruskal- Wallis, Levene and Generalized Additive Models (GAM) were used to verify the hypotheses. All examined forests were characterized by a large diversity of stand structure. A particularly high frequency of highly differentiated patches (STR > 0,6) was recorded in the alder swamp forest. The patch mosaic in the examined plots was different – apart from the stands with a strongly pronounced mosaic character (especially subalpine spruce forests), there were also stands with high spatial homogeneity (mainly fir forests). The stand structure in the distinguished patches was generally poorly related to the other studied features. Consequently, all hypotheses were rejected. These results indicate a very complex, mixed pattern of forest natural dynamics regardless of site conditions. In beech forests and lowland multi-species deciduous forests, small-scale disturbances of the gap dynamics type dominate, which are overlapped with less frequent medium-scale disturbances. In more difficult site conditions, large-scale catastrophic disturbances, which occasionally appear in communities formed under the influence of gap dynamics (mainly spruce forests) or cohort dynamics (mainly pine forests), gain importance.

scholarly journals Relationships between Structural Indices and Conventional Stand Attributes in an Old-Growth Forest in Southeast Europe

Forests ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 4 ◽  
Author(s):  
Srđan Keren ◽  
Miroslav Svoboda ◽  
Pavel Janda ◽  
Thomas A. Nagel
Keyword(s):  
Species Diversity ◽  
Tree Species ◽  
Structural Heterogeneity ◽  
Tree Species Diversity ◽  
Southeast Europe ◽  
Old Growth ◽  
Old Growth Forest ◽  
Plot Area ◽  
Stand Attributes ◽  
Structural Indices

Structural indices are often proposed as guiding measures for increasing structural heterogeneity. However, few studies have examined the association between such indices and conventional stand attributes. The primary objectives of this study were to evaluate changes in structural heterogeneity and tree species diversity at different plot sizes and to quantify the relationships between conventional stand attributes (mean tree diameter, absolute tree density, basal area, species proportion) and structural indices in a mixed old-growth forest in Southeast Europe. Paired tests were used to identify significant changes in structural heterogeneity with increased plot area, while the relationships between stand attributes and analyzed indices (Gini, diameter differentiation, species mingling, and Shannon’s index) were evaluated with Pearson’s correlations. The index values of Gini, diameter differentiation, and tree species mingling were rather stable with the increase of plot size, whereas tree species diversity increased significantly with the increase of plot area from 200 m2 to 1500 m2. The measures of tree species mingling and tree species diversity were strongly associated with each other, while their association with diameter variability was weak to moderately strong. Tree species mingling index was strongly associated with the changes in tree species proportions. However, conventional stand attributes were generally not strongly correlated with the examined indices. For restoring and maintaining old-growth characteristics, forest managers may use structural indices to increase small-scale structural heterogeneity, tree species mingling, and diversity, but only as an additional set of measures, not as surrogates for conventional stand attributes.

scholarly journals Species Association of the Dominant Tree Species in an Old-Growth Forest and Implications for Enrichment Planting for the Restoration of Natural Degraded Forest in Subtropical China

Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 957 ◽  
Author(s):  
Liu ◽  
Zhu ◽  
Wang ◽  
Ma ◽  
Meng
Keyword(s):  
Tree Species ◽  
Rank Correlation ◽  
Economic Benefits ◽  
Natural Forests ◽  
Subtropical China ◽  
Old Growth ◽  
Species Association ◽  
Old Growth Forest ◽  
Enrichment Planting ◽  
Adult Trees

Subtropical natural forests are unique due to their ecological and economic functions. However, most of these forests are highly degraded, which impairs the ability to provide ecological and economic benefits. Enrichment planting is an important approach to restore natural degraded forests. Species arrangement is of great importance to inform enrichment planting. Species association refers to the interrelationship of different species occupying a habitat and is a static description of the organic connection formed by the interaction of species. Species association, therefore, provides a scientific basis for species arrangement in enrichment planting. Additionally, because an old-growth forest is a climax community that has attained great age without significant disturbance, the species association in an old-growth forest can provide valuable information on the reference conditions for forest management. In this study, the species association between dominant tree species (including saplings and adult trees) was investigated in an old-growth forest in the Gutianshan National Nature Reserve in Zhejiang province in subtropical China. The objective of the study was to inform species arrangement for enrichment planting. The result showed that the overall species association exhibited a significant net positive association, indicating a dynamic balance of stable structure and species composition in the old-growth forest. Additionally, the pairwise species association was examined using the χ2 test, the Dice index, and Spearman’s rank correlation coefficient; significant positive and negative pairwise species associations were detected. Based on the species association and the light requirements of the tree species, an optimal species arrangement was determined to support enrichment planting for restoring natural degraded forests. It is expected that the results of this study will contribute to the restoration of natural degraded forests in subtropical China.

