Comparing indices of understory light availability between hemlock and hardwood forest patches

2009 ◽  
Vol 39 (10) ◽  
pp. 1949-1957 ◽  
Author(s):  
Michael F. Tobin ◽  
Peter B. Reich
Keyword(s):  
Sugar Maple ◽  
Forest Canopy ◽  
Light Availability ◽  
Canopy Structure ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Canopy Openness ◽  
Forest Patches ◽  
Two Indices

We evaluated whether two indices of light availability resolved differences among microsites within deeply shaded understories (<12% of above-canopy photosynthetic photon flux density (PPFD)) and also whether marked differences in forest canopy structure affected how the two indices related to direct measures of incident photosynthetically active radiation (PAR). Incident PAR was measured with gallium–arsenide–phosphide photodiodes at numerous points in two adjacent forest patches in Michigan, USA: one dominated by the evergreen conifer eastern hemlock ( Tsuga canadensis (L.) Carrière), and the other by the deciduous hardwood sugar maple ( Acer saccharum Marsh.). The two indices tested were canopy openness, measured with the LI-COR LAI-2000 plant canopy analyzer, and the percentage of above-canopy PPFD measured in the understory during overcast conditions (%PPFD). Canopy openness and %PPFD did not effectively predict the long-term mean of daily PPFD. However, both indices reliably predicted the long-term mean of daily median PPFD, an alternative standard of directly measured incident PAR that reduces the relative contribution of sunflecks. The relationships of both indices with mean daily median PPFD differed between hemlock and hardwood patches. Hence, the effect of canopy structure should be considered when using these indices to draw conclusions about differences in light availability between forest patches, particularly when narrow ranges of light availability in deep shade are important.

Evaluation of irradiance metrics with respect to predicting sapling growth

2007 ◽  
Vol 37 (7) ◽  
pp. 1203-1213 ◽  
Author(s):  
Richard K. Kobe ◽  
Leah J. Hogarth
Keyword(s):  
Acer Saccharum ◽  
Sugar Maple ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Canopy Openness ◽  
Beam Radiation ◽  
White Ash ◽  
Sapling Growth ◽  
Efficient Measurement

Accurate and efficient measurement of photosynthetically active radiation (PAR) is critical in ecological studies. We evaluated 25 metrics of PAR with respect to predicting growth of sugar maple ( Acer saccharum Marsh.) and white ash ( Fraxinus americana L.) saplings from understory to large gap conditions. PAR metrics were derived from gallium arsenide photodiodes, hemispherical canopy photographs (film and digital), and a LI-COR LAI-2000 plant canopy analyzer. In general, percent canopy openness, estimated with film photographs or LAI-2000, best predicted growth. Mean daily photosynthetic photon flux density (PPFD) from photodiodes ranked intermediate; direct beam radiation (from digital and film photographs) was among the poorest growth predictors. Metrics that integrate direct radiation may be relatively poor predictors of growth, because sunflecks were above PPFD levels at which photosynthesis saturates but fully contributed to the calculation of mean daily PPFD. Mean daily PPFD based on truncated sunflecks (to PPFD levels at which photosynthesis saturates) improved predictions of white ash radial growth. Film canopy photographs and the LAI-2000 had relatively low measurement error (indicated by repeatability). High contrast in film photographs, compared to digital, reduced ambiguity in manual thresholding. From a plant-centered perspective, percent canopy openness measured with either the LAI-2000 or film hemispherical photographs provided the best growth predictions.

A simple and efficient method to estimate microsite light availability under a forest canopy

1996 ◽  
Vol 26 (1) ◽  
pp. 151-154 ◽  
Author(s):  
Sylvain Parent ◽  
Christian Messier
Keyword(s):  
Efficient Method ◽  
Forest Canopy ◽  
Light Availability ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Broadleaf Forest ◽  
The Mean ◽  
Sky Conditions ◽  
Overcast Sky

This study presents a new, simple, and efficient method for estimating microsite light availability in the understory of a forest. The percentage of above-canopy photosynthetic photon flux density (%PPFD) transmitted above 16 microsites in the understory of a mixed conifer–broadleaf forest was measured every minute between 07:00 and 19:00 for both a completely overcast and a cloudless day. Instantaneous measures of %PPFD were also taken at different times on 3 overcast days. The instantaneous measures of %PPFD were strongly and directly related (P < 0.001) among themselves and with mean daily %PPFD values. These results demonstrate the usefulness of using an instantaneous measure of %PPFD taken under overcast sky conditions for estimating the mean daily %PPFD at any microsite under a forest canopy.

