scholarly journals Strong temporal variation in treefall and branchfall rates in a tropical forest is explained by rainfall: results from five years of monthly drone data for a 50-ha plot

2021 ◽  
Author(s):  
Raquel Fernandes Araujo ◽  
Samuel Grubinger ◽  
Carlos Henrique Souza Celes ◽  
Robinson I. Negrón-Juárez ◽  
Milton Garcia ◽  
...  
Keyword(s):  
Tropical Forest ◽  
Temporal Variation ◽  
Forest Canopy ◽  
Barro Colorado Island ◽  
Weibull Function ◽  
Wet Season ◽  
Canopy Disturbance ◽  
Dead Trees ◽  
Standing Dead ◽  
Standing Dead Trees

Abstract. A mechanistic understanding of how tropical tree mortality responds to climate variation is urgently needed to predict how tropical forest carbon pools will respond to anthropogenic global change, which is altering the frequency and intensity of storms, droughts, and other climate extremes in tropical forests. We used five years of approximately monthly drone-acquired RGB imagery for 50 ha of mature tropical forest on Barro Colorado Island, Panama, to quantify spatial structure, temporal variation, and climate correlates of canopy disturbances, i.e., sudden and major drops in canopy height due to treefalls, branchfalls, or collapse of standing dead trees. Treefalls accounted for 77 % of the total area and 60 % of the total number of canopy disturbances in treefalls and branchfalls combined. The size distribution of canopy disturbances was close to a power function for sizes above 25 m2, and best fit by a Weibull function overall. Canopy disturbance rates varied strongly over time and were higher in the wet season, even though windspeeds were lower in the wet season.  The strongest correlate of temporal variation in canopy disturbance rates was the frequency of 1-hour rainfall events above the 99.4th percentile (here 35.7 mm hour−1, r = 0.67). We hypothesize that extreme high rainfall is associated with both saturated soils, increasing risk of uprooting, and with gusts having high horizontal and vertical windspeeds that increase stresses on tree crowns. These results demonstrate the utility of repeat drone-acquired data for quantifying forest canopy disturbance rates over large spatial scales at fine temporal and spatial resolution, thereby enabling strong tests of linkages to drivers. Future studies should include high frequency measurements of vertical and horizontal windspeeds and soil moisture to better capture proximate drivers, and incorporate additional image analyses to quantify standing dead trees in addition to treefalls.

scholarly journals Strong temporal variation in treefall and branchfall rates in a tropical forest is related to extreme rainfall: results from 5 years of monthly drone data for a 50 ha plot

2021 ◽  
Vol 18 (24) ◽  
pp. 6517-6531
Author(s):  
Raquel Fernandes Araujo ◽  
Samuel Grubinger ◽  
Carlos Henrique Souza Celes ◽  
Robinson I. Negrón-Juárez ◽  
Milton Garcia ◽  
...  
Keyword(s):  
Tropical Forest ◽  
Temporal Variation ◽  
Forest Canopy ◽  
Tree Mortality ◽  
Extreme Rainfall ◽  
Barro Colorado Island ◽  
Weibull Function ◽  
Wet Season ◽  
Wind Speeds ◽  
Canopy Disturbance

