The Influence of Understory Vegetation Cover on Germination and Seedling Establishment in a Tropical Lowland Wet Forest

Biotropica ◽  
1986 ◽  
Vol 18 (4) ◽  
pp. 273 ◽  
Author(s):  
Robert J. Marquis ◽  
Helen J. Young ◽  
H. Elizabeth Braker
2012 ◽  
Vol 124 ◽  
pp. 730-741 ◽  
Author(s):  
Brian M. Wing ◽  
Martin W. Ritchie ◽  
Kevin Boston ◽  
Warren B. Cohen ◽  
Alix Gitelman ◽  
...  

2018 ◽  
pp. 27 ◽  
Author(s):  
J. Torralba ◽  
P. Crespo-Peremarch ◽  
L. A. Ruiz

<p>LiDAR technology –airborne and terrestrial- is becoming more relevant in the development of forest inventories, which are crucial to better understand and manage forest ecosystems. In this study, we assessed a classification of species composition in a Mediterranean forest following the C4.5 decision tree. Different data sets from airborne laser scanner full-waveform (ALS<sub>FW</sub>), discrete (ALS<sub>D</sub>) and terrestrial laser scanner (TLS) were combined as input data for the classification. Species composition were divided into five classes: pure Quercus ilex plots (QUI); pure Pinus halepensis dense regenerated (HALr); pure P. halepensis (HAL); pure P. pinaster (PIN); and mixed P. pinaster and Q. suber (mPIN). Furthermore, the class HAL was subdivided in low and dense understory vegetation cover. As a result, combination of ALS<sub>FW</sub> and TLS reached 85.2% of overall accuracy classifying classes HAL, PIN and mPIN. Combining ALS<sub>FW</sub> and ALS<sub>D</sub>, the overall accuracy was 77.0% to discriminate among the five classes. Finally, classification of understory vegetation cover using ALS<sub>FW</sub> reached an overall accuracy of 90.9%. In general, combination of ALS<sub>FW</sub> and TLS improved the overall accuracy of classifying among HAL, PIN and mPIN by 7.4% compared to the use of the data sets separately, and by 33.3% with respect to the use of ALS<sub>D</sub> only. ALS<sub>FW</sub> metrics, in particular those specifically designed for detection of understory vegetation, increased the overall accuracy 9.1% with respect to ALS<sub>D</sub> metrics. These analyses show that classification in forest ecosystems with presence of understory vegetation and intermediate canopy strata is improved when ALS<sub>FW</sub> and/or TLS are used instead of ALS<sub>D</sub>.</p>


2006 ◽  
Vol 36 (11) ◽  
pp. 2943-2954 ◽  
Author(s):  
Cristina M Rumbaitis del Rio

Catastrophic windthrow and postdisturbance salvage logging each have the potential to profoundly influence understory vegetation communities. This study compared understory vegetation cover, composition, and diversity in Routt National Forest, a subalpine forest in northwestern Colorado that sustained a 10 000 ha blowdown in 1997 and was partially salvage logged in 1999. Understory and edaphic variables were measured in five heavily wind-disturbed Picea–Abies stands, five stands salvage logged 20 months after the blowdown, and five intact stands. Understory species cover and diversity were greater in blown down areas than in salvage-logged or control areas. Community composition of each treatment area was distinct and related to a gradient in organic soil depth, which reflected the severity of understory disturbance. Composition and diversity in blowdown areas relative to control areas stabilized in the 5 years following the blowdown, but vegetation cover continued to increase. Blowdown areas contained early and late successional species. Salvage-logged areas exhibited a shift towards graminoid dominance. This structural change could delay future conifer seedling establishment. The interaction among disturbance severity, understory vegetation composition, and regeneration dynamics should be considered in future decisions to salvage log similar areas because the long-term effects of salvage logging are unknown.


1999 ◽  
Vol 29 (12) ◽  
pp. 1997-2002 ◽  
Author(s):  
Jeff P Castelli ◽  
Brenda B Casper ◽  
Jon J Sullivan ◽  
Roger Earl Latham

Early succession was followed in a 2.5-ha gap created by a severe wind storm in a 5.5-ha fragment of eastern North American deciduous forest. Understory vegetation cover by species, light, soil moisture, and levels of several major nutrients were measured in 1 × 2 m census plots 3 years prior to the disturbance. Coincidentally, the storm felled 50-55% of the trees over a portion of these plots. Vegetation cover by species was again measured in all plots 3 years following the disturbance. Species were grouped by growth form, and group cover values used to examine changes in the composition of the vegetation and to determine whether these changes were correlated with any measured predisturbance environmental variables. Given the size of the gap, shade-intolerant tree species were expected to increase but did not, most likely because of repression by the shrub layer. The main response to the disturbance appeared to occur through reorganization of existing vegetation. The value of predisturbance species cover data and limitations of our sample sizes are discussed.


2008 ◽  
Vol 318 (1-2) ◽  
pp. 47-61 ◽  
Author(s):  
Catherine L. Cardelús ◽  
Michelle C. Mack ◽  
Carrie Woods ◽  
Jennie DeMarco ◽  
Kathleen K. Treseder

2020 ◽  
Vol 12 (2) ◽  
pp. 298 ◽  
Author(s):  
Linyuan Li ◽  
Jun Chen ◽  
Xihan Mu ◽  
Weihua Li ◽  
Guangjian Yan ◽  
...  

Vegetation cover estimation for overstory and understory layers provides valuable information for modeling forest carbon and water cycles and refining forest ecosystem function assessment. Although previous studies demonstrated the capability of light detection and ranging (LiDAR) in the three-dimensional (3D) characterization of forest overstory and understory communities, the high cost inhibits its application in frequent and successive survey tasks. Low-cost commercial red–green–blue (RGB) cameras mounted on unmanned aerial vehicles (UAVs), as LiDAR alternatives, provide operational systems for simultaneously quantifying overstory crown cover (OCC) and understory vegetation cover (UVC). We developed an effective method named back-projection of 3D point cloud onto superpixel-segmented image (BAPS) to extract overstory and forest floor pixels using 3D structure-from-motion (SfM) point clouds and two-dimensional (2D) superpixel segmentation. The OCC was estimated from the extracted overstory crown pixels. A reported method, called half-Gaussian fitting (HAGFVC), was used to segement green vegetation and non-vegetation pixels from the extracted forest floor pixels and derive UVC. The UAV-based RGB imagery and field validation data were collected from eight forest plots in Saihanba National Forest Park (SNFP) plantation in northern China. The consistency of the OCC estimates between BAPS and canopy height model (CHM)-based methods (coefficient of determination: 0.7171) demonstrated the capability of the BAPS method in the estimation of OCC. The segmentation of understory vegetation was verified by the supervised classification (SC) method. The validation results showed that the OCC and UVC estimates were in good agreement with reference values, where the root-mean-square error (RMSE) of OCC (unitless) and UVC (unitless) reached 0.0704 and 0.1144, respectively. The low-cost UAV-based observation system and the newly developed method are expected to improve the understanding of ecosystem functioning and facilitate ecological process modeling.


2009 ◽  
Vol 142 (12) ◽  
pp. 2997-3004 ◽  
Author(s):  
Susan Cordell ◽  
Rebecca Ostertag ◽  
Barbara Rowe ◽  
Linda Sweinhart ◽  
Lucero Vasquez-Radonic ◽  
...  

Biotropica ◽  
1996 ◽  
Vol 28 (1) ◽  
pp. 82 ◽  
Author(s):  
Bette A. Loiselle ◽  
Eric Ribbens ◽  
Orlando Vargas

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