University of Minnesota wordmark


Browse subject: tropical subtropical forestry
Number of records: 323

International Society of Tropical Foresters
About this Resource: The ISTF website provides information on the society and its regional and national organizations, the tables of contents of the ISTF newsletter from 1998 onwards, details of international meetings and courses, and details of funding opportunuties. A section is provided for students, listing publications of interest, student organizations, internships, and study programs. There is also a section for younger students and teachers. This site also provides information and articles on current issues in tropical forestry, and a selection of links to related web sites.

CSIRO Tropical Forest Research Centre
About this Resource: This resource is a division of CSIRO which is a scientific global research organization. The site provides research project information and contacts. This information is sorted by topic or group for easy searching. Facilities and staff expertise are explained and a photo gallery is provided for educational purposes. Links to CSIRO divisions pertaining to tropical forestry are provided as well.

European Tropical Forest Research Network (ETFRN)
About this Resource: European Tropical Forest Research Network (ETFRN) is a forum for communication between European organisations, researchers, EU institutions and others concerned with (sub-)tropical forest research. The ETFRN Network seeks to promote the involvement of European research expertise towards the conservation and wise use of forests and woodlands in tropical and subtropical countries. At this site there is access to a newsletter and other publications, a question and answer service, and a National Focal Points Directory. Information can be found by topic or region and there is information about funding and training courses.

Outlook on fertilizer use efficiency in the tropics
About this Resource: In this paper efficiency of applied fertilizers under tropical conditions is examined. Understanding of the fertilizer efficiency is particularly important for the developing countries mainly because there is need for enhancement of crop yields at a reduced cost. Many of the soil, plant and climatic factors of the tropical regions that contribute to the efficiency of the applied fertilizers have been discussed. Many of the tropical soils are acidic in nature and in these soils efficiency of applied fertilizer is relatively poor, mainly because plant roots are unable to grow and function to their fullest extent in utilizing the soils available nutrients. To enhance yield potentials there is need for understanding of interaction between crop species and soil and climatic variables. Incorporation and adoptation of a suitable application time can greatly enhance efficiency of urea form of nitrogen. Research findings in tropical soils have shown that an initial broadcast application of P and subsequent band treatment is more effective than either method of application alone. Current crop yields in tropical countries are far below the known yield potentials. Such low production potentials are attributed to the lack of suitable crop germplasms and understanding of improved agronomic practices. Intensification of research activities in fertilizer use efficiency in tropical countries is suggested.

Reduced-impact logging: Challenges and opportunities
About this Resource: Over the past two decades, sets of timber harvesting guidelines designed to mitigate the deleterious environmental impacts of tree felling, yarding, and hauling have become known as “reduced-impact logging” (RIL) techniques. Although none of the components of RIL are new, concerns about destructive logging practices and worker safety in the tropics stimulated this recent proliferation of semi-coordinated research and training activities related to timber harvesting. Studies in Southeast Asia, Africa, and South and Central America have clearly documented that the undesired impacts of selective logging on residual stands and soils can be substantially reduced through implementation of a series of recommended logging practices by crews that are appropriately trained, supervised, and compensated. Whether reducing the deleterious impacts of logging also reduces profits seems to depend on site conditions (e.g., terrain, soil trafficability, and riparian areas), whether the profits from illegal activities are included in the baseline, and the perspective from which the economic calculations are made. A standardized approach for calculating logging costs using RILSIM software is advocated to facilitate comparisons and to allow uncoupling RIL practices to evaluate their individual financial costs and benefits. Further complicating the matter is that while there are elements common to all RIL guidelines (e.g., directional felling), other components vary (e.g., slope limits of 17-40° with ground-based yarding). While use of RIL techniques may be considered as a prerequisite for sustaining timber yields (STY), in particular, and sustainable forest management (SFM), in general, RIL should not be confounded with STY and SFM. This confusion is particularly problematic in forests managed for light-demanding species that benefit from both canopy opening and mineral soil exposure as well as where harvesting intensities are high and controlled primarily by minimum diameter cutting limits. These qualifications notwithstanding, since logging is the most intensive of silvicultural treatments in most tropical forests managed for timber, some aspects of RIL are critical (e.g., protection of water courses) whether forests are managed for STY, SFM, or even replacement by agricultural crops.

Tropical Forest Conservation and Development: A Bibliography
About this Resource: This site is a database of bibliographies for tropical forestry and covers the topics of tropical forest resources; deforestation; conservation; indigenous peoples; management; policy; trade and industrial development; nontimber forest products; research, education, and training; and history.

Tropical Resources Institute
About this Resource: TRI supports projects that aim to develop practical solutions to issues relating to conservation and management of tropical resources. The website provides information on student oppurtunities in the program as well as other studies in tropical forestry offered at Yale. There is a listing of publications and links to other resources.

International Tropical Timber Organization (ITTO)
About this Resource: ITTO is an intergovernmental organization promoting the conservation and sustainable management, use and trade of tropical forest resources. The ITTO's website provides information about the organization and what they do, projects being worked on, and news and events of the organization and the industry in general. Site also provides publications such as council documents and articles from journals.

Tropical Forest Foundation
About this Resource: The TFF is dedicated to the conservation of tropical forests through sustainable forestry. The primary focus of the Tropical Forest Foundation is to demonstrate and teach sustainable forest management through Reduced-impact Logging. This website offers users information about the Foundation as well as publications such as newsletters, bulletins, and other reports. The site also gives information about how the industry can help, Reduced-impact Logging, forestry in the future, and their sponsors.

Tropical Forest Resource Group
About this Resource: The Tropical Forest Resource Group's website discusses information about the Group such as members, consulting, and background. The site also provides information about training courses run by the Group, projects the Group is working on, and publication information for the Group.