Abstract. A mechanistic understanding of how tropical-tree mortality responds to climate variation is urgently needed to predict how tropical-forest carbon pools will respond to anthropogenic global change, which is altering the frequency and intensity of storms, droughts, and other climate extremes in tropical forests. We used 5 years of approximately monthly drone-acquired RGB (red–green–blue) imagery for 50 ha of mature tropical forest on Barro Colorado Island, Panama, to quantify spatial structure; temporal variation; and climate correlates of canopy disturbances, i.e., sudden and major drops in canopy height due to treefalls, branchfalls, or the collapse of standing dead trees. Canopy disturbance rates varied strongly over time and were higher in the wet season, even though wind speeds were lower in the wet season. The strongest correlate of monthly variation in canopy disturbance rates was the frequency of extreme rainfall events. The size distribution of canopy disturbances was best fit by a Weibull function and was close to a power function for sizes above 25 m2. Treefalls accounted for 74 % of the total area and 52 % of the total number of canopy disturbances in treefalls and branchfalls combined. We hypothesize that extremely high rainfall is a good predictor because it is an indicator of storms having high wind speeds, as well as saturated soils that increase uprooting risk. These results demonstrate the utility of repeat drone-acquired data for quantifying forest canopy disturbance rates at fine temporal and spatial resolutions over large areas, thereby enabling robust tests of how temporal variation in disturbance relates to climate drivers. Further insights could be gained by integrating these canopy observations with high-frequency measurements of wind speed and soil moisture in mechanistic models to better evaluate proximate drivers and with focal tree observations to quantify the links to tree mortality and woody turnover.

Gradual and sudden forest canopy gaps in Allegheny northern hardwood forests

1992 ◽  
Vol 22 (2) ◽  
pp. 139-143 ◽  
Author(s):  
Marianne E. Krasny ◽  
Mark C. Whitmore
Keyword(s):  
New York ◽  
Forest Canopy ◽  
Hardwood Forests ◽  
Line Transect ◽  
Gap Dynamics ◽  
Northern Hardwood Forests ◽  
Northern Hardwood ◽  
Dead Trees ◽  
Standing Dead ◽  
Standing Dead Trees

To determine the importance of gradual tree death to gap dynamics in Allegheny northern hardwood forests, line transect surveys of gaps and gap makers were conducted in three mature forests in central New York. Of the total number of gaps, 71.7% were classified as gradual gaps, meaning they were partial openings in the canopy caused by either trees with greater than 50% branch loss or standing dead trees. Sudden gaps, caused by trees that had fallen, constituted 9.7% of the total number of gaps. Another 18.6% of the gaps had mixed causes. American beech (Fagusgrandifolia Ehrh.), which is subject to beech bark disease in the study area, was the predominant gap maker, representing 52.4% of the gap makers compared with 25.6% of the canopy trees. It is suggested that future studies of forest gap dynamics include measures of gaps forming over a period of time, particularly in forests subject to decline and biotic diseases and in other forests where gradual tree death and standing dead trees are known to be important.

scholarly journals Occurrence of termites (Isoptera) on living and standing dead trees in a tropical dry forest in Mexico

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4731 ◽  
Author(s):  
Nancy Calderón-Cortés ◽  
Luis H. Escalera-Vázquez ◽  
Ken Oyama
Keyword(s):  
Forest Canopy ◽  
Dead Wood ◽  
Tropical Dry Forest ◽  
Dry Forest ◽  
Dead Tree ◽  
Ecological Processes ◽  
Dead Trees ◽  
Standing Dead ◽  
Standing Dead Trees ◽  
Main Factor

Termites play a key role as ecosystem engineers in numerous ecological processes though their role in the dynamics of wood degradation in tropical dry forests, particularly at the level of the crown canopy, has been little studied. In this study, we analysed the occurrence of termites in the forest canopy by evaluating the density and proportion of living and standing dead trees associated with termites in deciduous and riparian habitats of the tropical dry forest in Chamela, Mexico. The results indicated that 60–98% of standing dead trees and 23–59% of living trees in Chamela were associated with termites. In particular, we found that the density of standing dead trees was higher in deciduous forests (0.057–0.066 trees/m2) than in riparian forests (0.022 and 0.027 trees/m2), even though the proportion of trees was not significantly different among habitats. Additionally, we found a higher density of trees associated with termites in trees of smaller size classes (0.01–0.09 trees/m2) than in larger class sizes (0–0.02 trees/m2). Interestingly, 72% of variation in the density of trees associated with termites is explained by the density of standing dead trees. Overall, these results indicate that standing dead tree availability might be the main factor regulating termite populations in Chamela forest and suggest that termites could play a key role in the decomposition of above-ground dead wood, mediating the incorporation of suspended and standing dead wood into the soil.

