scholarly journals Through enhanced tree dynamics carbon dioxide enrichment may cause tropical forests to lose carbon

2004 ◽  
Vol 359 (1443) ◽  
pp. 493-498 ◽  
Author(s):  
Christian Körner
Keyword(s):  
Tropical Forests ◽  
Forest Dynamics ◽  
Forest Inventories ◽  
C Storage ◽  
Theoretical Approaches ◽  
C Cycle ◽  
Net Uptake ◽  
And Storage ◽  
Biodiversity Effects

The fixation and storage of C by tropical forests, which contain close to half of the globe's biomass C, may be affected by elevated atmospheric CO 2 concentration. Classical theoretical approaches assume a uniform stimulation of photosynthesis and growth across taxa. Direct assessments of the C balance either by flux studies or by repeated forest inventories also suggest a current net uptake, although magnitudes sometimes exceed those missing required to balance the global C cycle. Reasons for such discrepancies may lie in the nature of forest dynamics and in differential responses of taxa or plant functional types. In this contribution I argue that CO 2 enrichment may cause forests to become more dynamic and that faster tree turnover may in fact convert a stimulatory effect of elevated CO 2 on photosynthesis and growth into a long–term net biomass C loss by favouring shorter–lived trees of lower wood density. At the least, this is a scenario that deserves inclusion into long–term projections of the C relations of tropical forests. Species and plant functional type specific responses (‘biodiversity effects’) and forest dynamics need to be accounted for in projections of future C storage and cycling in tropical forests.

The distribution of organic carbon in major components of forests located in five life zones of Venezuela

1997 ◽  
Vol 13 (5) ◽  
pp. 697-708 ◽  
Author(s):  
M. Delaney ◽  
S. Brown ◽  
A. E. Lugo ◽  
A. Torres-Lezama ◽  
N. Bello Quintero
Keyword(s):  
Tropical Forests ◽  
Aboveground Biomass ◽  
Dead Wood ◽  
Clear Trend ◽  
Soil C ◽  
Forest Inventories ◽  
Biomass Components ◽  
Life Zone ◽  
Data Gap

ABSTRACTOne of the major uncertainties concerning the role of tropical forests in the global carbon cycle is the lack of adequate data on the carbon content of all their components. The goal of this study was to contribute to filling this data gap by estimating the quantity of carbon in the biomass, soil and necromass for 23 long-term permanent forest plots in five life zones of Venezuela to determine how C was partitioned among these components across a range of environments. Aboveground biomass C ranged from 70 to 179 Mg ha−1 and soil C from 125 to 257 Mg ha−1, and they represented the two largest C components in all plots. The C in fine litter (2.4 to 5.2 Mg ha−1), dead wood (2.4 to 21.2 Mg ha−1) and roots (23.6 to 38.0 Mg ha−1) accounted for less than 13% of the total C. The total amount of C among life zones ranged from 302 to 488 Mg ha−1, and showed no clear trend with life zone. In three of the five life zones, more C was found in the dead (soil, litter, dead wood) than in the live (biomass) components (dead to live ratios of 1.3 to 2.3); the lowland moist and moist transition to dry life zones had dead to live ratios of less than one. Results from this research suggest that for most life zones, an amount equivalent to between 20 and 58% of the aboveground biomass is located in necromass and roots. These percentages coupled with reliable estimates of aboveground biomass from forest inventories enable a more complete estimation of the C content of tropical forests to be made.

scholarly journals Direct estimates of downslope deadwood movement over 30 years in a temperature forest illustrate impacts of treefall on forest ecosystem dynamics

2016 ◽  
Vol 46 (3) ◽  
pp. 351-361 ◽  
Author(s):  
Brad Oberle ◽  
Amy M. Milo ◽  
Jonathan A. Myers ◽  
Maranda L. Walton ◽  
Darcy F. Young ◽  
...  
Keyword(s):  
Forest Dynamics ◽  
Forest Ecosystems ◽  
Ecosystem Dynamics ◽  
Small Scale ◽  
Forest Inventories ◽  
Lower Elevation ◽  
Large Trees ◽  
Forest Dynamics Plot ◽  
Import And Export

