Adrian Ares

University of Guam | UOG · College of Natural and Applied Sciences

Riparian-management zones protect aquatic species and their habitats in managed forests, yet the effects of riparian-management alternatives warrant further study. We examined effects of alternative riparian-buffer widths on fish and amphibians in small headwater streams with upland forest thinning in western Oregon, USA. Previously, we reported ap...

Forest conservation buffers provide ecosystem services such as soil and water conservation, wildlife habitat, and clean air. This research studied the experiences and intentions of participants in forest buffer contract programs in Virginia, USA provided by governmental conservation agencies. These programs offer technical assistance and share cost...

Participation among private forest owners, logging contractors, and wood products manufacturers in the forest certification sector remains low. Those that enroll are mainly large-acreage owners and specialized manufacturers. Little is known about certification perspectives across the supply chain and how they relate. Comparing what owners, contract...

During the last three decades, the area dedicated to tree plantations in northeast of Argentina has increased five-fold at the expense of the native semideciduous Atlantic Forest. Silvicultural practices such as thinning affect the understory and forest floor incrementing vegetation cover and diversity that may impact ecological functions such as c...

During the last three decades, the area dedicated to tree plantations in northeast of Argentina has increased five-fold at the expense of the native semideciduous Atlantic Forest. Silvicultural practices such as thinning affect the understory and forest floor incrementing vegetation cover and diversity that may impact ecological functions such as c...

A large research effort was initiated in the 1990s in western United States and Canada to investigate how the development of old-growth structures can be accelerated in young even-aged stands that regenerated following clearcut harvests, while also providing income and ecosystem services. Large-scale experiments were established to compare effects...

Poverty and hunger in Africa are prevalent and will increase in absolute terms with population growth and continued land degradation. Therefore, there is a need for sustainable agricultural strategies, such as conservation agriculture (CA) and integrated pest management (IPM). Among CA practices, intercropping holds the promise of providing benefit...

Sustainable intensification (SI) is a term increasingly used for a type of approach applied to international agricultural projects. Despite its widespread use, many still do not understand or know about the various facets of this composite paradigm. A review of the literature has led to the formalization of three principles, which convey the curren...

Conservation agriculture involves minimum soil disturbance, continuous ground cover, and diversified crop rotations or mixtures. Conservation agriculture production systems (CAPS) have the potential to improve soil quality if appropriate cropping systems are developed. In this study, five CAPS including different cropping patterns and cover crops u...

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...

Because forest ecosystems have the capacity to store large quantities of carbon (C), there is interest in managing forests to mitigate elevated CO2 concentrations and associated effects on the global climate. However, some mitigation techniques may contrast with management strategies for other goals, such as maintaining and restoring biodiversity....

Concerns about climate change have generated worldwide interest in managing forests for the uptake and storage of carbon (C). Simultaneously, preserving and enhancing structural, functional, and species diversity in forests remains an important objective. Therefore, understanding tradeoffs and synergies among C storage and sequestration and diversi...

The Density Management Study and Young Stand Thinning and Diversity Study were initiated to investigate whether alternative thinning treatments can accelerate the development of forests toward late-successional structures. An overview of overstory and understory vegetation responses indicates that the magnitude and direction of thinning eff ects in...

Tree mortality shapes forest structural development and the resulting dead wood provides habitat for many species. However, the effects of thinning on mortality and large snag recruitment have been variable and remain poorly understood. We examined thinning effects on tree mortality at eleven Density Management Study (DMS) sites in western Oregon....

Soil salinity is a worldwide limitation for agriculture productivity and simplified procedures to assess salinity are needed. In this study, an efficient method for estimating electrical conductivity (EC) on a saturation extract (ECex) from readings in saturated soil-paste to assess soil salinity was improved. EC values measured in a saturation ext...

Background/Question/Methods Concerns about climate change have stirred worldwide interest in managing forests for the uptake and storage of carbon (C). Simultaneously, preserving and enhancing structural, functional, and species diversity in forests remains important. Linkages between carbon and plant diversity arise from a variety of processes a...