scholarly journals Classification of Tree Species as Well as Standing Dead Trees Using Triple Wavelength ALS in a Temperate Forest

2019 ◽  
Vol 11 (22) ◽  
pp. 2614 ◽  
Author(s):  
Nina Amiri ◽  
Peter Krzystek ◽  
Marco Heurich ◽  
Andrew Skidmore
Keyword(s):  
Tree Species ◽  
Feature Selection Method ◽  
Silver Fir ◽  
Maximum Point ◽  
Individual Tree ◽  
Dead Trees ◽  
Multi Wavelength ◽  
Standing Dead ◽  
Standing Dead Trees ◽  
532 Nm

Knowledge about forest structures, particularly of deadwood, is fundamental for understanding, protecting, and conserving forest biodiversity. While individual tree-based approaches using single wavelength airborne laserscanning (ALS) can successfully distinguish broadleaf and coniferous trees, they still perform multiple tree species classifications with limited accuracy. Moreover, the mapping of standing dead trees is becoming increasingly important for damage calculation after pest infestation or biodiversity assessment. Recent advances in sensor technology have led to the development of new ALS systems that provide up to three different wavelengths. In this study, we present a novel method which classifies three tree species (Norway spruce, European beech, Silver fir), and dead spruce trees with crowns using full waveform ALS data acquired from three different sensors (wavelengths 532 nm, 1064 nm, 1550 nm). The ALS data were acquired in the Bavarian Forest National Park (Germany) under leaf-on conditions with a maximum point density of 200 points/m 2 . To avoid overfitting of the classifier and to find the most prominent features, we embed a forward feature selection method. We tested our classification procedure using 20 sample plots with 586 measured reference trees. Using single wavelength datasets, the highest accuracy achieved was 74% (wavelength = 1064 nm), followed by 69% (wavelength = 1550 nm) and 65% (wavelength = 532 nm). An improvement of 8–17% over single wavelength datasets was achieved when the multi wavelength data were used. Overall, the contribution of the waveform-based features to the classification accuracy was higher than that of the geometric features by approximately 10%. Our results show that the features derived from a multi wavelength ALS point cloud significantly improve the detailed mapping of tree species and standing dead trees.

scholarly journals Standing Dead Trees are a Conduit for the Atmospheric Flux of CH4 and CO2 from Wetlands

Wetlands ◽  
2017 ◽  
Vol 38 (1) ◽  
pp. 133-143 ◽  
Author(s):  
Mary Jane Carmichael ◽  
Ashley M. Helton ◽  
Joseph C. White ◽  
William K. Smith
Keyword(s):  
Atmospheric Flux ◽  
Dead Trees ◽  
Standing Dead ◽  
Standing Dead Trees

scholarly journals MENAKAR SIFAT INVASIF SPESIES AKASIA MANGIUM (Acacia mangium Willd.) DI HUTAN PENELITIAN DAN PENDIDIKAN BUKIT SOEHARTO

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
Sutedjo Sutedjo ◽  
Warsudi Warsudi
Keyword(s):  
Acacia Mangium ◽  
Dead Trees ◽  
Standing Dead ◽  
Standing Dead Trees

