Salvage logging cause short- and mid-term changes of successional trajectories following forest disturbance

Author(s):  
Simon Thorn

<p>Following natural forest disturbances, additional anthropogenic disturbance may alter community recovery and successional trajectories by affecting the occurrences of species, functional groups and evolutionary lineages. However, our understanding is limited of whether rare, common, or dominant species, functional groups, or evolutionary lineages are most strongly affected by an additional disturbance, such as salvage logging. Here, we used a generalized diversity concept based on Hill numbers to quantify the community differences of vascular plants, bryophytes, lichens, wood-inhabiting fungi, saproxylic beetles, and birds following disturbances and experimental salvage logging. Most species groups showed no significant changes in dissimilarities between logged and unlogged plots over the first years of succession, indicating that salvage logging did not contribute to an accelerated decrease of initial dissimilarities. These dissimilarities between communities of were mainly driven by rare species. Trends in species dissimilarities only partially match the trends in dissimilarities of functional groups and evolutionary lineages, with little significant changes in successional trajectories. This talk highlights that salvage logging following natural disturbances can alter successional trajectories in early stages of forest succession following natural disturbances and that those changes persist over time. However, community changes over time may differ remarkably in different taxonomic groups and are best detected based on taxonomic, rather than functional or phylogenetic dissimilarities.</p>

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Simon Thorn ◽  
Anne Chao ◽  
Kostadin B. Georgiev ◽  
Jörg Müller ◽  
Claus Bässler ◽  
...  

Abstract Forests are increasingly affected by natural disturbances. Subsequent salvage logging, a widespread management practice conducted predominantly to recover economic capital, produces further disturbance and impacts biodiversity worldwide. Hence, naturally disturbed forests are among the most threatened habitats in the world, with consequences for their associated biodiversity. However, there are no evidence-based benchmarks for the proportion of area of naturally disturbed forests to be excluded from salvage logging to conserve biodiversity. We apply a mixed rarefaction/extrapolation approach to a global multi-taxa dataset from disturbed forests, including birds, plants, insects and fungi, to close this gap. We find that 75 ± 7% (mean ± SD) of a naturally disturbed area of a forest needs to be left unlogged to maintain 90% richness of its unique species, whereas retaining 50% of a naturally disturbed forest unlogged maintains 73 ± 12% of its unique species richness. These values do not change with the time elapsed since disturbance but vary considerably among taxonomic groups.


2005 ◽  
Vol 5 (2) ◽  
pp. 151-156 ◽  
Author(s):  
Rodolfo Salm ◽  
Euphly Jalles-Filho ◽  
Cynthia Schuck-Paim

In this study we propose a model that represents the importance of large arborescent palms in the dynamics of seasonally-dry Amazonian forests. Specifically, the model is aimed at guiding the investigation of the role of large arborescent palms on forest regeneration and succession. Following disturbance, the high level of luminosity reaching recently formed forest gaps favors the quick proliferation of shade-intolerant lianas that, by casting shade on the crowns of mature forest trees and increasing tree-fall probability, suppress forest succession. Due to their columnar architecture palm trees are, however, not severely affected by vines. As the palms grow, the canopy at the gaps becomes gradually higher and denser, progressively obstructing the passage of light, thus hindering the growth of shade-intolerant lianas and enabling late-successional tree development and forest regeneration. Owing to the long time associated with forest regeneration, the model cannot be tested directly, but aspects of it were examined with field data collected at an Attalea maripa-rich secondary forest patch within a matrix of well-preserved seasonally-dry forest in the Southeastern Amazon. The results indicate that (1) forest disturbance is important for the recruitment of large arborescent palms species, (2) these palms can grow rapidly after an event of disturbance, restoring forest canopy height and density, and (3) secondary forest dominated by palm trees species may be floristically similar to nearby undisturbed forests, supporting the hypothesis that the former has undergone regeneration, as purported in the model.


