Understanding and Integrating Local Perceptions of Trees and Forests into Incentives for Sustainable Landscape Management

We examine five forested landscapes in Africa (Cameroon, Madagascar, and Tanzania) and Asia (Indonesia and Laos) at different stages of landscape change. In all five areas, forest cover (outside of protected areas) continues to decrease despite local people's recognition of the importance of forest products and services. After forest conversion, agroforestry systems and fallows provide multiple functions and valued products, and retain significant biodiversity. But there are indications that such land use is transitory, with gradual simplification and loss of complex agroforests and fallows as land use becomes increasingly individualistic and profit driven. In Indonesia and Tanzania, farmers favor monocultures (rubber and oil palm, and sugarcane, respectively) for their high financial returns, with these systems replacing existing complex agroforests. In the study sites in Madagascar and Laos, investments in agroforests and new crops remain rare, despite government attempts to eradicate swidden systems and their multifunctional fallows. We discuss approaches to assessing local values related to landscape cover and associated goods and services. We highlight discrepancies between individual and collective responses in characterizing land use tendencies, and discuss the effects of accessibility on land management. We conclude that a combination of social, economic, and spatially explicit assessment methods is necessary to inform land use planning. Furthermore, any efforts to modify current trends will require clear incentives, such as through carbon finance. We speculate on the nature of such incentive schemes and the possibility of rewarding the provision of ecosystem services at a landscape scale and in a socially equitable manner.     

Controlling nitrate leaching in irrigated agriculture

The impact of improved irrigation and nutrient practices on ground water quality was assessed at the Nebraska Management System Evaluation Area using ground water quality data collected from 16 depths at 31 strategically located multilevel samplers three times annually from 1991 to 1996. The site was sectioned into four 13.4-ha management fields: (i) a conventional furrow-irrigated corn (Zea mays L.) field; (ii) a surge-irrigated corn field, which received 60% less water and 31% less N fertilizer than the conventional field; (iii) a center pivot-irrigated corn field, which received 66% less water and 37% less N fertilizer than the conventional field; and (iv) a center pivot-irrigated alfalfa (Medicago sativa L.) field. Dating (3H/3He) indicated that the uppermost ground water was <1 to 2 yr old and that the aquifer water was stratified with the deepest water approximately 20 yr old. Recharge during the wet growing season in 1993 reduced the average NO3-N concentration in the top 3 m 20 mg L(-1), effectively diluting and replacing the NO3-contaminated water. Nitrate concentrations in the shallow zone of the aquifer increased with depth to water. Beneath the conventional and surge-irrigated fields, shallow ground water concentrations returned to the initial 30 mg NO3-N L(-1) level by fall 1995; however, beneath the center pivot-irrigated corn field, concentrations remained at approximately 13 mg NO3-N L(-1) until fall 1996. A combination of sprinkler irrigation and N fertigation significantly reduced N leaching with only minor reductions (6%) in crop yield.     

Short-Term Influence of Tank Tracks on Vegetation and Microphytic Crusts in Shrubsteppe Habitat

Artemisia tridentata Nutt.) habitat within the Idaho Army National Guard Orchard Training Area in southwestern Idaho. The purpose of this study was to determine the short-term (1–2 years) influence of tank tracks on vegetation and microphytic crusts in shrubsteppe habitat. The two types of tank tracks studied were divots (area where one track has been stopped or slowed to make a sharp turn) and straight-line tracks. Divots generally had a stronger influence on vegetation and microphytic crusts than did straight-line tracks. Tank tracks increased cover of bare ground, litter, and exotic annuals, and reduced cover of vegetation, perennial native grasses, sagebrush, and microphytic crusts. Increased bare ground and reduced cover of vegetation and microphytic crusts caused by tank tracks increase the potential for soil erosion and may reduce ecosystem productivity. Reduced sagebrush cover caused by tank tracks may reduce habitat quality for rodents. Tank tracks may also facilitate the invasion of exotic annuals into sagebrush habitat, increasing the potential for wildfire and subsequent habitat degradation. Thus, creation of divots and movement through sagebrush habitat by tanks should be minimized.     

