Soil microbial community (SMC) structure affects several ecosystem services (soil-carbon mineralization and stabilization), yet responds to edaphic conditions. Stemflow, water that drains over the ...exterior surface of trees, concentrates precipitation to soils near the trunk, thereby altering edaphic conditions. While recognizing that a suite of factors can affect soils, our research investigates the potential linkages between soil moisture, chemistry, and SMC structure within near-trunk soils from two species of contrasting stemflow production (Fagus grandifolia Ehrh. American beech, AB and Liriodendron tulipifera L. yellow poplar, YP) across seasons. Variations in SMC structure were determined by Nonmetric MultiDimensional Scaling (NMDS) analysis of Denaturing Gradient Gel Electrophoresis (DGGE) banding patterns. Sequencing/BLAST analysis of dominant DGGE-bands were conducted for shared and unique bands occurring in both AB and YP stemflow-influenced soils. Findings suggest species-specific differences in stemflow potentially alter moisture dynamics, pH, mineral nutrients, and soil-C near-trunk soils. SMC structure also increases in variability under low stemflow flux (i.e., for YP). However, SMC structural variability decreases for near-stem soils across individual trees and seasons when stemflow flux is consistently high (i.e., for AB). Differences in canopy structure that govern stemflow production may be a plant trait capable of altering SMC structure. Variation in SMC structure may be related to tree species stemflow input fluctuation response to seasonal change. Future investigations should consider intricate interrelationships among stemflow and species composition of the SMC in near-trunk soils in order to better contextualize the effect of stemflow on SMC vis-à-vis other factors, such as litter quality.
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•Examined stemflow effects on soil moisture, nutrients & microbial community structure.•Soil moisture, pH & mineral nutrients differed between high & low stemflow flux.•Stemflow alterations to edaphic conditions produced dissimilar microbial communities.•Stemflow may be a plant trait that alters soil microbial community structure.
In Situ Method to Measure and Map Bark pH Köhler, S.; Levia, D. F.; Jungkunst, H. F. ...
Journal of wood chemistry and technology,
11/2015, Volume:
35, Issue:
6
Journal Article
Peer reviewed
Bark pH is an essential parameter which partly governs the chemistry of the bark as well as its suitability as a microhabitat to a wide range of epiphytic organisms. Bark pH is known to vary with ...tree species, epiphytic cover, stemflow channelization, and anthropogenic influences. To date, reliable methods to quantify the spatial and temporal dimensions of bark pH have remained elusive. The aim of the present study was to develop and validate an in situ method to measure the surface pH of bark with high spatial resolution. Agar-agar panels, prepared with a pH indicator, were used to quantify and map the spatial variation of bark pH for cacao trees in Indonesia. Fine-scale changes of bark pH were clearly detectable and quantifiable with our bark pH mapping method. Bark pH was found to vary as a function of bark microrelief and the presence of epiphytes. The use of pH reference panels validated the bark pH measurements obtained from our method. The bark pH measurement method developed, described, and validated in this article is inexpensive and straightforward. It has the potential for wide adoption by scientists across disciplines who are interested in bark pH and its effect on life in the cortisphere. Unlike conventional methods to measure bark pH in deionized water or KCl extracts, our method is able to identify fine-scale spatial changes in bark pH that are relevant for the colonization of bark by organisms.
Leaf area index is a critical input into computations and models seeking to estimate or predict a whole host of ecophysiological processes, including carbon sequestration and evapotranspirational ...losses from forest ecosystems. The aim of this study was to derive and validate a generalized allometric equation for eastern white pine (
Pinus strobus L.) that would estimate and predict foliar biomass on the basis of trunk diameter at breast height (dbh, 1.37
m above-ground level). Coupled with locally derived specific leaf areas, this generalized equation would be a useful predictor of LAI for input to ecological models and a useful comparator to LAI estimated by remote sensing techniques or plant canopy analyzers. The generalized allometric equation was developed by using site-specific allometric equations from the four provenances of eastern white pine. Nine eastern white pine trees were destructively sampled over a 9-year period to form the validation data set. The generalized allometric equation derived and validated in this work is:
y
=
0.004
x
2.308 where
y
=
foliar dry weight (kg) and
x
=
dbh (cm) (
R
2
=
0.967,
p
<
0.000). There was strong agreement between the derived generalized allometric equation and the validation data set with a mean absolute error of only 2.60
kg. The allometric equation derived and validated in this study may be used with confidence by foresters, forest ecologists, and other plant scientists seeking estimates of foliar biomass or LAI for use in ecological models in natural and planted eastern white pine forests.
Leaching of nutrients from aboveground vegetative surfaces of canopy trees represents an important component of the intra-system nutrient cycle in forested ecosystems. The hypothesis tested is that ...there is no difference in winter stemflow leachate concentration or quantity among different storm types and meteorological conditions. Non-hierarchical cluster analysis demonstrated that there was an association between precipitation event type and chemical enrichment of stemflow drainage from the leafless crowns of deciduous canopy trees monitored over two successive winter seasons. Three clusters were derived on the basis of chemical enrichment. Stemflow was most enriched during snow-to-rain events. Rain and rain-to-snow events also enriched stemflow but to a lesser extent than snow-to-rain events. Snow, sleet, and rain shower events enriched stemflow the least. Stemflow from all precipitation events were chemically enriched compared to the incident bulk precipitation. The extent of chemical enrichment was inversely proportional to stemflow volume generated by canopy trees during discrete precipitation events. Other factors affecting the amount of winter stemflow leaching were precipitation type (influences interception efficiency) and intra-storm temperature regime. Stemflow from precipitation events of long duration and low intensity with air temperature oscillations around the freezing point was the most enriched because of the longer residence time of intercepted precipitation with the leafless crown. Because stemflow leachate quantities were found to differ among precipitation events as a function of meteorological conditions, it is possible that the winter biometeorology of deciduous forests could potentially impact tree vigor, forest stand productivity, and species composition of deciduous forests.
