scholarly journals Tree-, stand- and site-specific controls on landscape-scale patterns of transpiration

2018 ◽  
Vol 22 (1) ◽  
pp. 13-30 ◽  
Author(s):  
Sibylle Kathrin Hassler ◽  
Markus Weiler ◽  
Theresa Blume
Keyword(s):  
Spatial Variability ◽  
Sap Flow ◽  
Temporal Dynamics ◽  
Flow Patterns ◽  
Landscape Scale ◽  
Tree Stand ◽  
Site Specific ◽  
As Species ◽  
Individual Trees ◽  
Transfer Models

Abstract. Transpiration is a key process in the hydrological cycle, and a sound understanding and quantification of transpiration and its spatial variability is essential for management decisions as well as for improving the parameterisation and evaluation of hydrological and soil–vegetation–atmosphere transfer models. For individual trees, transpiration is commonly estimated by measuring sap flow. Besides evaporative demand and water availability, tree-specific characteristics such as species, size or social status control sap flow amounts of individual trees. Within forest stands, properties such as species composition, basal area or stand density additionally affect sap flow, for example via competition mechanisms. Finally, sap flow patterns might also be influenced by landscape-scale characteristics such as geology and soils, slope position or aspect because they affect water and energy availability; however, little is known about the dynamic interplay of these controls. We studied the relative importance of various tree-, stand- and site-specific characteristics with multiple linear regression models to explain the variability of sap velocity measurements in 61 beech and oak trees, located at 24 sites across a 290 km2 catchment in Luxembourg. For each of 132 consecutive days of the growing season of 2014 we modelled the daily sap velocity and derived sap flow patterns of these 61 trees, and we determined the importance of the different controls. Results indicate that a combination of mainly tree- and site-specific factors controls sap velocity patterns in the landscape, namely tree species, tree diameter, geology and aspect. For sap flow we included only the stand- and site-specific predictors in the models to ensure variable independence. Of those, geology and aspect were most important. Compared to these predictors, spatial variability of atmospheric demand and soil moisture explains only a small fraction of the variability in the daily datasets. However, the temporal dynamics of the explanatory power of the tree-specific characteristics, especially species, are correlated to the temporal dynamics of potential evaporation. We conclude that transpiration estimates on the landscape scale would benefit from not only consideration of hydro-meteorological drivers, but also tree, stand and site characteristics in order to improve the spatial and temporal representation of transpiration for hydrological and soil–vegetation–atmosphere transfer models.

scholarly journals Tree-, stand- and site-specific controls on landscape-scale patterns of transpiration

2017 ◽  
Author(s):  
Sibylle K. Hassler ◽  
Markus Weiler ◽  
Theresa Blume
Keyword(s):  
Spatial Variability ◽  
Sap Flow ◽  
Temporal Dynamics ◽  
Stand Density ◽  
Landscape Scale ◽  
Tree Stand ◽  
Site Specific ◽  
As Species ◽  
Individual Trees ◽  
Transfer Models

Abstract. Transpiration is a key process in the hydrological cycle and a sound understanding and quantification of transpiration and its spatial variability is essential for management decisions as well as for improving the parameterisation of hydrological and soil–vegetation–atmosphere transfer models. For individual trees, transpiration is commonly estimated by measuring sap flow. Besides evaporative demand and water availability, tree-specific characteristics such as species, size or social status control sap flow amounts of individual trees. Within forest stands, properties such as species composition, basal area or stand density additionally affect sap flow, for example via competition mechanisms. Finally, sap flow patterns might also be influenced by landscape-scale characteristics such as geology, slope position or aspect because they affect water and energy availability; however, little is known about the dynamic interplay of these controls. We studied the relative importance of various tree-, stand- and site-specific characteristics with multiple linear regression models to explain the variability of sap velocity measurements in 61 beech and oak trees, located at 24 sites spread over a 290 km2-catchment in Luxembourg. For each of 132 consecutive days of the growing season of 2014 we modelled the daily sap velocities of these 61 trees and determined the importance of the different predictors. Results indicate that a combination of tree-, stand- and site-specific factors controls sap velocity patterns in the landscape, namely tree species, tree diameter, the stand density, geology and aspect. Compared to these predictors, spatial variability of atmospheric demand and soil moisture explains only a small fraction of the variability in the daily datasets. However, the temporal dynamics of the explanatory power of the tree-specific characteristics, especially species, are correlated to the temporal dynamics of potential evaporation. Thus, transpiration estimates at the landscape scale would benefit from not only considering hydro-meteorological drivers, but also including tree, stand and site characteristics in order to improve the spatial representation of transpiration for hydrological and soil–vegetation–atmosphere transfer models.

