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.

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

THE DISTRIBUTION OF DERMACENTOR TICKS IN CANADA IN RELATION TO BIOCLIMATIC ZONES

1967 ◽  
Vol 45 (4) ◽  
pp. 517-537 ◽  
Author(s):  
P. R. Wilkinson
Keyword(s):  
British Columbia ◽  
Deciduous Forest ◽  
Strong Association ◽  
Eastern Deciduous Forest ◽  
Egg Development ◽  
The North ◽  
Winter Activity ◽  
Bioclimatic Zone ◽  
Soil Temperatures ◽  
Time Of Year

Dermacentor andersoni has been collected north of Jasper, Alberta, close to 54° N. and near 53° N. in British Columbia. Spread to the north and northwest is probably limited by low summer soil temperatures, which would act principally by slowing egg development, thus disrupting the seasonal cycle of the tick. To the southwest, mild winters may fail to release diapause at the correct time of year. Aspect and slope are important factors. Altitude spread of records is from 1000–7000 ft. The most generally applicable description of its distribution is the ecotone between western grassland and moister regions, including clearings and rocky outcrops m the montane and Columbia forests, and shrubby areas of the prairies. In British Columbia, a series of randomly selected transects indicated a strong association between the tick's presence and several species of shrubs growing without tree shade.Each bioclimatic zone tends to have a characteristic group of rodents as main hosts of the immature stages. The prairie and montane regions differ in the indigenous hosts available to the adult tick.East of 105° D. andersoni is replaced by D. variabilis, which is adapted to the more humid summers of the eastern deciduous forest zones, and differs considerably from D. andersoni in its phenology. There are no reliable records of indigenous D. variabilis north of 52° latitude.D. albipictus occurs from the east to the west coast. Because of the winter activity of its larvae, allowing the whole summer for egg development, it is able to penetrate much farther north than the other two species. There are two records close to 60° latitude.

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.

The biology of Canadian weeds. 130. Solidago nemoralis Ait.

2004 ◽  
Vol 84 (4) ◽  
pp. 1221-1233 ◽  
Author(s):  
Jerry G. Chmielewski ◽  
John C. Semple
Keyword(s):  
United States ◽  
North America ◽  
Deciduous Forest ◽  
Sandy Soils ◽  
The United States ◽  
Eastern Deciduous Forest ◽  
Rock Outcrops ◽  
Native North American ◽  
Forest Region ◽  
Riparian Habitats

Solidago nemoralis, the gray goldenrod, is a polycarpic hemicryptophyte that reproduces vegetatively from branched caudices. This native North American species is morphologically variable throughout its range, and includes an eastern (ssp. nemoralis) and western (ssp. decemflora) race. The eastern subspecies occurs throughout the eastern deciduous forest region of North America and is commonly diploid, though tetraploids do occur throughout. The western race typically occurs on the prairies and is strictly tetraploid. The species occupies riparian habitats, rock outcrops and open fields and roadsides and grows best in well-drained sandy soils in full sunlight. Although the species is weedy in both Canada and the United States it is not noxious. Key words: Solidago nemoralis, gray goldenrod, verge d'or des bois, Asteraceae, Compositae

scholarly journals Saproxylic Diptera assemblages in a temperate deciduous forest: implications for community assembly

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e6027
Author(s):  
Julia J. Mlynarek ◽  
Amélie Grégoire Taillefer ◽  
Terry A. Wheeler
Keyword(s):  
Sugar Maple ◽  
Deciduous Forest ◽  
Temperate Deciduous Forest ◽  
Decay Stage ◽  
Old Growth Forest ◽  
Temperate Deciduous ◽  
Species Type ◽  
Temperate Deciduous Forests ◽  
Decaying Wood ◽  
Two Stages

Saproxylic insects, those associated directly or indirectly with decaying wood for all or part of their life cycle, compose a large proportion of forest organisms. Flies (Diptera) are often the most abundant and species-rich group of insects in forest microhabitats, yet most work to date on saproxylic insect diversity and ecology has focused on beetles (Coleoptera). We compared saproxylic Diptera assemblages reared from two tree species (sugar maple and American beech) at two stages of decay (early/young and advanced/old) for a total of 20 logs in an eastern Canadian Nearctic old-growth forest. We found that communities are distinct within both species type and decay stage of wood. Early decay stage wood is more variable in community composition than later decay stage; however, as the age of the decaying wood increases, the abundance of Diptera increases significantly. Most indicator species are discernible in later decay stage and wood type. We venture to suggest that stochastic and deterministic processes may play a role in driving Diptera communities in temperate deciduous forests. To retain the highest saproxylic Diptera diversity in a forest, a variety of decaying wood types at different stages of decomposition is necessary.