The Condor ◽  
2019 ◽  
Vol 121 (4) ◽  
Author(s):  
Julianna M A Jenkins ◽  
Damon B Lesmeister ◽  
Eric D Forsman ◽  
Katie M Dugger ◽  
Steven H Ackers ◽  
...  

Abstract Dispersal among breeding sites in territorial animals (i.e. breeding dispersal) is driven by numerous selection pressures, including competition and spatiotemporal variation in habitat quality. The scale and trend of dispersal movements over time may signal changing conditions within the population or on the landscape. We examined 2,158 breeding dispersal events from 694 male and 608 female individually marked Northern Spotted Owls (Strix occidentalis caurina) monitored over 28 yr on 7 study areas to assess the relative importance of individual (sex, experience), reproductive (annual productivity, mate availability), and environmental (forest alteration, presence of competitor) sources of variation in breeding dispersal distance. Median breeding dispersal distance was 3.17 km, with 99% of all breeding dispersal events <37 km. Mean annual dispersal distances increased by 2.43 km in Oregon and 9.40 km in Washington between 1990 and 2017, which coincided with increases in annual detections of nonnative Barred Owl (S. varia). Frequency of breeding dispersal events, both among and within individuals, also increased over time. Female owls moved farther than males (median of 3.26 and 3.10 km, respectively), and birds with less experience (territory tenure) moved farther than those with more experience. Owls that were single in the year prior to dispersal moved 13–31% farther than those paired prior to dispersal. The greatest environmental change occurring over the course of our study was the expansion of Barred Owl populations. Breeding dispersal distance was positively related to Barred Owls in the study area and disturbance within the originating territory. While it appears that social factors continue to be important drivers of breeding dispersal distance in Spotted Owls, increased competition from Barred Owls and habitat alteration have a contributing effect. Increased breeding dispersal distances should be of concern for conservation efforts and considered in population monitoring because changing dispersal behavior may lead to higher rates of mortality and/or emigration from historical study areas.


Oryx ◽  
2019 ◽  
pp. 1-10 ◽  
Author(s):  
Maria Therese Bager Olsen ◽  
Jonas Geldmann ◽  
Mike Harfoot ◽  
Derek P. Tittensor ◽  
Becky Price ◽  
...  

AbstractThe USA is the largest consumer of legally, internationally-traded wildlife. A proportion of this trade consists of species listed in the Appendices of CITES, and recorded in the CITES Trade Database. Using this resource, we quantified wildlife entering the USA for 82 of the most frequently recorded wildlife products and a range of taxonomic groups during 1979–2014. We examined trends in legal trade and seizures of illegally traded items over time, and relationships between trade and four national measures of biodiversity. We found that: (1) there is an overall positive relationship between legal imports and seizures; (2) Asia was the main region exporting CITES-listed wildlife products to the USA; (3) bears, crocodilians and other mammals (i.e. other than Ursidae, Felidae, Cetacea, Proboscidea, Primates or Rhinocerotidae) increased in both reported legal trade and seizures over time; (4) legal trade in live specimens was reported to be primarily from captive-produced, artificially-propagated or ranched sources, whereas traded meat was primarily wild sourced; (5) both seizures and legally traded items of felids and elephants decreased over time; and (6) volumes of both legally traded and seized species were correlated with four attributes of exporting countries: species endemism, species richness, number of IUCN threatened species, and country size. The goal of our analysis was to inform CITES decision-making and species conservation efforts.


2021 ◽  
Vol 21 (2) ◽  
pp. 71-84
Author(s):  
Wanessa Scopel ◽  
Victor Wilson Botteon ◽  
Mayara Ribeiro de Araújo ◽  
Eduardo Luiz Scopel ◽  
Margarida Flores Roza-Gomes ◽  
...  

