Quercus michauxii regeneration in and around aging canopy gaps

2004 ◽  
Vol 34 (6) ◽  
pp. 1359-1364 ◽  
Author(s):  
L L Battaglia ◽  
B S Collins ◽  
P B Weisenhorn
Keyword(s):  
Seedling Growth ◽  
Forest Canopy ◽  
Seedling Survival ◽  
Canopy Gaps ◽  
Canopy Openness ◽  
Quercus Michauxii ◽  
Canopy Opening ◽  
Multiple Disturbance ◽  
Maximum Root ◽  
Floods And Droughts

Floodplain forests are subject to frequent windstorms, which create canopy gaps and microtopographic heterogeneity. Forest regeneration may be enhanced when light and microtopographic conditions are both favorable, but slower growing canopy species may still require multiple disturbance events to reach the canopy. In 2001, we revisited a cohort of Quercus michauxii Nutt. seedlings planted in 1995 on pit–mound microsites that were constructed in and around canopy gaps to determine patterns of seedling persistence and investigate the effects of canopy openness and microtopography on seedling survival and growth. After 7 years, canopy openness in gap centers had decreased to levels that did not differ from levels in forest canopy. Seedling height and maximum root depth were greatest in gap centers, where light was initially greater but seedling growth rates declined over time. Soil moisture was greater in pits, where establishment and survival were very low. Roots of some seedlings reached from mound surfaces to depths and moisture levels comparable to those of adjacent pits, which might facilitate survival in both floods and droughts. Quercus michauxii can persist on elevated sites in aging gaps, and positive feedback in sites favorable for recruitment can enhance seedling growth; ascent into the canopy will likely require additional canopy-opening events.

Butterfly behavioural responses to natural Bornean tropical rain-forest canopy gaps

2011 ◽  
Vol 28 (1) ◽  
pp. 45-54 ◽  
Author(s):  
James S. Pryke ◽  
Sven M. Vrdoljak ◽  
Paul B. C. Grant ◽  
Michael J. Samways
Keyword(s):  
Rain Forest ◽  
Tropical Rain Forest ◽  
Forest Canopy ◽  
Canopy Gaps ◽  
Tree Canopy ◽  
Canopy Openness ◽  
Butterfly Species ◽  
Behavioural Responses ◽  
Light Heterogeneity ◽  
Closed Canopy

Abstract:Natural tree canopy gaps allow sunlight to penetrate to the forest floor, a major environmental component and resource for many tropical rain-forest species. We compare here how butterflies use sunny areas created by the natural gaps in canopies in comparison with adjacent closed-canopy areas. We chose butterflies as our focal organisms as they are taxonomically tractable and mobile, yet habitat sensitive. Previous studies have shown that butterfly diversity in tropical forests responds to varying degrees of canopy openness. Here we assess butterfly behavioural responses to gaps and equivalent sized closed-canopy patches. Butterfly occupancy time and behaviour were simultaneously observed 61 times in gaps and 61 times in equivalent sized closed-canopy patches across four sites in a tropical rain forest in northern Borneo. Out of the 20 most frequently recorded species, 12 were more frequently recorded or spent more time in gaps, four occurred more frequently in closed-canopy areas, and four showed no significant differences. Overall agonistic, basking, patrolling and resting were more common in gaps compared with the closed canopy. Many butterfly species have complex behavioural requirements for both gaps and closed canopies, with some species using these different areas for different behaviours. Each butterfly species had particular habitat requirements, and needed both canopy gaps and closed canopy areas for ecological and behavioural reasons, emphasizing the need for natural light heterogeneity within these systems.

Do dipterocarp seedlings really partition tropical rain forest gaps?

1992 ◽  
Vol 335 (1275) ◽  
pp. 369-378 ◽  
Keyword(s):  
Rain Forest ◽  
Seedling Survival ◽  
Canopy Gaps ◽  
Forest Recovery ◽  
Canopy Openness ◽  
Tropical Rain Forests ◽  
Rain Forests ◽  
Regeneration Dynamics ◽  
Closed Forest ◽  
Survival And Growth

The theory of gap regeneration dynamics proposes that different species of tree partition canopy gaps because they are preferentially adapted to a particular gap size class. A variety of gap sizes would therefore favour the regeneration of a range of species. The theory has been used to explain the extraordinarily high tree species diversity of tropical rain forests. A test was mounted in lowland evergreen dipterocarp rain forest in the Danum Valley, Sabah, East Malaysia by the creation of ten, artificial canopy gaps ranging in size from 10 m 2 to 1500 m 2 (6 to 30% canopy openness). The responses of established populations of seedlings of three dipterocarp species ( Hopea nervosa , Parashorea malaanonan and Shorea johorensis ) with contrasting silvicultural reputations were monitored for 40 months in these gaps and under closed forest. There were significant differences in survival and growth under closed forest between these three species. However, in gaps, the most important determinant of seedling survival and growth was seedling size at the time of gap creation, regardless of species. An ability to persist for long periods under closed forest and slowly accumulate growth may bestow an enormous size advantage on seedlings when gaps occur. Generalizations on the regeneration dynamics of dipterocarp rain forests need to be modified in the light of this result. Further observations for several years are important to see whether forest recovery eventually converges on predictions from the original paradigm.

