Economically optimal nitrogen rate reduces soil residual nitrate

Post-harvest residual soil NO(3)-N (RSN) is susceptible to transfer to water resources. Practices that minimize RSN levels can reduce N loss to the environment. Our objectives were (i) to determine if the RSN after corn (Zea mays L.) harvest can be reduced if N fertilizer is applied at the economically optimal N rate (EONR) as compared to current producer practices in the midwestern USA and (ii) to compare RSN levels for N fertilizer rates below, at, and above the EONR. Six experiments were conducted in producer fields in three major soil areas (Mississippi Delta alluvial, deep loess, claypan) in Missouri over 2 yr. Predominant soil great groups were Albaqualfs, Argiudolls, Haplaquolls, and Fluvaquents. At four transects in each field, six treatment N rates from 0 to 280 kg N ha(-1) were applied, the EONR was determined, and the RSN was measured to a 0.9-m depth from five treatment plots. The EONR at sampling sites varied from 49 to 228 kg N ha(-1) depending on site and year. Estimated average RSN at the EONR was 33 kg N ha(-1) in the 0.9-m profile. This was at least 12 kg N ha(-1) lower than RSN at the producers' N rates. The RSN increased with increasing Delta EONR (total N applied - EONR). This relationship was best modeled by a plateau-linear function, with a low RSN plateau at N rates well below the EONR. A linear increase in RSN began anywhere from 65 kg N ha(-1) below the EONR to 20 kg N ha(-1) above the EONR at the three sites with good data resolution near the EONR. Applying N rates in excess of the EONR produced elevated RSN values in all six experiments. Our results suggest that applying the EONR will produce environmental benefits in an economically sound manner, and that continued attempts to develop methods for accurately predicting EONR are justified.     

Baboon loud calls advertise male quality: acoustic features and their relation to rank,age, and exhaustion

Free-ranging adult male baboons give loud two-syllable wahoo calls during dawn choruses, interactions between groups, when chasing females, and in aggressive interactions with other males. Previous research has shown that the rate and duration of these contest wahoos are correlated with a males competitive ability: high-ranking males call more often, call at faster rates, and call for longer bouts than do low-ranking males. Here we report that acoustic features of wahoos also reveal information about male competitive ability. High-ranking males give wahoos with higher fundamental frequencies (F0) and longer hoo syllables. Within-subject analyses revealed that, as males fall in rank, the hoo syllables tend to shorten within a period of months. As males age and continue to fall in rank, F0 declines, hoo syllables shorten, and formant dispersion decreases. Independent of age and rank, within bouts of calling F0 declines and hoo syllables become shorter. Because wahoos are often given while males are running or leaping through trees, variation in these acoustic features may function as an indicator of a males stamina. The acoustic features of contest wahoos thus potentially allow listeners to assess a males competitive ability.Communicated by C. Nunn     

Herbicide Transport in Goodwater Creek ExperimentalWatershed: I. Long‐Term Research on Atrazine1

Lerch, R.N., E.J. Sadler, K.A. Sudduth, C. Baffaut, and N.R. Kitchen, 2010. Herbicide Transport in Goodwater Creek Experimental Watershed: I. Long‐Term Research on Atrazine. Journal of the American Water Resources Association (JAWRA) 1‐15. DOI: 10.1111/j.1752‐1688.2010.00503.x Abstract: Atrazine continues to be the herbicide of greatest concern relative to contamination of surface waters in the United States (U.S.). The objectives of this study were to analyze trends in atrazine concentration and load in Goodwater Creek Experimental Watershed (GCEW) from 1992 to 2006, and to conduct a retrospective assessment of the potential aquatic ecosystem impacts caused by atrazine contamination. Located within the Central Claypan Region of northeastern Missouri, GCEW encompasses 72.5 km² of predominantly agricultural land uses, with an average of 21% of the watershed in corn and sorghum. Flow‐weighted runoff and weekly base‐flow grab samples were collected at the outlet to GCEW and analyzed for atrazine. Cumulative frequency diagrams and linear regression analyses generally showed no significant time trends for atrazine concentration or load. Relative annual loads varied from 0.56 to 14% of the applied atrazine, with a median of 5.9%. A cumulative vulnerability index, which takes into account the interactions between herbicide application, surface runoff events, and atrazine dissipation kinetics, explained 63% of the variation in annual atrazine loads. Based on criteria established by the U.S. Environmental Protection Agency, atrazine reached concentrations considered harmful to aquatic ecosystems in 10 of 15 years. Because of its vulnerability, atrazine registrants will be required to work with farmers in GCEW to implement practices that reduce atrazine transport.     

