Enclosure utilization,activity budgets,and social behavior of captive chamois (Rupicapra rupicapra) during the rut

An observational study of chamois behavior during the rut was conducted at the Los Angeles Zoo. The herd consisted of an adult male, two adult females, two subadult females, and two kids (1.1). During the 13-week study, observers collected scan data on all animals and recorded all occurrences of selected social behaviors during interactions which involved the adult male. Scan observations showed that open areas of the enclosure close to the public were the least preferred, and areas with good rest places were used most. Overall the herd spent 73% of their time stationary, 13% foraging/feeding, 6% moving, and less than 5% each in object investigation, maintenance, play, and social behavior. The adult male rested and fed less, and stood vigilant and engaged in social behavior more frequently than the others. