Selective logging in the Amazon Biome holds significant importance economically and environmentally. Due to its potential for forest degradation, monitoring these areas is of utmost importance. We ...assessed canopy openness in sustainably logged forest areas in Eastern Amazonia using hemispherical photos taken in areas that were logged in different years (2004, 2007, 2017, 2019, and 2021), along with one unlogged control area to evaluate the time period over which the effects of logging remained detectable. Timeframes of detectability varied across logging features considered (e.g. log landings, logging roads and skid trails). Canopy openness of log landings used to store logs was still greater than that of unlogged forests controls >17 years after logging had ceased while the impacts of logging roads and skid trails were still detectable at least 5 years after cessation of logging. The detection of the impacts of selective tree harvesting on the forest several years after the end of operations provides confidence for larger-scale quantification of historical low-intensity logging over Amazonia through high-resolution imagery. More generally, the study also highlighted the importance of monitoring selective tree extraction areas to understand their influence on forest disturbance and the occurrence of regeneration processes.
•The selective logging in the Brazilian Amazon is a significant economic activity.•The selective logging on Fazenda Rio Capim significantly impacted the forest canopy.•Following canopy opening the logged area becomes viable for forest regeneration.•The effects of selective logging over the years are still detectable.
•Below canopy microclimatic conditions differ along land-use systems.•Forests are cooler and more humid than oil palm and rubber monocultures.•Canopy openness is a key driver of below-canopy ...microclimate.•The ENSO event of 2015 led to warmer and drier conditions in all land-uses.•During ENSO, forests buffered best the change in below-canopy microclimate.
Oil palm and rubber expansion is a main driver of the widespread deforestation of tropical rainforests taking place in South-East Asia, particularly in Indonesia. The replacement of forests with monoculture plantations of rubber and oil palm reduces biodiversity and carbon pools but also modifies canopy structure, which is an important determinant of microclimate. There is, however, a lack of quantitative information characterizing the effect of such land transformation on microclimate. We report the first medium-term observations of below-canopy microclimatic conditions (air temperature, relative humidity, vapour pressure deficit and soil temperature) across forest, jungle rubber agroforest, oil palm and rubber monoculture plantations in Sumatra/Indonesia. The data set covers a period of approximately three years (2013–2016) and includes one of the strongest El Niño-Southern Oscillations (ENSO) of the last decades. Forests were up to 2.3 and 2.2 °C cooler than oil palm and rubber monocultures respectively. The monocultures were also drier (11.9% and 12.8% less in oil palm and rubber respectively) and had higher vapour pressure deficit (632 Pa and 665 Pa higher in oil palm and rubber respectively) than the forest, while differences in soil temperature were less pronounced. Conversion from forest to other land uses, especially to monocultures, also amplified the diurnal range of all microclimatic variables studied. Jungle rubber stands out as the transformed land-use system that maintains more stable microclimatic conditions. Our results indicate that canopy openness is a key driver of below-canopy microclimate, and hence could be used in climate models to better evaluate climatic feedbacks of land-use change to rubber and oil palm. The ENSO event of 2015 led to warmer and drier conditions than in the previous two years in all four land-use systems, especially in the forest (up to 2.3 °C warmer, 8.9% drier and up to 351 Pa more during ENSO). The relative effect of ENSO was lower in the monoculture plantations, where below-canopy microclimate is generally more similar to open areas. Forests exhibited the largest differences with the pre-ENSO years, but still maintained more stable microclimatic conditions (lower temperatures and vapour pressure deficit and higher relative humidity) due to their higher climate regulation capacity. During ENSO, microclimatic conditions in jungle rubber were comparable to those in the monocultures, suggesting that while forests buffered the increase of temperature, jungle rubber might have surpassed its buffering capacity to extreme events. This capacity of buffering extreme climatic events should be considered when assessing the effects of land-use change.
•Norway spruce is one of the most important target trees in forestry.•We studied bird communities throughout the Czech Republic.•Representation of deciduous trees and longhorns have effect on the ...species richness.•Bird communities exhibited a strong relationship with spruce outside of its native range.•It is important to leave deciduous trees within the stand.
