Long-term performance and herbivory of tree seedlings planted into primary and secondary forests of Central Amazonia

2013 ◽  
Vol 29 (4) ◽  
pp. 301-311 ◽  
Author(s):  
Julieta Benítez-Malvido ◽  
Miguel Martínez-Ramos

Abstract:Plant survival and growth in tropical rain forest are affected by different biotic and abiotic forces. As time elapses and plants grow the relative importance of such forces as regeneration inhibitors and/or facilitators may change according to habitat and species. To detect within- and among-species divergences in performance over time in different habitats we followed, for nearly a decade, the survival, growth and herbivory of seedlings of the native tree species: Chrysophyllum pomiferum, Micropholis venulosa and Pouteria caimito. In Central Amazonia, young seedlings were planted into old-growth and secondary forests dominated by Vismia spp. One year after planting, C. pomiferum ranked first (i.e. fast growth, fewer dead and less herbivory) for both habitats, followed by M. venulosa and P. caimito. Initial trends changed over time. In the long term, M. venulosa ranked first for both habitats, followed by C. pomiferum and P. caimito ranked consistently lowest. Within-species divergences in growth and herbivory were greater in secondary forest. Initial seedling responses cannot always be used to predict species persistence in the long term. Contrary to previous estimations, old-growth-forest species can persist under Vismia spp. stands, at least when planted.

2021 ◽  
Author(s):  
Charlotte Smith ◽  
John Healey ◽  
Erika Berenguer ◽  
Paul Young ◽  
Ben Taylor ◽  
...  

There is growing recognition of the potential of large-scale restoration in the Amazon as a “nature-based solution” to climate change. However, our knowledge of forest loss and recovery beyond Brazil is limited, and carbon emissions and accumulation have not been estimated for the whole biome. Combining a 33-year land cover dataset with estimates of above-ground biomass and carbon sequestration rates, we evaluate forest loss and recovery across nine Amazonian countries and at a local scale. We also estimate the role of secondary forests in offsetting old-growth deforestation emissions and explore the temporal trends in forest loss and recovery. We find secondary forests across the biome to have offset just 9.7% of carbon emissions from old-growth deforestation, despite occupying 27.6% of deforested land. However, these numbers varied between countries ranging from 9.0% in Brazil to 23.8% in Guyana for carbon offsetting, and 24.8% in Brazil to 56.9% in Ecuador for forest area recovery. We reveal a strong, negative spatial relationship between old-growth forest loss and recovery by secondary forests, showing that regions with the greatest potential for large-scale restoration are also those that currently have the lowest recovery (e.g. Brazil dominates deforestation and emissions but has the lowest recovery). Our findings identify three important challenges for policy makers: (1) incentivising large-scale restoration in highly deforested regions, (2) protecting secondary forests without disadvantaging landowners who depend on farm-fallow systems, and (3) preventing further deforestation. Combatting all of these successfully is essential to ensuring that the Amazon biome achieves its potential in mitigating anthropogenic climate change.


1988 ◽  
Vol 127 ◽  
Author(s):  
M. G. Piepho ◽  
P. J. Turner ◽  
P. W. Reimus

ABSTRACTRadiolysis may significantly affect the long-term performance of nuclear waste packages in a geologic repository. Radiolysis of available moisture and air in an unsaturated or saturated environment will create transient species that can significantly change the pH and/or Eh of the available moisture. These changes can influence rates of containment corrosion, waste form dissolution, and radionuclide solubilities and transport.Many of the pertinent radiochemical reactions are not completely understood, and most of the associated rate constants are poorly characterized. To help identify the important radiochemical reactions, rate constants, species, and environmental conditions, an importance theory code, SWATS (Sensitivity With Adjoint Theory-Sparse version)-LOOPCHEM, has been developed for the radiolytic chemical kinetics model in the radiolysis code LOOPCHEM. The LOOPCHEM code calculates the concentrations of various species in a radiolytic field over time. The SWATS-LOOPCHEM code efficiently calculates: 1) the importance (relative to a defined response of interest) of each species concentration over time, 2) the sensitivity of each parameter of interest, and 3) the importance of each equation in the radiolysis model. The calculated results will be used to guide future experimental and modeling work for determining the importance of radiolysis on waste package performance. A demonstration (the importance of selected concentrations and the sensitivities of selected parameters) of the SWATS-LOOPCHEM code is provided for illustrative purposes, and no attempt is made at this time to interpret the results for waste package performance assessment purposes.