Modeling organic carbon dynamics under no-tillage and plowed systems in tropical soils of Brazil using CQESTR
About this Resource: CQESTR simulates the effect of management practices on soil organic carbon (SOC) stocks. The beta version of the model had been calibrated and validated for temperate regions. Our objective was to evaluate the CQESTR model performance for simulating carbon dynamics as affected by tillage practices in two tropical soils (Ultisol and Oxisol) in southeastern and northeastern Brazil. In the southeast (20.75 S 42.81 W), tillage systems consisted of no tillage (NT); reduced tillage (RT) (one disc plow and one harrow leveling [RT1] or one heavy disc harrow and one harrow leveling [RT2]); and conventional tillage (CT) (two heavy disc harrows followed by one disc plow and two harrow levelings). In the northeast (7.55 S 45.23 W), tillage systems consisted of NT, RT (one chisel plow and one harrow leveling), and CT (one disk plow, two heavy disk harrowings, and two harrow levelings). CQESTR underestimated SOC at both sites, especially under NT systems, indicating that adjustments (e.g., the inclusion of clay mineralogy factor) are necessary for more accurate simulation of SOC in the tropics. In spite of this, measured and simulated values of SOC in the 0-20cm depth were well correlated (southeast, R ² =0.94, p <0.01; northeast, R ² =0.88, p <0.05). With respect to initial conditions (native forest), CQESTR estimated a decrease in SOC stocks in plowed and no-tillage systems. In 2006, in the southeast, SOC stocks were 28.8, 23.7, 23.2, and 22.0Mgha⁻¹ under NT, RT2, RT1, and CT, respectively; in the northeast, stocks were 36.0, 33.8, and 32.5Mgha⁻¹ under NT, RT, and CT, respectively. The model estimated carbon emissions varying from 0.36 (NT) to 1.05Mgha⁻¹ year⁻¹ (CT) in the southeast and from 0.30 (NT) to 0.82 (CT) Mgha⁻¹ year⁻¹ in the northeast. CQESTR prediction of SOC dynamics illustrates acceptable performance for the two tropical soils of Brazil.

International Institute of Tropical Forestry (IITF)
About this Resource: The IITF's goal is to address aspects of physical, social, and economic issues in managing tropical forests. This website contains information on the Caribbean National Forest, international programs, the IITF Library, recent publications, products and services, and state and private forestry programs. There are links to conservation groups, federal agencies, land management, and state and private forestry sites.

Exploratorium Science Of Gardening: Control; Make it grow . . . bigger, lusher, juicer
About this Resource: The Exploratorium Museum of Science, Art and Human Perception explores "the science of gardening". Segments of this web service explores garden feed, control techniques, and blooms. Site visitors will discover video clips, interactive features and articles rich with photographs. The importance of seeds as a source for biodiversity is covered in a article. Designed for the general public, the Museum also elaborates on the wonders of hybrid production as it assists us with the novel crops and plants.

University of Florida, Environmental Horticulture
About this Resource: Environmental horticulture deals with breeding, propagating, installing, and maintaining plants to improve the human environment. The website describes research done by the department in the areas of floriculture production, foliage production, horticultural taxonomy, plant restoration conservation biology, plant molecular biology, and turfgrass. There are links to classes, programs, and plant information databases and information about children's gardening, floriculture, foliage, home gardening, turfgrass, and trees and shrubs. There are also links to related publications.

Massive cellular disruption occurs during early imbibition of Cuphea seeds containing crystallized triacylglycerols
About this Resource: The transition from anhydrobiotic to hydrated state occurs during early imbibition of seeds and is lethal if lipid reserves in seeds are crystalline. Low temperatures crystallize lipids during seed storage. We examine the nature of cellular damage observed in seeds of Cuphea wrightii and C. lanceolata that differ in triacylglycerol composition and phase behavior. Intracellular structure, observed using transmission electron microscopy, is profoundly and irreversibly perturbed if seeds with crystalline triacylglycerols are imbibed briefly. A brief heat treatment that melts triacylglycerols before imbibition prevents the loss of cell integrity; however, residual effects of cold treatments in C. wrightii cells are reflected by the apparent coalescence of protein and oil bodies. The timing and temperature dependence of cellular changes suggest that damage arises via a physical mechanism, perhaps as a result of shifts in hydrophobic and hydrophilic interactions when triacylglycerols undergo phase changes. Stabilizers of oil body structure such as oleosins that rely on a balance of physical forces may become ineffective when triacylglycerols crystallize. Recent observations linking poor oil body stability and poor seed storage behavior are potentially explained by the phase behavior of the storage lipids. These findings directly impact the feasibility of preserving genetic resources from some tropical and subtropical species.

Smithsonian Tropical Research Institute
About this Resource: The Smithsonian Tropical Research Institute (STRI) traces its' ninety year history to the construction of the Panama Canal. Today, the Institute is engaged in a variety of research projects and this Home Page serves as a portal to a wide array of relevant information. The "What We Do" link accesses a host of details associated with the Institute's research programs; the Earl S. Tupper Library; and explanations with regard to education, fellowships, internships and STRI's international activities. As an example, STRI's Center for Tropical Forest Science (CTFS) links research at 17 sites throughout the tropics in collaboration with institutions in 14 countries. STRI is also a member of the Organization for Tropical Studies (OTS). STRI has active cooperative agreements with universities, research institutions, and both governmental, non governmental organizations in Latin America, North America, Europe and Asia. CTFS links to field sites, newsletters and bibliographies. The Earl S. Tupper Tropical Sciences Library is a comprehensive resource for tropical biology and conservation and the website describes the Library. Because the Smithsonian Institution is involved in a transformation of its' online library resources, a link has been established to the Smithsonian's Digital Library. The Home Page emphasizes news and events; webcams link to Barro Colorado Island (BCI) and several databases are featured, these include: the Marine Environmental Sciences Program (MESP) which monitors a variety of physical and biological parameters on the Atlantic and Pacific coasts of Panama. The STRI Bibliography (1911-2003) cites publications by staff, visitors, fellows and students that result from research supported by the Smithsonian Tropical Research Institute. Maps comprises a map library and there is an online tree atlas of the Panama Canal Watershed. The T-ESP website link describes the Institute's Terrestrial Environmental Science Program (TESP).