Quantifying the influence of individual trees on slope stability at landscape scale

2021 ◽  
Vol 286 ◽  
pp. 112194
Author(s):  
Raphael I. Spiekermann ◽  
Sam McColl ◽  
Ian Fuller ◽  
John Dymond ◽  
Lucy Burkitt ◽  
...  
Keyword(s):  
Slope Stability ◽  
Landscape Scale ◽  
Individual Trees

Improved analysis of thermally sensed crop water status and mapping spatial variability for site specific irrigation scheduling

2008 ◽  
Author(s):  
Victor Alchanatis ◽  
Steven Evett ◽  
Shabtai Cohen ◽  
Yafit Cohen ◽  
Moshe Meron ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Water Status ◽  
Irrigation Scheduling ◽  
Crop Water ◽  
Site Specific

scholarly journals Identifying essential ecological factors underpinning the development of a conservation plan for the Endangered Australian tree Alectryon ramiflorus

Oryx ◽  
2015 ◽  
Vol 49 (3) ◽  
pp. 453-460 ◽  
Author(s):  
Peter J. Brown ◽  
Kevin R. Wormington ◽  
Philip Brown
Keyword(s):  
Soil Chemistry ◽  
Vegetation Type ◽  
Ecological Factors ◽  
Iucn Red List ◽  
Habitat Requirements ◽  
As Species ◽  
Disjunct Populations ◽  
Conservation Plan ◽  
Sparse Population ◽  
Individual Trees

AbstractReintroduction of rare and threatened species often fails to yield quantifiable conservation benefits because insufficient attention is focused on the species’ habitat requirements and biology. We demonstrate the value of such data in informing a recovery plan for Alectryon ramiflorus S.Reyn. (Sapindaceae), a tree species endemic to a region on the southern coast of Queensland, Australia. When the species was categorized as Endangered on the IUCN Red List in 1997 the total known population consisted of only 26 adult plants, in five disjunct populations in remnant patches of native vegetation. Analysis of vegetation type, soil chemistry and composition data comparing remnant patches with and without A. ramiflorus revealed that the species is not restricted to a specific soil type but prefers sites with relatively fertile soil and a more complex vegetation structure. The species is cryptically dioecious, displays asynchronous flowering between individuals, and requires insect-vectored pollination. The low rate of seedling production recorded within individual patches was attributed to the scarcity of trees of both genders, asynchronous flowering of individual trees and, in smaller patches, a sparse population of pollinating insect species. Successful reintroduction of A. ramiflorus will require consideration of these aspects of demographic success. The findings highlight the importance to species recovery plans of the knowledge of habitat requirements, interspecific relationships and critical dependencies, as well as species reproductive biology.

Spatial variability and temporal dynamics of HABs in Northeast China

2018 ◽  
Vol 90 ◽  
pp. 280-294 ◽  
Author(s):  
Chong Fang ◽  
Kaishan Song ◽  
Lin Li ◽  
Zhidan Wen ◽  
Ge Liu ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Northeast China ◽  
Temporal Dynamics

scholarly journals Effects of Spatial Variability and Relic DNA Removal on the Detection of Temporal Dynamics in Soil Microbial Communities

mBio ◽  
2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Paul Carini ◽  
Manuel Delgado-Baquerizo ◽  
Eve-Lyn S. Hinckley ◽  
Hannah Holland‐Moritz ◽  
Tess E. Brewer ◽  
...  
Keyword(s):  
Microbial Community ◽  
Spatial Variability ◽  
Spatial Heterogeneity ◽  
Microbial Communities ◽  
Temporal Variability ◽  
Temporal Dynamics ◽  
Microbial Community Composition ◽  
Soil Microbial Communities ◽  
Environmental Preferences ◽  
Soil Microbial

