Terrestrial Ecosystem Dynamics in Senegal’s Agro-silvopastoral Center-East Region in the Second Half of the Twentieth Century

2015 ◽  
pp. 139-161
Author(s):  
Aliou Diouf ◽  
Matthew G. Hatvany
Keyword(s):  
Twentieth Century ◽  
Terrestrial Ecosystem ◽  
Ecosystem Dynamics ◽  
East Region

scholarly journals A new terrestrial biosphere model with coupled carbon, nitrogen, and phosphorus cycles (QUINCY v1.0; revision 1772)

2019 ◽  
Author(s):  
Tea Thum ◽  
Silvia Caldararu ◽  
Jan Engel ◽  
Melanie Kern ◽  
Marleen Pallandt ◽  
...  
Keyword(s):  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
Ecosystem Dynamics ◽  
Soil Conditions ◽  
Monitoring Networks ◽  
Nitrogen And Phosphorus ◽  
Element Cycling ◽  
Terrestrial Biosphere ◽  
Ecosystem Monitoring ◽  
Terrestrial Ecosystem Model

Abstract. The dynamics of terrestrial ecosystems are shaped by the coupled cycles of carbon, nitrogen and phosphorus, and strongly depend on the availability of water and energy. These interactions shape future terrestrial biosphere responses to global change. Many process-based models of the terrestrial biosphere have been gradually extended from considering carbon-water interactions to also including nitrogen, and later, phosphorus dynamics. This evolutionary model development has hindered full integration of these biogeochemical cycles and the feedbacks amongst them. Here we present a new terrestrial ecosystem model QUINCY (QUantifying Interactions between terrestrial Nutrient CYcles and the climate system), which is formulated around a consistent representation of element cycling in terrestrial ecosystems. This new model includes i) a representation of plant growth which separates source (e.g. photosynthesis) and sink (growth rate of individual tissues, constrained by nutrients, temperature, and water availability) processes; ii) the acclimation of many ecophysiological processes to meteorological conditions and/or nutrient availabilities; iii) an explicit representation of vertical soil processes to separate litter and soil organic matter dynamics; iv) a range of new diagnostics (leaf chlorophyll content; 13C, 14C, and 15N isotope tracers) to allow for a more in-depth model evaluation. We present the model structure and provide an assessment of its performance against a range of observations from global-scale ecosystem monitoring networks. We demonstrate that the framework is capable of consistently simulating ecosystem dynamics across a large gradient in climate and soil conditions, as well as across different plant functional types. To aid this understanding we provide an assessment of the model's sensitivity to its parameterisation and the associated uncertainty.

scholarly journals Structural diversity across arbuscular mycorrhizal, ectomycorrhizal, and endophytic plant—fungus networks

2018 ◽  
Author(s):  
Hirokazu Toju ◽  
Hirotoshi Sato ◽  
Satoshi Yamamoto ◽  
Akifumi S. Tanabe
Keyword(s):  
Network Architecture ◽  
High Throughput Sequencing ◽  
Latitudinal Gradient ◽  
Terrestrial Ecosystem ◽  
Arbuscular Mycorrhizal ◽  
Structural Diversity ◽  
Terrestrial Ecosystems ◽  
Ecosystem Dynamics ◽  
Plant Seed ◽  
Scale Properties

AbstractBackgroundBelow-ground linkage between plant and fungal communities is one of the major drivers of terrestrial ecosystem dynamics. However, we still have limited knowledge of how such plant–fungus associations vary in their community-scale properties depending on fungal functional groups and geographic locations.MethodsBased on high-throughput sequencing of root-associated fungi in eight forests along the Japanese Archipelago, we performed a comparative analysis of arbuscular mycorrhizal, ectomycorrhizal, and saprotrophic/endophytic associations across a latitudinal gradient from cool-temperate to subtropical regions.ResultsIn most of the plant–fungus networks analyzed, host–symbiont associations were significantly specialized but lacked “nested” architecture, which has been commonly reported in plant–pollinator and plant–seed disperser networks. Meanwhile, the structure of arbuscular mycorrhizal networks was differentiated from that of ectomycorrhizal and saprotrophic/endophytic networks, characterized by high connectance. Our data also suggested that geographic factors affected the organization of plant–fungus network structure. For example, the southernmost subtropical site analyzed in this study displayed lower network-level specificity of host–symbiont associations and higher (but still low) nestedness than northern localities.ConclusionsOur comparative analyses suggest that arbuscular mycorrhizal, ectomycorrhizal, and saprotrophic/endophytic plant–fungus associations often lack nested network architecture, while those associations can vary, to some extent, in their community-scale properties along a latitudinal gradient. Overall, this study provides a basis for future studies that will examine how different types of plant–fungus associations collectively structure terrestrial ecosystems.

