scholarly journals Trade-off between allocation to reproductive ramets and rhizome buds in Carex brevicuspis populations along a small-scale elevational gradient

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Xin-sheng Chen ◽  
Ya-fang Li ◽  
Yong-hong Xie ◽  
Zheng-miao Deng ◽  
Xu Li ◽  
...  
Keyword(s):  
Elevational Gradient ◽  
Small Scale ◽  
Trade Off ◽  
Rhizome Buds

scholarly journals Do forest over- and understory respond to the same environmental variables when viewed at the taxonomic and trait level?

2021 ◽  
Author(s):  
Kenny Helsen ◽  
Yeng-Chen Shen ◽  
Tsung-Yi Lin ◽  
Chien-Fan Chen ◽  
Chu-Mei Huang ◽  
...  
Keyword(s):  
Functional Diversity ◽  
Environmental Filtering ◽  
Soil Nutrient ◽  
Woody Species ◽  
Elevational Gradient ◽  
Functional Trait ◽  
Environmental Drivers ◽  
Small Scale ◽  
Diversity Patterns ◽  
Soil Variation

While the relative importance of climate filtering is known to be higher for woody species assemblages than herbaceous assemblage, it remains largely unexplored whether this pattern is also reflected between the woody overstory and herbaceous understory of forests. While climatic variation will be more buffered by the tree layer, the understory might also respond more to small-scale soil variation, next to experiencing additional environmental filtering due to the overstory's effects on light and litter quality. For (sub)tropical forests, the understory often contains a high proportion of fern and lycophyte species, for which environmental filtering is even less well understood. We explored the proportional importance of climate proxies and soil variation on the species, functional trait and (functional) diversity patterns of both the forest overstory and fern and lycophyte understory along an elevational gradient from 850 to 2100 m a.s.l. in northern Taiwan. We selected nine functional traits expected to respond to soil nutrient or climatic stress for this study and furthermore verified whether they were positively related across vegetation layers, as expected when driven by similar environmental drivers. We found that climate was a proportionally more important predictor than soil for the species composition of both vegetation layers and trait composition of the understory. The stronger than expected proportional effect of climate for the understory was likely due to fern and lycophytes' higher vulnerability to drought, while the high importance of soil for the overstory seemed driven by deciduous species. The environmental drivers affected different response traits in both vegetation layers, however, which together with additional overstory effects on understory traits, resulted in a strong disconnection of community-level trait values across layers. Interestingly, species and functional diversity patterns could be almost exclusively explained by climate effects for both vegetational layers, with the exception of understory species richness. This study illustrates that environmental filtering can differentially affect species, trait and diversity patterns and can be highly divergent for forest overstory and understory vegetation, and should consequently not be extrapolated across vegetation layers or between composition and diversity patterns.

Belowground bud banks of four dominant macrophytes along a small-scale elevational gradient in Dongting Lake wetlands, China

2015 ◽  
Vol 122 ◽  
pp. 9-14 ◽  
Author(s):  
Xin-sheng Chen ◽  
Zheng-miao Deng ◽  
Yong-hong Xie ◽  
Feng Li ◽  
Zhi-yong Hou ◽  
...  
Keyword(s):  
Elevational Gradient ◽  
Dongting Lake ◽  
Small Scale ◽  
Bud Banks ◽  
Lake Wetlands

scholarly journals Life-history of the South American darter, Characidium pterostictum (Crenuchidae): evidence for small scale spatial variation in a piedmont stream

2008 ◽  
Vol 6 (4) ◽  
pp. 591-598 ◽  
Author(s):  
Fernando Gertum Becker ◽  
Silene de Carvalho ◽  
Sandra Maria Hartz
Keyword(s):  
Life History ◽  
Spatial Variation ◽  
Life History Theory ◽  
Spatial Scales ◽  
Gonadosomatic Index ◽  
Sampling Site ◽  
Small Scale ◽  
Upstream Site ◽  
Trade Off ◽  
Disturbed Site