Male baboon responses to experimental manipulations of loud “wahoo calls”: testing an honest signal of fighting ability

Among male chacma baboons (Papio hamadryas ursinus), rank positions in the dominance hierarchy are fiercely contested. Physical fighting is costly but relatively rare in this species. Instead, disputes are frequently resolved using displays that include loud, repetitive “wahoo” (two-syllable bark) vocalizations. We previously found that males of all ranks adjust their contest behavior based on the relative fighting ability of opponents and that length of the second syllable (“hoo” duration), calling rate, and fundamental frequency reliably indicate fighting ability. To test whether males indeed attend to hoo duration when assessing opponents, we designed two sets of playback experiments in which call sequence pairs were identical except for this single modified feature. In experiment 1, we used calls recorded from high-ranking males unfamiliar to all subjects. In experiment 2, callers were familiar rivals that ranked one position below subjects in the dominance hierarchy. In paired analyses, subjects in both experiments responded more strongly to sequences with more intense signal features (most commonly associated with high-quality males) compared to sequences with relatively less exaggerated features (most often associated with low-quality males). Results suggest that males can use acoustic features to both indirectly evaluate strangers and to monitor the changing condition of those rivals that present the biggest intragroup threat to their position in the dominance hierarchy. Taken together with our previous research, baboons appear to follow a classic assessor strategy—signal features related to rank and condition are salient to males and directly affect their propensity to respond to rivals.     

Mating system shift in a pronghorn population

Summary At the National Bison Range (western Montana, USA), pronghorn (Antilocapra american) maintained a territorial mating system from as early as 1965 through 1978. Preliminary observations in 1981 suggested that the mating system had changed. Data from the ruts, 1982–1984 revealed a progressive decay in territoriality. In this paper, data from the territorial years 1969–1978 are contrasted with data from the decay years 1982–1984, with results as follow: 1. In 1982–84, fewer territories were defended than in 1969–78. This was attributable to a smaller proportion of males defending territories in 1982–84, not to a smaller number of males. 2. In 1982–84, most territory owners either abandoned their territories early in ruts, or lost control of females on them following frequent, persistent intrusions by non-territorial males. Abandonment and loss of control did not occur in 1969–78. 3. In 1982–84, territorial males that maintained control of females on their territories did so by shrinking their zones of defense to small areas around female groups. 4. In 1982–84, following the disruption or severe disturbance of all territories, many females left territories, and mated elsewhere, with non-territorial males. In 1969–78, most females remained on territories throughout rut, and mated with territory owners. —The mating system change followed catastrophic winter mortality, 1978–79, that removed 75% of the males, including all males older than 5 years, and all male fawns, from the population. In 1982–84, the number of males present was not different from the number of males in 1969–1978, but the frequency distribution of male ages was strongly shifted toward younger ages. The small number of older males, 1982–84, likely resulted in smaller proportions of males initially defending territories, and in less effective territory defense. When females then clustered on the few territories where defense was at first successful, they attracted large numbers of non-territorial males. The resulting high rates of raids on these territories, coupled with reduced defense radii by territorial males, allowed females only 12% reclining time (summer percentage was 39%). This increased energy cost, plus an apparently greater risk of injury on weakly defended territories, appeared to prompt many females to seek calmer matings elsewhere. Also, if female pronghorn practiced mate selection based upon horn or body size, they may have reduced their efforts to remain on territories in 1982–84. Males from 1969–78 were larger than males from 1982–84, and showed greater variance in horn size. At least two conditions appear to influence the tendency of males to be territorial. First, males must be at least three years old before they attempt to defend a territory. Second, the declining proportion of males defending territories, 1982–84, that coincided with an increasing number of males three years and older, suggests that males also decide whether or not to attempt territory defense based upon the frequency of territorial defense in the population.     