Epiphyte Flora and Diversity on Basal Trunks of Six Old-Growth Forest Tree Species in Southern and Middle Boreal Finland

1996 ◽  
Vol 28 (5) ◽  
pp. 443-463 ◽  
Author(s):  
Mikko Kuusinen
Keyword(s):  
Tree Species ◽  
Boreal Forests ◽  
Forest Tree ◽  
Old Growth ◽  
Epiphytic Lichen ◽  
Generalist Species ◽  
Salix Caprea ◽  
Forest Tree Species ◽  
Old Growth Forest ◽  
Habitat Generalist

AbstractEpiphytic lichen and bryophyte species composition, richness and diversity were surveyed on basal trunks of six common old-growth forest tree species, Picea abies, Pinus sylvestris, Betula pendula, Alnus incana, Salix caprea and Populus tremula, in two old-growth forest areas, one in southern and one in middle boreal Finland. The average species numbers per tree ranged from 18 (Picea) to 27 (Salix) in the southern and from 20 (Populus) to 31 (Salix) in the middle boreal area. A few widespread habitat-generalist species, such as the foliose lichens Hypogymnia physodes and Platismatia glauca, were most abundant on all the tree species, except Populus. Most other epiphyte species showed at least a slight preference for one or two tree species. Populus proved to have the most distinct flora characterized by the abundance of certain, rather specialized crustose lichens and bryophytes. The number of species that occurred on only one tree species was highest on Populus (9) in the southern and on Alnus (18) in the middle boreal area. Differences in bark acidity and structure were the most likely explanations for the differences between tree species in the epiphytic flora and diversity. Salix and Populus were the most important of the tree species studied for the conservation of epiphyte diversity in the boreal forests of Finland.

Decay and nitrogen dynamics of litter from disjunct, congeneric tree species in old-growth stands in northeastern China and Wisconsin

1993 ◽  
Vol 71 (5) ◽  
pp. 693-699 ◽  
Author(s):  
Xiaoyuan Geng ◽  
John Pastor ◽  
Bradley Dewey
Keyword(s):  
Leaf Litter ◽  
Tree Species ◽  
Nitrogen Dynamics ◽  
Northeastern China ◽  
Decay Rates ◽  
Congeneric Species ◽  
Old Growth ◽  
Litter Bag ◽  
Old Growth Forest ◽  
Litter Decay

Decay and nitrogen dynamics of leaf litter from four tree species in an old-growth forest in northeastern China was measured in a litter-bag experiment and compared with decomposition of congeneric species in a Wisconsin old-growth forest with similar climatic regimes and soil. Leaf litter decay in both China and Wisconsin decreased in the order Acer > Populus > Quercus > Pinus and was negatively correlated with initial lignin content (r = 0.961, P < 0.001). Decay was also correlated with other chemical properties depending on locale. In contrast with decay rates, N-immobilization kinetics were not correlated with litter chemistry or comparable between congeners. Principal component analysis showed that almost half the total variation in litter decay is explained by grouping congeneric species according to litter quality. In northern mixed hardwood–conifer forests, generic similarity implies functional similarity in decomposition and nutrient cycling. Key words: decomposition, China, litter, nitrogen, Wisconsin.

scholarly journals Biodiversity recovery of Neotropical secondary forests

2019 ◽  
Vol 5 (3) ◽  
pp. eaau3114 ◽  
Author(s):  
Danaë M. A. Rozendaal ◽  
Frans Bongers ◽  
T. Mitchell Aide ◽  
Esteban Alvarez-Dávila ◽  
Nataly Ascarrunz ◽  
...  
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Tree Species ◽  
Anthropogenic Disturbance ◽  
Secondary Forests ◽  
Old Growth ◽  
Rarefaction Analysis ◽  
Old Growth Forest ◽  
Dual Strategy ◽  
Tropical Landscapes

Old-growth tropical forests harbor an immense diversity of tree species but are rapidly being cleared, while secondary forests that regrow on abandoned agricultural lands increase in extent. We assess how tree species richness and composition recover during secondary succession across gradients in environmental conditions and anthropogenic disturbance in an unprecedented multisite analysis for the Neotropics. Secondary forests recover remarkably fast in species richness but slowly in species composition. Secondary forests take a median time of five decades to recover the species richness of old-growth forest (80% recovery after 20 years) based on rarefaction analysis. Full recovery of species composition takes centuries (only 34% recovery after 20 years). A dual strategy that maintains both old-growth forests and species-rich secondary forests is therefore crucial for biodiversity conservation in human-modified tropical landscapes.

