scholarly journals Geomorphic transience moderates topographic controls on tropical canopy foliar traits

2020 ◽  
Vol 23 (8) ◽  
pp. 1276-1286 ◽  
Author(s):  
K. Dana Chadwick ◽  
Gregory P. Asner
Keyword(s):  
Topographic Controls ◽  
Foliar Traits

WHITE SPRUCE AND THE SPRUCE BUDWORM: DEFINING THE PHENOLOGICAL WINDOW OF SUSCEPTIBILITY

1997 ◽  
Vol 129 (2) ◽  
pp. 291-318 ◽  
Author(s):  
Robert K. Lawrence ◽  
William J. Mattson ◽  
Robert A. Haack
Keyword(s):  
Picea Glauca ◽  
High Performance ◽  
Choristoneura Fumiferana ◽  
Spruce Budworm ◽  
White Spruce ◽  
Shoot Elongation ◽  
Larval Survival ◽  
Strongly Correlated ◽  
Negative Effect ◽  
Foliar Traits

AbstractSynchrony of insect and host tree phenologies has often been suggested as an important factor influencing the susceptibility of white spruce, Picea glauca (Moench) Voss, and other hosts to the spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae). We evaluated this hypothesis by caging several cohorts of spruce budworm larvae on three white spruce populations at different phenological stages of the host trees, and then comparing budworm performance with host phenology and variation of 13 foliar traits. The beginning of the phenological window of susceptibility in white spruce occurs several weeks prior to budbreak, and the end of the window is sharply defined by the end of shoot growth. Performance was high for the earliest budworm cohorts that we tested. These larvae began feeding 3–4 weeks prior to budbreak and completed their larval development prior to the end of shoot elongation. Optimal synchrony occurred when emergence preceded budbreak by about 2 weeks. Larval survival was greater than 60% for individuals starting development 1–3 weeks prior to budbreak, but decreased to less than 10% for those starting development 2 or more weeks after budbreak and thus completing development after shoot elongation ceased. High performance by the budworm was most strongly correlated with high levels of foliar nitrogen, phosphorous, potassium, copper, sugars, and water and low levels of foliar calcium, phenolics, and toughness. These results suggest that advancing the usual phenological window of white spruce (i.e. advancing budbreak prior to larval emergence) or retarding budworm phenology can have a large negative effect on the spruce budworm’s population dynamics.

scholarly journals Linking Foliar Traits to Belowground Processes

2020 ◽  
pp. 173-197
Author(s):  
Michael Madritch ◽  
Jeannine Cavender-Bares ◽  
Sarah E. Hobbie ◽  
Philip A. Townsend
Keyword(s):  
Remote Sensing ◽  
Plant Traits ◽  
Spatial Scales ◽  
Root Turnover ◽  
Litter Chemistry ◽  
Plant Chemistry ◽  
Fine Root Turnover ◽  
Belowground Processes ◽  
Remote Sensing Techniques ◽  
Foliar Traits

AbstractAbove- and belowground systems are linked via plant chemistry. In forested systems, leaf litter chemistry and quality mirror that of green foliage and have important afterlife effects. In systems where belowground inputs dominate, such as grasslands, or in ecosystems where aboveground biomass is frequently removed by burning or harvesting, foliar traits may provide important information regarding belowground inputs via exudates and fine-root turnover. Many, if not most, of the plant traits that drive variation in belowground processes are also measurable via remote sensing technologies. The ability of remote sensing techniques to measure fine-scale biodiversity and plant chemistry over large spatial scales can help researchers address ecological questions that were previously prohibitively expensive to address. Key to these potential advances is the idea that remotely sensed vegetation spectra and plant chemistry can provide detailed information about the function of belowground processes beyond what traditional field sampling can provide.

scholarly journals Asymmetric responses to simulated global warming by populations of Colobanthus quitensis along a latitudinal gradient

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3718 ◽  
Author(s):  
Ian S. Acuña-Rodríguez ◽  
Cristian Torres-Díaz ◽  
Rasme Hereme ◽  
Marco A. Molina-Montenegro
Keyword(s):  
Global Warming ◽  
Latitudinal Gradient ◽  
Biomass Accumulation ◽  
South Shetland Islands ◽  
Plant Populations ◽  
Colobanthus Quitensis ◽  
Growing Seasons ◽  
Long Term Experiment ◽  
Foliar Traits ◽  
The Antarctic