2021 ◽  
Author(s):  
Alejandro Gonzalez Ollauri ◽  
Slobodan Mickovski ◽  
Rohinton Emmanuel ◽  
Albert Sorolla Edo

<p>Live cribwalls are Nature-based solutions consisting of timber-based structures acting as retention walls at the toe of slopes and embankments subjected to instability and erosion events. The structure of live cribwalls resembles a multi-level crib made of timber logs from different plant species (e.g. pine, spruce, hazelnut, etc.). The crib structure is then backfilled with earth materials in which locally-available plant cuttings and/or saplings are inserted to establish a dense cover of native vegetation, providing added reinforcement and stability to the cribwall over time; particularly after the complete decay of the timber structure is reached. However, the effect of vegetation on the reinforcement of live cribwalls has not been examined systematically. Information on how vegetation can contribute to reinforce cribwalls hydrologically and mechanically is essential to evaluate the long-term performance of these Nature-based solutions against hydro-meteorological hazards. In this study, we propose a novel conceptual, numerical model based on empirical knowledge to evaluate the reinforcement effect of vegetation on live cribwalls over time. We also demonstrate how the proposed model can be applied to other Nature-based solutions concerned with slope protection and erosion control, such as live gratings or palisades.</p>


Author(s):  
Minesh K. Patel ◽  
Georgios P. Balomenos

<p>The <span>long-term performance and safety of bridges is of paramount importance. Researchers have placed significant focus on the degradation and deterioration of bridge materials such as steel and concrete, but significantly less is known about the long-term behavior of bridge bearings. Uncertainty in the bearing behavior over time leads to challenges about when the bearings should be inspected and potentially replaced. However, bearing demands vary greatly based on the design of the bridge (e.g. differences in bridge material, girder type, span, height, and location). This paper finds trends in lifetime bearing demands from seismic, thermal, and traffic loading when the bridge design and location parameters are considered. These results can be used to identify which of the parameters have the greatest influence on the lifetime bearing demands which can then be used, in turn, to evaluate bearing long-term performance.</span></p>


1987 ◽  
Vol 17 (7) ◽  
pp. 697-704 ◽  
Author(s):  
James K. Agee ◽  
Mark H. Huff

Fuel succession was quantified for a 515-year chronosequence in a Tsugaheterophylla/Pseudotsugamenziesii forest. Postfire stand ages selected were 1, 3, 19, 110, 181, and 515. After initial reductions due to mortality from fire in the first 3 years, live aboveground biomass in the tree component increased over time to over 1100 t/ha. Shrub and herb layer biomass was highest in year 19 and year 515. Dead aboveground biomass had different trends for different fuel size classes; normalized fuel loadings of five dead and down fuel categories peaked at four different stand ages: 1-h and 10-h timelag (TL) fuels, age 1; 100-h TL fuels, age 19; 1000-h TL fuels, age 110; >1000-h TL fuels, age 515. Surface fire behavior was highest early in the sere and lowest at ages 110–181. Old-growth forest patches appear to be best buffered against forest fire by mature forest patches rather than old growth or recently burned natural stands.


2017 ◽  
Vol 399 ◽  
pp. 197-205 ◽  
Author(s):  
Peter Jaloviar ◽  
Milan Saniga ◽  
Stanislav Kucbel ◽  
Ján Pittner ◽  
Jaroslav Vencurik ◽  
...  

2020 ◽  
Vol 7 (2) ◽  
pp. 191-206
Author(s):  
Arthi Shankar Kozhumam ◽  
Riti Chandrashekhar ◽  
Ananya Rattani ◽  
Sumedha Gupta Ariely

This study describes evidence for multiple attachments by orphaned and separated children (OSC) to caregivers and explores predictive relationships between attachment and family social relationships. A sample of forty-three longitudinal children residing in residential care between 15 and 144 months at the time of assessment and forty-two newer-to-care children (entering one to thirteen months before testing) was interviewed in summer 2019. Caregiver attachment was measured using the IPPA Guardian scale, and family social relations were measured using the PROMIS Pediatric Family Relationships scale. Longitudinal children displayed similar attachment scores across a one-year time span regardless of whether they nominated the same or different favourite caretaker. Results are discussed in the context of evidence for multiple attachments and the way attachment can predict social relations for new but not longitudinal children. This paper supports that OSCs form multiple attachments to caregivers over time, with attachment starting and remaining relatively strong in the long-term.


2005 ◽  
Vol 21 (4) ◽  
pp. 397-406 ◽  
Author(s):  
Julieta Benítez-Malvido ◽  
Miguel Martínez-Ramos ◽  
José Luis C. Camargo ◽  
Isolde D. K. Ferraz

In the Central Amazon we investigated whether seedling performance (survival, and relative growth rates in height and leaf numbers) was affected by initial seedling size (height and leaf numbers) in habitats that varied in their degree of human disturbance: cattle pasture, young secondary forest, 1-ha forest fragment and old-growth forest. Additionally, effects of photosynthetically active radiation (PAR), litter standing crop (LSC) and insect herbivory were evaluated 12 mo after transplantation in seedlings from the native canopy trees Chrysophyllum pomiferum, Micropholis venulosa and Pouteria caimito. Seedling performance changed rank across the understorey environment depending on species. Seedlings of Chrysophyllum thrived in all conditions but under high PAR, Micropholis thrived only in intermediate light conditions, whereas Pouteria thrived under high PAR. Effects of initial seedling size, PAR and herbivory after 1 y were specific to species, whereas LSC had no effect on performance. Initially larger seedlings resulted in lower survival for Chrysophyllum and Pouteria. Herbivory affected seedling performance in all species. Negative effects of herbivory were intensified under low PAR. Overall, our results showed that, as seedlings, species of the same family and characteristic of old-growth forests respond differently to the environmental constraints present in contrasting human-disturbed conditions. Larger seedlings may not always present greater tolerance to physical and biotic mortality risks.


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