Germination and survival of tree species in disturbed forests of the highlands of Chiapas, Mexico

2000 ◽  
Vol 78 (10) ◽  
pp. 1309-1318 ◽  
Author(s):  
Angélica Camacho-Cruz ◽  
Mario González-Espinosa ◽  
Jan H.D Wolf ◽  
Bernardus HJ De Jong
Keyword(s):  
Tree Species ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Persea Americana ◽  
Forest Types ◽  
Old Growth ◽  
Old Growth Forest ◽  
Native Tree Species ◽  
Natural Recruitment ◽  
Direct Sowing

Germination and seedling survival of native tree species were studied in nursery (June-November 1998) and forest stands with varying dominance by pines in the central highlands of Chiapas (Mexico; June 1998 - November 1999). Species used are regarded as typical of mid- and late-successional habitats: Cornus disciflora Sessé & Mociño ex DC., Cornus excelsa H.B.K., Drimys granadensis L.f. var. mexicana (DC.) A.C. Smith, Liquidambar styraciflua L., Persea americana L., Quercus laurina H. & B., and Ternstroemia lineata (DC.) ssp. chalicophyla (Loesener) Bartholomew. Nursery treatments included presence and composition of litter collected from replicated plots of three forest types: old-growth forest, mixed pine-oak forest, and pine-dominated forest. Germination and seedling emergence of P. americana in the nursery were complete for all factor combinations. Cornus disciflora and L. styraciflua showed highest germination (p < 0.05) when sown in soil from old-growth forest and covered with litter of oak-broad-leaved species. In the field, differences (p < 0.05) among forest types (degree of pine dominance) were observed for C. disciflora (lowest germination in pinelands, 17%), D. granadensis (highest survival in old-growth forest, 23%), and Q. laurina (higher survival in pinelands, 54%). Natural recruitment and survival of seedlings were higher in old-growth forests. We conclude that oak litter may favor germination and early establishment of the studied species. However, the reintroduction of some of the studied species (C. excelsa, Q. laurina, and T. lineata) may be attempted with direct sowing on the forest floor of severely disturbed and species-poor pinelands.Key words: Cornus, Liquidambar, litter, Persea, Pinus, Quercus, seedling establishment, seeds.

Gap-phase structure of a subalpine old-growth forest

1991 ◽  
Vol 21 (12) ◽  
pp. 1730-1741 ◽  
Author(s):  
Kenneth P. Lertzman ◽  
Charles J. Krebs
Keyword(s):  
Phase Structure ◽  
Turnover Time ◽  
Silver Fir ◽  
Similar Distribution ◽  
Old Growth ◽  
Coast Mountains ◽  
Distinctive Features ◽  
Old Growth Forest ◽  
Closed Canopy ◽  
Gap Phase

We examined four stands in a subalpine old-growth forest in the Coast Mountains of southwestern British Columbia for gap-phase structure. Though the stands varied in the proportions of each species, all had a similar distribution of area under closed canopy and in gaps (overall means: 29% closed canopy, 52% expanded gap, 18% canopy gap). Median areas of canopy gaps and expanded gaps were 41 and 203 m2, respectively. Most gaps (90%) had more than one gap maker, and gap makers within a gap were often from mortality events separated in time. Half of all gap makers died standing, and only 13% were windthrown. Pacific silver fir (Abiesamabilis (Dougl.) Forbes) was represented among gap makers in a much higher proportion than among canopy trees in general (64 vs. 45%). The estimated forest turnover time varied from 280–1000 years, depending on assumptions about the time taken for gaps to be filled. Distinctive features of gap-phase structure and dynamics in this forest are the high proportion of area in gap, small gap size, multiple gap makers of varying stages of decay, and long tenure of gaps before they are filled.

Relations between tree canopy composition and understorey vegetation in a European beech-sessile oak old growth forest in Western Romania

Biologia ◽  
2017 ◽  
Vol 72 (12) ◽  
Author(s):  
Michaela Dölle ◽  
Any Mary Petritan ◽  
Iovu Adrian Biris ◽  
Ion Catalin Petritan
Keyword(s):  
European Beech ◽  
Tree Canopy ◽  
Herb Layer ◽  
Natural Forests ◽  
Canopy Layer ◽  
Old Growth ◽  
Understorey Vegetation ◽  
Sessile Oak ◽  
Old Growth Forest ◽  
Western Romania

AbstractThe diversity relationship between tree and herb layer has often been investigated, but the results are contradictory. Moreover, few studies of deciduous European species have been conducted to date in natural or near-natural forests, while such studies in old-growth forest with considerable co-dominance of oak are missing.In one of the best preserved natural European beech-sessile oak forests (Runcu-Grosi Natural Reserve, Western Romania) we investigated whether there is a correlation between canopy-layer diversity and herb-layer diversity. Structural diversity, vegetation composition, ecological and functional traits were evaluated. Our results show that the herb-layer diversity is higher under canopy with greater tree-layer diversity, and the diversity of both layers depend on whether the overstorey is dominated by beech or sessile oak. Herb layers of plots with oak co-dominance showed higher indicator values for light and temperature, and a higher proportion of graminoides and shrub species. In contrast, herb-layer in beech plots is dominated by juvenile trees, mainly beech and competitive herb species. Oak plots are characterised by a generally more evenly distributed herb-layer composition. Species richness of herb-layer was higher under a diversely structured overstorey, which was mainly achieved when oak was present in the canopy, and correlated negatively with litter thickness, which was highest in beech plots. We conclude that the identity of the dominant canopy species is most important for herb layer species composition and diversity. Furthermore, the plots with oak occurrence in the overstorey even with weak proportion (around 20% of stand basal area) features a higher biodiversity of species in the understorey.

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