Effects of forest disturbance and regeneration on tree species composition and traits in DR Congo

Despite their key role in biodiversity conservation, forests of the Congo Basin are increasingly threatened by human activities. Whereas deforestation is very conspicuous, it remains challenging to monitor the impact of forest degradation under a more or less intact canopy. Likewise, the outcomes of forest regeneration following agricultural abandonment remain poorly studied in the Congo Basin. Here, we surveyed 125 vegetation quadrats across 25 forest inventory plots in the Yangambi region, and based on historical land-use maps. We aimed to assess both the impact of anthropogenic disturbance and forest recovery on tree species diversity, tree functional traits, community composition, canopy cover, and forest structure, as compared to undisturbed old-growth forest. We found that undisturbed old-growth forest harboured more tree individuals, particularly individuals with a smaller diameter, as well as species with a higher wood density when compared to both disturbed old-growth and regrowth forest. Moreover, species diversity was highest in disturbed old-growth forest. Tree species composition was significantly different between undisturbed old-growth forest and the other two forest categories. Our findings indicate that anthropogenic disturbance results in a degraded forest structure and may reduce the forest's ability to store carbon. Whereas species diversity recovered 60 years after agricultural abandonment, species composition remained different from undisturbed old-growth forest. Our study illustrates the need for more extensive vegetation surveys in the Congo Basin in order to quantify the effects of human disturbance under a closed canopy.

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Biodiversity recovery of Neotropical secondary forests

Science Advances ◽

10.1126/sciadv.aau3114 ◽

2019 ◽

Vol 5 (3) ◽

pp. eaau3114 ◽

Cited By ~ 69

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.

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Long-term effects of stump removal and tree species composition on the diversity and structure of soil fungal communities

FEMS Microbiology Ecology ◽

10.1093/femsec/fiaa061 ◽

2020 ◽

Vol 96 (5) ◽

Author(s):

Dixi Modi ◽

Suzanne Simard ◽

Jean Bérubé ◽

Les Lavkulich ◽

Richard Hamelin ◽

...

Keyword(s):

Species Composition ◽

Fungal Community ◽

Tree Species ◽

Management Practice ◽

Tree Regeneration ◽

Root Disease ◽

Fungal Communities ◽

Tree Species Composition ◽

The Impact

ABSTRACT Stump removal is a common forest management practice used to reduce the mortality of trees affected by the fungal pathogen-mediated root disease, Armillaria root rot, but the impact of stumping on soil fungal community structure is not well understood. This study analyzed the long-term impact of stumping and tree species composition on the abundance, diversity and taxonomic composition of soil fungal communities using internal transcribed spacer (ITS) marker-based DNA metabarcoding in a 48-year-old trial at Skimikin, British Columbia. A total of 108 samples were collected from FH (fermented and humus layers), and soil mineral horizons (A and B) from stumped and unstumped plots of six tree species treatments (pure stands and admixtures of Douglas-fir, western red-cedar and paper birch). Fungal α-diversity in the A horizon significantly increased with stumping regardless of tree species composition, while β-diversity was significantly affected by stumping in all the horizons. We also observed that the relative abundance of the saprotrophic fungal community declined while that of the ectomycorrhizal fungal community increased with stumping. In conclusion, increase in ectomycorrhizal fungal associations, which are positively associated with tree productivity, suggests that stumping can be considered a good management practice for mitigating root disease and promoting tree regeneration.

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Stand structure indices as tools to support forest management: an application in Trentino forests (Italy)

Journal of Forest Science ◽

10.17221/75/2012-jfs ◽

2013 ◽

Vol 59 (No. 4) ◽

pp. 159-168 ◽

Cited By ~ 20

Author(s):

F. Pastorella ◽

A. Paletto

Keyword(s):

Spatial Distribution ◽

Forest Management ◽

Species Diversity ◽

Species Composition ◽

Tree Species ◽

Stand Structure ◽

Composite Index ◽

Mutual Position ◽

Tree Species Composition ◽

North East

Stand structure and species diversity are two useful parameters to provide a synthetic measure of forest biodiversity. The stand structure is spatial distribution, mutual position, diameter and height differentiation of trees in a forest ecosystem and it highly influences habitat and species diversity. The forest stand and species diversity can be measured through indices that provide important information to better address silvicultural practices and forest management strategies in the short and long-term period. These indices can be combined in a composite index in order to evaluate the complex diversity at the stand level. The aim of the paper is to identify and to test a complex index (S-index) allowing to take into account both the tree species composition and the stand structure. S-index was applied in a case study in the north-east of Italy (Trentino province). The results show that the Norway spruce forests in Trentino province are characterized by a medium-low level of complexity (S-index is in a range between 0.14 and 0.46) due to a low tree species composition rather than to the stand structure (diametric differentiation and spatial distribution of trees).  

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

Forests ◽

10.3390/f11010004 ◽

2019 ◽

Vol 11 (1) ◽

pp. 4 ◽

Cited By ~ 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.

