scholarly journals Canopy Gap Dynamics, Disturbances, and Natural Regeneration Patterns in a Beech-Dominated Hyrcanian Old-Growth Forest

2021 ◽  
Vol 27 (1) ◽  
Author(s):  
Ramezanali Akbari Mazdi ◽  
Asadollah Mataji ◽  
Asghar Fallah
Keyword(s):  
Complex Structure ◽  
Gap Size ◽  
Gap Dynamics ◽  
Old Growth ◽  
Closure Rate ◽  
The North ◽  
Old Growth Forest ◽  
Gap Closure ◽  
Forest Sustainability ◽  
North Of Iran

Canopy gaps play a crucial role in forest dynamic processes and help preserve biodiversity, influence nutrient cycles, and maintain the complex structure of the forests. This study aimed to quantify the gap dynamics, regeneration establishment, and gap closure in a natural old-growth Hyrcanian forest in the north of Iran. We used a repeated inventory of gap size-frequency and fraction in beech (Fagus orientalis) dominant forest over a 9-year interval (2010–2019). The total gap area documented in 2010, 2016, and 2019 was 2,487, 6,890, and 8,864 m2, respectively. The gap area ranged from the smallest sizes of 139, 83, and 153 m2 to the largest sizes 906, 1,668, and 871 m2 in 2010, 2016, and 2019, respectively. Gap fraction significantly increased from 0.52%, 1.93%, and 3.7 in 2010, 2016, and 2019, respectively. The size distribution of gaps was strongly skewed to the medium class (200-500 m2), with approximately 60% of the gaps. Results revealed that total regenerations are not in correlation with gap size. Small gaps were closed within a few years through rapid horizontal canopy expansion of neighboring beech trees. The gap closure rate decreased by increasing the gap size (70% in 71 m2 to 10% in 1,600 m2). The highest density and greatest regeneration growth occurred mostly along the eastern part of gaps. The spatial distributions of regeneration density demonstrated differences in different gap size classes, which probably resulted from heterogeneity in the microenvironment within the gap and the differences in the regeneration responses to these variations. This investigation provided useful data for managing natural regenerations based on forest sustainability. The changes in gap patterns observed between 2010 and 2019 highlight the high value of repeated gap inventories for better comprehending the disturbance regeneration and dynamics of natural gaps. Keywords: Gap size, Gap development, Special distribution, Regeneration density, Gap closure

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.

Gap dynamics in an Ohio Acer–Fagus forest and speculations on the geography of disturbance

1990 ◽  
Vol 20 (5) ◽  
pp. 632-641 ◽  
Author(s):  
James R. Runkle
Keyword(s):  
Deciduous Forest ◽  
Small Scale ◽  
Gap Dynamics ◽  
Gap Formation ◽  
Eastern Deciduous Forest ◽  
Old Growth Forest ◽  
Canopy Trees ◽  
Gap Closure ◽  
Canopy Composition ◽  
Tree Falls

Thirty-six forest gaps were monitored for 12 years in an old-growth forest dominated by Acersaccharum Marsh. and Fagusgrandifolia Ehrh. Most gaps were formed by single tree falls, although some larger ones were created by the deaths of two to four canopy trees. Gap closure rates suggest that most saplings need the occurrence of more than one gap to reach the canopy. Newer, small-scale disturbances, because of their geometry, occur near older disturbances at high rates. After gaps form, woody vegetation increases in density for 5–10 years and then decreases in density. The four main species of this study show different patterns of response, with optima as follows: small gaps of all ages for Acer, old gaps of all sizes for Fagus, large young gaps for Fraxinusamericana L., and large gaps of all ages for Liriodendrontulipifera L. The presence, size distribution, and species composition of saplings immediately preceding gap formation help determine which species will dominate the gap. In general, the processes occurring in gaps are sufficient to maintain the stand at its current canopy composition. A map of disturbances found in different parts of the eastern deciduous forest suggests that many forests, particularly those located near the center of the biome, renew themselves primarily by way of gaps.

Natural gap dynamics in a Central European mixed beech—spruce—fir old-growth forest

Ecoscience ◽  
2009 ◽  
Vol 16 (1) ◽  
pp. 39-47 ◽  
Author(s):  
Kata Kenderes ◽  
Kamil Král ◽  
Tomáš Vrška ◽  
Tibor Standovár
Keyword(s):  
Gap Dynamics ◽  
Old Growth ◽  
Central European ◽  
Old Growth Forest

Tradable Disturbance Permits for Old-growth Forest Conservation: Experimental Evaluation of Implementation Options

2017 ◽  
Vol 7 (1-2) ◽  
pp. 73-107
Author(s):  
Orsolya Perger ◽  
Curtis Rollins ◽  
Marian Weber ◽  
Wiktor Adamowicz ◽  
Peter Boxall
Keyword(s):  
Experimental Evaluation ◽  
Forest Conservation ◽  
Old Growth ◽  
Old Growth Forest

Old-growth forest reserves in Slovenia: the past, present, and future

2012 ◽  
Vol 163 (6) ◽  
pp. 240-246 ◽  
Author(s):  
Thomas A. Nagel ◽  
Jurij Diaci ◽  
Dusan Rozenbergar ◽  
Tihomir Rugani ◽  
Dejan Firm
Keyword(s):  
Stand Structure ◽  
Growth Conditions ◽  
Ecosystem Functions ◽  
Future Research ◽  
Old Growth ◽  
Forest Reserves ◽  
The Past ◽  
Old Growth Forest ◽  
Forest Remnants ◽  
Basic Characteristics

