Effectiveness of a Coral-Derived Surfacing Material for Reducing Sediment Production on Unpaved Roads, Schoffield Barracks, Oahu, Hawaii

This study evaluated the effectiveness of two application rates of a coral-derived surfacing material for both traffic and nontraffic road conditions using simulated rainfall (110–120 mm h⁻¹ for 30–90 min) on 0.75-m (wide) × 5.0-m (long) plots of similar slope (roughly 0.1 m m⁻¹). The coral is a locally available material that has been applied to unpaved roads surfaces on Schoffield Barracks, Oahu, Hawaii (USA), where this experiment was conducted. The simulations show that compared with a bare control plot, the coral-based surface application rates of 80 and 160 kg m⁻² (equivalent to only 10- and 20-mm thicknesses) reduced road sediment production by 75% and 95%, respectively, for nontraffic conditions. However, after two passes of the research vehicle during wet conditions, sediment production rates for the two coral treatments were not significantly different from those on the bare road plots. The overall effectiveness of the coral-derived surfacing material is unsatisfactory, primarily because the on-road surface thickness associated with the application rates tested was too small. These rates were selected to bracket those applied to training roads in the study area. Furthermore, the composition of the coral-based material does not facilitate the development of a sealed, erosion-resistant surface. When applied at the low rates tested, the coral material breaks down under normal traffic conditions, thereby losing its ability to counter shearing forces exerted by overland flow on long hillslopes where erosion measures are most needed. These simulations, combined with observations on roads in the study area, indicate that this material is not an appropriate road surfacing material for the site—at least for the low application rates examined. These results are preliminary; extended testing of higher applications rates at the hillslope scale under natural climate and traffic conditions is needed to better judge the effectiveness of this material over time.     

Motivations Influencing the Adoption of Conservation Easements

Abstract: The use of conservation easements as a conservation mechanism for private land has increased greatly in the past decade; conservation easements now protect over 15 million ha across the United States from residential and commercial development. We used a mailed survey and in‐depth telephone interviews to determine factors that motivate private landowners in Iowa, Illinois, Michigan, Ohio, and Wisconsin (U.S.A.) to place conservation easements on their properties. The mailed survey asked about characteristics of landowners, their properties, and their opinions on 9 factors related to the decision to place an easement. A follow‐up telephone interview was completed with 19 mail‐survey participants to gain an in‐depth understanding of the action and to triangulate the results with the questionnaire. Place attachment, which is a measure of personal connection to a location or property, was the greatest motivation for implementation of an easement. Results of a principal components analysis suggested contributing to the public good underlaid several of the strong motivational factors for participation. Financial reasons were the lowest ranked motivational factor; however, financial concerns may facilitate placement of an easement that would otherwise not be realized. We believe that our results may be transferable to places where land protected by easements is not dominated by traditional farming (row crops, pastures, and hay), timber harvesting, or nonextractive uses (e.g., habitat for wild animals, recreation, and protection of ecosystem services).     

An Empirical Evaluation of Private Landowner Participation in Voluntary Forest Conservation Programs

The use of voluntary programs targeting resource conservation on private land has become increasingly prevalent in environmental policy. Voluntary programs potentially offer significant benefits over regulatory and market-based approaches. This article examines the factors affecting landowner participation in voluntary forest conservation programs using a combination of parcel-level GIS and remotely sensed data and semi-structured interviews of landowners in Monroe County, Indiana. A logistic regression model is applied to determine the probability of participation based on landowner education, membership in other non-forest voluntary programs, dominant land use activity, parcel size, distance from urban center, land resource portfolios, and forest cover. Both land use activity and the spatial configuration of a landholder’s resource portfolio are found to be statistically significant with important implications for the design and implementation of voluntary programs.

The Aquatic Conservation Strategy of the Northwest Forest Plan

Abstract:  Implemented in 1994, the Aquatic Conservation Strategy of the Northwest Forest Plan was designed to restore and maintain ecological processes for aquatic and riparian area conservation on federal lands in the western portion of the Pacific Northwest. We used decision support models to quantitatively evaluate changes in the condition of selected watersheds. In the approximately 10 years since strategy implementation, watershed condition scores changed modestly, but conditions improved in 64% of 250 sampled watersheds, declined in 28%, and remained relatively the same in 7%. Watersheds that had the largest declines included some where wildfires burned 30–60% of their area. The overall statistical distribution of the condition scores did not change significantly, however. Much of the increase in watershed condition was related to improved riparian conditions. The number of large trees (>51 cm diameter at breast height) increased 2–4%, and there were substantial reductions in tree harvest and other disturbances along streams. Whether such changes will translate into longer-term improvements in aquatic ecosystems across broader landscapes remains to be seen.     