Recovery of a Subtropical Dry Forest After Abandonment of Different Land Uses
About this Resource: We studied the ecological characteristics of 45-50-yr-old subtropical dry forest stands in Puerto Rico that were growing on sites that had been deforested and used intensively for up to 128 yr. The study took place in the Guánica Commonwealth Forest. Our objective was to assess the long-term effects of previous land use on this forest--i.e., its species composition, structure, and functioning. Previous land-use types included houses, farmlands, and charcoal pits. Stands with these land uses were compared with a nearby mature forest stand. The speed and path of forest recovery after deforestation and land-use abandonment depended on the conditions of the land. Study areas where land uses had removed the forest canopy and altered soil conditions (houses and farmlands) required a longer time to recover and had a different species composition than study areas where land uses retained a forest canopy (charcoal pits). Different forest attributes recovered at different rates. Crown area index, stem density, and litterfall rate recovered faster than stemwood and root, biomass, tree height, and basal area. Where previous land uses removed the canopy, Leucaena leucocephala, a naturalized alien pioneer species, dominated the regrowth. Native species dominated abandoned charcoal pits and mature forest. The change in species composition, including the invasion of alien species, appears to be the most significant long-term effect of human use and modification of the landscape.

Gardening and Home Horticulture Publications : Arizona Extension Service
About this Resource: Publications on gardening and home horticulture, available for sale and/or in HTML/PDF formats. Accessible through the University of Arizona - College of Agriculture and Life Sciences. A few in Spanish.

Development of equations for predicting Puerto Rican subtropical dry forest biomass and volume
About this Resource: Carbon accounting, forest health monitoring and sustainable management of the subtropical dry forests of Puerto Rico and other Caribbean Islands require an accurate assessment of forest aboveground biomass (AGB) and stem volume. One means of improving assessment accuracy is the development of predictive equations derived from locally collected data. Forest inventory and analysis (FIA) measured tree diameter and height, and then destructively sampled 30 trees from 6 species at an upland deciduous dry forest site near Ponce, Puerto Rico. This data was used to develop best parsimonious equations fit with ordinary least squares procedures and additive models fit with nonlinear seemingly unrelated regressions that estimate subtropical dry forest leaf, woody, and total AGB for Bucida buceras and mixed dry forest species. We also fit equations for estimating inside and outside bark total and merchantable stem volume using both diameter at breast height (d.b.h.) and total height, and diameter at breast height alone for B. buceras and Bursera simaruba. Model fits for total and woody biomass were generally good, while leaf biomass showed more variation, possibly due to seasonal leaf loss at the time of sampling. While the distribution of total AGB into components appeared to remain relatively constant across diameter classes, AGB variability increased and B. simaruba and B. buceras allocated more carbon into branch biomass than the other species. When comparing our observed and predicted values to other published dry forest AGB equations, the equation developed in Mexico and recommended for areas with rainfall >900 mm/year gave estimates substantially lower than our observed values, while equations developed using dry forest data from forest in Australia, India and Mexico were lower than our observed values for trees with d.b.h. <25 cm and slightly higher for trees with d.b.h. >30 cm. Although our ability to accurately estimate merchantable stem volume and live tree AGB for subtropical dry forests in Puerto Rico and other Caribbean islands has been improved, much work remains to be done to sample a wider range of species and tree sizes.

Carbon Supply and Storage in Tilled and Nontilled Soils as Influenced by Cover Crops and Nitrogen Fertilization
About this Resource: Soil carbon (C) sequestration in tilled and nontilled areas can be influenced by crop management practices due to differences in plant C inputs and their rate of mineralization. We examined the influence of four cover crops {legume [hairy vetch (Vicia villosa Roth)], nonlegume [rye (Secale cereale L.)], biculture of legume and nonlegume (vetch and rye), and no cover crops (or winter weeds)} and three nitrogen (N) fertilization rates (0, 60 to 65, and 120 to 130 kg N ha-1) on C inputs from cover crops, cotton (Gossypium hirsutum L.), and sorghum [Sorghum bicolor (L.) Moench)], and soil organic carbon (SOC) at the 0- to 120-cm depth in tilled and nontilled areas. A field experiment was conducted on Dothan sandy loam (fine-loamy, siliceous, thermic Plinthic Paleudults) from 1999 to 2002 in central Georgia. Total C inputs to the soil from cover crops, cotton, and sorghum from 2000 to 2002 ranged from 6.8 to 22.8 Mg ha-1. The SOC at 0 to 10 cm fluctuated with C input from October 1999 to November 2002 and was greater from cover crops than from weeds in no-tilled plots. In contrast, SOC values at 10 to 30 cm in no-tilled and at 0 to 60 cm in chisel-tilled plots were greater for biculture than for weeds. As a result, C at 0 to 30 cm was sequestered at rates of 267, 33, -133, and -967 kg C ha-1 yr-1 for biculture, rye, vetch, and weeds, respectively, in the no-tilled plot. In strip-tilled and chisel-tilled plots, SOC at 0 to 30 cm decreased at rates of 233 to 1233 kg C ha-1 yr-1. The SOC at 0 to 30 cm increased more in cover crops with 120 to 130 kg N ha-1 yr-1 than in weeds with 0 kg N ha-1 yr-1, regardless of tillage. In the subtropical humid region of the southeastern United States, cover crops and N fertilization can increase the amount of C input and storage in tilled and nontilled soils, and hairy vetch and rye biculture was more effective in sequestering C than monocultures or no cover crop.

University of Maine Cooperative Extension Publications Store
About this Resource: Publications covering diverse topics are listed at the top of the web page. Generally, available for purchase. The link will identify subjects and redirect the site visitor to a description of a title.

Benefits of low kenaf loading in biobased composites of poly(L-lactide) and kenaf fiber
About this Resource: Bast fibers from stems of kenaf (Hibiscus cannabinus, L.), a warm-season tropical herbaceous annual plant, were dispersed into poly-L-lactide (PLLA) matrix by melt-mixing followed by compression molding. Low fiber fractions (1-5%) were investigated. The composites showed a slight lowering of thermal stability when evaluated by thermogravimentric analysis. X-ray diffraction and differential scanning calorimetry indicated an influence of kenaf on the crystallization of PLLA. The fiber dispersion in the polymer matrix was established by polarized optical microscopy. Scanning electron microscopy showed good fiber-matrix adhesion as revealed by the combination of dispersion, interaction, and crystallinity, which enabled an increase in the mechanical properties of the composite that scaled with concentration.