Deadwood plays important roles in forest ecosystems by storing carbon, influencing hydrology, and provisioning countless organisms. Models for these processes often assume that deadwood does not move and ignore redistribution that occurs when trees fall. To evaluate the effects of treefall, we provide the first direct estimates for the magnitude, direction, and drivers of deadwood movement in a long-term oak–hickory forest dynamics plot in Missouri, USA. Among 1871 total pieces of deadwood, logs today pointed downslope more often than branches and occurred at lower elevation than snags. Of these, 477 logs retained tags from which we reconstructed movement using new formulae for reconciling survey coordinates and calculating log shape. Relocated logs occurred at lower elevation than their original rooting location, with the magnitude of the drop dependent on log size, degree of decay, and slope. Although changes in elevation were modest, the log centroids moved up to several meters horizontally. Consequently, as large trees fall, they predictably redistribute deadwood downhill, suggesting that models of deadwood dynamics in small inventory plots may gain accuracy by incorporating import and export along with recruitment and decay. We highlight implications of small-scale deadwood movement for forest inventories, carbon dynamics, and biodiversity.

Soil carbon: A measure of ecosystem response in a changing world?

2005 ◽  
Vol 85 (Special Issue) ◽  
pp. 467-480 ◽  
Author(s):  
H. H. Janzen
Keyword(s):  
Agricultural Soils ◽  
Global Carbon Cycle ◽  
Ecosystem Response ◽  
Soil C ◽  
Four Dimensions ◽  
C Storage ◽  
C Dynamics ◽  
C Cycle ◽  
Global Carbon

The global carbon (C) cycle is changing, as evident from abrupt increases in atmospheric CO2. These changes have sparked interest in agricultural soils as potential repositories for excess atmospheric C. Our perspective on soil C, therefore, has shifted: once, we focused mainly on how soil C affected productivity within agroecosystems; now we see also how C dynamics in agricultural soils exert influences far beyond the farm. We have long used soil C as an indicator of soil quality; now we may want to use soil C also as a broader indicator of ecosystem response. To prompt further discussion, I offer some tentative thoughts about how we might use soil C as an indicator on a changing earth. They include: using soil C to measure changes across time, not only across space; devising more sensitive measures of soil C change; quantifying soil C across four dimensions; measuring the nature of C, as well as its amount; using soil C alongside other indicators; finding better ways of admitting our uncertainty; establishing long-term sites for our successors to measure soil C change; and following flows of C past the farm fences. Recent worries about global warming have focused our attention on “sequestering” soil C to remove atmospheric CO2. That aim may be worthy, but perhaps too narrow; a broader goal might be to ensure the productivity, permanence, and health of our agroecosystems and adjacent environments – and use C storage as a measure of progress toward that goal. Key words: Soil organic matter, global carbon cycle, carbon sequestration, global change

scholarly journals Long-term nitrogen addition decreases carbon leaching in nitrogen-rich forest ecosystems

2013 ◽  
Vol 10 (1) ◽  
pp. 1451-1481 ◽  
Author(s):  
X. Lu ◽  
F. S. Gilliam ◽  
G. Yu ◽  
L. Li ◽  
Q. Mao ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Critical Role ◽  
C Sequestration ◽  
Nitrogen Addition ◽  
N Deposition ◽  
N Addition ◽  
Soil C ◽  
Rooting Zone ◽  
C Cycle

