Susan E. Crow

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Verified

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• PhD
• Professor (Full) at University of Hawaiʻi at Mānoa

To date, research on the role of organic matter dynamics in maintaining the health of (sub)tropical Andisols (i.e., volcanic ash-derived soils) is limited. High concentrations of poorly and noncrystalline minerals in these soils favor greater soil organic matter (SOM) accumulation than in phyllosilicate-dominant soils, yet SOM abundance and composi...

There are growing efforts to incorporate agroforestry into ecosystem service incentive programs. Indigenous and other place-based multi-strata agroforestry systems are important conservation and agricultural strategies, yet their ecosystem services, including carbon sequestration benefits, have received little research attention. To fill this gap,...

Soil health is recognized as an important ecosystem property sensitive to human impact. As a concept, soil health cannot be directly measured, and so assessment and modeling efforts largely rely upon key biological, chemical, and physical indicators. Efforts to develop an overall soil health index are largely lacking due to significant statistical...

Soil health conceptualized as a measurable ecosystem property provides a powerful tool for monitoring progress in restoration projects or implementation of best management practices to improve degraded lands and promote sustainable agroecosystems. We surveyed soils collected from a range of land uses (i.e., protected native and non-native forest, m...

Predicting soil organic carbon (SOC) is problematic in tropical soils because mechanisms of SOC (de)stabilization are not resolved. We aimed to identify such storage mechanisms in a tropical soil landscape constrained by 100 years of similar soil inputs and agricultural disturbance under the production of sugarcane, a C 4 grass and bioenergy feedst...

Mathematical models are essential for integrating different processes that control rates of soil carbon dynamics and for assessing carbon sequestration and the related climate benefits. Many models have been proposed in the literature, with no overall consensus on the best model that can provide relevant insights at a large range of scales and for...

Soils are an enticing reservoir for nature-based climate solutions, but long timescales are required to store amounts of C of relevance to mitigate warming acknowledging its impermanence. Scientific clarity on the controlling factors in soil C persistence should help to disambiguate debates related to permanence in the climate policy domain. Howeve...

Tropical regions hold one third of the world’s soil organic carbon, but few experiments have warmed tropical soils in situ. The vulnerability of these soils to climate change-induced losses is uncertain with many hypothesizing these soils would be less sensitive to climate change because already-high temperatures in tropical systems might limit mic...

Converting lignocellulose to bioenergy and biobased products requires targeted breakdown of complex plant polymers that protect structural sugars. To identify lignophenolic compounds that promote enzymatic hydrolysis, the lignophenolic composition of biomass across 12 species and varieties of the Poaceae (grass) family were measured using copper (I...

Soils are a promising reservoir to store carbon (C) and mediate greenhouse gas emissions; however, long timescales are required to store amounts of C of relevance to mitigate climate change. Here we conceptually and computationally connect the concepts of permanence (policy) and persistence (biogeosciences) to the amount of warming that is avoided...

Understanding the controls on the amount and persistence of soil organic carbon (C) is essential for predicting its sensitivity to global change. The response may depend on whether C is unprotected, isolated within aggregates, or protected from decomposition by mineral associations. Here, we present a global synthesis of the relative influence of e...

Soil health conceptualized as a measurable ecosystem property provides a powerful tool for monitoring progress in restoration projects or implementation of best management practices to promote sustainable agroecosystems. We surveyed soils collected from a range of land uses (i.e., protected native and non-native forest, managed pasture, unmanaged p...

The efficacy of C4 grasses as feedstocks for liquid fuel production and their climate mitigation potential remain unresolved in the tropics. To identify highly convertible C4 grasses, we measured final fuels and postprocess biomass produced in two laboratory-scale conversion pathways across 12 species and varieties within the Poaceae (grass) family...

As the extent of secondary forests continues to expand throughout the tropics, there is a growing need to better understand the ecosystem services, including carbon (C) storage provided by these ecosystems. Despite their spatial extent, there are limited data on how the ecosystem services provided by secondary forest may be enhanced through the res...

Ecosystems play a fundamental role in climate change mitigation by photosynthetically fixing carbon from the atmosphere and storing it for a period of time in organic matter. Although climate impacts of carbon emissions by sources can be quantified by global warming potentials, the appropriate formal metrics to assess climate benefits of carbon rem...

