John Toland Van Stan

John Toland Van Stan
Cleveland State University · Department of Biological, Geological, and Environmental Sciences

Ph.D.

About

140
Publications
51,292
Reads
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2,065
Citations
Introduction
My research seeks to enhance our understanding of the interface between hydrological processes and vegetated ecosystem functioning, as this is critical to the advancement of natural resource & watershed management. You can find news and updates on my lab's twitter account: @Prof_Van_Stan.
Additional affiliations
July 2017 - July 2021
Georgia Southern University
Position
  • Managing Director
August 2012 - July 2017
Georgia Southern University
Position
  • Professor (Assistant)
August 2006 - May 2012
University of Delaware
Position
  • Doctoral Research Fellow

Publications

Publications (140)
Presentation
Full-text available
Plant canopies play critical intermediary roles in the movements of water in both directions along the soil-plant-atmosphere continuum. From the atmosphere to the soil, plant canopies intercept and redirect precipitation and condensation into heterogeneous spatiotemporal patterns of water, nutrient and organismal fluxes at the surface. From the soi...
Article
Biddick and Van Stan II introduce how certain plant species harvest rain.
Article
Full-text available
Water flows through forests in many ways, so it is difficult to understand and predict where and when it will flow. Understanding how water flows through forests is important, as it affects many of the services that forests offer to people, like lumber for houses and cleaner air. Water scientists (called hydrologists) have a way to reduce the compl...
Preprint
The stemflow may wash canopy-dwelling metazoans to the litter and soils below; however, metazoans transported by stemflow have been typically ignored in past research. In fact, the visual presence of metazoans in stemflow collection bins was reported as “contamination.” Thus, we know little about these organisms’ transfer from plant canopies to the...
Article
Full-text available
Tea is a mix of natural plant chemicals dissolved in water. You should not drink it, but a weak tea drips through a tree’s branches and runs down its trunk when it is raining. The main ingredients in both tea and tree tea are organic molecules. Some, like tannins, are colorful and give tea and tree tea their brownish colors. Others, including sugar...
Article
Full-text available
The forest floor is the forest’s graveyard. There, broken branches and fallen trunks are laid to rest. However, this deadwood still has an important role to play. New deadwood is still covered in bark—a tissue that protects a living tree’s insides from the outside world. The bark makes it difficult for water to enter the dead tree. It repels the ra...
Article
Full-text available
If you look up during a storm or when it is foggy, you may see little rivers flowing down the tree branches above your head. These are called branchflows, and they play an important part in moving water along trees and through forests. For scientists who study water, branchflows are really weird! They do not flow on top of something, like rivers th...
Article
Full-text available
Stemflow is the spatially‐concentrated input of rain water at the base of a tree, resulting from precipitation draining down tree branches to the stem. Depending on tree shape, stemflow can represent a significant fraction of total rainfall that contacts the tree’s canopy area, and can become chemically enriched along its drainage path. As a result...
Article
Full-text available
Snowpack accumulation in forested watersheds depends on the amount of snow intercepted in the canopy and its partitioning into sublimation, unloading, and melt. A lack of canopy snow measurements limits our ability to evaluate models that simulate canopy processes and predict snowpack. We tested whether monitoring changes in wind‐induced tree sway...
Article
Full-text available
Over geologic timescales, forests have intercepted precipitation and thereby modified the intensity, duration, and spatial patterns of water fluxes to forest soils. Across a range of environmental conditions, persistent focused water flows can dissolve carbonate substrates, and form conical dissolution features—termed “dissolution cones.” These con...
Article
Full-text available
Rainfall partitioning by plant canopies can play key roles in dryland ecohydrology by altering the amount, timing and patterns of water receipt to soils. Here, we synthesized interception, throughfall and stemflow observations from 2,297 rainfall events across 40 dryland sites, including 48 plant species. Then, we developed general empirical models...
Book
Full-text available
Compared to leaves, bark is under-studied with regards to its role in the water cycle. This is an important knowledge gap as, unlike leaves, bark is ever-present in forest ecosystems and can represent a significant interface for water interaction. Bark is also porous, hygroscopic, present in litter layers from shedding, as well as on fallen woody d...