Evaluating relationships among tree growth rate, shade tolerance, and browse tolerance following disturbance in an eastern deciduous forest

2009 ◽  
Vol 39 (12) ◽  
pp. 2460-2469 ◽  
Author(s):  
Lisa M. Krueger ◽  
Chris J. Peterson ◽  
Alejandro Royo ◽  
Walter P. Carson
Keyword(s):  
Forest Dynamics ◽  
Shade Tolerance ◽  
Deciduous Forest ◽  
Species Turnover ◽  
Light Availability ◽  
Woody Species ◽  
Plant Performance ◽  
Eastern Deciduous Forest ◽  
Interspecific Differences ◽  
The Impact

Interspecific differences in shade tolerance among woody species are considered a primary driving force underlying forest succession. However, variation in shade tolerance may be only one of many interspecific differences that cause species turnover. For example, tree species may differ in their sensitivity to herbivory. Nonetheless, existing conceptual models of forest dynamics rarely explicitly consider the impact of herbivores. We examined whether browsing by white-tailed deer ( Odocoileus virginianus Zimmermann) alters the relationship between light availability and plant performance. We monitored growth and survival for seedlings of six woody species over 2 years within six windthrow gaps and the nearby intact forest in the presence and absence of deer. Browsing decreased seedling growth for all species except beech ( Fagus grandifolia Ehrh.). More importantly, browsing altered growth rankings among species. Increased light availability enhanced growth for three species when excluded from deer, but browsing obscured these relationships. Browsing also reduced survival for three species; however, survival rankings did not significantly differ between herbivory treatments. Our results indicated that browsing and light availability operated simultaneously to influence plant growth within these forests. Thus, existing models of forest dynamics may make inaccurate predictions of the timing and composition of species reaching the canopy, unless they can account for how plant performance varies as a result of a variety of environmental factors, including herbivory.

Endothelial gaps: time course of formation and closure in inflamed venules of rats

1997 ◽  
Vol 272 (1) ◽  
pp. L155-L170 ◽  
Author(s):  
P. Baluk ◽  
A. Hirata ◽  
G. Thurston ◽  
T. Fujiwara ◽  
C. R. Neal ◽  
...  
Keyword(s):  
Substance P ◽  
Light Microscopy ◽  
Half Life ◽  
Time Course ◽  
Gap Formation ◽  
Gap Closure ◽  
Silver Nitrate Staining ◽  
Plasma Leakage ◽  
Scanning Em ◽  
Endothelial Gaps

In the rat trachea, substance P causes rapid but transient plasma leakage. We sought to determine how closely the number, morphology, and size of endothelial gaps correspond to the time course of this leakage. Endothelial gaps were examined by scanning electron microscopy (EM), by transmission EM, or by light microscopy after silver nitrate staining. Substance P-induced leakage of the particulate tracer Monastral blue peaked at 1 min but decreased with a half-life of 0.3 min. The number of silver-stained gaps also peaked at 1 min then decreased significantly more slowly (half-life 1.9 min) than the leakage. Scanning EM revealed two types of endothelial gaps, designated vertical gaps and oblique slits. Vertical gaps predominated at peak leakage, whereas oblique slits became more common as the leakage diminished. Measurements of the mean diameter of vertical gaps made by light microscopy, scanning EM, and transmission EM were all in the range of 0.36-0.47 micron. Fingerlike endothelial cell processes that appeared during gap formation became shorter as the leakage diminished (mean length: 1.44 microns at 1 min compared with 1.06 microns at 3 min after substance P), suggesting a role in gap closure. We conclude that the plasma leakage occurring immediately after an inflammatory stimulus results from the rapid formation of endothelial gaps. Multiple factors, including alterations in gap morphology, gap closure, and changes in driving force, are likely to participate in the rapid decrease in the leakage.

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