 Akasia mangium (Acacia mangium Willd) bukan tumbuhan asli Kalimantan namun sejak puluhan tahun tumbuh berkembang pesat di berbagai wilayah Kalimantan termasuk Kalimantan Timur. Dikenal sebagai tumbuhan yang mampu tumbuh di lahan kritis sehingga pada awal tahun 1990-an dijadikan tanaman  reboisasi sekaligus pengendali alang-alang di wilayah kritis hutan penelitian dan pendidikan Universitas Mulawarman di Bukit Soeharto. Mengherankan, bahwa beberapa tahun taerkhir sebagian praktisi kehutanan dan reklamasi pascatambang merasa gamang menggunakan A. mangium, khawatir jika jenis tersebut akan benar benar menjadi spesies invasif.  Gejala untuk menolak bahkan menghindari  A. mangium sebagai komoditas kehutanan terutama sebagai jenis pengendali lahan kritis mulai meluas. Untuk mengetahui seberapa benar anggapan Acacia mangium sebagai jenis invasif maka dilakukan evaluasi dengan melakukan analisis vegetasi terhadap 3 ha tegakan hutan A. mangium yang ditanam di Bukit Soeharto sebagai uji petik yang saat sekarang telah berumur sekitar 25 tahun. Hasil evaluasi membuktikan bahwa jumlah tanaman per ha (kerapatan) pohon A. mangium menurun (kurang dari jumlah saat ditanam atau sekitar 800 individu/ha). Jumlah yang menurun itupun cenderung mengelompok. Sebagian pohon bahkan ditemukan dalam kondisi mati generasi (standing dead trees). Sementara itu jumlah spesies pohon setempat (local trees species) juga mulai muncul di antara tegakan A.mangium. Dengan demikian terbukti  bahwa A. mngium bukanlah tipe invasif  yang sesungguhnya dan tidak ada alasan utuk menolak penggunaannya sebagai tanaman pengendali lahan kritis selama potensi ancaman terjadinya kebakaran lahan hutan dapat dicegah.

scholarly journals The structure of forest stands in the Tatra National Park: The results of 2016–2017 inventory

2019 ◽  
Vol 80 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Jan Bodziarczyk ◽  
Jerzy Szwagrzyk ◽  
Tomasz Zwijacz-Kozica ◽  
Antoni Zięba ◽  
Janusz Szewczyk ◽  
...  
Keyword(s):  
Picea Abies ◽  
Fagus Sylvatica ◽  
National Park ◽  
Forest Stands ◽  
Protection Zone ◽  
Dead Trees ◽  
Standing Dead ◽  
Elevation Zone ◽  
Standing Dead Trees ◽  
Tatra National Park

Abstract The composition and structure of forest stands in the Tatra National Park were examined using data gathered in 2016 and 2017 from 617 circular sample plots (0.05 ha each). The diameter at breast height of all living trees, standing dead trees, snags, and wind throws was measured along with diameters and lengths of fallen logs within the plot boundaries. Tree height was measured for all living trees within the core (0.01 ha) of the sample plots. Using the obtained data, height-diameter curves were calculated for all major tree species and in the case of spruce, the height-diameter relationships were also calculated separately for each of the three elevation zones (up to 1200 m, between 1200 and 1400 m, above 1400 m). For each elevation zone and park protection zone, we also determined the volumes of live and dead trees. The volume of living trees in the Tatra National Park amounted to 259 m3/ha, which was higher than the volume of dead trees (176 m3/ha). Snags constituted the largest part of the dead wood whilst over 97% of the standing dead trees were spruce Picea abies. Among living trees, the share of spruce ranged from 81% in the low elevation zone to 98% in the middle zone. Other significant species in the lower zone were Abies alba (11%) and Fagus sylvatica (4.5%), while in the middle and upper elevation zones only Sorbus aucuparia occurred in significant numbers. Furthermore, in the lower elevation zone, Fagus sylvatica was the only species displaying significantly higher volumes in the ‘strict protection’ zone compared to the other park areas. In the ‘landscape protection’ zone, Picea abies was the most dominant species and the share of other species in the lowest elevation zones calculated based on tree density was smaller than calculated based on tree volume, indicating problems with stand conversion from spruce monoculture to mixed forest.

Decay patterns and carbon density of standing dead trees in California mixed conifer forests

2015 ◽  
Vol 353 ◽  
pp. 136-147 ◽  
Author(s):  
Stella J.M. Cousins ◽  
John J. Battles ◽  
John E. Sanders ◽  
Robert A. York
Keyword(s):  
Conifer Forests ◽  
Carbon Density ◽  
Mixed Conifer ◽  
Dead Trees ◽  
Mixed Conifer Forests ◽  
Standing Dead ◽  
Standing Dead Trees
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