Article
Full-text available
You may not pay much attention to fungi growing on the bark of trees in your neighborhood, but there are many fungal species that scientists know have joined the “bark side.” The fungi living on bark do many interesting and surprising things. For example, bark fungi may prowl the bark in search of resources or new habitats. Fungi create tiny versio...
Presentation
Full-text available
Come join the Bark Side of the Water Cycle! Here's our video abstract for an AGU presentation based on our Perspective article in Frontiers in Forests & Global Change. https://youtu.be/CGzFNU70yUg
Article
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Bark-water interactions are understudied processes in wooded ecosystems. This collection of research highlights evidence of the important roles that bark can play in controlling the amount of water that is returned to the atmosphere during storms, or makes it to the soil, groundwater, and streams, as well as the chemical makeup of that water. As ba...
Article
Contour-felled log debris (CFD) and log erosion barriers (LEB) are two restoration practices used worldwide on hillslopes to avoid soil erosion after wildfires. Although significant work has evaluated the effectiveness of these practices on soil loss prevention, their effects on soil properties have been little researched to date. Here, the effects...
Article
Full-text available
As the outermost layer of stems and branches, bark is exposed to the influence of atmospheric conditions, i.e., to changes in the air’s relative humidity and wetting during storms. The bark is involved in water interception by tree canopies and stemflow generation, but bark–water relations are often overlooked in ecohydrological research and insuff...
Article
Rainwater is altered hydrologically and chemically as it passes through tree canopies to reach the soil surface, but this aspect of urban forest ecosystems has received less attention than that of natural ecosystems. Hydrological partitioning and changes in solute composition of rainfall were examined in an urban forest within Guangzhou city, in so...
Article
Natural forest regeneration can be a slow and difficult-to-predict process because it is the result of complex interactions between seedling establishment success and site factors. Here, we applied a novel “lifetime” modelling approach to account for seed emergence and seedling survival across site conditions (i.e., seed protection and canopy cover...
Article
The Cerrado savanna of Brazil is considered the most biodiverse savanna in the world and its vegetation acts as an interface between rainfall and recharge processes for the largest aquifer system (Guarani) in South America. Understanding how major Cerrado tree species affect the amount and patterns of rainfall at the surface, therefore merits scien...
Article
Full-text available
All animals need water to live, but not all of them need to drink it from their surroundings. Drinking free water from rivers or puddles is just one of many ways that animals get the water they need. Until recently, koalas were thought to get most of their water from the leaves that they eat. But, after years of koala watchers getting caught in the...
Article
For one‐third of Earth’s land surface, precipitation passes through tree canopies (as throughfall or stemflow) before entering watersheds. Over a century of research has described fluxes of water and solutes along these “hydrologic highways”, yet little is known about their “traffic” – that is, the organisms and nonliving particulates frequently di...
Article
Pollen shedding can produce rapid, abundant exchanges of nutrient-rich biomass from plant canopies to the surface. When pollen deposits onto understory plants, it can be washed off during storms via throughfall (a drip flux) and stemflow (a flux down plant stems). Pollen deposition may also alter the organismal community on plant surfaces, changing...
Article
Full-text available
There are scientific gray areas where it is unclear whether process representations and assumptions in models have adequate empirical basis. Nonetheless, useful insights can come from interpreting data with the aid of models that use hypothetical parameterizations or process representations, even if they are uncertain and speculative. Indeed, virtu...
Article
Full-text available
The study of stemflow fungi began over 50 years ago. Past work has been performed in different climatic regions of the world, with different sampling methods, by mycologists focusing on different taxonomical groups. Therefore, we aim to synthesize this work to delineate major conclusions and emerging hypothesis. Here, we present: (1) a systematic c...
Article
Full-text available
To date, the perspective of forest ecohydrologists has heavily focused on leaf-water interactions—leaving the ecohydrological roles of bark under-studied, oversimplified, or omitted from the forest water cycle. Of course, the lack of study, oversimplification, or omission of processes is not inherently problematic to advancing ecohydrological theor...