Bird‐community responses to habitat creation in a long‐term,large‐scale natural experiment

Ecosystem function and resilience are compromised when habitats become fragmented due to land‐use change. This has led to national and international conservation strategies aimed at restoring habitat extent and improving functional connectivity (i.e., maintaining dispersal processes). However, biodiversity responses to landscape‐scale habitat creation and the relative importance of spatial and temporal scales are poorly understood, and there is disagreement over which conservation strategies should be prioritized. We used 160 years of historic post‐agricultural woodland creation as a natural experiment to evaluate biodiversity responses to habitat creation in a landscape context. Birds were surveyed in 101 secondary, broadleaf woodlands aged 10–160 years with ≥80% canopy cover and in landscapes with 0‐17% broadleaf woodland cover within 3000 m. We used piecewise structural equation modeling to examine the direct and indirect relationships between bird abundance and diversity, ecological continuity, patch characteristics, and landscape structure and quantified the relative conservation value of local and landscape scales for bird communities. Ecological continuity indirectly affected overall bird abundance and species richness through its effects on stand structure, but had a weaker influence (effect size near 0) on the abundance and diversity of species most closely associated with woodland habitats. This was probably because woodlands were rapidly colonized by woodland generalists in ≤10 years (minimum patch age) but were on average too young (median 50 years) to be colonized by woodland specialists. Local patch characteristics were relatively more important than landscape characteristics for bird communities. Based on our results, biodiversity responses to habitat creation depended on local‐ and landscape‐scale factors that interacted across time and space. We suggest that there is a need for further studies that focus on habitat creation in a landscape context and that knowledge gained from studies of habitat fragmentation and loss should be used to inform habitat creation with caution because the outcomes are not necessarily reciprocal.     

Male–female socio-spatial relationships and reproduction in wild chimpanzees

Recent research on primates and other taxa has shown that the relationships individuals form with members of the same sex affect their reproductive success. Evidence showing that intersexual relationships also influence reproduction, however, is more equivocal. Here, we show that male chimpanzees living in an exceptionally large community display long-term tendencies to associate with particular females. These association patterns are likely to arise because individuals of both sexes selectively range in specific areas of the communal territory, with males inheriting the ranging patterns of their mothers. These differentiated male–female socio-spatial relationships involved males of widely varying ranks, and their effect on reproduction is as strong as that of male dominance rank, which in turn is as strong a predictor of reproductive success at Ngogo as in other smaller chimpanzee communities. These results show that male–female socio-spatial relationships can play a large role in chimpanzee male reproductive strategies, although they probably neither weaken nor strengthen the relationship between male dominance rank and reproductive success. Our results linking male–female socio-spatial relationships to reproduction in chimpanzees suggest that the gap between the social and mating systems of humans and their closest living relatives may not be as large as previously thought.     

Infrared Measurement of Fluorocarbons,Carbon Tetrachloride,Carbonyl Sulfide,And Other Atmospheric Trace Gases

A cryogenic procedure for concentrating trace gases in the atmosphere has been developed and applied to the ambient air at Research Triangle Park, NC, Atlantic Beach, NC, and New York City. The concentrated gases have been analyzed by long path infrared absorption spectroscopy, with a detectability down to partial pressures of 10^?11 atmospheres. Carbonyl sulfide has been detected at partial pressures in the range 1 × 10^?10 atm. to 3 × 10^?10 atm. Carbon tetrachloride was always detected with a rather narrow partial pressure range of 0.7 × 10^?10 atm. to 1.1 × 10^?10 atm. Fluorocarbon-11 values ranged from about 1.3 × 10^?10 atm. at Research Triangle Park to 8 × 10^?10 atm. at New York City. Fluo-rocarbon-12 covered the range 1.8 × 10^?10 atm. to 1.0 × 10^?9 atm. Hydrocarbon pollutants varied widely in concentration, but were always detected, even in the clean rural air.     