The loss of critical habitat provided by late successional forests has prompted the search for management options that can accelerate the development of late successional forest structure in young stands. We examined operational-scale commercial thinning treatments at seven sites to evaluate if thinning could accelerate development of late successi...

Snags and hardwoods contribute to biological, structural, and functional diversity in old-growth forests. In the US Pacific Northwest, only general knowledge about regional patterns is available to determine target density of snags and hardwood trees. To investigate their variability at relevant scales for silviculture, we examined snag and hardwoo...

Afforestation of grasslands can increase C sequestration and provide additional economic and environmental benefits. Pine plantations, however, have often been found to deplete soil organic C and trigger detrimental effects on soils. We examined soil characteristics under a 45-year-old Pinus radiata stand and under adjacent grassland on maritime du...

Concurrent nutrient and radiation limitation in forests may engender trade-offs between P-use and radiation-use efficiency in tree species. To quantify these trade-offs, structural and physiological traits were examined among five rain-forest species subjected to four levels of fertilization and two levels of radiation in a glasshouse experiment. S...

Eastern black walnut (Juglans nigra L.) has potential for agroforestry practices in the eastern United States because of its value for nuts and timber; however, practices for optimum nut production are poorly defined. Studies were conducted to determine the type of planting material that can assure successful establishment of black walnut for nut p...

Eastern black walnut (Juglans nigra L.) has potential for agroforestry practices in the eastern United States because of its value for nuts and timber; however, practices for optimum nut production are poorly defined. Studies were conducted to determine the type of planting material that can assure successful establishment of black walnut for nut p...

1. Edaphic specialization among species may lead to greater productivity and resource use efficiency across heterogenous landscapes than could be achieved in the absence of specialization. Although this idea has been tested conceptually and in garden experiments, it has rarely been examined in undisturbed forests. 2. To address this gap in our know...

Resource availability and disturbance are important factors that shape the composition, structure, and functioning of ecosystems. We investigated the effects of soil fertility and disturbance on plant-soil interactions and nutrient cycling in a diverse tropical rainforest. Our goal was to determine how common soil specialisation is among species an...

Question: Can augmented forest stand complexity increase understory vegetation richness and cover and accelerate the development of late-successional features? Does within-stand understory vegetation variability increase after imposing treatments that increase stand structural complexity of the overstory? What is the relative contribution of indivi...

Growth and physiological performance of multipurpose tree species can be severely constrained by low phosphorus (P) availability in highly weathered soils. Limitations to plant growth are accentuated by seasonal dry periods. The overall objective of this study was to examine P fertilization and irrigation effects on survival, growth, biomass partit...

Orchard production of eastern black walnut (Juglans nigra L.,) cultivars may be the best way to stabilize the Supply of nuts. The objective of this study was to determine if the relationship between trunk cross-sectional area (TCSA) and nut yield is different between cultivars of black walnut and native trees. Data were collected from 13 stands of...

Thinning even-aged coniferous stands in the Pacific Northwest is aimed at accelerating development of late-successional features, while maintaining long-term forest productivity. We examined effects of thinning on overstory and understory vegetation 11 years after harvest in 40- to 60-year old forests dominated by Douglas-fir (Pseudotsuga menziesii...

Questions: Is the introduced timber species Fraxinus uhdei invasive in Hawai'i? Has logging disturbance facilitated the spread of Fraxinus and other alien species?Location: Windward Mauna Kea, island of Hawai'i.Methods: We surveyed 29 plots which were established before selective logging of the native tree Acacia koa in 1971 to determine if Fraxinu...

The stable carbon (C) composition of tree rings expressed as δ13C, is a measure of intrinsic water-use efficiency and can indicate the occurrence of past water shortages for tree growth. We examined δ13C in 3- to 5-year-old rings of Douglas-fir (Pseudotsuga menziesii (Mirb) Franco) trees to elucidate if decreased water supply or uptake was a critic...

Stand basal area, a stochastic growth model (KOA), and GIS were used to simulate and spatially integrate potential timber production of the native koa (Acacia koa) in uplands on the island of Hawaii. Vegetation patterns were examined to estimate potential impacts on the ecosystem from increased forest activities and to select suitable areas for woo...