Article
The authors regret that the abstract and key words for this article were not included in the final publication—despite these having been included in the manuscript submission throughout the peer review process. The abstract and key words are obviously important components of a publication, especially in the digital age where they are (1) the only p...
Article
Full-text available
This study evaluates soil hydraulic conductivity (SHC) and water repellency (SWR) in three mixed forest stands in relation to site plant and soil characteristics. The studied forest stands were: i) Pinus nigra Arn. ssp salzmannii and Quercus ilex; ii) Pinus nigra Arn. ssp salzmannii and Juniperus Thurifera; iii) Pinus nigra Arn. ssp salzmannii, Que...
Presentation
Full-text available
These are the introductory videos for an #AGU2020 virtual conference session "Precipitation Partitioning by Vegetation." The first interaction between precipitation and land surface is often with a plant canopy, which partitions precipitation into throughfall, stemflow or interception. Studying these processes answers important questions for many f...
Article
Full-text available
Post-fire environmental conditions can heavily influence the natural regeneration of pine species in Mediterranean forests. Therefore, enhancing post-fire recovery of pine species is fundamental for effective ecological restoration of Mediterranean forests. In this study, the effects of a post-fire restoration treatment on the seedling emergence an...
Article
Full-text available
The role of crop canopies in the global water cycle is a topic of increasing international interest. How much rain and sprinkler-irrigation water are returned to the atmosphere or reach the soils beneath crop canopies, and the pathways of those water inputs at the soil, are linked to agricultural productivity and sustainability. This concise-format...
Article
Full-text available
In vegetated landscapes, rain must pass through plant canopies and litter to enter soils. As a result, some rainwater is returned to the atmosphere (i.e., interception, I) and the remainder is partitioned into a canopy (and gap) drip flux (i.e., throughfall) or drained down the stem (i.e., stemflow). Current theoretical and numerical modeling frame...
Article
When it rains over vegetation, plants have an opportunity to get a limited supply of freshwater. A portion of rain drains directly to the soil down a plant stem, in a hydrologic flux called “stemflow.” For short vegetation with shallow roots, which provide ground cover for most vegetated ecosystems around the globe (including forest understories),...
Presentation
Full-text available
Here, we visit a community of trees living along the Georgia coast, just above the high tide line, on a little lump of sand called a "hammock." This hammock plant community is battered by a hurricane. The plants that survive soon realize that they have fallen prey to a hydrological torture wrack - one composed of the salty corpses of their neighbor...
Article
Full-text available
Hurricanes can cause immediate catastrophic destruction of marsh vegetation and erosion of soils; however, they also have long-lasting ecological impacts. Those impacts include the deposition of tremendous amounts of saltmarsh litter (‘wrack’) onto upland ecosystems, the hydrologic effects of which have not previously been investigated. When Hurric...
Presentation
Full-text available
The science comic 'Roots of the Past nourish present research' leads two students on a wild time travel to the first observations and observatories of plants and precipitation – the story of ecohydrology. Using past knowledge and new technologies they develop ideas for their own research.
Presentation
Full-text available
Der Wissenschaftscomic 'Wurzeln der Vergangenheit ernähren Forschung der Gegenwart' führt zwei Studierende auf ein wilde Zeitreise zu den ersten Beobachtungen und Observatorien von Pflanzen und Niederschlag – der Geschichte der Ökohydrologie. Dabei entwickeln sie Ideen für Ihre eigene Forschung.
Article
Full-text available
A portion of precipitation drains to the surface down plant stems, as “stemflow.” Although per observations to date, stemflow rarely represents >2% of gross precipitation in forests, it can result in larger water fluxes to near-stem soils that are hypothetically more important to roots. The ecohydrological importance of stemflow is often predicated...
Chapter
Full-text available
This is a fun, short (2-page) outreach contribution to the national Society of Municipal Arborists' Roundtable discussion, "Where Urban Forests, Stormwater, and Watersheds Meet." Here, I briefly discuss why/how precipitation partitioning by urban forests is relevant to urban watershed management. In an effort to highlight the many tricks trees have...