scholarly journals Mosaics of canopy openness induced by tropical cyclones in lowland rain forests with contrasting management histories in northeastern Australia

2000 ◽  
Vol 16 (6) ◽  
pp. 883-894 ◽  
Author(s):  
SIMON J. GROVE ◽  
STEPHEN M. TURTON ◽  
DANNY T. SIEGENTHALER
Keyword(s):  
Forest Management ◽  
Forest Canopy ◽  
Canopy Openness ◽  
Old Growth ◽  
Lowland Rain Forest ◽  
Forest Sites ◽  
Local Topography ◽  
Marked Points ◽  
Impacted Site

Tropical Cyclone ‘Rona’ crossed the coast of the Daintree lowlands of northeastern Australia in 1999. This study reports on its impact on forest canopy openness at six lowland rain forest sites with contrasting management histories (old-growth, selectively logged and regrowth). Percentage canopy openness was calculated from individual hemispherical photographs taken from marked points below the forest canopy at nine plots per site 3–4 mo before the cyclone, and at the same points a month afterwards. Before the cyclone, when nine sites were visited, canopy openness in old-growth and logged sites was similar, but significantly higher in regrowth forest. After the cyclone, all six revisited sites showed an increase in canopy openness, but the increase was very patchy amongst plots and sites and varied from insignificant to severe. The most severely impacted site was an old-growth one, the least impacted a logged one. Although proneness to impact was apparently related to forest management history (old-growth being the most impacted), underlying local topography may have had an equally strong influence in this case. It was concluded that the likelihood of severe impact may be determined at the landscape-scale by the interaction of anthropogenic with meteorological, physiographic and biotic factors. In the long term, such interactions may caution against pursuing forest management in cyclone-prone areas.

scholarly journals Immediate and Delayed Effects of Severe Winds on an Old-Growth Forest in Kentucky: A Forty-Year Retrospective

Forests ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 271 ◽  
Author(s):  
Susan Jones-Held ◽  
Michael Held ◽  
Joe Winstead ◽  
William Bryant
Keyword(s):  
Sugar Maple ◽  
Forest Canopy ◽  
Basal Area ◽  
The United States ◽  
Tree Regeneration ◽  
Forest Recovery ◽  
Total Density ◽  
Old Growth Forest ◽  
Long Term Studies

Wind disturbance is an important factor that can affect the development of the forests of the Central Hardwood Region of the United States. However, there have been few long-term studies of the recovery of these systems following wind damage. Long-term studies of protected forest systems, such as Dinsmore Woods in Northern Kentucky, within the fragmented forest of this region are valuable as they provide a resource to document and understand the effect of both abiotic and biotic challenges to forest systems. This study is a 40-year analysis of both overstory and understory changes in the forest system at Dinsmore Woods as the result of damage caused by severe winds in the spring of 1974. The forest was surveyed before and immediately following the windstorm and then at 10-year intervals. Although the windstorm had an immediate effect on the forest, the pattern of damage was complex. The forest canopy (diameter at breast height (DBH) ≥ 30 cm) experienced an irregular pattern of damage while in the subcanopy (DBH ≤ 30 cm) there was a 25% reduction in total basal area. However, the major effects of the windstorm were delayed and subsequently have altered forest recovery. Ten years following the disturbance declines were seen in total density and basal area in the canopy and subcanopy of the forest as a consequence of windstorm damage. In the past 20 years the total basal area of the canopy has increased and exceeds the pre-disturbance total basal area. In contrast, the subcanopy total basal area continued to decline 20 years post-disturbance and has not recovered. Further openings in the canopy and subcanopy due to the delayed windstorm effects helped to establish a dense understory of native shrubs and sugar maple which have affected tree regeneration and is reflected in the continual decline in species diversity in the subcanopy and sapling strata over the 40-year period.

scholarly journals Canopy structure drives orangutan habitat selection in disturbed Bornean forests

