Tree canopy displacement at forest gap edges

2002 ◽  
Vol 32 (2) ◽  
pp. 247-254 ◽  
Author(s):  
Christine C Muth ◽  
F A Bazzaz
Keyword(s):  
Light Availability ◽  
Tree Canopy ◽  
Individual Plant ◽  
Structure And Dynamics ◽  
High Resource ◽  
Canopy Trees ◽  
Tree Canopies ◽  
Canopy Depth ◽  
Vertical Gap ◽  
Sessile Organisms

Although plants are sessile organisms, they can forage for resources and avoid neighbors by growing towards areas with high resource availability and reduced competition. Apparently because of this morphological flexibility, tree canopies are rarely positioned directly above their stem bases and are often displaced. To determine if contrasts in light availability lead to the development of canopy displacement, we investigated the responses of tree canopies to the heterogeneous light environments at the edges of six experimental gaps. Canopies and trunks of gap edge trees were mapped, and their spatial distributions were analyzed. We found that tree canopies were displaced towards gap centers. The magnitude and precision of canopy displacement were greater for subcanopy trees than for canopy trees. The magnitude and precision of canopy displacement were generally greater for earlier successional trees and hardwoods than for later successional trees and conifers. Canopy depth was significantly greater on gap-facing sides of trees than on forest-facing sides of trees. Thus, trees along gap edges foraged for light by occupying both horizontal and vertical gap space. This morphological flexibility has implications for individual plant success, as well as forest structure and dynamics.

scholarly journals Integrating high resolution drone imagery and forest inventory to distinguish canopy and understory trees and quantify their contributions to forest structure and dynamics

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243079
Author(s):  
Raquel Fernandes Araujo ◽  
Jeffrey Q. Chambers ◽  
Carlos Henrique Souza Celes ◽  
Helene C. Muller-Landau ◽  
Ana Paula Ferreira dos Santos ◽  
...  
Keyword(s):  
Remote Sensing ◽  
High Resolution ◽  
Light Availability ◽  
Structural Complexity ◽  
Field Work ◽  
Growth And Survival ◽  
Structure And Dynamics ◽  
Old Growth Forest ◽  
Canopy Trees ◽  
Understory Trees

Tree growth and survival differ strongly between canopy trees (those directly exposed to overhead light), and understory trees. However, the structural complexity of many tropical forests makes it difficult to determine canopy positions. The integration of remote sensing and ground-based data enables this determination and measurements of how canopy and understory trees differ in structure and dynamics. Here we analyzed 2 cm resolution RGB imagery collected by a Remotely Piloted Aircraft System (RPAS), also known as drone, together with two decades of bi-annual tree censuses for 2 ha of old growth forest in the Central Amazon. We delineated all crowns visible in the imagery and linked each crown to a tagged stem through field work. Canopy trees constituted 40% of the 1244 inventoried trees with diameter at breast height (DBH) > 10 cm, and accounted for ~70% of aboveground carbon stocks and wood productivity. The probability of being in the canopy increased logistically with tree diameter, passing through 50% at 23.5 cm DBH. Diameter growth was on average twice as large in canopy trees as in understory trees. Growth rates were unrelated to diameter in canopy trees and positively related to diameter in understory trees, consistent with the idea that light availability increases with diameter in the understory but not the canopy. The whole stand size distribution was best fit by a Weibull distribution, whereas the separate size distributions of understory trees or canopy trees > 25 cm DBH were equally well fit by exponential and Weibull distributions, consistent with mechanistic forest models. The identification and field mapping of crowns seen in a high resolution orthomosaic revealed new patterns in the structure and dynamics of trees of canopy vs. understory at this site, demonstrating the value of traditional tree censuses with drone remote sensing.

Tree canopy displacement and neighborhood interactions

2003 ◽  
Vol 33 (7) ◽  
pp. 1323-1330 ◽  
Author(s):  
Christine C Muth ◽  
F A Bazzaz
Keyword(s):  
Community Dynamics ◽  
Basal Area ◽  
Tree Canopy ◽  
Forest Community ◽  
Spatial Proximity ◽  
Forest Plot ◽  
High Resource ◽  
Canopy Position ◽  
Canopy Area ◽  
Canopy Depth

Competitive interactions among plants are largely determined by spatial proximity. However, despite their sessile nature, plants have the ability to avoid neighbors by growing towards areas with high resource availability and reduced competition. Because of this flexibility, tree canopies are rarely centered directly above their stem bases and are often displaced. We sought to determine how a tree's competitive neighborhood influences its canopy position. In a 0.6-ha temperate forest plot, all trees greater than 10 cm DBH (n = 225) were measured for basal area, height, canopy depth, and trunk position. Canopy extent relative to trunk base was determined in eight subcardinal directions, and this information was used to reconstruct canopy size, shape, and position. We found that trees positioned their canopies away from large neighbors, close neighbors, and shade-tolerant neighbors. Neighbor size, expressed as basal area or canopy area, was the best indication of a neighbor's importance in determining target tree canopy position. As neighborhood asymmetry increased, the magnitude of canopy displacement increased, and the precision with which canopies avoided neighbors increased. Flexibility in canopy shape and position appears to reduce competition between neighbors, thereby influencing forest community dynamics.