Chapter
There are multiple distinct habitats for microbiota inhabiting the plant microbiome (phyllosphere, endosphere, litter, rhizosphere) and habitats that act as additional sources (and sinks) of microbes and nutrients for the plant microbiome (atmosphere, pedosphere, bedrock, and fauna). These habitats harbor distinctive microbial communities that diff...
Chapter
The amount and patterning of precipitation beneath vegetation is determined by throughfall and stemflow. Throughfall is the portion of precipitation that falls through, or drips from, the canopy; whereas, stemflow is the portion that drains down the stem. This chapter briefly synthesises throughfall and stemflow methods, data and major drivers of v...
Chapter
Dissolved organic matter (DOM) is a master variable that modulates the form and function of many ecosystems. Approximately, half of the mass of DOM is carbon. Fluxes of DOM transfer carbon and other vital elements between ecosystems and between organisms (e.g., trees to bacteria) and components (e.g., vegetation to soil) within ecosystems. The DOM...
Chapter
This chapter presents a history of the interdisciplinary field focused on improving our understanding of the first step in the terrestrial hydrologic cycle: precipitation partitioning by vegetation. We describe the origins of interest, rooted in observations from “The Father of Botany,” Theophrastus (350 BCE) and synthesize the early formal hydrolo...
Chapter
Redistribution of precipitation water by plant canopies increases the spatial variation of net precipitation at the surface, affecting soil moisture patterns, localized preferential flow, and soil biogeochemical processes. This chapter reviews methods for assessing and the current state of knowledge on spatial patterns of the two net precipitation...
Chapter
Trees impact surface stormwater runoff, soil moisture, streamflow, water quality, and air temperatures by intercepting precipitation (rain and snow), enhancing soil water infiltration, shading surfaces, and evapotranspiring water. These impacts affect human health and well-being. Many of these tree impacts remain to be more accurately quantified an...
Chapter
The interception of precipitation by vegetation has important consequences for climate and water resources. Although canopy interception has been studied for centuries, many fundamental unknowns remain. We present persistent questions that reflect challenges in measuring, representing, and understanding how terrestrial ecosystems intercept, partiti...
Chapter
Water storage on tree crowns, trunks, the understory, and litter is, in many respects, one of the simplest water balance components of vegetated ecosystems, but one that is rarely parameterized in detail. Interception processes are often analogized and parameterized as the dynamic (filling and emptying) of static reservoirs, but canopy storage rese...
Chapter
For close to a century, scientists have recognized the important role of throughfall and stemflow (precipitation water that falls through plant canopies and runs down plant stems, respectively) in the cycling of materials. These “hydrologic highways” carry atmospherically deposited and canopy-derived materials from the top of the plant canopy to th...
Book
This book presents research on precipitation partitioning processes in vegetated ecosystems, putting them into a global context. It describes the processes by which meteoric water comes into contact with the vegetation's canopy, typically the first surface contact of precipitation on land. It also discusses how precipitation partitioning by vegetat...
Article
Full-text available
Study region: Maize farmland in Varamin, located southwest of Tehran (Iran). Study focus: The aims of this study were to: (1) monitor throughfall and stemflow during rainstorms beneath maize canopies over two growing seasons (2015, 2016); (2) evaluate the effect of maize canopy structure (leaf area index, plant height) on throughfall, stemflow, an...
Poster
Full-text available
In 2020, let's make stemflow unit-ed again: https://youtu.be/4vPk9m45V0c ... From inside the stemflow research community, the past decade’s progress might look great: 1) the number of papers published on stemflow per year has doubled; 2) citations of stemflow publications have more than doubled; and 3) the number of research sites monitoring stemf...
Article
Full-text available
The interception of rainfall by trees enriches rainwater with tree-derived dissolved organic matter (tree-DOM), which represents the first terrigenous source of DOM during storm events. The tree-DOM is then exported from the canopy via rainfall that drips from leaves and branches (throughfall) or is funneled down the tree trunk (stemflow) to the fo...