scholarly journals The Western Arctic Linkage Experiment (WALE): Overview and Synthesis

2008 ◽  
Vol 12 (7) ◽  
pp. 1-13 ◽  
Author(s):  
A. D. McGuire ◽  
J. E. Walsh ◽  
J. S. Kimball ◽  
J. S. Clein ◽  
S. E. Euskirchen ◽  
...  
Keyword(s):  
Twentieth Century ◽  
Climate Model ◽  
Temporal Trends ◽  
Ecosystem Dynamics ◽  
Climate Data ◽  
Ecosystem Models ◽  
Vegetation Productivity ◽  
Regional Hydrology ◽  
Coupling Strategy ◽  
Western Arctic

Abstract The primary goal of the Western Arctic Linkage Experiment (WALE) was to better understand uncertainties of simulated hydrologic and ecosystem dynamics of the western Arctic in the context of 1) uncertainties in the data available to drive the models and 2) different approaches to simulating regional hydrology and ecosystem dynamics. Analyses of datasets on climate available for driving hydrologic and ecosystem models within the western Arctic during the late twentieth century indicate that there are substantial differences among the mean states of datasets for temperature, precipitation, vapor pressure, and radiation variables. Among the studies that examined temporal trends among the alternative climate datasets, there is not much consensus on trends among the datasets. In contrast, monthly and interannual variations of some variables showed some correlation across the datasets. The application of hydrology models driven by alternative climate drivers revealed that the simulation of regional hydrology was sensitive to precipitation and water vapor differences among the driving datasets and that accurate simulation of regional water balance is limited by biases in the forcing data. Satellite-based analyses for the region indicate that vegetation productivity of the region increased during the last two decades of the twentieth century because of earlier spring thaw, and the temporal variability of vegetation productivity simulated by different models from 1980 to 2000 was generally consistent with estimates based on the satellite record for applications driven with alternative climate datasets. However, the magnitude of the fluxes differed by as much as a factor of 2.5 among applications driven with different climate data, and spatial patterns of temporal trends in carbon dynamics were quite different among simulations. Finally, the study identified that the simulation of fire by ecosystem models is particularly sensitive to alternative climate datasets, with little or no fire simulated for some datasets. The results of WALE identify the importance of conducting retrospective analyses prior to coupling hydrology and ecosystem models with climate system models. For applications of hydrology and ecosystem models driven by projections of future climate, the authors recommend a coupling strategy in which future changes from climate model simulations are superimposed on the present mean climate of the most reliable datasets of historical climate.

scholarly journals Water Quality Status of Tono and Vea Reservoirs for Aquaculture Development in the Upper East Region of Ghana

2019 ◽  
pp. 1-14
Author(s):  
Etornyo Agbeko ◽  
Nelson W. Agbo ◽  
Thomas K. Agyemang ◽  
Daniel Adjei-Boateng
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Anthropogenic Activities ◽  
Ecosystem Dynamics ◽  
Total Hardness ◽  
Reservoir Water ◽  
East Region ◽  
Water Quality Variable ◽  
Upper East Region ◽  
Aquaculture Development

