scholarly journals Forest structural parameters and aboveground biomass in old-growth and secondary forests along an elevational gradient in Mexico

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Martina Alrutz ◽  
Jorge Antonio Gómez Díaz ◽  
Ulf Schneidewind ◽  
Thorsten Krömer ◽  
Holger Kreft
Keyword(s):  
Climate Change ◽  
Forest Structure ◽  
Aboveground Biomass ◽  
Basal Area ◽  
Elevational Gradient ◽  
Stem Density ◽  
Secondary Forests ◽  
Old Growth ◽  
Old Growth Forest ◽  
Old Growth Forests

Background: Tropical montane forests are important reservoirs of carbon and biodiversity but are threatened by deforestation and climate change. It is important to understand how forest structure and aboveground biomass change along gradients of elevation and succession. Questions: What are the interactive effect of elevation and two stages of succession on forest structure parameters? Studied species: Tree communities. Study site and dates: Cofre de Perote, Veracruz, Mexico. August to December 2015. Methods: We studied four sites along an elevational gradient (500, 1,500, 2,500, and 3,500 m). At each elevation and each forest type, we established five 20 × 20 m plots (n = 40 plots). Within each plot, we measured stem density, mean diameter at breast height (dbh), and tree height and derived basal area and aboveground biomass (AGB). Results: AGB peaked at 2,500 m and was significantly related to elevation and succession, with higher values in old-growth forests than in secondary forests at higher altitudes. Lower values of mean dbh and basal area were found at higher elevations. At the lowest elevation, both successional stages had the same values of stem density and AGB. At both lower elevations, secondary forests had higher values of dbh and basal area. There were high biomass stocks in the old-growth forest at 2,500 and 3,500 m. Conclusions: Old-growth forests at higher elevations are threatened by deforestation, consequently these remaining fragments must be preserved because of their storage capacity for biomass and their ability to mitigate climate change.

scholarly journals Recovery of Forest Structure Following Large-Scale Windthrows in the Northwestern Amazon

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 667
Author(s):  
J. David Urquiza Muñoz ◽  
Daniel Magnabosco Marra ◽  
Robinson I. Negrón-Juarez ◽  
Rodil Tello-Espinoza ◽  
Waldemar Alegría-Muñoz ◽  
...  
Keyword(s):  
Forest Structure ◽  
Large Scale ◽  
Tree Mortality ◽  
Basal Area ◽  
Forest Recovery ◽  
Old Growth ◽  
Study Region ◽  
Central Amazon ◽  
Old Growth Forest ◽  
Study Sites

The dynamics of forest recovery after windthrows (i.e., broken or uprooted trees by wind) are poorly understood in tropical forests. The Northwestern Amazon (NWA) is characterized by a higher occurrence of windthrows, greater rainfall, and higher annual tree mortality rates (~2%) than the Central Amazon (CA). We combined forest inventory data from three sites in the Iquitos region of Peru, with recovery periods spanning 2, 12, and 22 years following windthrow events. Study sites and sampling areas were selected by assessing the windthrow severity using remote sensing. At each site, we recorded all trees with a diameter at breast height (DBH) ≥ 10 cm along transects, capturing the range of windthrow severity from old-growth to highly disturbed (mortality > 60%) forest. Across all damage classes, tree density and basal area recovered to >90% of the old-growth values after 20 years. Aboveground biomass (AGB) in old-growth forest was 380 (±156) Mg ha−1. In extremely disturbed areas, AGB was still reduced to 163 (±68) Mg ha−1 after 2 years and 323 (± 139) Mg ha−1 after 12 years. This recovery rate is ~50% faster than that reported for Central Amazon forests. The faster recovery of forest structure in our study region may be a function of its higher productivity and adaptability to more frequent and severe windthrows. These varying rates of recovery highlight the importance of extreme wind and rainfall on shaping gradients of forest structure in the Amazon, and the different vulnerabilities of these forests to natural disturbances whose severity and frequency are being altered by climate change.