Preprint
Full-text available
In vegetated landscapes, rain must pass through plant canopies and litter to enter soils. As a result, some rainwater is returned to the atmosphere (i.e., interception, I) and the remainder is partitioned into a canopy (and gap) drip flux (i.e., throughfall) or drained down the stem (i.e., stemflow). Current theoretical and numerical modelling fram...
Article
Full-text available
The first contact between precipitation and the land surface is often a plant canopy. The resulting precipitation partitioning by vegetation returns water back to the atmosphere (evaporation of intercepted precipitation) and redistributes water to the subcanopy surface as a "drip" flux (throughfall) and water that drains down plant stems (stemflow)...
Article
Full-text available
Arboreal epiphytes (plants residing in forest canopies) are present across all major climate zones and play important roles in forest biogeochemistry. The substantial water storage capacity per unit area of the epiphyte "bucket" is a key attribute underlying their capability to influence forest hydrological processes and their related mass and ener...
Article
Aim of study: To understand throughfall (TF) sensitivity to variability in rainfall amount (Pg) for typical forest sites across the main climate types of Iran.Area of study: Nine forest stands of several common native and introduced tree species situated in all common Iranian climate types, but located primarily in northern Iran.Material and method...
Presentation
Full-text available
This is the story of Precipita, the waterwitch of Leipzig Germany, and the critical roles that urban forests play in protecting the city from her hydrological whims! As we made this comic with the City of Leipzig in Germany we also translated it into German. The science comic is based on a book chapter "Urban Forestry: An Underutilized Tool in Wa...
Article
Full-text available
Forest canopy surfaces (phyllosphere) host a dynamic, diverse, and populous bacterial community that is washed thoroughly by storms. Interactions with the phyllosphere dramatically alter the composition of rainfall reaching the surface. Here, we report how rainfall bacterial community composition is altered as it drains from canopy surfaces/through...
Article
Full-text available
Scientists are trained to tell stories, scientific stories. Training is also needed to comprehend and contextualize these highly nuanced and technical stories because they are designed to explicitly convey scientific results, delineate their limitations, and describe a reproducible “plot” so that any thorough reenactment can achieve a similar concl...
Article
Full-text available
Non-vascular vegetation has been shown to capture considerable quantities of rainfall, which may affect the hydrological cycle and climate at continental scales. However, direct measurements of rainfall interception by non-vascular vegetation are confined to the local scale, which makes extrapolation to the global effects difficult. Here we use a p...
Presentation
Full-text available
Since the beginning of human settlement, people have observed water in its many forms, recording the ways that water supports and subverts life... like a cunning and capricious witch. This is the story of Precipita, the waterwitch of Leipzig Germany, and the critical roles that urban forests play in protecting the city from her hydrological whims!...
Article
Full-text available
Dissolved organic matter (DOM) drives carbon (C) cycling in soils. Current DOM work has paid little attention to interactions between rain and plant canopies (including their epiphytes), where rainfall is enriched with tree-derived DOM (tree-DOM) prior to reaching the soil. Tree-DOM during storms reaches soils as throughfall (drip through canopy ga...
Article
Full-text available
Stemflow, a precipitation and solute supply to soils near tree stems, can play a wide array of roles in ecosystem functioning. However, stemflow’s ecohydrological functions have been primarily studied in forests with voluminous stemflow because resource subsidy is currently considered stemflow’s only impact on near-stem soils. This common assumptio...
Article
Full-text available
Rainfall onto trees entrains dissolved organic matter (tree-DOM). Tree-DOM is then exported down stems in stemflow and through leaves, branches, and gaps as throughfall. We synthesize tree-DOM literature, presenting trends in and controls of tree-DOM concentrations, fluxes, and chemistry. Tree-DOM concentrations are higher in stemflow (7-482 mg-C L...
Article
Full-text available
The temporal dynamics of forest canopy rainfall partitioning are important to forest ecology and management as it influences all subsequent hydrological processes along the rainfall-to-discharge flow path. Despite a growing body of literature on the importance of coupled hydrological–ecological interactions during periodic forest life cycle events,...