Home Garden Publications : Hawaii Extension Service
About this Resource: Full text publications on home gardening, accessible through the University of Hawaii at Manoa, College of Tropical Agriculture and Human Resources.

Hurricane Katrina: perspective from the southern horticultural laboratory
About this Resource: Surviving extremes of climate is a fundamental component of horticultural production and research. The Southern Horticultural Laboratory has weathered many storms including Hurricane Camille and now Hurricane Katrina. The name of the research station has changed twice, both times following massive hurricanes. Before Hurricane Camille in 1969, the station title was the Tung Research Unit. After the devastation of the tung industry by Camille, the research focus changed to blueberries and other small fruit crops with a corresponding name change to Small Fruit Research Unit in 1976. The research objectives expanded to include ornamental research in 2001. Post Hurricane Katrina, the unit was renamed the Thad Cochran Southern Horticultural Laboratory to reflect the station's expanded research mission. This paper chronicles how the station reacted to the devastation of Hurricane Katrina. It also evaluates economic vitality of commodities researched at the station in contrast with storm effects on pecan and the demise of tung production. Katrina produced some temporary interruptions in production but no drastic restructuring of the type experienced with tung production after Camille is anticipated. Hurricanes are inevitable for the Gulf Coast region. Wise planning and implementation of preventative measures to protect horticultural crops and research will determine future success.

PLANTanswers | Texas Cooperative Extension
About this Resource: A plant question/answer forum which provides information primarily in question and answer format. Texas Cooperative Extension also identifies a wide assortment of PLANTanswer publications - topics covered include: recommended plants, varietal trials, gardening guides, growing information, ornamental plants, varietals, plants that are unique for/within Texas and miscellaneous material. Two notable features of this service include heros for horticulture - friends of horticulture in Texas - and recipes.

Texas Poinsettia Producers Guide
About this Resource: Designed to assist commercial poinsettia producers with many of the cultural and economic problems experienced under Texas growing conditions. Areas discussed include: history; forms and styles; economics and marketing; cultural characteristics; cultivars; production schedule; height control; irrigation; selecting a growing medium; water quality; nutrition; insect and mite management; diseases and control. A service of the Aggie Horticulture Network with Texas A&M University.

Forest Policy and Environment Programme (ODI)
About this Resource: The FPEP is a product of the Overseas Development Institute and focuses on policy in tropical forest districts. The website discusses the research being done and the people involved with it. The site also provides news, network information, publication information and ordering, and links to other related sites.

Fruit Gardening in the Landscape
About this Resource: Designed to give homeowners a brief overview of the fruits that grow well in Texas and the problems that may be encountered with others covers: apples; blackberries; blueberries; chestnuts; figs; grapes; jujubes; loquats; peaches; nectarines; plums; pears; pecans; persimmons; Pistachios; Pomegranates; Raspberries; Strawberries; tropical and subtropical fruits; and walnuts. Subject themes addressed include: selecting the best variety; geographic adaptation of varieties; climate; managing crops; and controlling problems.

Microbial community responses in forest mineral soil to compaction, organic matter removal, and vegetation control
About this Resource: We tested three disturbance hypotheses in young conifer plantations: H1: soil compaction and removal of surface organic matter produces sustained changes in microbial community size, activity, and structure in mineral soil; H2: microbial community characteristics in mineral soil are linked to the recovery of plant diversity; and H3: community responses are strongly modified by regional climate. Microbial biomass, respiration, carbon utilization, and phospholipid fatty acids were compared at two subtropical installations and one Mediterranean-type climate installation of the North American Long-Term Soil Productivity study. Treatments included combinations of compaction (none vs. severe), organic matter removal (none vs. complete), and weed control (none vs. complete), plus an uncut reference stand. Weed control resulted in the only consistent decline or shift in microbial indices at the subtropical sites. At the Mediterranean-type climate site, overstory harvesting resulted in declines in microbial biomass, respiration, and fungal phospholipid fatty acids that far outweighed the effects of the soil disturbance treatments. Severe compaction had no effect on community size or activity at any site. Microbial communities were generally tolerant of postharvest soil disturbance, leading to a rejection of the experimental hypotheses, with the exception of a link between microorganisms and recovery of plant diversity (H2) at the subtropical sites.

Forestry Images : Forest Health, Natural Resources & Silviculture Images
About this Resource: A link to over 22,000 digital images devoted to forestry, natural resources, silviculture, incluing: forest pests, trees, understory and rangeland plants, wildlife, people, places and scenes. A substantial number of photos are public sector images; the downloading and use of which simply requires a registration. Availability results from a joint project involving The Bugwood Network, USDA's Forest Service, and the University of Georgia (engaging the Warnell School of Forest Resources and the College of Agricultural and Environmental Sciences).

Home Garden Vegetable : Hawaii Extension Service
About this Resource: Full-text publications on home grown vegetables, from the University of Hawaii at Manoa, College of Tropical Agriculture and Human Resources.