Spray Volume, Canopy Density, and Other Factors Involved in Thinner Efficacy

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 553d-553
Author(s):  
C.R. Unrath
Keyword(s):  
Tree Height ◽  
Tree Canopy ◽  
Tree Size ◽  
Water Volume ◽  
Canopy Density ◽  
The North ◽  
Run Off ◽  
Tree Canopies ◽  
Average Water ◽  
Water Volumes

Historically, most airblast chemical applications to apple orchards used a single “average” water volume, resulting in variability of coverage with tree size and also the greatest variable in chemical thinning. This coverage variability can be eliminated by properly quantifying the tree canopy, as tree row volume (TRV), and relating that volume to airblast water rate for adequate coverge. Maximum typical tree height, cross-row limb spread, and between-row spacing are used to quantify the TRV. Further refinement is achieved by adjusting the water volume for tree canopy density. The North Carolina TRV model allows a density adjustment from 0.7 gal/1000 ft3 of TRV for young, very open tree canopies to 1.0 gal/1000 ft3 of TRV for large, thick tree canopies to deliver a full dilute application for maximum water application (to the point of run-off). Most dilute pesticide applications use 70% of full dilute to approach the point of drip (pesticide dilute) to not waste chemicals and reduce non-target environmental exposure. From the “chemical load” (i.e., lb/acre) calculated for the pesticide dilute application, the proper chemical load for lower (concentrate) water volumes can be accurately determined. Another significant source of variability is thinner application response is spray distribution to various areas of the tree. This variability is related to tree configuration, light, levels, fruit set, and natural thinning vs. the need for chemical thinning. Required water delivery patterns are a function of tree size, form, spacing, and density, as well as sprayer design (no. of nozzles and fan size). The TRV model, density adjustments, and nozzle patterns to effectively hit the target for uniform crop load will be addressed.

scholarly journals Competition for Light Affects Alfalfa Biomass Production More Than Its Nutritive Value in an Olive-Based Alley-Cropping System

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 233
Author(s):  
Alberto Mantino ◽  
Cristiano Tozzini ◽  
Enrico Bonari ◽  
Marcello Mele ◽  
Giorgio Ragaglini
Keyword(s):  
Biomass Production ◽  
Nutritive Value ◽  
Alley Cropping ◽  
Light Availability ◽  
Agroforestry Systems ◽  
Tree Canopy ◽  
Soil Protection ◽  
Olive Orchard ◽  
Competition For Light ◽  
Perennial Legumes

Cropping among trees with perennial legumes is one option for increasing agro-ecosystem services, such as improving the nitrogen supply and increasing soil protection by herbaceous vegetation. Moreover, cropping under the canopy of olive trees should diversify the farm production, compared to the traditional fallow management. Among perennial legumes, alfalfa (Medicago sativa L.) produces abundant biomass under Mediterranean rainfed condition. Based on this, a two-year field experiment was implemented in southern Tuscany in a rainfed olive orchard to test the competition for light effects on alfalfa biomass production and nutritive value. Light availability under the tree canopy was measured by hemispherical photos. In both years, the alfalfa yield of under-canopy varied according to the tree presence. A significant relationship between biomass production and light availability was recorded. The nutritive value of under-canopy alfalfa was similar to that of the open-grown alfalfa. However, same significant differences did however occur, between shaded and sole crop. When differences were found, under-canopy herbage was characterised by a higher content of crude protein and a lower content of fibre with respect to open-grown. In a hilly silvoarable olive orchard, alfalfa biomass accumulation was reduced mainly due to scarce light availability, therefore tree management such as pruning and plantation layout can enhance the herbage productivity. Studying shade tolerant forage legumes in order to enhance the yield and nutritive value of herbage production in rainfed agroforestry systems is essential.