Old-growth forests: Data gaps and challenges

2003 ◽  
Vol 79 (3) ◽  
pp. 645-651 ◽  
Author(s):  
Ole Hendrickson
Keyword(s):  
Ecosystem Services ◽  
Sustainable Forest Management ◽  
Ecosystem Approach ◽  
Ecosystem Change ◽  
Secondary Forests ◽  
Old Growth ◽  
Old Growth Forest ◽  
Old Growth Forests ◽  
Considerable Impact ◽  
Growth Features

How much old growth is there? How much was there? Is remaining old growth disappearing? If so, how fast and why? Is any more old growth being created? How fragmented are old-growth forests? What other forest types and land uses surround them? Scientists see these as challenging questions, never to be fully resolved. Policy makers see information gaps and want answers. They assume that because the public values old-growth forests, their continuing availability must be assured. Forest managers need to be convinced that old-growth forests provide unique values before taking costly measures to conserve them. The relative stability of old-growth forests is interesting from a management perspective. Are old-growth forests more resistant to high-intensity disturbances, such as crown fires and violent storms? Do they resist insect outbreaks? A related issue is the quality of ecosystem services provided by old-growth forests. Do they have an exceptional ability to provide clean water, to stabilize hydrologic regimes, and to moderate local climates? Can they be used to test hypotheses about complexity, stability, resilience, and ecosystem change? These questions provide a strong rationale for developing working definitions of old-growth forests, for retaining areas of old-growth forest, and for replicating old-growth features in landscapes managed for timber production. Old-growth forests are desirable sites for monitoring, serving as benchmarks for adaptive management. Knowledge about old-growth forests has already had a considerable impact on policy and management, particularly in coastal regions. Current research and monitoring systems may not be adequate for the task of identifying and describing the biological complexity and diversity inherent in old-growth forests. New investments in collecting and managing data from old-growth (and secondary) forests are needed, and will pay manifold dividends to future generations of Canadians. This paper suggests that the central role of old-growth forests in developing sustainable forest management should create an incentive for the forest science, policy, and management communities to unite in support of their conservation. Key words: biodiversity, gene conservation, resilience, ecosystem approach, information management, ecosystem services

scholarly journals Old-growth forest loss and secondary forest recovery across Amazonian countries

2021 ◽  
Author(s):  
Charlotte Smith ◽  
John Healey ◽  
Erika Berenguer ◽  
Paul Young ◽  
Ben Taylor ◽  
...  
Keyword(s):  
Climate Change ◽  
Carbon Emissions ◽  
Large Scale ◽  
Secondary Forest ◽  
Temporal Trends ◽  
Forest Recovery ◽  
Forest Loss ◽  
Secondary Forests ◽  
Old Growth ◽  
Old Growth Forest

There is growing recognition of the potential of large-scale restoration in the Amazon as a “nature-based solution” to climate change. However, our knowledge of forest loss and recovery beyond Brazil is limited, and carbon emissions and accumulation have not been estimated for the whole biome. Combining a 33-year land cover dataset with estimates of above-ground biomass and carbon sequestration rates, we evaluate forest loss and recovery across nine Amazonian countries and at a local scale. We also estimate the role of secondary forests in offsetting old-growth deforestation emissions and explore the temporal trends in forest loss and recovery. We find secondary forests across the biome to have offset just 9.7% of carbon emissions from old-growth deforestation, despite occupying 27.6% of deforested land. However, these numbers varied between countries ranging from 9.0% in Brazil to 23.8% in Guyana for carbon offsetting, and 24.8% in Brazil to 56.9% in Ecuador for forest area recovery. We reveal a strong, negative spatial relationship between old-growth forest loss and recovery by secondary forests, showing that regions with the greatest potential for large-scale restoration are also those that currently have the lowest recovery (e.g. Brazil dominates deforestation and emissions but has the lowest recovery). Our findings identify three important challenges for policy makers: (1) incentivising large-scale restoration in highly deforested regions, (2) protecting secondary forests without disadvantaging landowners who depend on farm-fallow systems, and (3) preventing further deforestation. Combatting all of these successfully is essential to ensuring that the Amazon biome achieves its potential in mitigating anthropogenic climate change.

scholarly journals Recovery of Logged Tropical Montane Rainforests as Potential Habitats for Hainan Gibbon

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 711
Author(s):  
Kexin Fan ◽  
Yue Xu ◽  
Pengcheng Liu ◽  
Runguo Zang
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Basal Area ◽  
Food Plants ◽  
Secondary Forests ◽  
Old Growth ◽  
Relative Growth ◽  
Clear Cutting ◽  
Old Growth Forest ◽  
Hainan Gibbon