The functions and interactions of individual microbial populations and their genes in agricultural soils amended with biochar remain elusive but are crucial for a deeper understanding of nutrient cycling and carbon (C) sequestration. In this study, we coupled DNA stable isotope probing (SIP) with shotgun metagenomics in order to target the active c...

As part of an integrated energy and climate system, biomass production for bioenergy based on the tropical perennial C4 grass energycane can both offset fossil fuels and store soil carbon (C). We measured energycane yields, root biomass, soil C pools, and soil C stocks in a four‐year field trial and modeled C flow from plants to soils in the surfac...

The magnitude of carbon (C) loss to the atmosphere via microbial decomposition is a function of the amount of C stored in soils, the quality of the organic matter, and physical, chemical, and biological factors that comprise the environment for decomposition. The decomposability of C is commonly assessed by laboratory soil incubation studies that m...

Ecosystems play a fundamental role in climate change mitigation by taking up carbon from the atmosphere and storing it for a period of time in organic matter. Although climate impacts of carbon emissions can be quantified by global warming potentials, it is not necessarily clear what are appropriate formal metrics to assess climate benefits of carb...

Radiocarbon is a critical constraint on our estimates of the timescales of soil carbon cycling that can aid in identifying mechanisms of carbon stabilization and destabilization and improve the forecast of soil carbon response to management or environmental change. Despite the wealth of soil radiocarbon data that have been reported over the past 75...

Abstract. The magnitude of carbon (C) loss to the atmosphere via microbial decomposition is a function of the amount of C stored in soils, the quality of the organic matter, and physical, chemical and biological factors that comprise the environment for decomposition. The decomposability of C is commonly assessed by laboratory soil incubation studi...

Our ability to reliably use radiocarbon ( ¹⁴ C) dates of mollusk shells to estimate calendar ages may depend on the feeding preference and habitat of a particular species and the geology of the region. Gastropods that feed by scraping are prone to incorporation of carbon from the substrate into their shells as evidenced by studies comparing the rad...

The incorporation of biochar into soil is a promising management strategy for sustainable agriculture owing to its potential to sequester carbon and improve soil fertility. Expanding the addition of biochar to large-scale agriculture hinges on its lasting beneficial effects on the microbial community. However, there exists a significant knowledge g...

Radiocarbon is a critical constraint on our estimates of the timescales of soil carbon cycling that can aid in identifying mechanisms of carbon stabilization and destabilization, and improve forecast of soil carbon response to management or environmental change. Despite the wealth of soil radiocarbon data that has been reported over the past 75 yea...

The presence of large numbers of free-ranging feral cats (Felis catus) has raised concern in terms of both native species predation and potential disease transmission in Hawai'i. A disease of particular concern is toxoplasmosis, caused by Toxoplasma gondii, a zoonotic protozoan parasite. We tested soil samples and cat fecal samples from cat colonie...

Background: The environmental costs of fossil fuel consumption are globally recognized, opening many pathways for the development of regional portfolio solutions for sustainable replacement fuel and energy options. The purpose of this study was to create a baseline carbon (C) budget of a conventionally managed sugarcane (Saccharum officinarum) pro...

Soil organic matter (SOM) turnover increasingly is conceptualized as a tension between accessibility to microorganisms and protection from decomposition via physical and chemical association with minerals in emerging soil biogeochemical theory. Yet, these components are missing from the original mathematical models of belowground carbon dynamics an...

Accurately capturing dynamic soil response to disturbance effects in agroecosystem models remains elusive, thereby limiting projections of climate change mitigation potential. Perennial grasses cultivated in zero‐tillage management systems hold promise as sustainable agroecosystems. High‐yielding tropical C 4 grasses often have extensive rooting sy...

The International Soil Radiocarbon Database (ISRaD) is an open-source, community resource intended to improve constraints on global carbon models and provide a centralized repository for soil fraction data, including incubations and interstitial measurements.

The presence of large numbers of free-ranging feral cats (Felis catus) has raised concern in terms of both native species predation and potential disease transmission in Hawai'i. A disease of particular concern is toxoplasmosis, caused by Toxoplasma gondii, a zoonotic protozoan parasite. We tested soil samples and cat fecal samples from cat colonie...