Structure and Regeneration of Sal (Shorea robusta Gaertn. f.) Forests in Shiwalik Region of Kumaun Himalaya, India

2017 ◽  
Vol 40 (1) ◽  
pp. 1-8
Author(s):  
Bhawna Adhikari ◽  
◽  
Bhawana Kapkoti ◽  
Neelu Lodhiyal ◽  
L.S. Lodhiyal ◽  
...  
Keyword(s):  
Tree Species ◽  
Basal Area ◽  
Tree Canopy ◽  
Canopy Density ◽  
Kumaun Himalaya ◽  
Shorea Robusta ◽  
Canopy Trees ◽  
Dense Forest ◽  
Open Forest ◽  
Sal Forest

Present study was carried out to assess the structure and regeneration of Sal forests in Shiwalik region of Kumaun Himalaya. Vegetation analysis and tree canopy density was determined by using quadrat and densitometer, respectively. Density of seedlings, saplings and trees was 490-14067, 37-1233, and 273-863 ind.ha-1 respectively. The basal area was 0.12-5.44 m2 ha-1 reported for saplings and 25.4-77.6 m2 ha-1 for trees. Regeneration of Sal was found good in Sal mixed dense forest followed by Sal open forest and Sal dense forest, respectively. Regeneration of Sal was assisted by the presence of associated tree species as well as the sufficient sunlight availability on ground due to adequate opening of canopy trees in Sal forest. Thus it is concluded that the density of tree canopy, sunlight availability and also associated tree species impacted the regeneration of Sal in the region.

Photosynthesis and physiological traits of evergreen broadleafed saplings during winter under different light environments in a temperate forest

2006 ◽  
Vol 84 (1) ◽  
pp. 60-69 ◽  
Author(s):  
Yoshiyuki Miyazawa ◽  
Kihachiro Kikuzawa
Keyword(s):  
Temperate Forest ◽  
Light Availability ◽  
Net Photosynthesis ◽  
Carbon Gain ◽  
Leaf Mass Per Area ◽  
Camellia Japonica ◽  
Leaf Mass ◽  
Unit Leaf ◽  
Canopy Trees ◽  
Photosynthetic Traits

Photosynthetic traits of the evergreen broadleafed species Camellia japonica L. and Quercus glauca Thunb. were continuously investigated during autumn and winter using saplings that grew in different light environments (gap, deciduous canopy understory, and evergreen canopy understory) in a temperate forest. Light-saturated rates of net photosynthesis in midwinter and spring were lower than those in autumn. Photosynthetic capacity, scaled to a common leaf temperature of 25 °C, increased or remained stable after autumn and then decreased in spring in most leaves. Photosynthetic traits per unit leaf area were different among leaves in different light environments of both Camellia and Quercus during most periods. However, photosynthetic traits per unit leaf mass did not differ among leaves in different light environments, suggesting that differences in photosynthetic traits were mainly due to different leaf mass per area among leaves. Photosynthetic rates under light availability typical in the environment were lower in winter than in autumn in leaves in the sun in a gap but were not different in leaves in the shade under evergreen canopy trees. Thus, the importance of winter carbon gain for annual carbon gain is small in leaves in a gap but is large in leaves under evergreen canopy trees.

scholarly journals Late canopy closure delays senescence and promotes growth of the spring ephemeral wild leek (Allium tricoccum)

Botany ◽  
2017 ◽  
Vol 95 (5) ◽  
pp. 457-467 ◽  
Author(s):  
Pierre-Paul Dion ◽  
Julie Bussières ◽  
Line Lapointe
Keyword(s):  
Light Availability ◽  
Growing Season ◽  
Tree Canopy ◽  
Strong Impact ◽  
Bud Burst ◽  
Growth And Survival ◽  
Spring Ephemerals ◽  
Spring Ephemeral ◽  
Tree Leaf ◽  
Allium Tricoccum

Spring ephemerals take advantage of the high light conditions in spring to accumulate carbon reserves through photosynthesis before tree leaves unfold. Recent work has reported delayed leaf senescence under constant light availability in some spring ephemerals, such as wild leek (Allium tricoccum). This paper aims to establish whether tree canopy composition and phenology can influence the growth of spring ephemerals through changes in their phenology. Wild leek bulbs were planted in 31 plots in southern Quebec, Canada, under canopies varying in composition and densities. Light availability and tree phenology were measured, along with other environmental conditions, and their effect on the growth of wild leeks was assessed with a redundancy analysis. Higher light availability resulted in better growth of wild leeks. The plants postponed their senescence under trees with late bud-burst, and thus better bulb growth and seed production were achieved. The tree litter and temperature and moisture levels of the soil also influenced the growth and survival of wild leeks. Thus, tree leaf phenology appears to have a strong impact on the growth of spring ephemerals by modulating the length of their growing season and their photosynthetic capacity. This underlines the importance of considering the variation of light availability throughout the growing season in the study of spring ephemerals.

scholarly journals Stem Flow, Throughfall, and Canopy Interception of Rainfall by Citrus Tree Canopies

HortScience ◽  
1997 ◽  
Vol 32 (6) ◽  
pp. 1059-1160 ◽  
Author(s):  
Y.C. Li ◽  
A.K. Alva ◽  
D.V. Calvert ◽  
M. Zhang
Keyword(s):  
Tree Canopy ◽  
Storm Event ◽  
Citrus Paradisi ◽  
Citrus Tree ◽  
Canopy Interception ◽  
Canopy Effect ◽  
Tree Canopies ◽  
Stem Flow ◽  
Citrus Cultivar ◽  
Rain Events