As the world’s rarest ape, the main threat facing Hainan gibbon (Nomascus hainanus) is habitat degradation and loss caused by human disturbances. The insufficient area and continuous human disturbance in most of the existing habitats can hardly maintain the future recovery and development of the gibbon population. A large area of secondary tropical montane rainforest in recovery was retained in Bawangling National Nature Reserve after disturbance. Therefore, it is of great significance to study the recovery of these secondary forests for the protection and restoration of Hainan gibbon habitat. To explore the recovery of secondary tropical rainforests after different disturbances, and whether they have the potential to serve as the future habitats for Hainan gibbon, we calculated four dynamic indexes (including recruitment rate, mortality/loss rate, relative growth rate and turnover rate) of abundance and basal area for the total community and for food plants of Hainan gibbon based on data from two censuses of secondary forests recovered nearly 45 years after different disturbances (clear-cutting and selective-logging) and old-growth forest of tropical montane rainforest. The results are as follows: (1) There were no significant differences in recruitment rates, mortality rates and turnover rates of abundance and basal area between recovered clear-cutting forests, selectively logged forests and old-growth forests. (2) Abundance, basal area and species of small (1 < DBH ≤ 10 cm) and medium (10 ≤ DBH < 30 cm) food plants in the two disturbed forests were higher, while those of large food plants (DBH ≥ 30 cm) in the two forests were lower than in old-growth forests. (3) For the common food species occurring in all three kinds of communities, the relative growth rate of most small trees in clear-cutting forest was higher than that of old-growth forest. Our research demonstrates that the lack of large food plants is the key limiting factor for the development of the secondary mountain rainforest as habitats for Hainan gibbon at present. However, it has great potential to transform into suitable habitats through targeted restoration and management due to the high recruitment rate and relative growth rate of the small- and medium-sized food plants.

Geostatistically modeling stem size and increment in an old-growth forest

1994 ◽  
Vol 24 (7) ◽  
pp. 1354-1368 ◽  
Author(s):  
Franco Biondi ◽  
Donald E. Myers ◽  
Charles C. Avery
Keyword(s):  
Spatial Patterns ◽  
Growth Rates ◽  
Spatial Dependence ◽  
Basal Area ◽  
Tree Density ◽  
Individual Growth ◽  
Old Growth ◽  
Model Estimate ◽  
Stem Size ◽  
Old Growth Forest

Geostatistics provides tools to model, estimate, map, and eventually predict spatial patterns of tree size and growth. Variogram models and kriged maps were used to study spatial dependence of stem diameter (DBH), basal area (BA), and 10-year periodic basal area increment (BAI) in an old-growth forest stand. Temporal variation of spatial patterns was evaluated by fitting spatial stochastic models at 10-year intervals, from 1920 to 1990. The study area was a naturally seeded stand of southwestern ponderosa pine (Pinusponderosa Dougl. ex Laws. var. scopulorum) where total BA and tree density have steadily increased over the last decades. Our objective was to determine if increased stand density simply reduced individual growth rates or if it also altered spatial interactions among trees. Despite increased crowding, stem size maintained the same type of spatial dependence from 1920 to 1990. An isotropic Gaussian variogram was the model of choice to represent spatial dependence at all times. Stem size was spatially autocorrelated over distances no greater than 30 m, a measure of average patch diameter in this forest ecosystem. Because patch diameter remained constant through time, tree density increased by increasing the number of pine groups, not their horizontal dimension. Spatial dependence of stem size (DBH and BA) was always much greater and decreased less through time than that of stem increment (BAI). Spatial dependence of BAI was close to zero in the most recent decade, indicating that growth rates in 1980–1990 varied regardless of mutual tree position. Increased tree crowding corresponded not only to lower average and variance of individual growth rates, but also to reduced spatial dependence of BAI. Because growth variation was less affected by intertree distance with greater local crowding, prediction of individual growth rates benefits from information on horizontal stand structure only if tree density does not exceed threshold values. Simulation models and area estimates of tree performance in old-growth forests may be improved by including geostatistical components to summarize ecological spatial dependence.

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 Are vegetation–soil systems drivers of ecosystem carbon contents along an elevational gradient in a highland temperate forest?

2019 ◽  
Vol 49 (3) ◽  
pp. 296-304 ◽  
Author(s):  
Isela Jasso-Flores ◽  
Leopoldo Galicia ◽  
Felipe García-Oliva ◽  
Angelina Martínez-Yrízar
Keyword(s):  
Climate Change ◽  
Aboveground Biomass ◽  
Soil Depth ◽  
Global Climate ◽  
Elevational Gradient ◽  
Litter Layer ◽  
Upward Migration ◽  
Soil Carbon Stock ◽  
Ecosystem Carbon ◽  
Soil Systems