Abstract. Dissolved organic carbon (DOC) plays a critical role in the carbon (C) cycle of forest soils, and has been recently connected with global increases in nitrogen (N) deposition. Most studies on effects of elevated N deposition on DOC have been carried out in N-limited temperate regions, with far fewer data available from N-rich ecosystems, especially in the context of chronically elevated N deposition. Furthermore, mechanisms for excess N-induced changes of DOC dynamics have been suggested to be different between the two kinds of ecosystems, because of the different ecosystem N status. The purpose of this study was to experimentally examine how long-term N addition affects DOC dynamics below the primary rooting zones (the upper 20 cm soils) in typically N-rich lowland tropical forests. We have a primary assumption that long-term continuous N addition minimally affects DOC concentrations and effluxes in N-rich tropical forests. Experimental N addition was administered at the following levels: 0, 50, 100 and 150 kg N ha−1 yr−1, respectively. Results showed that seven years of N addition significantly decreased DOC concentrations in soil solution, and chemo-physical controls (solution acidity change and soil sorption) rather than biological controls may mainly account for the decreases, in contrast to other forests. We further found that N addition greatly decreased annual DOC effluxes from the primary rooting zone and increased water-extractable DOC in soils. Our results suggest that long-term N deposition could increase soil C sequestration in the upper soils by decreasing DOC efflux from that layer in N-rich ecosystems, a novel mechanism for continued accumulation of soil C in old-growth forests.

scholarly journals Long-term nitrogen addition decreases carbon leaching in a nitrogen-rich forest ecosystem

2013 ◽  
Vol 10 (6) ◽  
pp. 3931-3941 ◽  
Author(s):  
X. Lu ◽  
F. S. Gilliam ◽  
G. Yu ◽  
L. Li ◽  
Q. Mao ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Critical Role ◽  
C Sequestration ◽  
Nitrogen Addition ◽  
N Deposition ◽  
N Addition ◽  
Soil C ◽  
Rooting Zone ◽  
C Cycle

Abstract. Dissolved organic carbon (DOC) plays a critical role in the carbon (C) cycle of forest soils, and has been recently connected with global increases in nitrogen (N) deposition. Most studies on effects of elevated N deposition on DOC have been carried out in N-limited temperate regions, with far fewer data available from N-rich ecosystems, especially in the context of chronically elevated N deposition. Furthermore, mechanisms for excess N-induced changes of DOC dynamics have been suggested to be different between the two kinds of ecosystems, because of the different ecosystem N status. The purpose of this study was to experimentally examine how long-term N addition affects DOC dynamics below the primary rooting zones (the upper 20 cm soils) in typically N-rich lowland tropical forests. We have a primary assumption that long-term continuous N addition minimally affects DOC concentrations and effluxes in N-rich tropical forests. Experimental N addition was administered at the following levels: 0, 50, 100 and 150 kg N ha−1 yr−1, respectively. Results showed that seven years of N addition significantly decreased DOC concentrations in soil solution, and chemo-physical controls (solution acidity change and soil sorption) rather than biological controls may mainly account for the decreases, in contrast to other forests. We further found that N addition greatly decreased annual DOC effluxes from the primary rooting zone and increased water-extractable DOC in soils. Our results suggest that long-term N deposition could increase soil C sequestration in the upper soils by decreasing DOC efflux from that layer in N-rich ecosystems, a novel mechanism for continued accumulation of soil C in old-growth forests.

scholarly journals Fire Impacts on Recruitment Dynamics in a Seasonal Tropical Forest in Continental Southeast Asia

Forests ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 116
Author(s):  
Kanokporn Kaewsong ◽  
Daniel J. Johnson ◽  
Sarayudh Bunyavejchewin ◽  
Patrick J. Baker
Keyword(s):  
Southeast Asia ◽  
Tropical Forests ◽  
Functional Traits ◽  
Tree Species ◽  
Forest Dynamics ◽  
Fire Intensity ◽  
Spatial And Temporal Variability ◽  
Tree Recruitment ◽  
In Fire

The effects of forest fires on tree recruitment dynamics in tropical forests is important for predicting forest dynamics and ecosystem function in Southeast Asia. To our knowledge, no studies have examined the effects of fire intensity on community-level recruitment patterns in tropical forests due to the rarity of long-term observation datasets in fire-impacted tropical forests and the difficulty of quantifying fire intensity. We addressed two questions: (1) is tree recruitment among species affected by fire intensity? and if so, (2) are there specific plant functional traits associated with these responses? We used data from a long-term forest dynamics plot at the Huai Kha Khaeng (HKK) Wildlife Sanctuary in Thailand. The HKK plot occurs in a strongly seasonal tropical environment and has experienced several fires since its establishment in 1994. We found 46 tree species (52% of the 89 species analysed) showed evidence of reduced recruitment rates with increasing fire intensities during the most recent fire in 2005. Tree species in this flammable landscape have various leaf and wood functional traits associated with fire. Spatial and temporal variability in fire activity may lead to alterations in long-term taxonomic and functional composition of the forest due to selection on fire-related traits.