The increase in temperature as consequence of the recent global warming has been reported to generate new ice-free areas in the Antarctic continent, facilitating the colonization and spread of plant populations. Consequently, Antarctic vascular plants have been observed extending their southern distribution. But as the environmental conditions toward southern localities become progressively more departed from the species’ physiological optimum, the ecophysiological responses and survival to the expected global warming could be reduced. However, if processes of local adaptation are the main cause of the observed southern expansion, those populations could appear constrained to respond positively to the expected global warming. Using individuals from the southern tip of South America, the South Shetland Islands and the Antarctic Peninsula, we assess with a long term experiment (three years) under controlled conditions if the responsiveness of Colobanthus quitensis populations to the expected global warming, is related with their different foliar traits and photoprotective mechanisms along the latitudinal gradient. In addition, we tested if the release of the stress condition by the global warming in these cold environments increases the ecophysiological performance. For this, we describe the latitudinal pattern of net photosynthetic capacity, biomass accumulation, and number of flowers under current and future temperatures respective to each site of origin after three growing seasons. Overall, was found a clinal trend was found in the foliar traits and photoprotective mechanisms in the evaluated C. quitensis populations. On the other hand, an asymmetric response to warming was observed for southern populations in all ecophysiological traits evaluated, suggesting that low temperature is limiting the performance of C. quitensis populations. Our results suggest that under a global warming scenario, plant populations that inhabiting cold zones at high latitudes could increase in their ecophysiological performance, enhancing the size of populations or their spread.

Influence of foliar traits on forage selection by introduced red deer in New Zealand

2011 ◽  
Vol 12 (1) ◽  
pp. 56-63 ◽  
Author(s):  
Jennie N. Bee ◽  
Andrew J. Tanentzap ◽  
William G. Lee ◽  
Roger B. Lavers ◽  
Alan F. Mark ◽  
...  
Keyword(s):  
New Zealand ◽  
Red Deer ◽  
Foliar Traits

Topographic controls on gravity currents in porous media

2013 ◽  
Vol 734 ◽  
pp. 317-337 ◽  
Author(s):  
Samuel S. Pegler ◽  
Herbert E. Huppert ◽  
Jerome A. Neufeld
Keyword(s):  
Porous Media ◽  
Axisymmetric Flow ◽  
Early Time ◽  
Gravity Currents ◽  
Late Time ◽  
Horizontal Distance ◽  
Topographic Controls ◽  
Time Regime ◽  
Flow Transitions ◽  
Theoretical Results

AbstractWe present a theoretical and experimental study of the propagation of gravity currents in porous media with variations in the topography over which they flow, motivated in part by the sequestration of carbon dioxide in saline aquifers. We consider cases where the height of the topography slopes upwards in the direction of the flow and is proportional to the $n\text{th} $ power of the horizontal distance from a line or point source of a constant volumetric flux. In two-dimensional cases with $n\gt 1/ 2$, the current evolves from a self-similar form at early times, when the effects of variations in topography are negligible, towards a late-time regime that has an approximately horizontal upper surface and whose evolution is dictated entirely by the geometry of the topography. For $n\lt 1/ 2$, the transition between these flow regimes is reversed. We compare our theoretical results in the case $n= 1$ with data from a series of laboratory experiments in which viscous glycerine is injected into an inclined Hele-Shaw cell, obtaining good agreement between the theoretical results and the experimental data. In the case of axisymmetric topography, all topographic exponents $n\gt 0$ result in a transition from an early-time similarity solution towards a topographically controlled regime that has an approximately horizontal free surface. We also analyse the evolution over topography that can vary with different curvatures and topographic exponents between the two horizontal dimensions, finding that the flow transitions towards a horizontally topped regime at a rate which depends strongly on the ratio of the curvatures along the principle axes. Finally, we apply our mathematical solutions to the geophysical setting at the Sleipner field, concluding that topographic influence is unlikely to explain the observed non-axisymmetric flow.

Penetration of ultraviolet radiation in streams of eastern Pennsylvania: Topographic controls and the role of suspended particulates

2009 ◽  
Vol 71 (2) ◽  
pp. 189-201 ◽  
Author(s):  
Patrick Belmont ◽  
Donald P. Morris ◽  
Frank J. Pazzaglia ◽  
Stephen C. Peters
Keyword(s):  
Ultraviolet Radiation ◽  
Suspended Particulates ◽  
Topographic Controls ◽  
Eastern Pennsylvania

scholarly journals Leaf trait variation and field spectroscopy of generalist tree species on contrasting soil types

2016 ◽  
Author(s):  
Matheus Henrique Nunes ◽  
Matthew P. Davey ◽  
David Anthony Coomes
Keyword(s):  
Soil Type ◽  
Tree Species ◽  
Leaf Traits ◽  
Partial Least Square ◽  
Soil Types ◽  
Species Variation ◽  
Trait Variation ◽  
Field Spectroscopy ◽  
Specific Variation ◽  
Foliar Traits