It is generally believed that the interception of rain by the citrus tree canopy can substantially decrease the throughfall under the canopy as compared to that along the dripline or outside the canopy (incident rainfall). Therefore, the position of placement of soil-applied agrichemicals in relation to the tree canopy may be an important consideration to minimize their leaching during rain events. In this study, the distributions of rainfall under the tree canopies of three citrus cultivars, `Marsh' grapefruit (Citrus paradisi Macf.), `Hamlin' orange (Citrus sinensis L. Osbeck), and `Temple' orange (Citrus hybrid), were evaluated at four directions (north, south, east, west), two positions (dripline and under the canopy), and stem flow. There was not a significant canopy effect on rainfall amounts from stem flow or dripline, compared with outside canopy, for any citrus cultivar or storm event. However, throughfall varied significantly among the four cardinal directions under the canopy of all three citrus cultivars and was highly related to the wind direction. Among the three citrus cultivars evaluated in this study, throughfall, stem flow, and canopy interception accounted for 89.5% to 92.7%, 0.5% to 4.7%, and 5.8% to 9.3% of the incident rainfall, respectively.

scholarly journals Reflective Groundcover Improves Fruit Skin Color in ‘Honeycrisp’ Apples Grown under Protective Netting

2021 ◽  
pp. 1-8
Author(s):  
Giverson Mupambi ◽  
Nadia A. Valverdi ◽  
Hector Camargo-Alvarez ◽  
Michelle Reid ◽  
Lee Kalcsits ◽  
...  
Keyword(s):  
Skin Color ◽  
Light Availability ◽  
Fruit Weight ◽  
Cultural Practice ◽  
Apple Orchard ◽  
Tree Canopy ◽  
Film Material ◽  
Light Penetration ◽  
Color Development ◽  
Fruit Skin

In semiarid apple (Malus domestica) growing regions, high temperatures and excessive solar radiation can increase the risk of sunburn development. Protective netting is increasingly used as a cultural practice under these conditions to mitigate fruit sunburn losses. However, fruit skin color development can be negatively affected under protective nets due to the reduction in light availability. Reflective groundcovers have been previously reported to increase fruit color development, particularly in the inner parts of the tree canopy. Here, we compared two types of reflective groundcover: a woven polyethylene fabric and a film material with a grassed control without reflective material under a protective netting installation that reduced photosynthetically active radiation (PAR) by 17%. The experiment was conducted in a semiarid climate on a 5-year-old ‘Cameron Select Honeycrisp’ apple orchard near Quincy, WA. Light penetration into the canopy was measured with a PAR sensor. At harvest, fruit quality, yield, and size were assessed. The use of reflective groundcover between the rows significantly increased reflected PAR into the lower canopy. Moreover, reflective groundcovers significantly increased the amount of fruit with greater than 25% skin red color compared with the control. Reflective groundcover did not affect fruit weight, yield, and fruit number. The use of reflective groundcover under protective netting can increase light penetration into the canopy, thereby improving fruit skin red coloration in apple.

Structure and regeneration dynamics of three subtropical midmontane moist evergreen broad-leaved forests in southwestern China, with special reference to bamboo in the forest understories

2007 ◽  
Vol 37 (12) ◽  
pp. 2701-2714 ◽  
Author(s):  
Cindy Q. Tang ◽  
Tianxing Li ◽  
Xiaohong Zhu
Keyword(s):  
Tree Regeneration ◽  
Southwestern China ◽  
Structure And Dynamics ◽  
Seedling Bank ◽  
Canopy Trees ◽  
Mean Size ◽  
Bamboo Flowering ◽  
The Mean ◽  
Study Sites ◽  
Survival Of Seedlings

Two midmontane moist evergreen broad-leaved forests on the Ailao Mountains, Yunnan, and one on Mount Emei, Sichuan, southwestern China were studied to characterize the forest structure and dynamics as manifested in size, age, canopy gaps, regeneration modes, and the survival of seedlings. The most dominant canopy trees were species of Lithocarpus and Castanopsis of Fagaceae along with species of Machilus of Lauraceae and of Schima of Theaceae. The vertical structures of the forests were multilayered. All the canopy species had multimodal-shaped size and age distributions. In each forest of the study sites, the mean size of a canopy gap, caused mainly by the death of canopy trees, was smaller than 65 m2. No surviving seedlings of Fagaceae species were found in understories having bamboo with a coverage greater than 25% in any quadrat of the three forests. The poor seedling bank in the study forests is apparently due to the presence of bamboo in the understory. The tree regeneration may be synchronously related to the bamboo flowering event (interval approximately 55–60 years).

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