Effective soil management is critical to achieving climate change mitigation in plant-based renewable energy systems, yet limitations exist in our understanding of dynamic belowground responses to the cultivation of energy crops. To better understand the belowground dynamics following cultivation of a grassland in a high-yielding tropical perennial...

Improved quantification of the factors controlling soil organic matter (SOM) stabilization at continental to global scales is needed to inform projections of the largest actively cycling terrestrial carbon pool on Earth, and its response to environmental change. Biogeochemical models rely almost exclusively on clay content to modify rates of SOM tu...

Biochar is organic matter that has undergone combustion under low to no oxygen conditions (i.e., pyrolysis) resulting in a recalcitrant, high carbon material specifically for use as a soil amendment. Recently, fervent interest in the production of biochar to address issues of fertility, water holding capacity, remediation, climate change mitigation...

Soil organic matter (SOM) anchors global terrestrial productivity and food and fiber supply. SOM retains water and soil nutrients and stores more global carbon than do plants and the atmosphere combined. SOM is also decomposed by microbes, returning CO2, a greenhouse gas, to the atmosphere. Unfortunately, soil carbon stocks have been widely lost or...

Soil organic matter (SOM) supports the Earth's ability to sustain terrestrial ecosystems, provide food and fiber, and retains the largest pool of actively cycling carbon. Over 75% of the soil organic carbon (SOC) in the top meter of soil is directly affected by human land use. Large land areas have lost SOC as a result of land use practices, yet th...

Although biomass sorghum [Sorghum bicolor (L.) Moench] has been identified as a high yielding bioenergy feedstock crop on the continental USA, there is however lack of conclusive data on its performance in Hawaii (HI). The objectives of this study were to (i) determine the adaptability and productivity of two biomass sorghum hybrids, and (ii) ident...

Biomass is a promising renewable energy option that provides a more environmentally sustainable alternative to fossil resources by reducing the net flux of greenhouse gasses to the atmosphere. Yet, allometric models that allow the prediction of aboveground biomass (AGB), biomass carbon (C) stock non-destructively have not yet been developed for tro...

The natural capacity of the terrestrial landscape to capture and store carbon from the atmosphere can be used in cultivated systems to maximize the climate change mitigation potential of agricultural regions. A combination of inherent soil carbon storage potential, conservation management, and rhizosphere inputs should be considered when making lan...

Replacing fossil fuel with biofuel is environmentally viable from a climate change perspective only if the net greenhouse gas (GHG) footprint of the system is reduced. The effects of replacing annual arable crops with perennial bioenergy feedstocks on net GHG production and soil carbon (C) stock are critical to the system-level balance. Here, we co...

Perennial grasses can sequester soil organic carbon (SOC) in sustainably managed biofuel systems, directly mitigating atmospheric CO2 concentrations while simultaneously generating biomass for renewable energy. The objective of this study was to quantify SOC accumulation and identify the primary drivers of belowground C dynamics in a zero-tillage p...

This research was conducted to determine the potential for the use of Conservation Agriculture Production Systems (CAPS) in the hill region of Nepal, an area highly prone to food insecurity and soil losses. Conservation agriculture (CA) includes the practices of tillage reduction, soil cover maintenance, and optimal crop rotation. Farming in Nepal...

Mitigation of climate change via increased plant productivity and soil carbon (C) sequestration during land use change can be a powerful driver of the net greenhouse gas emissions of a sustainable production system. Yet the net climate change mitigation of managed forests is affected by both tradeoffs between C sequestration and non-renewable C emi...

The renewed interest in the use of sugarcane (Saccharin officinarum L.) for biofuel could provide a viable market for potential Hawaiian sugarcane feedstock producers. In Hawaii, sugarcane is grown as an irrigated 2-yr cycle crop. there is however little information on crop parameter attributes of 2-yr cycle sugarcane. Th is field study on Maui, Ha...

This book focuses on the latest research in conservation agriculture (CA), with an emphasis on the applicability of results worldwide. Using South Asia as a case study, it examines the history and current state of CA regionally and globally, and explores the long-term impacts the adoption of CA practices has on the livelihoods, agricultural product...