Abstract. Understanding the causes of variation in plant functional traits is a central issue in ecology, particularly in the context of global change. Analyses of the drivers of traits variation based on thousands of tree species are starting to unravel patterns of variation at the global scale, but these studies tend to focus on interspecific variation, and the contribution of intraspecific changes remains less well understood. Hyperspectroscopy is a recently developed technology for estimating the traits of fresh leaves. Few studies have evaluated its potential for assessing inter- and intra-specific trait variability in community ecology. Working with 24 leaf traits for European tree species on contrasting soil types, found growing on deep alluvial soils and nearby shallow chalk soils, we ask: (i) What contribution do soil type and species identity make to trait variation? (ii) When traits are clustered into three functional groups (light capture and growth, leaf structure and defence, as well as rock-derived nutrients), are some groups more affected by soil than others? (iii) What traits can be estimated precisely using field spectroscopy? (iv) Can leaf spectra be used to detect inter-soil as well as inter-specific variation in traits? The contribution of species and soil-type effects to variation in traits were evaluated using statistical analyses. Foliar traits were predicted from spectral reflectance using partial least square regression, and so inter- and intra-specific variation. Most leaf traits varied greatly among species. The effects of soil type were generally weak by comparison. Macronutrient concentrations were greater on alluvial than chalk soils while micronutrient concentration showed the opposite trend. However, structural traits, as well as most pigments and phenolic concentrations varied little with soil type. Field spectroscopy provided accurate estimates of species-level trait values, but was less effective at detecting subtle variation of rock-derived nutrients between soil types. Field spectroscopy was a powerful technique for estimating cross-species variation in foliar traits and Si predictions using spectroscopy appear to be promising. However, it was unable to detect subtle within-species variation of traits associated with soil type.

scholarly journals Foliar Spectra and Traits of Bog Plants across Nitrogen Deposition Gradients

2020 ◽  
Vol 12 (15) ◽  
pp. 2448
Author(s):  
Alizée Girard ◽  
Anna K. Schweiger ◽  
Alexis Carteron ◽  
Margaret Kalacska ◽  
Etienne Laliberté
Keyword(s):  
Least Squares ◽  
Nitrogen Deposition ◽  
Partial Least Squares ◽  
Plant Species ◽  
Spectral Properties ◽  
N Deposition ◽  
Morphological Properties ◽  
Dry Matter Content ◽  
Foliar Traits

Bogs, as nutrient-poor ecosystems, are particularly sensitive to atmospheric nitrogen (N) deposition. Nitrogen deposition alters bog plant community composition and can limit their ability to sequester carbon (C). Spectroscopy is a promising approach for studying how N deposition affects bogs because of its ability to remotely determine changes in plant species composition in the long term as well as shorter-term changes in foliar chemistry. However, there is limited knowledge on the extent to which bog plants differ in their foliar spectral properties, how N deposition might affect those properties, and whether subtle inter- or intraspecific changes in foliar traits can be spectrally detected. The objective of the study was to assess the effect of N deposition on foliar traits and spectra. Using an integrating sphere fitted to a field spectrometer, we measured spectral properties of leaves from the four most common vascular plant species (Chamaedaphne calyculata, Kalmia angustifolia, Rhododendron groenlandicum and Eriophorum vaginatum) in three bogs in southern Québec and Ontario, Canada, exposed to different atmospheric N deposition levels, including one subjected to a 18-year N fertilization experiment. We also measured chemical and morphological properties of those leaves. We found detectable intraspecific changes in leaf structural traits and chemistry (namely chlorophyll b and N concentrations) with increasing N deposition and identified spectral regions that helped distinguish the site-specific populations within each species. Most of the variation in leaf spectral, chemical, and morphological properties was among species. As such, species had distinct spectral foliar signatures, allowing us to identify them with high accuracy with partial least squares discriminant analyses (PLSDA). Predictions of foliar traits from spectra using partial least squares regression (PLSR) were generally accurate, particularly for the concentrations of N and C, soluble C, leaf water, and dry matter content (<10% RMSEP). However, these multi-species PLSR models were not accurate within species, where the range of values was narrow. To improve the detection of short-term intraspecific changes in functional traits, models should be trained with more species-specific data. Our field study showing clear differences in foliar spectra and traits among species, and some within-species differences due to N deposition, suggest that spectroscopy is a promising approach for assessing long-term vegetation changes in bogs subject to atmospheric pollution.

Topographic controls on glacier sediment–landform associations around the temperate North Patagonian Icefield

2009 ◽  
Vol 28 (25-26) ◽  
pp. 2817-2832 ◽  
Author(s):  
Neil F. Glasser ◽  
Stephan Harrison ◽  
Krister N. Jansson
Keyword(s):  
Topographic Controls
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