Factors influencing acquisition of ecological and exposure information about hazards and risks from contaminated sites

Considerable research indicates that a wide range of socio-economic factors influence attitudes and perceptions about environmental hazards and risks, and that social trust in those who manage a hazard is strongly correlated to judgements about risks and benefits. We suggest that there are three steps that lead to environmental risk perceptions: acquisition of information, interpretation and synthesis of different pieces of information, and understanding of that information in light of previous knowledge, perceptions, or attitudes. In this study we presented 211 college students in the sciences and non-sciences with ecological and exposure information using text, tables and maps to examine the factors that affect information acquisition and interpretation concerning ecological issues at a fictitious hazardous waste site. Students were allowed about an hour to read the materials and answer questions. The percent of students answering each question correctly varied from 4 to 82%, indicating that some questions were extremely difficult to answer. We attributed these differences to variations in the number of places information was presented (in text, tables, maps, or a combination) and the complexity of the information (how many pieces of information were required to answer the question correctly). The correlation between the number of students answering each question correctly and these combined measures (frequency, complexity) was −0.72. Thus, although there were differences in accuracy concerning ecological information as presented in this study, the major differences were accounted for by how the information was presented, and how much information was required. This suggests that risk communicators should carefully determine which ecological information is critical for the target audience, and ensure that it is presented several times (in different forms). That a lower percentage of people correctly answered questions that required synthesizing several pieces of information suggests that this complexity should be reduced where possible, or that the pieces of information should be tied clearly to the conclusion. Self-declaration of effort and perceptions of safety of the site did not markedly influence the relationship between accuracy, difficulty of finding information, and complexity of information. Other possible confounding variables (i.e., science vs non-science major) only accounted for about 27% of the variation in student’s overall score on ecological questions; age, ethnicity, and gender did not enter as significant variables. We cannot manage environmental hazards with appropriate stakeholder input unless we understand how to present environmental information to achieve a full understanding. Protection of human health and the environment requires that people understand ecological and exposure information, particularly on buffer lands.     

Detecting Invasive Sericea Lespedeza (<Emphasis Type="Italic">Lespedeza cuneata</Emphasis>) in Mid-Missouri Pastureland Using Hyperspectral Imagery

Missouri ranks second in cow-calf numbers in the United States and its pastureland has experienced invasion of various plant species. As one of the invasive weeds, sericea lespedeza is becoming a serious threat to pasturelands in this state. The in-situ field survey in these vast pastures is time consuming and often impossible because of accessibility. Typical aerial survey is also difficult to detect sericea because the plant is of similar size and color as natural grass and, thus, cannot be effectively discriminated in broadband aerial color photos. This study used an airborne hyperspectral image to map sericea and its invasiveness in a public grass field in Mid-Missouri. The maximal 1st-order derivative in red-near infrared region (650–800nm) was derived to separate sericea from fescue, the dominant grass in pastures in Missouri. With a simple threshold approach, sericea of various sizes were identified in the study area. It was also found that the maximal 1st-order derivatives of sericea patches were log-linearly related to sericea “volume,” a quasi 3-dimensional biophysical variable as an approximate measure of sericea invasiveness. The squared correlation coefficient (r ²) of the regression was 0.65 and the estimation error of sericea “volume” estimation was 11% based on ground measurements at 27 sample sites. With this empirical regression model, the quantitative distribution of sericea volume was mapped, which could serve as a first step in alerting landowners and the general public about the seriousness of sericea invasion in Missouri pasturelands.     

Climate change and indigenous natural resource management: a review of socio-ecological interactions in the Alinytjara Wilurara NRM region

This article examines key socio-ecological interactions identified during a climate change vulnerability assessment in the Alinytjara Wilurara natural resources management (NRM) region of South Australia. The complex local socio-ecological interactions are highlighted to guide a response to the challenge of adapting to climate change within the region. Recognising several key desert drivers which perpetuate degraded socio-ecological systems, this article recommends that a range of strategies be employed simultaneously to enhance local environmental management in association with remote indigenous communities, including: linking people and NRM more closely; tracking funding but ensuring systems can withstand periods of limited financial support; developing cross-sectoral and cross-institutional links; empowering and engaging communities; communicating effectively; and actively supporting local and traditional environmental knowledge. Unless climate change adaptation responses within the region are conceptualised and enacted within the context of complex local socio-ecological systems, NRM will not improve and social vulnerability will increase.     

Nitrogen Sources and Sinks Within the Middle Rio Grande,New Mexico1

Abstract: Relationships between discharge, land use, and nitrogen sources and sinks were developed using 5 years of synoptic sampling along a 300 km reach of the Rio Grande in central New Mexico. Average river discharge was higher during 2001 and 2005 “wet years” (15 m³/s) than during the drought years of 2002‐04 “dry years” (8.9 m³/s), but there were no differences in nitrogen loading from wastewater treatment plants (WWTPs) which were the largest and most consistent source of nitrogen to the river (1,330 kg/day). Average total dissolved nitrogen (TDN) concentrations remained elevated for 180 km downstream of the Albuquerque WWTP averaging 1.2 mg/l in wet years and 0.52 mg/l in dry years. Possible explanations for the constant elevated TDN concentrations downstream of the major point source include reduced nitrogen retention capacity, minimal contact with riparian or channel vegetation, large suspended sediment loads, and low algal biomass. Somewhat surprisingly, agricultural return flows had lower average nitrogen concentrations than river water originally diverted to agriculture in both wet (0.81 mg/l) and dry years (0.19 mg/l), indicating that the agricultural system is a sink for nitrogen. Lower average nitrogen concentrations in the river during the dry years can be explained by the input of agricultural returns which comprise the majority of river flow in dry years.     

珠江三角洲的耕地及其持续利用

耕地的持续利用是农业持续发展的前提和基础,是人类经济社会持续发展的根本保证。本文论述了珠江三角洲耕地的现状和经济快速增长所引发的耕地问题,并指出耕地的持续利用需要全社会的共同努力。     

丽江地区中低产耕地及其开发利用

本义探讨了丽江地区中低产耕地的特征,并从自然因素和人文因素分析了低产的原因,进而提出合理改良利用低产耕地的对策。