Vegetation control (VC) in forest plantations often increases growth of crop trees but can also affect biomass and nutrient partitioning to tree components. We examined above-ground biomass and macronutrients, leaf area and crown structure in 5-year old Douglas-fir (Pseudotsuga menziessi (Mirb.) Franco) growing with VC and with no vegetation contro...

Para estudiar el efecto de la fertilización con P y mejorar la tecnología de su aplicación en plantaciones comerciales de pejibaye (Bactris gasipaes) para palmito, en un suelo clasificado como Fluvaquentic Dystrudepts, se evaluó 0, 9, 18, 33, 48 y 108 kg.ha-1 de P2O5 sobre el crecimiento y rendimiento de palmito durante el primer año, y el doble de...

Ranchers need alternative livestock feeds when herbaceous forages become limiting in summer. Our objectives were to determine: (1) leaf and stem biomass components, (2) nutritive value [in vitro dry matter digestibility (IVDMD), total nonstructural carbohydrate (TNC), N, and N digestibility] of leaves for animal browse, (3) concentration of the sec...

BACKGROUND/PURPOSE This study was conducted in 2003 and 2004 to understand the effects of biomass-removal regimes on soil temperature on a highly-productive Coastal Washington site planted with Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). The study is part of the Fall River project that aims to determine the effect of biomass removal, soil c...

We assessed the effect of native bamboo and lianas on microclimate, tree regeneration and forest structure in a semi-deciduous Atlantic Forest subjected to selective timber extraction during the last century. We hypothetized that bamboo and liana cutting would increase incoming solar radiation in the understory promoting establishment and survival...

Sustainable forest production requires an understanding of the effects of site disturbance on tree growth and the consequences of soil amelioration and vegetation control practices. We assessed the impacts of biomass removals at harvest, soil compaction and tillage, and vegetation control on early growth of Douglas-frr in coastal Washington. Harves...

Soil P deficiency and acidity are two main limitations for trees growing on highly-weathered soils in the tropics. Sound decisions require understanding of the growth phases in tree crops and developing diagnosis, prediction and economic analysis to solve nutritional contrasts. Tree crops differ from annual crops in their growth stages. The diagnos...

The Fall River research site in coastal Washington is an affiliate installation of the North American Long-Term Soil Productivity (LTSP) network, which constitutes one of the world's largest coordinated research programs addressing forest management impacts on sustained productivity. Overall goals of the Fall River study are to assess effects of bi...

Leaf carbon capture strategies of native and exotic invasive plants were compared by examining leaf traits and their scaling relationships at community and global scales. Community-level leaf trait data were obtained for 55 vascular plant species from nutrient-enriched and undisturbed bushland in Sydney, Australia. Global-scale leaf trait data were...

Decision support systems can help improving nutrient management in agricultural and forest ecosystems. We suggest that the practical components of nutrient management are 1) Diagnosis, 2) Prediction, 3) Economic analysis, and 4) Recommendations. Nutrient management and agronomic information for perennial crops such as peach palm (Bactris gasipaes K...

Riverine silvopastoral practices with native pecan (Carya illinoinensis) are a suitable land use for areas subjected to seasonal flooding in southern and central regions of the United States. Nut, timber and forage production, and the economics of managed pecan silvopastures were examined in southeastern Kansas. During 1981-2000, annual hulled nut...

Browse of multipurpose tree species such as black locust could be used to broaden grazing options, but the temporal distribution of foliage has not been adequately studied. Our objective was to determine effects of harvest date, P fertilization (0 and 600kgha−1yr−1), and pollard height (shoots clipped at 5-, 50-, and 100-cm above ground) on foliar...

Many landowners in the United States have little knowledge of the potential economic returns from agroforestry practices. Economic simulators for temperate agroforestry practices have been generated; yet, there are few data sets on yields of timber and other products to validate and refine such models. The objectives of this study were to character...