To meet the growing demand for electricity, considerable effort has been invested in the construction of hydroelectric stations in Brazil. The environmental impacts caused by these projects have been significant, especially on fauna. To evaluate the biodiversity of edaphic invertebrates, a study was performed in an area surrounding a small hydroelectric station of Flor do Sertão, in the Santa Catarina state, Brazil, covering three distances (5, 15 and 30 meters) from the flooded region of the reservoir. From December 2010 to June 2011, surveys of edaphic invertebrates were performed by pitfall traps. The invertebrates collected at each distance were compared and their diversity was calculated through Hill numbers. The dynamics were analyzed through the Shannon index exponential and the inverse Simpson index, and correlated climatic variables to invertebrate diversity. A total of 14,074 specimens were collected from 24 taxonomic groups (Order). The analyses according to size and sample coverage showed few differences in invertebrate diversity between the distances. Values of richness and diversity of common groups are similar for all distances. There is a trend decrease in diversity dynamics for common individuals, with a strong decline in June. The diversity of edaphic invertebrates exhibited high correlation with temperature and no correlation with pluviosity.


2006 ◽  
Vol 17 (3) ◽  
Author(s):  
Matti Koivula ◽  
Tyler Cobb ◽  
Andrea Déchêne ◽  
Joshua Jacobs ◽  
John Spence

Forest fires are among the most important natural disturbances in the boreal region, but fire-initiated succession is increasingly often interrupted by salvage logging, i.e., post-fire removal of burned trees. Unfortunately, very little is known about the ecological effects of this practice. To address this knowledge gap and to examine other factors affecting the abundance of two fire-associated carabid species (Sericoda quadripuntata and S. bembidioides) we conducted three field studies based on pitfall trapping in recent burns in Alberta, Canada. The results suggest that the abundance of both species drastically decreased from the first to the third post-fire year and that fire severity was positively associated with abundance of both species. The combined effects of wildfire and forest harvesting were associated with higher catches of S. quadripunctata, but lower catches of S. bembidioides. We discuss these findings in the contexts of salvage logging and species ecology.


2016 ◽  
Vol 25 (6) ◽  
pp. 646 ◽  
Author(s):  
John L. Campbell ◽  
Daniel C. Donato ◽  
Joseph B. Fontaine

Removal of fire-killed trees (i.e. post-fire or salvage logging) is often conducted in part to reduce woody fuel loads and mitigate potential reburn effects. Studies of post-salvage fuel dynamics have primarily used chronosequence or modelling approaches, with associated limitations; longitudinal studies tracking fuels over time have been rare. We resampled a network of post-fire plots, comprising a range of logging intensities, 10 years after the 2002 Biscuit Fire (Oregon, USA). For surface woody fuels, which started from large treatment differences immediately following logging (stepwise increases with harvest intensity), we found converging trends among treatments at 10 years, with convergence nearly complete for fine fuels but not for coarse fuels. Fire-killed snags for the dominant species (Pseudotsuga menziesii) decayed while standing at a statistically significant rate (single-exponential k = 0.011), similar to or only slightly slower than down wood, suggesting that not all snag biomass will reach the forest floor. Live vegetation (largely resprouting sclerophyllous vegetation) is beginning to dominate surface fuel mass and continuity (>100% cover) and likely moderates differences associated with woody fuels. Post-fire logging had little effect on live fuels or their change over time, suggesting high potential for stand-replacing early-seral fire regardless of post-fire harvest treatments.


2004 ◽  
Vol 64 (3b) ◽  
pp. 707-718 ◽  
Author(s):  
G. M. Souza ◽  
R. V. Ribeiro ◽  
M. G. Santos ◽  
H. L. Ribeiro ◽  
R. F. Oliveira