Nutrient availability constrains the hydraulic architecture and water relations of savannah trees
About this Resource: Leaf and whole plant-level functional traits were studied in five dominant woody savannah species from Central Brazil (Cerrado) to determine whether reduction of nutrient limitations in oligotrophic Cerrado soils affects carbon allocation, water relations and hydraulic architecture. Four treatments were used: control, N additions, P additions and N plus P additions. Fertilizers were applied twice yearly, from October 1998 to March 2004. Sixty-three months after the first nutrient addition, the total leaf area increment was significantly greater across all species in the N- and the N + P-fertilized plots than in the control and in the P-fertilized plots. Nitrogen fertilization significantly altered several components of hydraulic architecture: specific conductivity of terminal stems increased with N additions, whereas leaf-specific conductivity and wood density decreased in most cases. Average daily sap flow per individual was consistently higher with N and N + P additions compared to the control, but its relative increase was not as great as that of leaf area. Long-term additions of N and N + P caused midday ΨL to decline significantly by a mean of 0.6 MPa across all species because N-induced relative reductions in soil-to-leaf hydraulic conductance were greater than those of stomatal conductance and transpiration on a leaf area basis. Phosphorus-fertilized trees did not exhibit significant changes in midday ΨL. Analysis of xylem vulnerability curves indicated that N-fertilized trees were significantly less vulnerable to embolism than trees in control and P-fertilized plots. Thus, N-induced decreases in midday ΨL appeared to be almost entirely compensated by increases in resistance to embolism. Leaf tissue water relations characteristics also changed as a result of N-induced declines in minimum ΨL: osmotic potential at full turgor decreased and symplastic solute content on a dry matter basis increased linearly with declining midday ΨL across species and treatments. Despite being adapted to chronic nutrient limitations, Cerrado woody species apparently have the capacity to exploit increases in nutrient availability by allocating resources to maximize carbon gain and enhance growth. The cost of increased allocation to leaf area relative to water transport capacity involved increased total water loss per plant and a decrease in minimum leaf water potentials. However, the risk of increased embolism and turgor loss was relatively low as xylem vulnerability to embolism and leaf osmotic characteristics changed in parallel with changes in plant water status induced by N fertilization.

American Horticultural Therapy Association
About this Resource: The American Horticultural Therapy Association champions therapuetic gardens and gardening. Since 1973, the Association has advanced horticulture as a therapy that aids in the improvement of human well-being. The Association is also engaged in the professional registration of horticultural therapists. The website is a source for organizational detail and activity.

Evaluation of birth and weaning traits of Romosinuano calves as purebreds and crosses with Brahman and Angus
About this Resource: The objectives of this work were to evaluate birth and weaning traits, to estimate genetic effects, including heterosis and direct and maternal breed effects, and to evaluate calving difficulty, calf vigor at birth, and calf mortality of Romosinuano as purebreds and as crosses with Brahman and Angus. Calves (n = 1,348) were spring-born from 2002 through 2005 and weaned in the fall of each year at about 7 mo of age. Traits evaluated included birth and weaning weight, ADG, BCS, and weaning hip height. Models used to analyze these traits included the fixed effects of year, sire and dam breeds, management unit, calf sex, cow age, and source of Angus sire (within or outside of the research herd). Calf age in days was investigated as a covariate for weaning traits. Sire within sire breed and dam within dam breed were random effects. Estimates of Romosinuano-Brahman and Romosinuano-Angus heterosis (P < 0.05) were 2.6 ± 0.3 (8.6%) and 1.4 ± 0.3 kg (4.7%) for birth weight, 20.5 ± 1.5 (9.5%) and 14.6 ± 1.4 kg (7.4%) for weaning weight, 79.2 ± 6.1 (9.8%) and 55.1 ± 6.0 g (7.5%) for ADG, 0.16 ± 0.03 (2.7%) and 0.07 ± 0.03 (1.2%) for BCS, and 2.77 ± 0.32 cm (2.4%) and 1.87 ± 0.32 cm (1.7%) for hip height. Heterosis for Brahman-Angus was greater (P < 0.05) than all Romosinuano estimates except those for Romosinuano-Brahman and Romosinuano-Angus BCS. Romosinuano direct effects were negative and lowest of the breeds, except for the Angus estimate for hip height. Romosinuano maternal effects were the largest of the 3 breeds for birth weight and hip height but intermediate to the other breeds for weaning weight and ADG. A large proportion of Brahman-sired calves from Angus dams (0.09 ± 0.03; n = 11) was born in difficult births and died before 4 d of age. Brahman and Angus purebreds and Romosinuano-sired calves from Brahman dams also had large proportions of calves that died before weaning (0.09 or greater). Results indicated that Romosinuano may be used as a source of adaptation to subtropical environments and still incorporate substantial crossbred advantage for weaning traits, although not to the extent of crosses of Brahman and Angus.

Carbon dioxide and high temperature effects on growth of young orange trees in a humid, subtropical environment
About this Resource: Rising atmospheric carbon dioxide (CO₂) concentration and global warming could impact growth of citrus trees. Five 2-year-old Ambersweet orange trees on Swingle citrumelo rootstocks were transplanted into soil containers in two temperature-gradient greenhouses on 9 August 1994 at Gainesville, FL, USA. Either 360 or 720μmol(CO₂)mol⁻¹ (air) was maintained in the greenhouses. Two containers were located in each of four temperature zones maintained at 1.5°C increments between each zone with a 4.5°C difference between zones 1 and 4. The main objective was to test the hypothesis that biomass growth ratios of CO₂-enriched to ambient CO₂-exposed young sweet orange trees would be similar to the large growth enhancements (about 2.6-fold) reported from Phoenix, AZ, USA during the first 3 years of growth of sour orange trees. One tree per container was harvested in 1995 and four trees per container were harvested in 1996. Growth parameters were different between years except leaf fresh weight and fine root biomass. Elevated CO₂ increased growth parameters except leaf growth and fine root biomass. Biomass response ratios to CO₂ (720/360) for 1995 and 1996, respectively, were 1.57 and 1.18 for shoot wood, 1.34 and 1.15 for total above-ground, 1.46 and 1.08 for tap roots, 1.67 and 1.54 for secondary roots, 1.29 and 0.95 for fine roots (NS-CO₂), 1.40 and 1.19 for total roots, 1.47 and 1.18 for total wood, and 1.37 and 1.17 for total plants. The decrease in response to CO₂ in the second year was attributed to crowding of shoot and root space. Components of shoot wood, total above ground, taproot, fine root, total root, total wood, and total plant biomass increased slightly (0.01< P <0.05) with increasing temperature. No CO₂ xtemperature interactions were significant. The hypothesis that elevated CO₂ would cause biomass increases of about 2.6-fold compared to ambient CO₂ treatments (as found in the midlattitude desert environment of Phoenix) was not supported. May through September mean maximum daily vapor pressure deficit (VPD) was 5.54 and 2.25kPa for Phoenix and Gainesville, respectively, a ratio of [almost equal to]2.5. High summertime VPD coupled with limited water flow capacity within citrus trees that lead to pronounced midday depressions in photosynthesis in ambient CO₂ is discussed as the underlying environmental cause of the large CO₂ enrichment effects in a midlattitude desert compared to the Gainesville humid subtropical climate.