ABSTRACT Few studies have comprehensively investigated the temporal variability in soil microbial communities despite widespread recognition that the belowground environment is dynamic. In part, this stems from the challenges associated with the high degree of spatial heterogeneity in soil microbial communities and because the presence of relic DNA (DNA from dead cells or secreted extracellular DNA) may dampen temporal signals. Here, we disentangle the relationships among spatial, temporal, and relic DNA effects on prokaryotic and fungal communities in soils collected from contrasting hillslopes in Colorado, USA. We intensively sampled plots on each hillslope over 6 months to discriminate between temporal variability, intraplot spatial heterogeneity, and relic DNA effects on the soil prokaryotic and fungal communities. We show that the intraplot spatial variability in microbial community composition was strong and independent of relic DNA effects and that these spatial patterns persisted throughout the study. When controlling for intraplot spatial variability, we identified significant temporal variability in both plots over the 6-month study. These microbial communities were more dissimilar over time after relic DNA was removed, suggesting that relic DNA hinders the detection of important temporal dynamics in belowground microbial communities. We identified microbial taxa that exhibited shared temporal responses and show that these responses were often predictable from temporal changes in soil conditions. Our findings highlight approaches that can be used to better characterize temporal shifts in soil microbial communities, information that is critical for predicting the environmental preferences of individual soil microbial taxa and identifying linkages between soil microbial community composition and belowground processes. IMPORTANCE Nearly all microbial communities are dynamic in time. Understanding how temporal dynamics in microbial community structure affect soil biogeochemistry and fertility are key to being able to predict the responses of the soil microbiome to environmental perturbations. Here, we explain the effects of soil spatial structure and relic DNA on the determination of microbial community fluctuations over time. We found that intensive spatial sampling was required to identify temporal effects in microbial communities because of the high degree of spatial heterogeneity in soil and that DNA from nonliving sources masks important temporal patterns. We identified groups of microbes with shared temporal responses and show that these patterns were predictable from changes in soil characteristics. These results provide insight into the environmental preferences and temporal relationships between individual microbial taxa and highlight the importance of considering relic DNA when trying to detect temporal dynamics in belowground communities.

scholarly journals Monitoring the Spatial Variability of Knapweed (Centaurea diluta Aiton) in Wheat Crops Using Geostatistics and UAV Imagery: Probability Maps for Risk Assessment in Site-Specific Control

Agronomy ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 880
Author(s):  
Montserrat Jurado-Expósito ◽  
Francisca López-Granados ◽  
Francisco Manuel Jiménez-Brenes ◽  
Jorge Torres-Sánchez
Keyword(s):  
Risk Assessment ◽  
Spatial Variability ◽  
Weed Management ◽  
Management Strategies ◽  
Indicator Kriging ◽  
Site Specific ◽  
Weed Density ◽  
Density Mapping ◽  
Probability Maps ◽  
Geostatistical Approach

Assessing the spatial distribution of weeds within a field is a key step to the success of site-specific weed management strategies. Centaurea diluta (knapweed) is an emerging weed that is causing a major agronomic problem in southern and central Spain because of its large size, the difficulty of controlling it, and its high competitive ability. The main objectives of this study were to examine the spatial variability of C. diluta density in two wheat fields by multivariate geostatistical methods using unmanned aerial vehicle (UAV) imagery as secondary information and to delineate potential control zones for site-specific treatments based on occurrence probability maps of weed infestation. The primary variable was obtained by grid weed density field samplings, and the secondary variables were derived from UAV imagery acquired the same day as the weed field surveys. Kriging and cokriging with UAV-derived variables that displayed a strong correlation with weed density were used to compare C. diluta density mapping performance. The accuracy of the predictions was assessed by cross-validation. Cokriging with UAV-derived secondary variables generated more accurate weed density maps with a lower RMSE compare with kriging and cokriging with RVI, NDVI, ExR, and ExR(2) (the best methods for the prediction of knapweed density). Cokriged estimates were used to generate probability maps for risk assessment when implementing site-specific weed control by indicator kriging. This multivariate geostatistical approach enabled the delineation of winter wheat fields into two zones for different prescription treatments according to the C. diluta density and the economic threshold.

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