Norway spruce (Picea abies) is one of the most important target trees in forestry. In Central Europe, it is grown primarily in forest plantations. However, the distribution area of this tree species is declining due to climate change and trends toward sustainable forest management. The question how artificial habitats such as plantations influence the native biota is still unclear. We aimed to investigate the influence of spruce plantations on bird communities at the country level. We focused on birds in relation to biotic, stand and land use characteristics. We studied bird communities (including woodpeckers) throughout the Czech Republic. All sites were situated in mature spruce forest plantations. Birds were sampled using the point count method, and nine environmental predictors were considered to potentially affect the bird community. Our results indicate that the representation of deciduous trees (within stands and in the surroundings) and longhorn beetles (as prey) have a predominant effect on the species richness of birds, including woodpeckers. The effects of longhorns and deciduous trees in the stand were positive, while deciduous forests in the surroundings had a negative effect. We also found several species associated with spruce, even in plantation forests. An important finding regarding the future management of spruce stands is that bird communities exhibited a strong relationship with spruce, even outside of its native range. Admixture with deciduous trees was favorable at the stand level, while at the landscape level, there is the need for adequate spruce-dominated forests, and deciduous forests may serve as obstacles. We argue that plantations cannot only be seen as tree farms or green deserts but also be used for biodiversity management. Nevertheless, it is important to leave deciduous trees within the stand until the end of the rotation period, as birds find food and nesting places in these trees.
Las condiciones ambientales influyen en varios procesos ecológicos y fenológicos de las especies vegetales, como la dispersión, el banco de semillas en el suelo y la germinación. El objetivo del ...presente estudio fue analizar la relación entre la abundancia de los individuos adultos y plántulas, la lluvia de semillas, la tasa de germinación y la supervivencia de Abies hickelii, con respecto a las condiciones ambientales en la Sierra Norte, Oaxaca, México. Se realizaron muestreos de vegetación, se colocaron trampas para la lluvia de semillas, se colectó el banco de semillas en el suelo y se cuantificó la germinación y su supervivencia. En cada sitio se midieron las condiciones ambientales (climáticas, edáficas, topográficas y lumínicas). Se registró que en el sitio de mayor altitud (3150 m), A. hickelii presentó mayor densidad de adultos y plántulas, y mayor porcentaje de germinación en comparación con los sitios de menor altitud. La abundancia de individuos adultos y plántulas de A. hickelii está relacionada con la apertura del dosel y la intensidad máxima de precipitación. La producción de semillas está relacionada con la precipitación total anual; mientras que la germinación y la supervivencia no se asociaron con ninguna de las variables ambientales analizadas. Este estudio consideró diferentes aspectos del ciclo de vida de A. hickelii y su relación con las condiciones del medio donde se establece, para conocer las variables ambientales más relevantes en cada etapa de su crecimiento. Esta información es relevante para especies endémicas y en peligro de extinción.
Riparian forests have cool and humid microclimates, and one aim of leaving forested buffer strips between clear-cut areas and streams is to conserve these microclimatic conditions. We used an ...experimental study set up of 35 streamside sites to study the impacts of buffer strip width (15 or 30 m) and selective logging within the buffer strips on summer-time air temperature, relative air humidity and canopy openness 12 years after logging. The buffer strip treatments were compared to unlogged control sites. We found that 15-meter buffer strips with or without selective logging and 30-meter buffer strips with selective logging were insufficient in maintaining temperature, relative humidity and canopy openness at similar levels than they were in control sites. In contrast, 30-meter buffer strips differed only little from control sites, although they did have significantly lower mean air humidity. Microclimatic changes were increased by southern or southwestern aspect of the clear-cut, and by logging on the opposite side of the stream. We also tested how the cover of three indicator mosses (Hylocomium splendens, Pseudobryum cinclidioides and Polytrichum commune) had changed (from pre-logging to 12 years post-logging) in relation to post-logging air temperature, relative air humidity and canopy openness. We found that each of the species responded to at least one of these physical conditions. Air humidity was the most significant variable for explaining changes in the cover of the indicator moss species, suggesting that the changes in this microclimatic component has biological impacts. We conclude that to preserve riparian microclimatic conditions and species dependent on those, buffer strips should exceed 30 m in width, and not be selectively logged. Wider buffer strips are required if the clear-cut is towards south or southwest, or if the two sides of the stream are logged at the same time or during subsequent years.