Herbicide Transport in Goodwater Creek Experimental Watershed: II. Long‐Term Research on Acetochlor,Alachlor, Metolachlor,and Metribuzin1

Lerch, R.N., E.J. Sadler, C. Baffaut, N.R. Kitchen, and K.A. Sudduth, 2010. Herbicide Transport in Goodwater Creek Experimental Watershed: II. Long‐Term Research on Acetochlor, Alachlor, Metolachlor, and Metribuzin. Journal of the American Water Resources Association (JAWRA) 1‐15. DOI: 10.1111/j.1752‐1688.2010.00504.x Abstract: Farmers in the Midwestern United States continue to be reliant on soil‐applied herbicides for weed control in crop production, and herbicide contamination of streams remains an environmental problem. The main objective of this study was to analyze trends in concentration and load of acetochlor, alachlor, metolachlor, and metribuzin in Goodwater Creek Experimental Watershed (GCEW) from 1992 to 2006. A secondary objective was to document the effects of best management practices (BMPs) implemented within GCEW on herbicide transport trends. Median relative herbicide loads, as a percent of applied, were 3.7% for metolachlor, 1.3% for metribuzin, 0.36% for acetochlor, and 0.18% for alachlor. The major decrease in alachlor use and increase in acetochlor use caused shifts in flow‐weighted concentrations that were observed over the entire concentration range. The smaller decrease in metolachlor use led to a consistent decreasing time trend only for the upper end of the concentration distribution. Metribuzin also showed moderate decreases in concentration with time since 1998. Annual loads were generally correlated to second quarter discharge. Despite extensive education efforts in the watershed, conservation BMPs within GCEW were mainly implemented to control erosion, and therefore had no discernable impact on reducing herbicide transport. Overall, changes in herbicide use and second quarter discharge had the greatest effect on trends in flow‐weighted concentration and annual load.     

Loud calls as indicators of dominance in male baboons (Papio cynocephalus ursinus)

Adult male baboons (Papio cynocephalus) give loud two-syllable 'wahoo' calls during dawn choruses, interactions between groups, when chasing females, and in aggressive interactions with other males. These 'contest' wahoos are acoustically different from 'alarm' wahoos given to predators. In a study of free-ranging baboons in the Okavango Delta, Botswana, we found no significant correlations between the acoustic features of wahoos and adult male size; however, acoustic features were correlated with male dominance rank, age, and calling bout length. Here we show that other measures of calling behavior also appear to function as honest indicators of stamina and competitive ability. High-ranking males were more likely than middle- or low-ranking males to participate in wahoo bouts. They called at significantly higher rates, and their bouts were longer and contained more calls. All males were significantly more likely to participate in wahoo bouts with another male if their opponent's rank was similar to their own. Bouts involving males of similar ranks were longer, contained more wahoos, and involved calling at higher rates, than other bouts. In contests between males of similar ranks, the subordinate and dominant were equally likely to end the bout, whereas in contests involving males of disparate ranks, subordinates were significantly more likely to end the bout. Bouts involving males of similar rank were significantly more likely than others to escalate and result in physical fighting.     

Forest ecological classification and mapping: Their application for ecosystem management in Newfoundland

A prerequisite to sustaining ecosystems is the inventory and classification of landscape structure and composition. Ecological classification and mapping involves the delineation of landscapes into easily recognizable units. Topography, soils, vegetation, physical landscape form, and successional pathways are delineation criteria commonly used.Damman (1967) developed a forest type classification system for Newfoundland using vegetation, soil and landforms as the defining criteria. Damman's forest types were used in combination with mensurational data to assign forest types to timber volume productivity classes. Since each of the Damman forest types is associated with characteristic soils, parent materials, moisture regime and topographic position, the mapping units are similar to Canada Land Inventory (CLI) mapping units. Field work to confirm the correlation between Damman forest types and CLI capability classes was initiated in 1993. CLI maps were recoded in 1994 and Damman forest types were determined; resulting ecosystem-based maps provide a common framework to assess forestry/wildlife interactions in an ecosystem planning process.     

Local Authority/AcademicCollaboration and Local Agenda 21 Policy Processes

This paper looks at a recent example of local authority/academiccollaboration over a protracted period of time from the different perspectives of those people who were directly involved in the process as key role players. The arena within which this collaboration took place (Local Agenda 21 policy-making in Manchester) has some particular characteristics of its own which influenced this process, and these are identified alongside some of the theoretical issues which affect the way collaborations of this kind are perceived and (much more rarely) are written about. The perspectivesof the client and of the contractor, as the authors reflect on their experiences in these roles, show that in practice processes of adjustment and of learning were taking place, because both sides for various reasons found that the dynamics of this situation meant that their preconceptions both of each other and of the contractual relationship they had thought they were entering had to be modified as the process unfolded. The paper concludes with both specific observations about this collaboration, and more general and more tentative comments about issues that might be experienced in future collaborations of this kind.