Biochemical responses during starvation and subsequent recovery in postlarval Pacific white shrimp,Penaeus vannamei

Postlarval shrimp, Penaeus vannamei Boone, 1931, were held individually in cages and exposed to two feeding regimes. One group was starved for 12 d and then fed during the following 12 d. A second group was fed throughout the 24 d study. Four individuals were sampled from each of the two groups on Days 0, 1, 2, 4, 8, 12, 13, 14, 16, 20, and 24. Molting and growth among the starved-fed postlarvae stopped after 2 d starvation, while fed postlarvae increased significantly in size throughout the 24 d study. Among the starved-fed postlarvae, water content increased rapidly in response to starvation. DNA and sterol concentrations increased significantly during starvation due to selective catabolism of cellular components. After 12 d, RNA concentration was not significantly different between the fed and starved-fed postlarvae, but became significantly higher in the starved-fed postlarvae 48 h after feeding resumed. Triacylglycerol reserves were severely depleted during the first day of starvation, while protein concentrations began to decrease after the second day of starvation. RNA, protein, and the polyamines spermidine and spermine, when expressed as a ratio to DNA, decreased in response to starvation. Concentrations of all measured parameters in the starved-fed postlarvae returned to levels similar to those in the fed group 8 to 12 d after feeding resumed. Results of this study suggest that triacylglycerol provides energy during short periods of starvation, while protein is utilized during prolonged starvation. The ratios of RNA:DNA, protein:DNA, spermidine:DNA, spermine:DNA, two unidentified amine compounds, and percent water content are all useful indicators of prolonged nutritional stress in postlarval P. vannamei.     

The evolution of female social relationships in nonhuman primates

Considerable interspecific variation in female social relationships occurs in gregarious primates, particularly with regard to agonism and cooperation between females and to the quality of female relationships with males. This variation exists alongside variation in female philopatry and dispersal. Socioecological theories have tried to explain variation in female-female social relationships from an evolutionary perspective focused on ecological factors, notably predation and food distribution. According to the current “ecological model”, predation risk forces females of most diurnal primate species to live in groups; the strength of the contest component of competition for resources within and between groups then largely determines social relationships between females. Social relationships among gregarious females are here characterized as Dispersal-Egalitarian, Resident-Nepotistic, Resident-Nepotistic-Tolerant, or Resident-Egalitarian. This ecological model has successfully explained differences in the occurrence of formal submission signals, decided dominance relationships, coalitions and female philopatry. Group size and female rank generally affect female reproduction success as the model predicts, and studies of closely related species in different ecological circumstances underscore the importance of the model. Some cases, however, can only be explained when we extend the model to incorporate the effects of infanticide risk and habitat saturation. We review evidence in support of the ecological model and test the power of alternative models that invoke between-group competition, forced female philopatry, demographic female recruitment, male interventions into female aggression, and male harassment. Not one of these models can replace the ecological model, which already encompasses the between-group competition. Currently the best model, which explains several phenomena that the ecological model does not, is a “socioecological model” based on the combined importance of ecological factors, habitat saturation and infanticide avoidance. We note some points of similarity and divergence with other mammalian taxa; these remain to be explored in detail. Received: 30 September 1996 / Accepted after revision: 20 July 1997     

Storm flow export of metolachlor from a coastal plain watershed

During an 18-month (1994-1995) survey of the surface water in an Atlantic Coastal Plain watershed, metolachlor was most frequently detected during storm flow events. Therefore, a sampling procedure, focused on storm flow, was implemented in June of 1996. During 1996, three tropical cyclones made landfall within 150 km of the watershed. These storms, as well as several summer thunderstorms, produced six distinct storm flow events within the watershed. Metolachlor was detected leaving the watershed during each event. In early September, Hurricane Fran produced the largest storm flow event and accounted for the majority of the metolachlor exports. During the storm event triggered by Hurricane Fran, the highest daily average flow (7.5 m2 s-1) and highest concentration (5.1 micrograms L-1) ever measured at the watershed outlet were recorded. Storm flow exports leaving the watershed represented 0.1 g ha-1 or about 0.04% of active ingredient applied.