Understanding aquatic ecosystem dynamics is fundamental to sustainable development of aquaculture. This study explores the water quality characteristics over temporal and spatial scale in Tono and Vea Reservoirs in the Upper East Region of Ghana for aquaculture development. Water samples and in-situ measurements were taken for fifteen months, from February 2015 to March 2016. Monthly water quality monitoring were based on stratified sampling from upstream, midstream and downstream zones of these reservoirs. Standard analytical methods for examination of water were employed during sampling and laboratory analysis of reservoir water quality. Phytoplankton analysis was done using light microscopy to obtain phylum abundance. Multivariate statistical methods were used to investigate water quality dataset obtained. Cluster analysis grouped fifteen months of water quality changes into three seasonality regimes (periods) based on temporal variation. Principal component analysis (PCA) reduced eighteen water quality variables into five and three factors with total variance of 88.26 % and 79.30% for Tono and Vea reservoirs, respectively. With pH > 7 and alkalinity > 20 but < 100 mg L-1 CaCO3, both reservoirs have alkaline water. Dissolved oxygen was > 5 mg L-1. Three phyla of phytoplankton were identified with dominant (in abundance) phylum as Chlorophyta (72%) occurring in Tono reservoir. To understand the spatial relationship using correspondence analysis (CA), the first axis of CA explained 84.2% and 64.3% of total variation in relative abundance of phytoplankton phyla for Tono and Vea reservoirs, respectively. Thus, Cyanophyta showed strong positive association with conductivity, total hardness, nitrate, sulphate, turbidity, water depth and dissolved oxygen which were responsive to the midstream and upstream zones of Tono reservoir. Whiles in Vea reservoir, Chlorophyta under same water quality variable showed responsiveness to the midstream and downstream zones. Reservoir water quality studied were within acceptable limits for fish culture but changes could be linked to anthropogenic activities on reservoir catchment area and seasonality regime. Results from this provide a baseline to enable information to enable assessment of aquaculture impact in Tono and Vea reservoirs. The use of multivariate analysis could be a reliable statistical method for assessing water quality on a spatio-temporal scale.

Tree death as a crucial geomorphic agent in temperate forests: effects of weak and severe disturbances from local to continental scale

2020 ◽  
Author(s):  
Pavel Šamonil ◽  
Pavel Daněk ◽  
James A. Lutz ◽  
Jakub Jaroš ◽  
Anna Rousová ◽  
...  
Keyword(s):  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
Ecosystem Dynamics ◽  
Retention Capacity ◽  
Tree Species Composition ◽  
Continental Scale ◽  
Standing Trees ◽  
Forested Landscapes ◽  
Tree Uprooting ◽  
Hillslope Processes

&lt;p&gt;Hillslope processes in terrestrial ecosystems are significantly modified by changes in climate and land use. At the same time they strongly influence ecosystem retention capacity, pedocomplexity and biodiversity. This undoubtedly makes hillslope processes one of the crucial components of terrestrial ecosystem dynamics. In this study we focus on the long overlooked biogeomorphological impact of tree death in forested landscapes. Tree uprooting caused by strong storms affects soil and regolith formation and movement quite differently from the decomposition of intact root systems of standing trees that died due to e.g. fire or bark beetle infestation. We quantify the biogeomorphic processes associated with tree death in various terrestrial forest ecosystems and specifically assess (i) the significance of these processes in hillslope dynamics (e.g. slope denudation) of forested landscapes and (ii) the extent to which infrequent severe disturbances can shape these dynamics.&lt;/p&gt;&lt;p&gt;We used data from repeated tree censuses carried out in ten permanent forest plots (13&amp;#8211;74 ha in area) located in Central Europe and North America, differing in a range of characteristics such as tree species composition, climate and disturbance regime. In total, life history of more than 134,000 trees was recorded over periods of up to 47 years, during which about one third of these trees died. Using this information together with empirical models and allometric equations we were able to quantify the average areas and volumes of soil annually affected by dying trees. These quantities differed markedly between sites with different disturbance regimes. Tree uprooting-related volumes accounted annually for 0.01&amp;#8211;13.5 m&lt;sup&gt;3&lt;/sup&gt;ha&lt;sup&gt;&amp;#8722;1&lt;/sup&gt; reaching maximum values on sites with occurrence of infrequent strong windstorms (Zofin and Boubin primeval forests, Czech Republic). Volumes related to trees that died standing ranged anually between 0.17 and 20.7 m&lt;sup&gt;3&lt;/sup&gt;ha&lt;sup&gt;&amp;#8722;1&lt;/sup&gt; and were highest in the presence of stand-replacing fires (Yosemite National Park, U.S.). Comparison of these quantities with long-term erosion rates derived using cosmogenic nuclides (&lt;sup&gt;10&lt;/sup&gt;Be) suggests that on certain sites, over the last few millennia, tree uprooting can be the main driver of soil erosion.&lt;/p&gt;

scholarly journals Predicting ecosystem dynamics at regional scales: an evaluation of a terrestrial biosphere model for the forests of northeastern North America