2017 ◽  
Vol 114 (31) ◽  
pp. 8307-8312 ◽  
Author(s):  
Andrew B. Davies ◽  
Marc Ancrenaz ◽  
Felicity Oram ◽  
Gregory P. Asner
Keyword(s):  
Forest Canopy ◽  
Habitat Restoration ◽  
Canopy Structure ◽  
Large Species ◽  
Anthropogenic Pressures ◽  
Term Survival ◽  
Ecological Requirements ◽  
Disturbed Forest ◽  
Fragmented Forests

The conservation of charismatic and functionally important large species is becoming increasingly difficult. Anthropogenic pressures continue to squeeze available habitat and force animals into degraded and disturbed areas. Ensuring the long-term survival of these species requires a well-developed understanding of how animals use these new landscapes to inform conservation and habitat restoration efforts. We combined 3 y of highly detailed visual observations of Bornean orangutans with high-resolution airborne remote sensing (Light Detection and Ranging) to understand orangutan movement in disturbed and fragmented forests of Malaysian Borneo. Structural attributes of the upper forest canopy were the dominant determinant of orangutan movement among all age and sex classes, with orangutans more likely to move in directions of increased canopy closure, tall trees, and uniform height, as well as avoiding canopy gaps and moving toward emergent crowns. In contrast, canopy vertical complexity (canopy layering and shape) did not affect movement. Our results suggest that although orangutans do make use of disturbed forest, they select certain canopy attributes within these forests, indicating that not all disturbed or degraded forest is of equal value for the long-term sustainability of orangutan populations. Although the value of disturbed habitats needs to be recognized in conservation plans for wide-ranging, large-bodied species, minimal ecological requirements within these habitats also need to be understood and considered if long-term population viability is to be realized.

scholarly journals Spatial and temporal variability of canopy cover and understory light in a Cerrado of Southern Brazil

2010 ◽  
Vol 70 (1) ◽  
pp. 19-24 ◽  
Author(s):  
JP. Lemos-Filho ◽  
CFA. Barros ◽  
GPM. Dantas ◽  
LG. Dias ◽  
RS. Mendes
Keyword(s):  
Rainy Season ◽  
Light Availability ◽  
Canopy Cover ◽  
Dry Season ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Spatial And Temporal Variability ◽  
Wet Season ◽  
Area Index ◽  
Understory Plants

Canopy cover has significant effects on the understory environment, including upon light availability for seedling growth. The aim of the present study was to verify spatial heterogeneity and seasonal changes in the canopy cover of a dense Cerrado area, and their relationship to understory photosynthetic active radiation availability. Leaf area index (LAI) values in the rainy season varied from 0.9 to 4.83, with 40% of the values ranging from 4.0 to 5.0, while in the dry season LAI varied from 0.74 to 3.3, with 53% of the values oscilating from 2.0 to 3.0. Understory light (Qi ) and the Lambert-Beer ratio (Qi/Qo) were taken around noon on sunny days (between 11:00 AM and 1:00 PM). They were also statistically different (p < 0.01) between the dry and wet seasons, with 72% of sampled points in the rainy season presenting photosynthetic photon flux density (PPFD) values lower than 250 μmol.m-2/s around noon, whereas in the dry season, most PPFD values varied from 1500 to 1817 μmol.m-2/s , thus providing high light availability for understory plants. In most of the studied sites, understory plants did not even receive enough light for 50% of their photosynthetic capacity in the wet season. In contrast during the dry season, Qi/Qo values of 0.8 to 1.0 were observed in more than 50% of the points, thereby allowing for photosynthetic light saturation. Thus, light variability around noon was higher during the dry season than in the wet season, its heterogeneity being related to spatial complexity in the canopy cover.

scholarly journals On the convertibility of different microsite light availability indices, relative illuminance and relative photon flux density

2001 ◽  
Vol 15 (6) ◽  
pp. 798-803 ◽  
Author(s):  
H. MURAOKA ◽  
H. HIROTA ◽  
J. MATSUMOTO ◽  
S. NISHIMURA ◽  
Y. TANG ◽  
...  
Keyword(s):  
Flux Density ◽  
Light Availability ◽  
Photon Flux ◽  
Photon Flux Density

scholarly journals Evaluation of hemispherical photos extracted from smartphone spherical panorama images to estimate canopy structure and forest light environment