MODERN PROBLEMATICS AND ANALYSIS OF EFFICIENCY OF APPLICATION OF DIFFERENT APPROACHES TO DESTRUCTION OF INFORMATION ON MAGNETIC MEDIA

2019 ◽  
Vol 2 (12) ◽  
pp. 154-164
Author(s):  
O. Semenenko ◽  
O. Vodchyts ◽  
V. Koverga ◽  
R. Lukash ◽  
O. Lutsenko
Keyword(s):  
Armed Forces ◽  
Information Storage ◽  
Storage Device ◽  
Magnetic Media ◽  
Long Term Storage ◽  
Physical Impact ◽  
And Storage ◽  
Term Storage

The introduction and active use of information transmission and storage systems in the Ministry of Defense (MoD) of Ukraine form the need to develop ways of guaranteed removal of data from media after their use or long-term storage. Such a task is an essential component of the functioning of any information security system. The article analyzes the problems of guaranteed destruction of information on magnetic media. An overview of approaches to the guaranteed destruction of information on magnetic media of different types is presented, and partial estimates of the effectiveness of their application are given by some generally accepted indicators of performance evaluation. The article also describes the classification of methods of destruction of information depending on the influence on its medium. The results of the analysis revealed the main problems of application of software methods and methods of demagnetization of the information carrier. The issue of guaranteed destruction of information from modern SSD devices, which are actively used in the formation of new systems of information accumulation and processing, became particularly relevant in the article. In today's conditions of development of the Armed Forces of Ukraine, methods of mechanical and thermal destruction are more commonly used today. In the medium term, the vector of the use of information elimination methods will change towards the methods of physical impact by the pulsed magnetic field and the software methods that allow to store the information storage device, but this today requires specialists to develop new ways of protecting information in order to avoid its leakage.

When Political Transitions Work

2018 ◽  
Author(s):  
Fanie du Toit
Keyword(s):  
South African ◽  
Well Being ◽  
Transition To Democracy ◽  
Political Transitions ◽  
Political Reconciliation ◽  
Peace Processes ◽  
Theoretical Approaches ◽  
African Experience ◽  
The One

Reconciliation emphasizes relationships as a crucial ingredient of political transition; this book argues for the importance of such a relational focus in crafting sustainable political transitions. Section I focuses on South Africa’s transition to democracy—how Mandela and De Klerk persuaded skeptical constituencies to commit to political reconciliation, how this proposal gained momentum, and how well the transition resulted in the goal of an inclusive and fair society. In developing a coherent theory of reconciliation to address questions such as these, I explain political reconciliation from three angles and thereby build a concept of reconciliation that corresponds largely with the South African experience. In Section II, these questions lead the discussion beyond South Africa into some of the prominent theoretical approaches to reconciliation in recent times. I develop typologies for three different reconciliation theories: forgiveness, agonism, and social restoration. I conclude in Section III that relationships created through political reconciliation, between leaders as well as between ordinary citizens, are illuminated when understood as an expression of a comprehensive “interdependence” that precedes any formal peace processes between enemies. I argue that linking reconciliation with the acknowledgment of interdependence emphasizes that there is no real alternative to reconciliation if the motivation is the long-term well-being of one’s own community. Without ensuring the conditions in which an enemy can flourish, one’s own community is unlikely to prosper sustainably. This theoretical approach locates the deepest motivation for reconciliation in choosing mutual well-being above the one-sided fight for exclusive survival at the other’s cost.

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