This study tested the hypothesis that dissipative efficiency of tropical tree species could be an ecological advantage in the forest succession process. Daily leaf gas exchanges of a pioneer species (Guazuma ulmifolia) and a late successional species (Cariniana legalis) were evaluated under well-irrigated conditions and by withholding irrigation. Analyses of network connectance (Cg) and plant autonomy (At) were carried out in order to assess metabolic network changes in response to environmental perturbation. As a global estimation of latent heat dissipation, the capacity to both maintain and cool leaf temperature in response to air temperature changes (deltaT = TºCair - TºCleaf) was evaluated. The changes observed in both the systemic parameters (Cg and At) and the physiological ones brought about by water deficit, associated with discrepant growth rates between both species, suggested that the initial formation of gap canopies composed by pioneer species could simply be a result of the higher photosynthetic rates of these species, and not necessarily because late successional species cannot cope with such a heterogeneous environment as that of a gap. Our results indicate that, in the absence of water constraints, the highest CO2 assimilation rates of pioneer species are supported by the efficiency of the whole dissipative structure, involving both degradation and dissipative processes. As a practical result, our study suggests the deltaT analysis in order to evaluate the efficiency of dissipative structures and as a aid in characterizing functional groups.


2016 ◽  
Vol 21 (2) ◽  
pp. 399-412
Author(s):  
Diana Marcela Rueda-Ramírez ◽  
Amanda Varela

<p>Se determinaron los cambios en composición, densidad y distribución espacial de la edafofauna de hojarasca entre dos usos de suelo (cafetal y bosque subandino) para entender el efecto del uso de suelo. Asimismo, se establecieron las relaciones entre las variables de la edafofauna y atributos de la hojarasca. Se colectaron muestras de hojarasca superficial durante la época seca y se extrajo la edafofauna, manualmente y mediante embudos Berlese modificados. Esta se identificó hasta el menor nivel taxonómico posible y se clasificó en grupos funcionales<span>. La composición faunística fue diferente entre los usos de suelo. La similitud en la composición fue menor al 50 % en dos de los tres grupos funcionales encontrados, pero la densidad total no presentó diferencias. En general hubo coeficientes de variación altos en la densidad faunística intermuestral para los diferentes grupos taxonómicos y, en consecuencia, una baja detectabilidad del patrón espacial. Sin embargo, se detectó un patrón espacial en la abundancia para Coleoptera, larvas de Diptera y biomasa de hojarasca, en el cafetal. La estructura fue más difícil de detectar en bosque, por los pequeños parches en este. La varianza de la abundancia fue mayor en el cafetal, para todos los grupos, excepto Acaridida y Formicidae. La densidad de Formicidae aumentó al hacerlo la humedad de la hojarasca, pero solo en cafetal. Se concluye que el establecimiento del cafetal afecta de manera diferencial a taxones y grupos funcionales de la edafofauna. Esto sienta las bases para definir los efectos del cambio de uso de suelo y los factores ambientales asociados con la distribución espacial de la edafofauna.</span></p><p><strong>Spatial Distribution, Composition and Density of the Leaflitter Edaphofauna in Forest and Coffee Plantation (Montenegro,Colombia)</strong></p><p>Changes in composition, density and spatial distribution on the litter edaphic fauna between two land uses (a coffee plantation and a tropical Andean forest) were established, in order to understand the soil use effects. Also, the relationships between the biotic variables and some litter features were evaluated. Superficial litter samples were collected during dry season. The edaphic fauna was extracted manually and with modified Berlese funnels; it was identified up to the lower taxonomic level and classified in functional groups. Differences in fauna composition were observed between the two land uses. Composition similarity was lower than 50 % for almost all functional groups found, but total density did not differ between the land uses. In general, there was a high variation in density among samples resulting in higher coefficients of variation for different taxonomic groups and consequently low detectability of spatial pattern. However a spatial pattern was detected only for Coleoptera, Diptera larvae and litter biomass in the coffee plantation. The structure in forest was more difficult to detect, due to the smaller patches on it. The variance of abundance was significantly higher in the coffee plantation for all groups, except Acaridida and Formicidae. Density of Formicidae increased with the enhancement of litter moisture, but only in the coffee plantation. In conclusion, the establishment of coffee plantation differentially affects taxa and functional groups of soil fauna. This is the basis for establishing the effects of soil change use, and the environmental factors associated with spatial distribution of edaphic fauna.</p>


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