Horticulture Publications : Nebraska Extension Service
About this Resource: HTML publications are available on a variety of topics involving horticulture; clustered under the following subject headings: ornamentals, vegetables, fruits, turf, and miscellaneous. Accessible through the University of Nebraska (Lincoln).

Agroecosystem management effects on soil carbon and nitrogen
About this Resource: The cumulative effects of long-term (1980-1990) tillage and crop rotation management on soil organic C and N concentrations and potential mineralization were determined. Tillage systems studied were conventional moldboard plow tillage and conservation tillage, with various crop rotations including: continuous soybean (Glycine max L.)-wheat (Triticum aestivum L.) cover (SW); continuous corn (Zea mays L.)-wheat cover (CW); and corn-wheat cover-soybean-wheat cover (CWSW). Surface soil (0-5, 5-10, and 10-20 cm depth increments) organic C and N concentrations and potential mineralization were determined for all tillage/rotation combinations in October 1990. After 10 years, surface soil organic C and N concentrations were 67% and 66% higher, respectively, under conservation tillage than plow tillage to a depth of 10 cm. Potential C and N mineralization followed a pattern similar to organic C and N distribution. However, differences in substrate quality below 10 cm indicated that conservation tillage promoted N immobilization. Crop rotation had less effect than tillage on soil organic C and N amounts and potential mineralization. Rotations with higher frequency of corn (CW and CWSW) had higher organic C and N concentrations and C mineralization than SW; crop rotation had no effect on potential N mineralization. Tillage system apparently influenced soil organic matter concentrations and mineralization via crop residue incorporation rather than any effects owing to concentration differences at the soil surface, while the effect of crop rotation was related to amount of crop residues added between 1980 and 1990.

Conservation tillage induced changes in organic carbon, total nitrogen and available phosphorus in a semi-arid alkaline subtropical soil
About this Resource: A multi-year experiment was conducted to compare the effects of conservation tillage (no-till and ridge-till) with conventional plow tillage on organic C, N, and resin-extractable P in an alkaline semi-arid subtropical soil (Hidalgo sandy clay loam, a fine-loamy, mixed, hyperthermic Typic Calciustoll) at Weslaco, TX (26°9'N 97°57'W). Tillage comparisons were established on irrigated plots in 1992 as a randomized block design with four replications. Soil samples were collected for analyses 1 month before cotton planting of the eighth year of annual cotton (planted in March) followed by corn (planted in August). No-till resulted in significantly (p<0.01) greater soil organic C in the top 4 cm of soil, where the organic C concentration was 58% greater than in the top 4 cm of the plow-till treatment. In the 4-8 cm depth, organic C was 15% greater than the plow-till control. The differences were relatively modest, but consistent with organic C gains observed in hot climates where conservation tillage has been adopted. Higher concentrations of total soil N occurred in the same treatments, however a significant (p<0.01) reduction in N was detected below 12 cm in the ridge-till treatment. The relatively low amount of readily oxidizable C (ROC) in all tillage treatments suggests that much of the soil organic C gained is humic in nature which would be expected to improve C sequestration in this soil. Against the background of improved soil organic C and N, bicarbonate extractable P was greater in the top 8 cm of soil. Some of the improvement, however, appeared to come from a redistribution or “mining” of P at lower soil depths. The results indicate that stratification and redistribution of nutrients were consistent with known effects of tillage modification and that slow improvements in soil fertility are being realized.

Reducing chilling injury and maintaining quality of horticultural crops with natural products and their derivatives.
About this Resource: Most tropical and subtropical crops are susceptible to chilling injury. They can not take the advantage of refrigeration to lengthen their storage and shelf lives because of the development of chilling injury symptoms when exposed to low temperatures. Therefore, how to reduce chilling injury and maintain quality of these crops after harvest becomes an important task. We have found that certain natural products and their derivatives seem to be effective in delaying the onset and reducing the severity of chilling injury symptoms. Of many natural products that we have tested, methyl jasmonate (MJ) and methyl salicylate (MS) were the most beneficial. These two natural volatile compounds consistently reduced chilling injury in mangoes, papayas, peppers, tomatoes, and zucchini squashes. MJ and MS were also found to enhance the resistance of tissues to chilling injury by increasing the gene expression of heat shock proteins, pathogenesis-related proteins, and alternative oxidase. Recent results also showed that MJ increased antioxidant capacities, antioxidant enzyme activities, and free radical scavenging capacities in the tissues. These results indicate that MJ can act to prevent chilling injury by a mechanism which involves protecting tissues from free radical injury.

American Society for Horticultural Science
About this Resource: The American Society for Horticultural Science (ASHS), established in 1903, facilitates research and education - serving as an agent for the promotion of horticulture. This link, connecting to ASHS's Home Page, is a source for the Society's news and announcements and also affords table of content information (with abstracts) to the Society's major publications for the past near-decade. The website incorporates member-only access as well; with full-text access to these publications. All site visitors can obtain membership information; there are a number of external links for anyone interested in horticultural research and career-based information is also available.

Lycopene: From plants to humans
About this Resource: Lycopene is a pigment that imparts a red or red-orange color to some fruits and vegetables. This carotenoid has been extensively studied over the last 10 years because of its potent antioxidant activity and medical evidence that dietary intake can reduce the incidence of cardiovascular disease and some cancers. The purpose of this review is to provide researchers in the areas of horticulture and food science a current summary of available information on lycopene in plants, stabilization and extraction, and potential health benefits as delineated in current medical studies.

