Spatial distributions of understory light along the grassland/forest continuum: effects of cover, height, and spatial pattern of tree canopies

Martens, Scott N.; Breshears, David D.; Meyer, Clifton W.

doi:10.1016/s0304-3800(99)00188-x

Cited by 176 publications

(194 citation statements)

References 40 publications

Supporting

Mentioning

170

Contrasting

Unclassified

Order By: Relevance

“…The tendency for light levels to increase and become more variable with increasing harvest aggregation (i.e., from uniform to gap cuts) corroborates field observations in Battaglia et al (2002). A greater amount of variance associated with decreasing canopy cover and increasing aggregation has also been reported by Martens et al (2000).…”

Section: Effect On Light Conditionssupporting

confidence: 80%

Managing understory light conditions in boreal mixedwoods through variation in the intensity and spatial pattern of harvest: A modelling approach

Beaudet

Harvey

Messier

et al. 2011

Forest Ecology and Management

View full text Add to dashboard Cite

a b s t r a c tIn the context of partial harvesting, adequately managing post-harvest light conditions are essential to obtain a desired composition of tree species regeneration. The objective of this study was to determine how varying the intensity and spatial pattern of harvest would affect understory light conditions in boreal mixedwood stands of northwestern Quebec using the spatially explicit SORTIE-ND light model. The model was evaluated based on comparisons of observed and predicted light levels in both mapped and un-mapped plots. In mapped plots, reasonably accurate predictions of the overall variation in light levels were obtained, but predictions tended to lack spatial precision. In un-mapped plots, SORTIE-ND accurately predicted stand-level mean GLI (Gap Light Index) under a range of harvest intensities. The model was then used to simulate nine silvicultural treatments based on combinations of three intensities of overstory removal (30%, 45% and 60% of basal area) and three harvest patterns (uniform, narrow strips, large gaps). Simulations showed that increasing overstory removal had less impact on light conditions with uniform harvests, and a more marked effect with more aggregated harvest patterns. Whatever the harvest intensity, uniform cuts almost never created high light conditions (GLI > 50%). Gap cuts, on the other hand, resulted in up to 40% of microsites receiving GLI > 50%. Our results suggest that either a 30% strip or gap cut or a 45-60% uniform partial harvest could be used to accelerate the transition from an aspen dominated composition to a mixedwood stand because both types of cut generate the greatest proportion of moderately low light levels (e.g., 15-40% GLI). These light levels tend to favour an accelerated growth response among shade-tolerant conifers, while preventing excessive recruitment of shade-intolerant species. A better understanding of how spatial patterns of harvest interact with tree removal intensity to affect understory light conditions can provide opportunities for designing silvicultural prescriptions that are tailored to species' traits and better suited to meet a variety of management objectives.

show abstract

Section: Effect On Light Conditionssupporting

confidence: 80%

Managing understory light conditions in boreal mixedwoods through variation in the intensity and spatial pattern of harvest: A modelling approach

Beaudet

Harvey

Messier

et al. 2011

Forest Ecology and Management

View full text Add to dashboard Cite

show abstract

“…Noy-Meir (2001) found that soil water content was positively correlated with the height of the nearest outcrop due to shading and a reduction in wind speed. Martens et al (2000) showed that as tree height increased, the mean understory light decreased, which can reduce water stress in nursed seedlings. The amelioration of microenvironment conditions is likely important for plant establishment in stressful environments with high irradiance, temperatures, and soil water deficits.…”

Section: Discussionmentioning

confidence: 99%

Role of nurse rocks on woody plant establishment in a South African grassland

Fujita

Mizuno

2015

Tropics

View full text Add to dashboard Cite

Many empirical studies have supported the facilitative effect of nurse plants, and several recent studies have reported similar phenomena with non-plant features, such as rocks. Few studies have explored the effect of rock height on plant establishment, although variation in height can affect establishment. This study examined whether rocky outcrops have positive effects on plant establishment, as do classic nurse plants, and explored the mechanisms involved in the nurse effects in a South African grassland. To answer these questions, we compared the number of individual woody plants at the edges of rocky outcrops and in the adjacent grassland matrix, as well as beneath a putative nurse plant (Euclea crispa) and in the adjacent grassland matrix. We also measured the heights of rocky outcrops and E. crispa and the proportions of grass cover. The results showed that larger numbers of woody seedlings occurred at the edges of rocky outcrops and beneath E. crispa compared with in the adjacent grassland matrix. A generalised linear model (GLM) showed that rock and E. crispa height positively affected the number of seedlings; the diaspores of most recorded species showed characteristics associated with dispersal by vertebrates. The GLM analysis showed that the proportion of grass cover had a negative effect on the number of seedlings. These results indicate that in addition to shrubs, rocky outcrops appear to have positive effects on the establishment of woody plants in South African grasslands, likely serving as perching structures for birds and providing favourable microhabitats.

show abstract

“…In multilayered stands, the variability of light conditions at the forest floor is controlled by trees of the lower stand layer with low-based crowns (Martens et al 2000). The irradiance pattern under the canopy of tall trees, with crown bases far from the ground, is rather uniform (Kuuluvainen, Pukkala 1987).…”

Section: Discussionmentioning

confidence: 99%

Factors controlling the regeneration process in unevenly aged silver fir forests: inferences from the spatial pattern of trees

Paluch¹

2006

J. For. Sci.

View full text Add to dashboard Cite

ABSTRACT:The main objective of this study was to prove the relationship between the spatial pattern of trees and distribution of advanced regeneration in structured Abies alba Mill. forests in the Western Carpathians (of southern Poland). In 13 sample plots (0.45-1.00 ha in size), the locations of all live trees above 15 cm in d 1.3 and all stumps of canopy trees (above 50 cm in d 1.3 ) were determined. In addition, in all plots the coordinates of all live and dead polestage trees (5-15 cm in d 1.3 ), in seven plots the coordinates of all live and dead younger saplings (0.5-1.3 m in height), and in eight plots the coordinates of all live and dead older saplings (above 1.3 m in height and below 5 cm in d 1.3 ) were registered. The univariate and bivariate Ripley's K-function was applied to test spatial independence of the patterns of trees representing different size categories. In each of the stands, younger and older saplings and pole-stage trees showed an aggregated pattern. The strongest attraction between trees of these size categories was detected at the scale 6, 5 and 10 m, respectively. At the scale below 10 m, a positive spatial correlation was frequently found between large firs and pole-stage trees and saplings. A spatial repulsion between advanced fir regeneration and trees of the middle stand layer was negligible or observable only in a relatively large scale above 15 m. The patterns of saplings and trees of the lower stand layer appeared to be spatially independent in most of the stands being studied. These results suggest that in unevenly aged fir forests, a stable mechanism is generating the aggregated patterns of regeneration functions and the factors involved are spatially linked with the distribution of large firs. Therefore, a hypothesis is advanced that the spatial pattern of regeneration in such forests is controlled by edaphic factors -in particular, the humus form -and that light conditions play only a secondary role.

show abstract

Spatial distributions of understory light along the grassland/forest continuum: effects of cover, height, and spatial pattern of tree canopies

Cited by 176 publications

References 40 publications

Managing understory light conditions in boreal mixedwoods through variation in the intensity and spatial pattern of harvest: A modelling approach

Managing understory light conditions in boreal mixedwoods through variation in the intensity and spatial pattern of harvest: A modelling approach

Role of nurse rocks on woody plant establishment in a South African grassland

Factors controlling the regeneration process in unevenly aged silver fir forests: inferences from the spatial pattern of trees

Contact Info

Product

Resources

About