2020 ◽  
Author(s):  
A. Z. Andis Arietta
Keyword(s):  
Image Quality ◽  
Forest Canopy ◽  
Dynamic Range ◽  
Canopy Structure ◽  
High Dynamic Range ◽  
Canopy Openness ◽  
Traditional Methods ◽  
Area Index ◽  
Site Factor ◽  
High Dynamic

AbstractHemispherical photography (HP) is one of the most commonly employed methods to estimate forest canopy structure and understory light environments. Traditional methods require expensive, specialized equipment, are tedious to deploy, and are sensitive to exposure settings. In contrast, modern smartphone cameras are readily available and make use of ever-improving software to produce images with high dynamic range and clarity, but lack suitable hemispherical lenses. Thus, despite the fact that almost all ecologists and foresters carry a high-powered, image processing device in our pockets, we have yet to fully employ it for the purpose of data collection. As an alternative, hemispherical images can be extracted from spherical panoramas produced by many smartphone camera applications. I compared hemispherical photos captured with a digital single lens reflex camera and 180° lens to those extracted from smartphone spherical panoramas (SSP) for 72 sites representing a range of canopy types and densities. I estimated common canopy and light measures (canopy openness, leaf area index, and global site factor) as well as image quality measures (total gap area, number of gaps, and relative gap size) to compare methods. The SSP HP method leverages built-in features of current generation smartphones including exposure metering over restricted field-of-view, high dynamic range tonal correction, computational sharpening, high pixel density, and automatic leveling via the phone’s built-in gyroscope to yield an accurate alternative to traditional HP in canopy estimation. Although the process of stitching together multiple photos occasionally produces artifacts in the SSP HP images, estimates of canopy openness and global site factor are highly correlated with those of traditional methods (R2> 0.9) and are comparable to under- or over-exposing traditional HP by 1-1.5 stops. In addition to superior image quality, SSP HP requires no additional equipment or exposure settings and is likely to prove more robust to uneven lighting conditions by avoiding wide-angles lenses and exploiting HDR images.

scholarly journals Temporal Effects of Thinning on the Leaf C:N:P Stoichiometry of Regenerated Broadleaved Trees in Larch Plantations

Forests ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 54
Author(s):  
Jin Xie ◽  
Qiaoling Yan ◽  
Junfeng Yuan ◽  
Rong Li ◽  
Xiaotao Lü ◽  
...  
Keyword(s):  
Stand Structure ◽  
Light Availability ◽  
Canopy Openness ◽  
C:N:P Stoichiometry ◽  
Soil C ◽  
Temporal Effects ◽  
Leaf Stoichiometry ◽  
Coniferous Plantations ◽  
Over Time

The shift from natural mixed broadleaved forests to pure coniferous plantations results in soil degradation and the unsustainable development of plantations due to the simple stand structure and low species diversity. Thinning can practically sustain the forest structure and promote the regeneration and growth of broadleaved trees in these pure coniferous plantations. The growth of regenerated broadleaved trees is closely related to leaf ecological stoichiometry, which is strongly restricted by environmental factors such as light, soil moisture, and nutrients after thinning. However, the temporal effects of thinning on leaf C:N:P stoichiometry are still not well understood, which constrains our understanding of implementing thinning in coniferous plantations to promote the regeneration and growth of broadleaved species, and further forming the mixed larch-broadleaf forests. Here, we compared canopy openness (i.e., light availability) and the soil and leaf stoichiometry for regenerated broadleaved trees in larch (Larix keampferi) plantations in short-term (1–3 years), medium-term (4–9 years), and long-term (≥10 years) periods after thinning, taking natural mixed broadleaved forests as a control in Northeast China. The results showed that the temporal effects of thinning were not significant with respect to soil C concentrations, but significant with respect to soil C:P and N:P ratios. The regenerated broadleaved trees adjusted their leaf N concentrations and C:N ratios in response to the changed environmental conditions after thinning over time. The responses of soil and leaf stoichiometry to thinning and their significant correlation indicated a strong interaction between the soil and understory regeneration following thinning. Thus, thinning affects the soil and leaf stoichiometry of regenerated trees over time. These findings provide new insights into the conversion of pure coniferous plantations into mixed larch-broadleaf forests by controlling thinning intervals.

Sign in / Sign up

Export Citation Format

Share Document