Drought-induced nitrous oxide flux dynamics in an enclosed tropical forest
About this Resource: El Niño-La Niña cycles strongly influence dry and wet seasons in the tropics and consequently nitrous oxide (N2O) emissions from tropical rainforest soils. We monitored whole-system and soil chamber N2O fluxes during 5-month-long droughts in the Biosphere 2 tropical forest to determine how rainfall changes N2O production. A consistent pattern of N2O flux changes during drought and subsequent wetting emerged from our experiments. Soil surface drying during the first days of drought, presumably increased gas transport out of the soil, which increased N2O fluxes. Subsequent drying caused an exponential decrease in whole-system (4.0±0.1% day-1) and soil chamber N2O flux (8.9±0.8% day-1; south chamber; and 13.7±1.1% day-1; north chamber), which was highly correlated with soil moisture content. Soil air N2O concentration ([N2O]) and flux measurements revealed that surface N2O production persisted during drought. The first rainfall after drought triggered a N2O pulse, which amounted to 25% of drought-associated reduction in N2O flux and 1.3±0.4% of annual N2O emissions. Physical displacement of soil air by water and soil chemistry changes during drought could not account for the observed N2O pulse. We contend that osmotic stress on the microbial biomass must have supplied the N source for pulse N2O, which was produced at the litter-soil interface. After the pulse, N2O fluxes were consistently 90% of predrought values. Nitrate change rate, nutrient, [N2O], and flux analyses suggested that nitrifiers dominated N2O production during the pulse and denitrifiers during wet conditions. N2O flux measurements in Biosphere 2, especially during the N2O pulse, demonstrate that large-scale integration methods, such as flux towers, are essential for improving ecosystem N2O flux estimates.

Influence of cover crops and irrigation rates on tomato yields and quality in a subtropical region
About this Resource: Intensive rainfall during summer causes substantial nutrient leaching in a subtropical region, where most vegetable lands lay fallow during this period. Also, an excessive amount of irrigation water supplied during the winter vegetable growing season leads to soil nutrient loss, which greatly impacts vegetable yields, especially in soils that possess a low capacity to retain soil water and nutrients. A 2-year field experiment was carried out to evaluate the effects of various summer cover crops and irrigation rates on tomato yields and quality, and on soil fertility in a subtropical region of Florida. The cover crops were sunn hemp [Crotalaria juncea (L.) 'Tropic Sun'], cowpea [Vigna unguiculata (L.) Walp, 'Iron Clay'], velvetbean [Mucuna deeringiana (Bort.) Merr.], and sorghum sudangrass [Sorghum bicolor x S. bicolor var. sudanense (Piper) Stapf.], with a weed-free fallow as a control. The cover crops were planted during late Spring 2001 and 2002, incorporated into the soil in the fall, and tomatoes [Lycopersicon esculentum (Mill.) 'Sanibel'] were grown on raised beds during Winter 2001-02 and 2002-03, respectively. Irrigation in various treatments was controlled when tensiometer readings reached -5, -10, -20, or -30 kPa. The cover crops produced from 5.2 to 12.5 Mg.ha(-1) of above ground dry biomass and 48 to 356 Mg.ha(-1) of N during 2001-02 and from 3.6 to 9.7 Mg.ha(-1) of dry biomass and 35 to 277 kg.ha(-1) of N during 2002-03. The highest N contribution was made by sunn hemp and the lowest by sorghum sudangrass. Based on 2-year data, tomato marketable yields were increased from 14% to 27% (p less than or equal to 0.05) by growing cover crops, and the greatest increase occurred in the sunn hemp treatment followed by the cowpea treatment. Irrigation at -10, -20, and -30 kPa significantly improved marketable yields by 14%, 12%, and 25% (p less than or equal to 0.05) for 2001-02, and 18%, 31%, and 34% (p less than or equal to 0.05) for 2002-03, respectively, compared to yields at the commonly applied rate, -5 kPa (control). Irrigation at -30 kPa used about 85% less water than at -5 kPa. Yields of extra-large fruit in the sunn hemp and cowpea treatments from the first harvest in both years averaged 12.6 to 15.2 Mg.ha(-1), and they were significantly higher than yields in the fallow treatment (10.2 to 11.3 Mg.ha(-1)). Likewise at -30 kPa yields of extra-large fruit from the first harvest for both years were 13.0 to 15.3 Mg.ha(-1) compared to 9.8 to 10.7 Mg.ha(-1) at -5 kPa. Soil NO3-N and total N contents in sunn hemp and cowpea treatments were significantly higher than those in fallow. The results indicate that growing legume summer cover crops in a subtropical region, especially sunn hemp and cowpea, and reducing irrigation rates are valuable approaches to conserve soil nutrients and water, and to improve soil fertility and tomato yields and quality.

Non-Citrus Fruit and Nut Crop Publications : Florida Extension Service
About this Resource: A link to the Florida Cooperative Extension publications on non-citrus fruit and nut publications. A listing from the Electronic Data Information Source (EDIS) is supported by the University of Florida's Institute of Food Science and Agricultural Sciences (UF/IFAS).

Rock-degrading endophytic bacteria in cacti
About this Resource: A plant-bacterium association of the cardon cactus (Pachycereus pringlei) and endophytic bacteria promotes establishment of seedlings and growth on igneous rocks without soil. These bacteria weather several rock types and minerals, unbind significant amounts of useful minerals for plants from the rocks, fix in vitro N₂, produce volatile and non-volatile organic acids, and reduce rock particle size to form mineral soil. This study revealed the presence of large populations of culturable endophytic bacteria inside the seeds extracted from wild plants, from seeds extracted from the guano of bats feeding on cactus fruit, in seedlings growing from these seeds, in the pulp of fruit, and in small, mature wild plants, and are comparable in size to populations of endophytic populations in some agricultural crops. The dominant culturable endophytes were isolates of the genera Bacillus spp., Klebsiella spp., Staphylococcus spp., and Pseudomonas spp. Based on partial sequencing of the 16s rRNA gene, the isolated strains had low similarity to known strains in these genera. However, these strains have higher molecular similarity among endophytes obtained from seeds, endophytes from roots, and some bacterial strains from the rhizoplane. Seedlings developed from seeds with endophytes contain the similar species of endophytes in their shoots, possibly derived from the seeds. This study shows the involvement of endophytic bacteria in rock weathering by cacti in a hot, subtropical desert and their possible contribution to primary colonization of barren rock. This study proposes that cacti capable of acquiring diverse populations of endophytes may give them an evolutionary advantage to gain a foothold on highly uncompromising terrain.