Old-growth forest reserves in Slovenia: the past, present, and future Slovenia has a small number of old-growth forest remnants, as well as many forest reserves approaching old-growth conditions. In this paper, we describe some of the basic characteristics of these old-growth remnants and the history of their protection in Slovenia. We then trace the long-term development of research in these old-growth remnants, with a focus on methodological changes. We also review some of the recent findings from old-growth research in Slovenia and discuss future research needs. The conceptual understanding of how these forests work has slowly evolved, from thinking of them in terms of stable systems to more dynamic and unpredictable ones due to the influence of natural disturbances and indirect human influences. In accordance with this thinking, the methods used to study old-growth forests have changed from descriptions of stand structure to studies that address natural processes and ecosystem functions.

Analysis of babA, cagE and cagA Genes in Helicobacter pylori from Upper Gastric Patients in the North of Iran

2019 ◽  
Vol 19 (3) ◽  
pp. 274-278 ◽  
Author(s):  
Saba Fakhrieh Asl ◽  
Mehrnaz Pourvahedi ◽  
Ali Mojtahedi ◽  
Mohammad Shenagari
Keyword(s):  
Helicobacter Pylori ◽  
Gastric Diseases ◽  
Specific Primers ◽  
The North ◽  
Different Types ◽  
North Of Iran ◽  
Gastric Biopsies ◽  
Pcr Method ◽  
Non Ulcer Dyspepsia ◽  
H Pylori

Objective:Helicobacter pylori is a Gram-negative bacterium which has a serious effect on up to half of the world’s population and has been related to different gastric diseases. The goal of this study was to assess the frequency of babA, cagE and cagA genotypes among H. pylori strains isolated from gastric biopsies of endoscopic patients in the north of Iran.Methods:The present study was performed on 90 strains of H. pylori isolated from patients with gastric diseases (Gastric ulcer (GU), Duodenal ulcer (DU), Gastritis (G), Non-ulcer dyspepsia (NUD) and Gastric adenocarcinoma (GC)). DNA was extracted from all isolated strains and PCR method was performed to detect the prevalence of babA2, cagE and cagA genes using specific primers.Results:Among 90 samples of H. pylori, babA2, cagE, and cagA genes were detected in 42.2%, 30% and 82.2% of strains respectively. The statistical analysis showed that the prevalence of cagA gene in GU, G, DU, and NUD was significantly higher than other genes. Moreover, cagA, and babA2 genes were significantly more prevalent in GC patients compared to cagE gene. Our isolates exhibited 8 distinct arrangements of virulence patterns. The occurrence of cagA (35.6%) was the most prevalent pattern followed by cagA/babA2 (20%) and cagA/babA2/cagE (14.4%).Conclusion:In summary, as first report from Guilan province in the north of Iran, we showed significant association between the presence of babA2, cagE, and cagA genes in different types of gastric disorders.

High Parasitic Contamination of Soil Samples in the North of Iran: a Potential Risk of Parasitic Infection for Tourists

2020 ◽  
Vol 20 ◽  
Author(s):  
Beheshteh Haghparast-kenari ◽  
Tooran Nayeri ◽  
Shahabeddin Sarvi ◽  
Mohammad Taghi Rahimi ◽  
Ehsan Ahmadpour ◽  
...  
Keyword(s):  
Contaminated Soil ◽  
Urban Areas ◽  
Intestinal Parasites ◽  
Parasitic Infection ◽  
Animal Husbandry ◽  
Soil Samples ◽  
Human Society ◽  
Public Parks ◽  
The North ◽  
North Of Iran

Background: Soil-transmitted parasites (STPs) are significant intestinal parasites that infect humans and animals and impose considerable burdens on human society and animal husbandry industries. Therefore, the present study aimed to determine the prevalence of parasitic elements of soil samples collected from the north of Iran. Methods: A total of 256 soil samples were collected from public parks, public places, vegetable gardens, sand heaps, and shadow areas near houses in the north of Iran and examined using the sucrose flotation method. Results: Out of 256 examined samples, 131 (51.2%) ones showed parasitic contamination including larvae (43%), oocysts (14.1%), and different eggs (6.6%). According to the results, the most and least common parasites observed in the samples were larvae (43%), as well as Toxascaris leonina, and Trichuris trichiura (0.4%), respectively. Moreover, the most and least contaminated locations were sand heaps (62.5%) and shadow areas near houses (45.6%), respectively. Regarding cities, Behshahr (68.3%) and Sari (67.5%) had the highest contaminated soil samples, whereas Chalus (37.5%) showed the lowest contamination. On the other hand, rural samples showed more contamination, compared to urban areas (P< 0.05). Conclusion: The findings of the present study indicate that the overall prevalence of STPs in examined areas and highly contaminated soil samples can be considered as a potential source of human contamination particularly tourists with STPs.

Old-growth forest carbon sinks overestimated

Nature ◽  
2021 ◽  
Vol 591 (7851) ◽  
pp. E21-E23
Author(s):  
Per Gundersen ◽  
Emil E. Thybring ◽  
Thomas Nord-Larsen ◽  
Lars Vesterdal ◽  
Knute J. Nadelhoffer ◽  
...  
Keyword(s):  
Forest Carbon ◽  
Carbon Sinks ◽  
Old Growth ◽  
Old Growth Forest
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