•Buffer strips should conserve cool and humid riparian microclimates.•15-meter buffer strips or selectively logged 30-meter strips are not sufficient.•Buffer strips need to be wider than 30 m and not selectively logged.
•Soil respiration (SR) showed spatial variation with a coefficient of variation (CV) from 25 % to 28 % in a mature beech forest.•The spatial variation in SR was well related with soil water content ...(SWC) but not soil temperature.•Canopy openness indirectly explain the spatial variation in SR via SWC.•CV of SR in forest ecosystems around the world including our data varied widely from 14 % to 62 %.
For accurate estimation of soil respiration (SR) in forest ecosystems, temporal and spatial variation in SR and the factors that control these variations must be considered. Although some of the factors underlying temporal variation in SR have been elucidated in recent decades, a large part of spatial variation in SR remains unexplained especially in forest ecosystems with complex structures. Our objectives were to demonstrate spatial variation in daily summed SR (SRdaily) and to examine if spatial variation in SRdaily can be explained by canopy openness which is one of the indexes of forest structure. We conducted simultaneous measurements of SRdaily, soil temperature (ST), and soil water content (SWC) at 121 points. We also measured canopy openness and some forest stand structure indexes in different seasons in 2012 and 2013. The coefficient of variation (CV) of SRdaily ranged from 25 % to 28 %, which was similar to that of SWC (21 % to 28 %). We also found that the spatial variation in SR in other forest ecosystems ranged widely (CV = 14 % to 62 %), and that in our site fell within the range. There was no significant relationship between ST and spatial variation in SRdaily; however, a significant relationship was observed between SWC and spatial variation in SRdaily (P < 0.01) excepted for the measurement conducted in June 2013. Multiple linear regression analysis indicated that canopy openness showed significant positive correlations with SWC during the growing season. And there was no significant relationships between SWC and forest stand structure indexes.
In this study, we found that canopy structure influenced SWC, which in turn determined the spatial variation in SR in this mature beech forest. The possible connections could give us new insight for adequate forest carbon management.
•Few open-source tools are available for digital hemispherical photography (DHP).•Existing R packages for DHP are limited to specific and partial processing steps.•The R package (hemispheR) allows a ...complete step-by-step DHP processing workflow.•Canopy estimates from the packages were validated against littertraps.
Hemispherical photography is a relevant tool to estimate canopy attributes such as leaf area index (LAI). Advancements in digital photography and image processing tools have supported long-lasting use of digital hemispherical photography (DHP). While some open-source tools exists for DHP, very few solutions have been made available in R programming packages, and none of these allows a full processing workflow to retrieve LAI and other canopy attributes from fisheye images.
To fill this gap, we developed an R package (hemispheR) to support the whole processing of DHP images in an automated, fast, and reproducible way. The package functions, which are designed for step-by-step single-image analysis, can be performed sequentially in a pipeline, while allowing inspecting the quality of each image processing step. The package allows to analyze both circular and fullframe fisheye images, collected either with upward facing (forest canopies) or downward facing (short canopies and crops) camera orientation. In addition, the package allows to implement two consolidated LAI methods (LAI-2000/2200 and 57° method).
A case study is presented to demonstrate the reliability of canopy attributes derived from hemispheR in temperate deciduous forests with variable canopy density and structure. Canopy attributes were validated against either results obtained from a reference proprietary software, either by benchmarking plot-level LAI with measurements obtained from littertraps. Results indicated hemispheR provide reliable openness and leaf area index in forest canopies as compared with reference values. We also found that combining hemispheR with other R packages further advance analysis of hemispherical canopy images, by reducing the sensitivity of results to camera exposure in both raw and non-raw canopy imagery.