The present study compares the reproduction, condition and size of the small characiform fish, Characidium pterostictum, sampled at close sites differing in severity of flash flood effects. Data were obtained from seasonal samples in two sites situated 8 km apart in the same stream. In the upstream site, habitat is more severely affected by flash floods than in the downstream site, and this difference was hypothesized to produce differences in life history and individual reproduction trade-off patterns, as predicted by life-history theory. The results provided evidence for small-scale spatial variation in life-history and trade-off patterns within the studied population. At the most severely disturbed site, C. pterostictum displayed a trade-off pattern that favored reproductive life-span (e.g., larger size, higher and seasonally stable condition, larger mean size of mature females) over instantaneous reproductive output (lower gonadosomatic index), while the opposite pattern was observed in the less disturbed site. Because of the differences in disturbance effects between each sampling site, these results suggest that within-stream variability in the severity of hydrological disturbance can influence life-history patterns at small spatial scales. An implication of the results is that fish occupying areas that are hydrologically more variable within a stream are not necessarily at an energetic or reproductive disadvantage, but may be simply under environmental conditions that favor distinct patterns of energy allocation (or trade-offs) and population persistence, as predicted by life-history theory. Therefore, plasticity in life-history is expected to be common in stream fish populations that are widespread in a stream system with spatially variable or patchy habitat characteristics.

Adjoint tomography with full envelope for scattering and intrinsic attenuation - resolution and trade-off

2021 ◽  
Author(s):  
Tuo Zhang ◽  
Christoph Sens-Schönfelder
Keyword(s):  
Spatial Distribution ◽  
High Frequency ◽  
Small Scale ◽  
Model Parameters ◽  
Mathematical Framework ◽  
Forward Simulation ◽  
Trade Off ◽  
Intrinsic Attenuation ◽  
Scale Heterogeneity ◽  
Rigorous Framework

<p>A rigorous framework exists for deterministic imaging the subsurface seismic velocity structure. Full-waveform inversion (FWI) that combines the forward simulation of waveforms with an adjoint (backward) simulation of the data misfit provides the gradient of the model misfit with respect to the changes in the model parameters. This gradient is used for iterative improvements of the model to minimize the data misfit. To investigate the small scale heterogeneity of the medium below the resolution limits the waveform tomography the envelopes of high-frequency seismic waves have been used to derive a statistical description of the small scale structure. Such studies employed a variety of misfit measures or empirical parameters and various assumptions about the spatial sensitivity of the measurements to derive some information about the spatial distribution of the high-frequency attenuation and scattering properties. A rigorous framework for the inversion of seismogram envelopes for the spatial imaging of heterogeneity and attenuation has been missing so far. Here we present a mathematical framework for the full envelope inversion that is based on a forward simulation of seismogram envelopes and an adjoint (backward) simulation of the envelope misfit, in full analogy to FWI. </p><p>Different from FWI that works with the wave equation, our approach is based on the Radiative Transfer Equation. In this study, the forward problem is solved by modelling the 2-D multiple nonisotropic scattering in a random elastic medium with spatially variable heterogeneity and attenuation using the Monte-Carlo method. The fluctuation strength <em>ε</em> and intrinsic quality factors <em>Q<sub>P</sub><sup>-1</sup></em> and <em>Q<sub>S</sub><sup>-1</sup></em> in the random medium are used to describe the spatial variability of attenuation and scattering. The misfit function is defined as the differences between the full observed and modelled envelopes.</p><p>We derived the sensitivity kernels corresponding to this misfit function that is minimized during the iterative adjoint inversion with the L-BFGS method. We have applied this algorithm in some numerical tests in the acoustic approximation. We show that it is possible in a rigorous way to image the spatial distribution of small scale heterogeneity and attenuation separately using seismogram envelopes. The resolution and the trade-off between scattering and intrinsic attenuation are discussed. Our analysis shows that relative importance of scattering and attenuation anomalies need to be considered when the model resolution is assessed. The inversions confirm, that the early coda is important for imaging the distribution of heterogeneity while later coda waves are more sensitive to intrinsic attenuation.</p>