This book focuses on the latest research in conservation agriculture (CA), with an emphasis on the applicability of results worldwide. Using South Asia as a case study, it examines the history and current state of CA regionally and globally, and explores the long-term impacts the adoption of CA practices has on the livelihoods, agricultural product...

Volcanic ash-derived soils are important globally for their C sequestration potential and because they are at risk of compaction and degradation due to land use change. Poorly or non-crystalline minerals impart enormous capacity for soils to store and stabilize C, but also unusual chemical and physical properties that make quantifying meaningful so...

Conservation agriculture (CA) systems composed of intercropping and strip tillage practices were evaluated on marginalized maize-based farming system in hill region of Nepal. On-farm experimental trials were conducted on the field of 25 smallholder farmers in three villages of central mid-hill region. Results indicated that although CA systems did...

The universally observed exponential increase in soil-surface CO2 efflux ('soil respiration'; F S) with increasing temperature has led to speculation that global warming will accelerate soil-organic-carbon (SOC) decomposition 1 , reduce SOC storage, and drive a positive feedback to future warming 2 . However, interpreting temperature–F S relationsh...

The terrestrial biosphere sequesters up to a third of annual anthropogenic carbon dioxide emis-sions, offsetting a substantial portion of greenhouse gas forcing of the climate system. Although a number of factors are responsible for this terrestrial carbon sink, atmospheric nitrogen deposition contributes by enhancing tree productivity and promotin...

Departing from the traditional agricultural model of input-heavy, intensive agriculture via the use of agrochemicals and irrigated water, many international development projects have started to promote conservation agriculture in developing countries. However, relying solely on technical expertise, largely generated outside the rural communities in...

A predator-proof fence was built at Kaena Point Natural Area Reserve, Hawaii in 2010 as part of an ecosystem restoration project. All non-native mammalian predators were removed and are now excluded. Non-native plants are being removed and native species are being outplanted. We monitored abundance and reproduction of Puffinus pacificus (wedge-tail...

Chemical functions – Humus is finely divided stable organic matter. Due to the large exposed surface area, humus contributes 30-70% of the cation exchange sites that adsorb plant nutrients that are eventually taken up by plants. Humus chelates micronutrients (usually iron, zinc, copper, or manganese) into soluble compounds, hence increasing their g...

Partially decomposed plant and animal remains have been accumulating in organic soils (i.e. >40% C content) for millennia, making them the largest terrestrial carbon store. There is growing concern that, in a warming world, soil biotic processing will accelerate and release greenhouse gases that further exacerbate climate change. However, the magni...

The chemistry and physical association of soil organic matter in the patchwork of successional forest stands in the eastern US is strongly controlled by past land use. Invasive earthworm activity in these same systems, however, may impart a chemical and physical disturbance exceeding that of land use legacy. We established eight plots within forest...

Controls on the allocation of carbon belowground by plants and the retention of this carbon as new soil organic carbon are poorly quantified, yet exert a large influence on the carbon balance of the terrestrial biosphere. While many studies have now quantified total belowground carbon flux (TBCF), and general global patterns have been identified, r...

Soil carbon (C) sequestration may partially offset rising atmospheric CO2 concentration. Napier grass (Pennisetum purpureum) and Guinea grass (Panicum maximum), in particular, are perennial C4 grasses with high capacity to produce large amounts of both aboveground and belowground biomass. Thus, they have a potential to sequester soil C while simult...

Tropical forests are important for many reasons, one of which is their ability to transfer large quantities of CO2 from the atmosphere to living biomass thereby potentially offsetting climate change. If the biomass is then harvested for commercial use, the stored carbon (C) is released back to the atmosphere. As a result, commercial rotational fore...

Physical separation of soil into various fractions has long been used to address questions concerning mechanisms of soil organic matter stabilization, processes contributing to soil carbon (C) accumulation, and the effects of land use, climate change, and management practice on soil quality and carbon sequestration. However, no published method wor...

Agricultural soils can serve as either a sink or a source for atmospheric carbon (C) and other greenhouse gases (GHG). This is particularly true for tropical soils where influences from climate and soil gradients are wide ranging. Current estimates of GHG flux from soil are often under or overestimated due to high variability in sample sites and in...