Vegetation–soil systems differentially influence the ecosystem processes related to the carbon cycle, particularly when one tree species is dominant over wide geographic regions that are undergoing climate change. The objective of this study was to quantify the stocks of ecosystem carbon in three vegetation–soil systems along a highland elevational gradient in central Mexico. The vegetation–soil systems, from lower to higher elevation, were dominated by Alnus jorullensis Kunth, Abies religiosa (Kunth) Schltdl. & Cham., and Pinus hartwegii Lindl., respectively. Above- and below-ground tree biomass was determined in each system, along with the litter, coarse woody material, roots, and litterfall. The A. religiosa system had the greatest stock of aboveground biomass carbon (216 ± 31 Mg C·ha−1). The A. jorullensis system had the greatest production of litterfall (3.1 ± 0.08 Mg·ha−1·year−1); however, the carbon content of this litter layer (1.2 ± 0.32 Mg C·ha−1) was lower than that of P. hartwegii (10.1 ± 0.28 Mg C·ha−1). Thus, the litter layer in the A. jorullensis system had markedly the shortest residence time (8 years), suggesting high rates of litter decomposition. The soil carbon stock (at soil depth of 1 m) was greater in A. jorullensis (189 Mg C·ha−1) and P. hartwegii (137 Mg C·ha−1) than in A. religiosa (68 Mg C·ha−1). The A. religiosa and A. jorullensis systems had the highest and lowest total ecosystem C content (301 and 228 Mg C·ha−1, respectively). Upward migration of the A. religiosa system in response to global climate change, however, could cause losses by 2030 of 187 Mg C·ha−1 associated with aboveground biomass.

scholarly journals Compared to Wildfire, Management Practices Reduced Old-Growth Forest Diversity and Functionality in Primary Boreal Landscapes of Eastern Canada

2021 ◽  
Vol 4 ◽  
Author(s):  
Maxence Martin ◽  
Pierre Grondin ◽  
Marie-Claude Lambert ◽  
Yves Bergeron ◽  
Hubert Morin
Keyword(s):  
Boreal Forests ◽  
Economic Value ◽  
Industrial Scale ◽  
Old Growth ◽  
Ecosystem Based Management ◽  
Old Growth Forest ◽  
Old Growth Forests ◽  
Boreal Landscapes ◽  
The Impact ◽  
Primary Forests

Large primary forest residuals can still be found in boreal landscapes. Their areas are however shrinking rapidly due to anthropogenic activities, in particular industrial-scale forestry. The impacts of logging activities on primary boreal forests may also strongly differ from those of wildfires, the dominant stand-replacing natural disturbance in these forests. Since industrial-scale forestry is driven by economic motives, there is a risk that stands of higher economic value will be primarily harvested, thus threatening habitats, and functions related to these forests. Hence, the objective of this study was to identify the main attributes differentiating burned and logged stands prior to disturbance in boreal forests. The study territory lies in the coniferous and closed-canopy boreal forest in Québec, Canada, where industrial-scale logging and wildfire are the two main stand-replacing disturbances. Based on Québec government inventories of primary forests, we identified 427 transects containing about 5.5 circular field plots/transect that were burned or logged shortly after being surveyed, between 1985 and 2016. Comparative analysis of the main structural and environmental attributes of these transects highlighted the strong divergence in the impact of fire and harvesting on primary boreal forests. Overall, logging activities mainly harvested forests with the highest economic value, while most burned stands were low to moderately productive or recently disturbed. These results raise concerns about the resistance and resilience of remnant primary forests within managed areas, particularly in a context of disturbance amplification due to climate change. Moreover, the majority of the stands studied were old-growth forests, characterized by a high ecological value but also highly threatened by anthropogenic disturbances. A loss in the diversity and functionality of primary forests, and particularly the old-growth forests, therefore adds to the current issues related to these ecosystems. Since 2013, the study area is under ecosystem-based management, which implies that there have been marked changes in forestry practices. Complementary research will be necessary to assess the capacity of ecosystem-based management to address the challenges identified in our study.

Forest Regrowth on the Cumberland Plateau and Implications for Productive Management

1983 ◽  
Vol 7 (4) ◽  
pp. 208-212 ◽  
Author(s):  
Robert N. Muller
Keyword(s):  
Species Composition ◽  
Basal Area ◽  
Stand Density ◽  
Cumberland Plateau ◽  
Old Growth ◽  
Nutrient Pools ◽  
Old Growth Forest ◽  
Composition And Structure ◽  
Second Growth ◽  
Commercial Species

Abstract An old-growth forest and a 35-year-old, second-growth forest on the Cumberland Plateau were studied to compare species composition and structure. Species composition and total basal area of the two stands did not differ, although total stand density was 19 percent lower and basal area of commercial species was 25 percent higher in the old-growth than in the second-growth stand. Analysis of size-class distributions showed that both stands were best represented by an inverse J-shaped distribution, which best describes old-age stands. The rapid regeneration of the second-growth stand seems to be the result of minimal disturbance to accumulated nutrient pools in the soil. The importance of these accumulated nutrient pools and implications for forest management on the Cumberland Plateau are discussed.

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