The influence of litter and humus accumulations and canopy openness on Piceasitchensis (Bong.) Carr. and Tsugaheterophylla (Raf.) Sarg. seedlings growing on logs

1987 ◽  
Vol 17 (12) ◽  
pp. 1475-1479 ◽  
Author(s):  
Mark E. Harmon
Keyword(s):  
Seedling Growth ◽  
Seedling Survival ◽  
Survival Rates ◽  
Canopy Cover ◽  
Tree Canopy ◽  
Canopy Openness ◽  
Growth And Survival ◽  
Lower Survival ◽  
Tree Canopy Cover ◽  
Humus Accumulation

The influence of litter and humus accumulations on the surface of logs and canopy openness upon growth and survival of Piceasitchensis (Bong.) Carr. and Tsugaheterophylla (Raf.) Sarg. seedlings was tested experimentally at Cascade Head Experimental Forest, near Otis, Oregon. This was done by adding litter and humus to the surface of freshly fallen logs. Survival rates of both species increased asymptotically as litter accumulations on logs increased. Mean maximum survival was 58% for Picea and 34% for Tsuga. Picea seedling survival peaked when tree canopy cover ranged from 70 to 80% with lower survival at either higher or lower values. Tsuga survival was highest under closed canopies. Seedling growth increased as litter–humus accumulation and canopy openness increased.

Dipterocarp seedling growth in rain forest canopy gaps during six and a half years

1996 ◽  
Vol 351 (1344) ◽  
pp. 1195-1203 ◽  
Keyword(s):  
Rain Forest ◽  
Forest Canopy ◽  
Niche Differentiation ◽  
Canopy Gaps ◽  
The Other ◽  
Canopy Openness ◽  
Gap Size ◽  
Hardwood Species ◽  
Flexible Response ◽  
Closed Forest

The growth of seedlings of 11 species of Dipterocarpaceae in artificial canopy gaps of different sizes in a lowland evergreen dipterocarp rain forest in Sabah has been followed for 77 months. Three species were abundant and studied in most detail. The main objective was to analyse the foresters’ observation, on which silviculture is based: as gap size increases, species that are more light-demanding win the race to fill the gap. Hopea nervosa seedlings had higher survival in closed forest than those of the other two well represented species, Parashorea malaanonan and Shorea johorensis . From seedling dem ography these two species groups can be called shade-tolerants and light-dem anders respectively. At 40 months the seedlings tallest at gap creation had increased their height advantage in all gap sizes. These were mainly H. nervosa . By 53 months, seedlings of Shorea johorensis had grown ahead of H. nervosa in all but closed forest and tiny gaps of 6 % and 8 % canopy openness (1 and 4 mol m -2 day -1 photosynthetically active radiation (p.a.r.) respectively). By 77 months they were even further ahead. Thus S. johorensis has a more flexible response. It is better able to use the extra p.a.r. of larger gaps 10% openness or more; 10 mol m -2 day -1 p.a.r. or more), and is a light-demander in a second sense, whereas H. nervosa is light-indifferent in this sense. Seedlings of P. malaanonan unexpectedly failed to show rapid height growth in the larger gaps at 53 and 77 months. This species alone suffered very serious apical dam age by herbivory. The 11 species under study occurred in various mixtures. To analyse success in gap-filling in the forest they were grouped by timber density into two classes. With increasing gap size, one group, six light hardwood species, known to be light-demanders, grow progressively ahead of the other group, four medium hardwood species, known to be shade-tolerant. P. malaanonan , also a light hardwood, grows only slowly because of herbivory. We find no evidence for fundamental niche differentiation. All species showed increasing rates of growth with increasing gap size. Species that responded more slowly might succeed in situations where they alone occur.

Selection of forest canopy gaps by male Cerulean Warblers in West Virginia

2014 ◽  
Vol 126 (2) ◽  
pp. 288-297 ◽  
Author(s):  
Kelly A. Perkins ◽  
Petra Bohall Wood
Keyword(s):  
West Virginia ◽  
Forest Canopy ◽  
Canopy Gaps ◽  
Cerulean Warblers ◽  
Selection Of

Factors influencing germination of Scolochloa festucacea caryopses

1972 ◽  
Vol 50 (11) ◽  
pp. 2085-2092 ◽  
Author(s):  
Alan L. Smith
Keyword(s):  
Ethyl Alcohol ◽  
Seedling Growth ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Anaerobic Conditions ◽  
Factors Influencing

Germination and seedling emergence increased with increasing caryopses weight in Scolochloa festucacea. Maximum seedling survival occurred when caryopses were planted 1 cm deep. Simulation of anaerobic conditions by soaking caryopses increased seedling emergence. Seedling emergence increased after imbibed caryopses were treated in a N2 atmosphere. Emergence also was increased by soaking caryopses in 95% ethyl alcohol up to 60 min. Stratification apparently improved germination but was not a requirement. Scolochloa festucacea caryopses were more tolerant of MgCl2 than NaCl in the germination media. Optimum seedling growth occurred at 20C.

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