2012 ◽  
Vol 367 (1586) ◽  
pp. 222-235 ◽  
Author(s):  
David Medvigy ◽  
Paul R. Moorcroft
Keyword(s):  
Large Scale ◽  
Regional Scale ◽  
Terrestrial Ecosystem ◽  
Ecosystem Dynamics ◽  
Terrestrial Biosphere ◽  
Ecosystem Responses ◽  
Decadal Scale ◽  
Biomass Dynamics ◽  
Constrained Model ◽  
Biosphere Model

Terrestrial biosphere models are important tools for diagnosing both the current state of the terrestrial carbon cycle and forecasting terrestrial ecosystem responses to global change. While there are a number of ongoing assessments of the short-term predictive capabilities of terrestrial biosphere models using flux-tower measurements, to date there have been relatively few assessments of their ability to predict longer term, decadal-scale biomass dynamics. Here, we present the results of a regional-scale evaluation of the Ecosystem Demography version 2 (ED2)-structured terrestrial biosphere model, evaluating the model's predictions against forest inventory measurements for the northeast USA and Quebec from 1985 to 1995. Simulations were conducted using a default parametrization, which used parameter values from the literature, and a constrained model parametrization, which had been developed by constraining the model's predictions against 2 years of measurements from a single site, Harvard Forest (42.5° N, 72.1° W). The analysis shows that the constrained model parametrization offered marked improvements over the default model formulation, capturing large-scale variation in patterns of biomass dynamics despite marked differences in climate forcing, land-use history and species-composition across the region. These results imply that data-constrained parametrizations of structured biosphere models such as ED2 can be successfully used for regional-scale ecosystem prediction and forecasting. We also assess the model's ability to capture sub-grid scale heterogeneity in the dynamics of biomass growth and mortality of different sizes and types of trees, and then discuss the implications of these analyses for further reducing the remaining biases in the model's predictions.

scholarly journals Role of Fire in the Global Land Water Budget during the Twentieth Century due to Changing Ecosystems

2017 ◽  
Vol 30 (6) ◽  
pp. 1893-1908 ◽  
Author(s):  
Fang Li ◽  
David M. Lawrence
Keyword(s):  
Twentieth Century ◽  
Water Budget ◽  
Boreal Forests ◽  
Precipitation Amount ◽  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
Vegetation Canopy ◽  
Vegetation Height ◽  
Global Land ◽  
Land Water

Fire is a global phenomenon and the primary form of terrestrial ecosystem disturbance on a global scale. It is tightly coupled with climate, ecosystems, carbon and water cycles, and human activities. Through biomass burning and fire-induced plant-tissue mortality, current and historical fires significantly affect terrestrial ecosystems, which can alter hydrology fluxes. This study provides the first quantitative assessment and understanding about the influence of fire on the global land water budget due to changing terrestrial ecosystems during the twentieth century. This is done by quantifying the difference between twentieth-century fire-on and fire-off simulations using the Community Earth System Model (CESM). Results show that fire significantly reduces the annual evapotranspiration (ET) over the global land by 0.6 × 103 km3 yr−1 and increases global total of runoff in almost the same quantity, while having almost no impact (0.0 × 103 km3 yr−1) on annual precipitation amount. Fire also weakens both the significant upward trend in total ET over global land prior to the 1950s and the downward trend from 1950 to about 1985 by approximately 35%. For the twentieth-century average, fire impact on ET and runoff is most clearly seen in the tropical savannas, African rain forests, and some boreal forests and southern Asian forests. Fire affects global ET and runoff through reducing vegetation canopy and vegetation height, which interact with fire-induced changes in biogeochemical cycle and result in drier and warmer surface air and higher wind speed. Globally speaking, reducing the vegetation canopy is the main pathway of fire’s impact on ET and runoff.

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