Most typical rock outcrop plants of the eastern United States occur either on calcareous or on non-calcareous outcrops, but not both. Often this is because their growth is inhibited in soil from the non-native substrate, as shown in this study for the granite outcrop endemic sedge Cyperus granitophilus when grown on limestone soil. For those rock o...

Background/Question/Methods In forest ecosystems, annual CO2 release from soil to the atmosphere (soil respiration; FS) accounts for ≥50% of gross primary productivity. Tropical broadleaf forests, in particular, account for ~30% of the global annual FS budget. Numerous studies have documented increased FS with increasing temperature. This is ofte...

The Chronic Nitrogen Addition Experiment at Harvard Forest in central Massacusetts, USA was established in 1988 to investigate the effects of increasing anthropogenic atmospheric N deposition on forests in the eastern United States. Located in an old red pine plantation and a mixed hardwood forest, the treated plots have received 50 and 150 kg N/ha...

Twenty years of chronic nitrogen (N) addition to mixed hardwood and red pine stands at the Harvard Forest Long-Term Ecological Research site in MA, USA profoundly impacted forest biogeochemistry and a variety of ecosystem functions. We analyzed carbon (C) and N content in bulk soil and different density fractions to examine changes in both light (a...

Global patterns suggest a positive correlation between temperature and total belowground carbon (C) flux and partitioning in temperate and tropical regions, but these relationships have yet to be tested within a given ecosystem type. We established a transect of nine permanent forest plots along an elevation gradient (800-1600 m) in native-dominate...

The landscapes colonized by invasive earthworms in the eastern U.S. are often patchworks of forest stands in various stages of successional development. We established six field sites in tulip poplar dominated forests in the Smithsonian Environmental Research Center in Edgewater, MD, that span mid (50–70years-three plots) and late (120–150years-thr...

Most plant species endemic to a rock outcrop system have high constancy to one substrate type. However, the complex geology of the Ozark region of Arkansas and Missouri has promoted a diversity of adaptive strategies and challenged the traditional classifications of edaphic adaptation. For example, the small aromatic mint Satureja arkansana ( =  Ca...

Changes in temperature, precipitation, and atmospheric carbon dioxide (CO2) concentration that are expected in the coming decades will have profound impacts on terrestrial ecosystem net primary production (NPP). Nearly all models linking forest NPP with soil carbon (C) predict that increased NPP will result in either unchanged or increased soil C s...

On the Svalbard archipelago, as in other high Arctic regions, tundra soil organic matter (SOM) is primarily plant detritus that is largely stabilized by cold, moist conditions and low nitrogen availability. However, the resistance of SOM to decomposition is also influenced by the quality of organic matter inputs to soil. Different plant communities...

Las plantas que crecen en afloramientos de rocas están sujetas a extremos factores ambientales y edáficos si se comparan con comunidades forestales vecinas que crecen en suelos más profundos. Especies endémicas y otras especies de suelos de afloramiento están bien adaptadas a la poca profundidad de los suelos de estos nichos, pero también pueden es...

Alterations in forest productivity and changes in the relative proportion of above- and belowground biomass may have nonlinear effects on soil organic matter (SOM) storage. To study the influence of plant litter inputs on SOM accumulation, the Detritus Input Removal and Transfer (DIRT) Experiment continuously alters above- and belowground plant inp...

We separated the effects of plant species controls on decomposition rates from environmental controls in northern peatlands using a full factorial, reciprocal transplant experiment of eight dominant bryophytes in four distinct peatland types in boreal Alberta, Canada. Standard fractionation techniques as well as compound-specific pyrolysis molecula...

To investigate the control of earthworm populations on leaf litter biopolymer decay dynamics, we analyzed the residues of Liriodendron tulipifera L. (tulip poplar) leaves after six months of decay, comparing open surface litter and litter bag experiments among forests with different native and invasive earthworm abundances. Six plots were establish...

Over the last 400-500 years invasive European earthworm populations have ýmoved steadily into North American forests either previously devoid of ýearthworms or that contained their own native populations. This has profound ýimpacts upon litter decay and soil organic matter dynamics. To determine the ýimpact of earthworm activity on the biopolymer a...