By providing a simple, transparent, and flexible image processing procedure, hemispheR supported the use of DHP for routine measurements and monitoring of forest canopy attributes. Hosting the package in a Git repository can further support development of the package, through either collaborative coding or forking projects.
•Canopy openness differs among individual trees within and across species.•Tree canopy openness variation influences seed dispersal and predation by rodents.•Seeds under larger canopies are more ...likely to be removed and dispersed further.•Individual variation in canopy openness leads to variation in seedling regeneration.•Crown pruning can promote seed dispersal by rodents and natural seedling regeneration.
Scatter-hoarding rodents are important seed predators and dispersers in various forest ecosystems and significantly influence the seed fate and seedling regeneration of many tree species. Canopy openness is believed to have an important influence on the foraging behavior of scatter-hoarding rodents, mainly because of the variation in predation risk between open and canopy microsites. Most of the current studies have mainly focused on the spatial variation in canopy openness within a forest or on comparisons among forests; however, the question of how variation in canopy openness at the individual tree scale affects seed-rodent interaction has received little attention, although tree-to-tree variation in canopy openness is ubiquitous. In this study, we measured the individual canopy openness of 45 trees belonging to three species in a subtropical forest, and compared seed dispersal and predation by rodents under the selected trees by labeling and tracking 4,500 seeds. Our results showed that canopy openness differed among individual trees both within and across species. More importantly, our results proved that individual tree variation in canopy openness significantly affected seed dispersal and predation by rodents, although not all species followed a consistent pattern. Seeds under trees with larger canopy openness were more likely to be removed rather than eaten in situ and dispersed farther. Our study highlights the pattern that individual tree characteristics (e.g., canopy openness) have profound effects on rodent-mediated seed dispersal services, which may further lead to tree-to-tree variation in seed fate and seedling regeneration. Our results also provide important implications for forest conservation and management: crown pruning can promote seed dispersal by rodents and natural seedling regeneration.
•We studied effects of defoliation, canopy openness, and competition on fir regeneration.•Plots represented a fir-hardwood gradient in two regions undergoing spruce budworm outbreaks.•Defoliation ...effects on height increment increased with height.•Height increment declined with defoliation, which was higher in larger height classes.•There were several significant interactions of the variables in reducing height increment.
Height increment of balsam fir (Abies balsamea (L.) Mill.) regeneration during a spruce budworm (Choristoneura fumiferana Clem.) outbreak can be affected by a variety of variables including defoliation, ground vegetation competition, canopy openness, the height of regeneration, and stand type. To disentangle how these variables interact to determine regeneration height increment, we sampled 36 plots in two regions showing contrasting climate, regional vegetation, and budworm outbreak severity. Linear mixed-effects models were used to analyze the effects of these five variables on height increment of balsam fir regeneration. In the Amqui (early defoliation) plots, height increment was significantly affected by a “cumulative defoliation × height of regeneration × hardwood content” interaction. Defoliation significantly reduced height increment when regeneration was >30 cm tall in softwood and mixedwood plots, but regeneration <30 cm tall in softwood and mixedwood plots and all regeneration in hardwood plots had light defoliation, which did not reduce height increment. Results were even more complex for the North Shore (late defoliation) plots, where there were three significant 3-way interactions affecting height increment: “height × hardwood content × ground vegetation cover”, “hardwood content × canopy openness × cumulative defoliation”, and “hardwood content × ground vegetation cover × cumulative defoliation”. Canopy openness was >25% in all softwood plots, and height increment substantially declined with increasing cumulative defoliation; however, in mixedwood and hardwood plots, canopy openness was <25% and height increment increased with defoliation. In softwood plots, height increment declined sharply with increasing cumulative defoliation at all ground vegetation cover levels, but in mixedwood and hardwood plots, height increment increased or decreased slightly with increasing cumulative defoliation. Results showed that the variables affecting height increment have surprisingly complex interactive effects.
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