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Impacts of Human Activities on Tree Species Composition Along the Forest Savanna Boundary in Nigeria

Indonesian Journal of Geography ◽

10.22146/ijg.9248 ◽

2016 ◽

Vol 47 (2) ◽

pp. 115 ◽

Cited By ~ 1

Author(s):

Christiana Ndidi Egbinola

Keyword(s):

Species Composition ◽

Tree Species ◽

Human Activities ◽

Detrended Correspondence Analysis ◽

Floristic Composition ◽

Forest Species ◽

Tree Species Composition ◽

Study Sites ◽

The Impact ◽

The Relationship

The study investigated the tree species composition along the forest-savanna boundary in Oyo state of Nigeria with the aim of assessing the impact of human activities on the floristic composition. A transect was placed along the study area and species data was collected from quadrats placed in study plots within different study sites. Detrended Correspondence Analysis (DCA) was used to determine vegetation assemblages, while both correlation and the analysis of variance (ANOVA) were used to show the relationship between species in the different study sites. Results of the DCA revealed three species assemblages, an area with only forest species, another with only savanna species and a third with both forest/savanna species. ANOVA results further revealed that within the forest and savanna assemblages, species in mature and successional sites were alike. The study therefore revealed that human activities’ within the region is leading to the establishment of savanna species and an elimination of forest species.

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Long-term changes in tree species composition in the Dinaric mountain forests of Slovenia

The Forestry Chronicle ◽

10.5558/tfc79227-2 ◽

2003 ◽

Vol 79 (2) ◽

pp. 227-232 ◽

Cited By ~ 27

Author(s):

Andrej Boncina ◽

Franc Gaspersic ◽

Jurij Diaci

Keyword(s):

Species Composition ◽

Tree Species ◽

European Beech ◽

Anthropogenic Factors ◽

Silver Fir ◽

Tree Species Composition ◽

Virgin Forest ◽

Forest Remnant ◽

The Impact

This study utilizes data from long-term research sites in managed fir-beech forests (Hrusica, Leskova dolina and Rog) and a virgin forest remnant (Rajhenav), used as a reference site. Data obtained from old forest management plans and forest inventories were analysed. The results of the study support the hypothesis that two main tree speciessilver fir (Abies alba Mill.) and European beech (Fagus sylvatica L.)alternate site dominance. The causes of species dominance alternation include both natural processes and anthropogenic factors, in particular silvicultural practices and the impact of ungulates. More than a hundred years ago, European beech dominated stand volume. The proportion of silver fir increased until 19401970 when a gradual decrease started. All indicators suggest that the proportion of silver fir will decrease further in the coming decades. Key words: tree species composition alternation, diameter distribution, silver fir, European beech, forest history, forest planning, managed forests, virgin forest remnant

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Diversity and Structure of an Arid Woodland in Southwest Angola, with Comparison to the Wider Miombo Ecoregion

Diversity ◽

10.3390/d12040140 ◽

2020 ◽

Vol 12 (4) ◽

pp. 140 ◽

Cited By ~ 2

Author(s):

John L. Godlee ◽

Francisco Maiato Gonçalves ◽

José João Tchamba ◽

Antonio Valter Chisingui ◽

Jonathan Ilunga Muledi ◽

...

Keyword(s):

Species Diversity ◽

Species Composition ◽

Tree Species ◽

National Park ◽

Democratic Republic Of Congo ◽

Basal Area ◽

Vegetation Diversity ◽

Tree Species Composition ◽

Composition And Structure ◽

Miombo Ecoregion

Seasonally dry woodlands are the dominant land cover across southern Africa. They are biodiverse, structurally complex, and important for ecosystem service provision. Species composition and structure vary across the region producing a diverse array of woodland types. The woodlands of the Huíla plateau in southwest Angola represent the extreme southwestern extent of the miombo ecoregion and are markedly drier than other woodlands within this ecoregion. They remain understudied, however, compared to woodlands further east in the miombo ecoregion. We aimed to elucidate further the tree diversity found within southwestern Angolan woodlands by conducting a plot-based study in Bicuar National Park, comparing tree species composition and woodland structure with similar plots in Tanzania, Mozambique, and the Democratic Republic of Congo. We found Bicuar National Park had comparatively low tree species diversity, but contained 27 tree species not found in other plots. Plots in Bicuar had low basal area, excepting plots dominated by Baikiaea plurijuga. In a comparison of plots in intact vegetation with areas previously disturbed by shifting-cultivation agriculture, we found species diversity was marginally higher in disturbed plots. Bicuar National Park remains an important woodland refuge in Angola, with an uncommon mosaic of woodland types within a small area. While we highlight wide variation in species composition and woodland structure across the miombo ecoregion, plot-based studies with more dense sampling across the ecoregion are clearly needed to more broadly understand regional variation in vegetation diversity, composition and structure.

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