Economics and livelihoods of small-scale inland fisheries in the Lower Mekong Basin: a survey of three communities in Cambodia

Water Policy ◽  
2009 ◽  
Vol 11 (S1) ◽  
pp. 31-51 ◽  
Author(s):  
Hap Navy ◽  
Madhusudan Bhattarai
Keyword(s):  
Water Allocation ◽  
Small Scale ◽  
Trade Off ◽  
Net Profit ◽  
Lower Mekong Basin ◽  
The Cost ◽  
High Degree ◽  
Related Trade ◽  
Socio Economic Factors

This paper presents economic analysis, viability and trade-off issues for small-scale (family) inland capture fisheries in three fishing communities, each representing a distinct floodplain characteristic in Cambodia. The average net profits of family fishing was US$12 and US$4.6 per trip during the open (October to May) and close (June to September) seasons, respectively; but real profit—deducting the cost for family labour from net profit—was only US$4.5 and US$1.6 during the open and close seasons, respectively. The return from family fishing varied greatly across sites surveyed, depending on the quality of the fishing grounds, hydro-ecology settings, local institutions, and socio-economic factors. The high degree of seasonality, the spatial variation of returns and costs of capture fisheries suggest interdependence of fishing activities with basin-level water allocation policies, and also related trade-off in the fisheries sector with water allocation and water resources management policies. There is also now an urgent need for synergy of the various rural development efforts with that of fisheries policies in the Mekong River Basin.

scholarly journals On Trade-offs and Communal Breeding The Behavioural Ecology of Agta Foragers

2021 ◽  
Author(s):  
Abigail Emma Page
Keyword(s):  
Life History Strategies ◽  
Energy Budgets ◽  
Small Scale ◽  
Network Centrality ◽  
Communal Breeding ◽  
Household Energy ◽  
Trade Off ◽  
Adaptive Value ◽  
Trade Offs ◽  
Fitness Consequences

Time is finite and no organism can avoid the allocation dilemma that this necessarily entails. A quintessential trade-off is that between parental investment and reproduction, otherwise known as the quality-quantity trade-off. However, humans may be exceptional among apes given our high quantity production of high quality offspring. This success has been argued only to be possible by breeding communally. In this thesis I explore questions surrounding trade-offs, communal breeding and their fitness consequences in a small-scale foraging society, the Agta. The first analysis examines the composition of Agta childcare using an innovative form of data collection to maximise sample sizes, previously a major limitation in hunter-gatherer research. The Agta, like many small-scale societies are prolific communal breeders. However, contra previous conclusions, juveniles and non-kin appeared to provide more allocare than grandmothers. Interactions with non-kin were associated with significant decreases in maternal workload, while interactions with siblings and grandmothers were not. The next analysis explores why both kin and non-kin behave cooperatively, finding support for kin selection among close kin and reciprocity for distant kin and non-kin allocare. Communal breeding appears to be an important mechanism to ensure enough childcare was received in the absence of other strategies to counter shortfalls in household energy budgets. The next analysis asks, what are the fitness consequences of maternal social networks and allocare? Mothers’ network centrality positively correlated with non-kin allocare as well as reproductive success, revealing the adaptive value of communal breeding. These results highlight the optimising nature of hunter-gatherer cooperation and life history strategies.

Sustainability of small-scale social-ecological systems in arid environments: trade-off and synergies of global and regional changes

2018 ◽  
Vol 14 (3) ◽  
pp. 791-807 ◽  
Author(s):  
Alicia Tenza ◽  
Julia Martínez-Fernández ◽  
Irene Pérez-Ibarra ◽  
Andrés Giménez
Keyword(s):  
Ecological Systems ◽  
Small Scale ◽  
Arid Environments ◽  
Trade Off ◽  
Social Ecological Systems ◽  
Social Ecological
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