Sustainable Management of Nutrients in Forage-Based Pasture Soils: Effect of Animal Congregation Sites
About this Resource: Background, Aim and Scope: Grazing animals have a dominant effect on the movement and utilization of nutrients through the soil and plant system, and thus on the fertility of pasture soils. Grazing can accelerate and alter the timing of nutrient transfers, and increase the amount of nutrients cycled from plant to soil. Long periods, position of shade, and water resources for grazing cattle can influence the spatial distribution of soil biochemical properties including soil organic carbon (C), total extractable inorganic nitrogen (TEIN), and Melich 1 extractable total phosphorus (TP). The objective of this study is to test whether cattle congregation sites typical on most Florida ranches, such as mineral feeders, water troughs, and shade areas are more nutrient-rich and may contribute more nutrients to surface and groundwater supply than in other pasture locations under Florida conditions. Materials and Methods: Baseline soil samples around and beneath three congregations sites in established (>10 yr) grazed beef cattle pastures at the United States Department of Agriculture (USDA), Agricultural Research Service (ARS), Subtropical Agricultural Research Station (STARS), Brooksville, FL, were collected in 2003, 2004, and 2005. Results: The levels of soil TEIN and TP were significantly (p <= 0.001) affected by the interaction of congregation sites and distance away from the center of the sites. Mineral feeders had the highest concentration of TP followed by shades and water troughs. The concentrations of soil TP decreased almost linearly with distance (x = meter) away from the center of the mineral feeders (-5.24x + 55.10; R2 = 0.92; p <= 0.001) and the shades (-6.25x + 57.21; R2 = 0.85; p <= 0.001). However, the level of TP around the water troughs (-0.25x + 16.91; R2 = 0.09) does not appear to change significantly with distance, staying close to about 13-18 mg kg-1. The levels of TEIN decreased linearly with distance away from the mineral feeders from the center of the shades. A linear model can describe the relationship between TEIN and distance away from the center of shades: -11.3x + 78.2; R2 = 0.95; p <= 0.001. The shaded sites (34.25 ± 1.7 mg kg-1) had higher levels than the mineral feeders (7.22 ± 0.60 mg kg-1) or water troughs (10.06 ± 0.8 mg kg-1) sites. Discussion: The higher soil TP near and around the mineral feeders can be attributed to the presence of phosphorus in the supplemental feeds. The average level of soil TP in the mineral feeders of 34.05 ± 0.44 mg kg-1 was not high enough to be of environmental concern. Losses of soil phosphorus by overland flow are becoming a big concern when the concentrations for soil phosphorus exceeded 150 mg kg-1 in the upper 20 cm of soils. With TN, the shaded sites (34.25 ± 1.7 mg kg-1) had either higher levels than the mineral feeders (7.22 ± 0.60 mg kg-1) or water trough (10.06 ± 0.80 mg kg-1) sites. Higher TEIN content at the shade sites may have been more likely due to frequent urination of animals and lack of vegetation immediately adjacent to shades. The lack of vegetation within and/or near the shades then had no uptake mechanism for removal of inorganic nitrogen, unlike the heavy demand for inorganic nitrogen by bahiagrass in other areas of the pasture. An accumulation of TEIN immediately adjacent to shades could lead to a potential point source that would be susceptible to leaching or gaseous losses to the environment. Conclusions: Early results of the study are suggesting that cattle congregation sites in beef cattle operations in Florida are not nutrient-rich, therefore may not contribute more nutrients to surface and groundwater supply under Florida conditions. Recommendations and Perspectives: Since there is no apparent vertical build up or horizontal movement of TEIN and TP in the landscape, we can then surmise that cattle congregation sites may be considered not a potential source of nutrients at the watershed level, at least on the sand ridge soils in Florida. Further research is continuing, including sampling at cattle congregation sites at other locations in north and south Florida, which started in July 2004.

Aggie Horticulture
About this Resource: This link contains files that relate to the teaching, research, extension and public service components of Texas A&M University's Department of Horticulture. Aggie Horticulture has been providing gardening and horticultural crop production information since 1994. The site points to a number of informational items. PLANTanswers is an archive of gardening information; there are images avaialble via the "Plant Pictures Pages".

New York State Agricultural Experiment Station
About this Resource: The Home Page for the New York State Agricultural Experiment Station (NYSAES) is designed so that site visitors can learn about core activities taking place at the Station, while staying abreast of future and current efforts. A "quick link" tab allows for quick access to major divisions - affiliated with Cornell University. These units conduct principal research into: entomology, food science, horticultural science and plant pathology. NYSAES employs 350 employees; they are engaged in 230 different projects. The Station is mission oriented and is particularly focused on advancing New York agriculture. The Geneva, New York (Fingerlakes region) is particularly suitable for fruit production; the Station housess the National Germplasm Repository for Apple and Grape. This leads NYSAES into work vinification and brewing technology. NYSAES includes the Hudson Valley Laboratories and the Frank A. Lee Library as just two facilites; all of which can be accessed from this location.

Agri-Business Assistant
About this Resource: Collection of links to agricultural firms, agencies, raw materials, sugar, tropical crops, commodities, and general topics.

Wild Blueberry Network Information Centre
About this Resource: A full-text collection of scientific information about wild blueberry (Vaccinium angustifolium Ait) production and marketing in Eastern Canada and Maine, including fact sheets, research reports, newsletters, names of specialists, history of the industry, and other related information for producers, agricultural representatives and researchers. Also includes information on lingonberry (Rubus chamaemorus) and cloudberry (Vaccinium idaea vitis-idaea).