The browse potential of black locust (Robinia pseudoacacia L.) and thornless honey locust [Gleditsia triacanthos f. inermis (L.) Zabel] has not been adequately tested. Our objective was to determine effects of fertilization and pollarding on biomass and foliar nutritive value in separate studies of black locust and thornless honey locust in Arkansa...

Patterns of biomass partitioning have been extensively studied in loblolly pine (Pinus taeda L.) plantations and natural stands, but not in silvopastoral practices, which are being promoted in southern United States. We conducted aboveground biomass harvests in 18-year-old loblolly pine growing in single-, double-, and quadruple-row configurations...

Soil properties and forest productivity can be affected by heavy equipment used for harvest and site preparation but these impacts vary greatly with site conditions and operational practices. We assessed the effects of ground-based logging on soil physical properties and subsequent Douglas-fir [Pseudotsuga menziesii (Mirb) Franco] growth on a highl...

Fraxinus uhdei (Wenz.) Lingelsh (tropical ash), a species introduced to Hawaii from Mexico, invades forests of the endemic tree Acacia koa A.Gray (koa). We examined physiological and morphological characteristics of koa and tropical ash to explore possible mechanisms that may facilitate invasion of koa forests by tropical ash. Seedlings of both spe...

Black walnut (Juglans nigra) is a prime tree species for agroforestry practices in the United States providing highly prized wood and nuts for human consumption and wildlife. In 54 black walnut stands in south central United States, the site index (i.e., mean dominant height [DH], at age 25 years) ranged between 5.2 and 21.4 m, and was independent...

Fraxinus uhdei (Wenz.) Lingelsh (tropical ash), a species introduced to Hawaii from Mexico, invades forests of the endemic tree Acacia koa A.Gray (koa). We examined physiological and morphological characteristics of koa and tropical ash to explore possible mechanisms that may facilitate invasion of koa forests by tropical ash. Seedlings of both spe...

Farm-level simulators such as the Agroforestry Estate Model use as inputs either yield tables or outputs from forest modeling tools. Forest models rely upon assumptions on site index, stem diameter (DBH) distribution, wood production and tree mortality, which may or may not apply to agroforestry practices. Differences may arise because of the effec...

Acute (broken and leaning) and transient (bending) damage to loblolly pine (Pinus taedaL.) were assessed in a case study of experimental agroforestry plantations following a December 2000 ice storm. Stand ages were 7-, 9-, and 17-years-old and tree density ranged from 150 to 3,360 trees ha-1 in rectangular and multi-row configurations. Wider tree s...

Peach palm (Bactris gasipaes Kunth) is increasingly grown in the tropics for its heart-of-palm and fruit. Determining fertilization response and diagnosing nutrient status in peach palm may require methods that consider the particularities in nutrient acquisition and recycling of perennial crops. Responses to nutrient additions, and the diagnostic...

Peach palm (Bactris gasipaes Kunth) agroecosystems for hearts-of-palm constitute a productive and sustainable land use for the humid tropics. Allometric models allow to predict biomass non-destructively at any time, and subsequently, to determine the span of growth phases, biomass and nutrient pools, and economic yields. The overall goals of this s...

Growth, survival, stem characteristics, resistance to wind, and canker disease of 51 poplar clones were evaluated at age 9 and 10 years, and compared to measurements at age 3 in two trials on the Lower Valley of the Colorado River, Argentina. About 30% of the clones in both trials had large changes in growth rankings at age 9 and 10 compared to ran...

Perennial tree crops develop through growth phases that differ in the rate of biomass and carbon build-up, and in the relative contribution of various pools and fluxes to nutrient cycles and nutrient supply for plant growth. To define these phases in peach palm (Bactris gasipaes) agroecosystems for heart-of-palm production, we estimated biomass in...

El agroecosistema de palmito (Bactris gasipaes) es un sistema de producción sostenible en los trópicos húmedos. Los métodos alométricos permiten predecir la producción de biomasa en forma no destructiva en cualquier momento y a partir de este dato determinar las fases de crecimiento del cultivo, los componentes de la biomasa y los nutrimentos asoci...