Knowledge of the vertical variation of bark water storage capacity (BWSC) is essential in understanding the processes of throughfall and stemflow yield in forest ecosystems. Determination of vertical ...variation of BWSC is also necessary to understand microscale variations in moisture availability that affect the diversity and distribution of corticolous lichen and bryophyte communities on tree boles. This field note reports that BWSC of a tree bole of Pinus strobus L. (eastern white pine; 28.4 cm dbh, 22.5 m tall) differs substantially as a function of height above ground. BWSC of the bottom section of the tree bole (5.6 L m−2) was approximately twice as much as the top section (2.5 L m−2). Total BWSC for this tree's bole was 52.5 L. Further research of the interactions among bark water storage capacity, stemflow yield, and the diversity and distribution of corticolous lichens and bryophytes will improve our understanding of the canopy water balance and the functional ecology of forest ecosystems.
Snowmelt induced stemflow is an under-studied and poorly understood hydrological process. The aim of the present manuscript is to set forth several testable hypotheses and conceptual models ...concerning the production of snowmelt induced stemflow. The first testable hypothesis is that tree species with lower canopy albedos of snow-covered and snow-free surfaces (portions of the canopy are usually exposed and snow-free while the remainder is covered) will generate larger snowmelt induced stemflow volumes than trees with higher canopy albedos of snow-covered and snow-free surfaces. It is also hypothesized that snow-to-rain events produce larger volumes of snowmelt induced stemflow than snow events of the same magnitude because of differences in precipitation type (snow-to-rain vs. snow) and the additional melt energy from the latent heat of fusion associated with rain infiltrating the intercepted snow mass. For deciduous tree species with similar branching geometries, it is hypothesized that larger longwave radiative flux will generate larger snowmelt induced stemflow volumes. The conceptual models describe the components and the flux directions necessary to generate snowmelt induced stemflow. Through a test of the hypotheses and conceptual models in subsequent work, it is hoped that quantitative models are developed that will be able to estimate snowmelt induced stemflow volumes and yield a new understanding of winter water flux in forested ecosystems.
This study assessed the climatic suitability for the expansion of Solenopsis invicta Buren (red imported fire ant) in Oklahoma under the present climate and with a doubling of atmospheric CO2 using ...three general circulation models (GCMs) (GFDL R30, OSU, UKMO). Oklahoma was chosen as the geographical focus because it has a dense network of meteorological stations and lies on the edge of the current biogeographic range of S. invicta. Meteorological data were spatially referenced with model data in GIS to produce a series of images of selected suitability indicators: (1) mean annual precipitation >510mm; (2) less than seven consecutive days with mean air temperature <1.1 C; and (3) mean winter air temperature >9.4 C. These indicator images were combined to produce suitability maps for the potential range of S. invicta. Under current climatic conditions, roughly three-quarters of Oklahoma is suitable for potential invasion by S. invicta. The GFDL R30, OSU, and UKMO show that the area suitable for colonization increases by approximately 26, 26, and 36%, respectively. In terms of actual land area, the increase with a warmer, wetter climate ranges from 35,300km2 to 47,600km2. The destructiveness of S. invicta on human livelihood necessitates a better understanding of the future expansion of the species for an uncertain future climate. PUBLICATION ABSTRACT
Nitrogen is an essential nutrient in the biogeochemistry of forested ecosystems. The influence of canopy lichens on the winter biogeochemistry of nitrate in broadleaved deciduous forests is examined ...and it is hypothesized that nitrate sequestration will not differ between winter precipitation events. Rejection of this hypothesis would mean that meteorological conditions of winter precipitation events have a detectable influence on nitrate sequestration by canopy lichens and nitrate input to the forest floor. Canopy lichens of the genus Parmelia were found to influence winter nitrate stemflow inputs to forest soils differentially. Epiphytic lichens on an individual Carya glabra Mill. (pignut hickory) canopy tree, centrally located within the stand of an open deciduous forest, actively sequestered nitrate leached from the tree's woody frame, lowering aqueous stemflow inputs at the tree base. The quantities of nitrate sequestered by corticolous lichens during the 2 February 1999 mixed-precipitation event were significantly greater than those during all other precipitation events examined. Greater rates of nitrate uptake during the 2 February 1999 event may be attributed to (1) its intermediate rain intensity, which would have soaked the lichen thalli in a nutrient-rich bath, and (2) an air temperature range between -2 degrees C and 8 degrees C that would have increased viscosity and surface tension of stemflow drainage, thereby decreasing stemflow velocity and increasing the contact time of stemflow water on the lichen thalli. Other precipitation events were either too cold to promote metabolic activity by canopy lichens or too warm and intense for an optimal contact time of stemflow with lichen thalli, resulting in lower quantities of nitrate sequestered. Meteorological conditions of winter precipitation events have been documented to influence sequestration of nitrate by corticolous lichens and decrease aqueous stemflow inputs to the forest floor of broadleaved deciduous forests.
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