Application of the wilderness travel simulation model to the Appalachian Trail in Vermont

The wilderness travel simulation model estimates complex recreation use patterns in park and wilderness environments. The model was applied to a section of the Appalachian Trail in Vermont, a linear, long-distance, multiple-access trail system characteristic of the eastern United States. Many portions of the trail, including the study area, are now experiencing high use. The model estimated the average number of trail encounters per party day to be 3.3 and the average number of camp encounters per party night to be 2.3. Other measures of recreation use were also estimated that should prove useful to trail management and administration. Three trail management scenarios were tested, providing several preliminary insights to managers: the desirability of use redistributions as opposed to across-the-board reductions and needed emphasis on spatial use patterns and campsite encounters. Only minor modifications to the program were needed in applying the model to the trail environment and the model functioned accurately according to the validity tests performed.     

ESTIMATING BASEFLOW VOLUME AND ITS UNCERTAINTY1

ABSTRACT: By using the exponential baseflow recession equation it is possible to estimate from a single discharge measurement the total volume of stream discharge during a baseflow period. If the discharge measurement is properly centered in the baseflow period the resulting estimate will be fairly precise, even if the baseflow recession coefficient is not known. Furthermore, based on an assumed probability distribution of the baseflow coefficient it is possible to estimate the uncertainty of the baseflow volume estimate. Estimates of baseflow volume and their uncertainty are potentially useful for estimating water budgets of lakes.     

Towards a global emergency plan for the environment

This editorial is based on a paper first produced by Winfried Böll entitled, A Global Emergency Plan for the Environment which appeared inThe Crisis of Global Environment: Demands for Global Politics published by The Foundation Development and Peace in 1989. Winfried Böll is the retired Ministerial Director of the Ministry for Economic Co-operation, West Germany. He lectures at the University of Duisburg on matters related to foreign aid and government and administration, he is also an advisor to the Board of the Foundation Development and Peace. The Foundation was established in 1987 at the initiative of former West German Chancellor, Willy Brandt. Its Executive Board, as well as its Board of Trustees and its members are composed of distinguished personalities from political, social, economic and scientific life who share a sense of global responsibility. The Foundation is non-partisan and non-profit-making.Its objectives are summarised below:     

FLOOD FREQUENCY ANALYSIS FOR EVALUATING WATERSHED CONDITIONS WITh RAINFALL-RUNOFF MODELS1

ABSTRACT: Many rainfall-runoff modeling studies compare flood quantiles for different land-use and/or flood mitigation scenarios. However, when flood quantiles are estimated using conventional statistical methods, comparisons may be misleading because the estimates often misrepresent the quantile relationship between scenarios. An alternate statistical procedure is proposed, in which rainfall-runoff modeling is used to evaluate an approximate relationship between flood quantiles for different scenarios. Monte Carlo experiments show that the proposed method produces flood quantile estimates that better reflect the differences between scenarios. The ratio between quantiles for different scenarios is more accurate, so comparisons of the scenarios using flood quantiles are more reliable.     

Analysis and application of forest fuels data

Recent advances in fire modeling permit quantitative estimations of fire behavior from quantitative inputs that describe the fuel array and conditions, such as weather and site data, under which it will burn. This paper describes the collection, analysis, and stratification of flammable forest fuels data for coniferous forest ecosystems in Montana and then illustrates the resource management application of these data in three areas: the development of the fire behavior model, a determination of the model's sensitivity to input errors as reflected by fire behavior prediction errors, and the development of a fire hazard simulator (TAROT). A new integrated stand simulator, GANDALF, is highlighted.Conclusions center on the need to integrate fire management into the land management planning decision-making process.This work was supported by a USDI National Park Service contract to Gradient Modeling, Inc., a nonprofit research foundation devoted to ecologic research and resource management applications, and by cooperative aid agreements between Gradient Modeling, Inc. and the USDA Forest Service, Intermountain Forest and Range Experiment Station, Northern Forest Fire Laboratory (Fire in Multiple Use Management, R, D, and A Program).     

Relationships between the movements,growth, age structures,and reproductive biology of the teleosts Sillago burrus and S. vittata in temperate marine waters

Sillago burrus and S. vittata both use sheltered, nearshore shallow waters ( 1.5 m) as nursery areas. However, the juveniles of the former species remain there for only a few months, before migrating into deeper waters (5 to 15 m) as they increase in size, whereas some juvenile S. vittata do not undergo a similar migration until considerably later. S. burrus rarely exceeded 2 yr of age and was never found beyond 4 yr of age. Although only a small number of S. vittata exceeded 2 yr of age, a few individuals of this species were caught between 4 and 7 yr old. The maximum and asymptotic lengths of S. burrus (251 and 180 mm, respectively) were far lower than those of S. vittata (325 and 320 mm, respectively), whereas the growth coefficients (K) were much higher for the former species, i.e. 2.4 vs 0.4. Virtually all S. burrus, and also those S. vittata that moved into deeper waters early in life, spawned at the end of their first year of life. Since relatively few S. burrus reached 2 yr of age, the attainment of almost full size by the end of their first year of life enables a relatively large number of eggs to be produced by fish at the end of their first year-for many, their only spawning period. Those individuals of S. vittata that remained in their shallow nursery areas until the end of their first year of life, did not reach maturity until the end of their second year of life. The proportions of mature gonads and the numbers of yolk-vesicle and yolk-granule oocytes and post-ovulatory follicles in ovaries were far higher in both S. burrus and S. vittata during December to February than in any other month, demonstrating that these two species spawn largely in these summer months. During this period, the ovaries of individual S. burrus and S. vittata often contained post-ovulatory follicles, as well as yolkvesicle and yolk-granule oocytes that ranged widely in size, strongly suggesting that both species are multiple spawners. During the spawning period of S. burrus, the ovaries possessed large numbers of hydrated oocytes and no post-ovulatory follicles or the reverse situation, and the oocytes tended to form several relatively discrete size groups. This indicates that S. burrus produces eggs in batches and that the spawning of the members of this species is synchronised. The presence of large numbers of yolk-granule oocytes with migrating nuclei in the ovaries of many S. vittata at certain times suggests that this species is also a batch- and synchronised spawner. Comparisons between the results of the present study and past work emphasise that the relationships between the timing of offshore movements and the sizes and ages at first maturity vary considerably amongst whiting species.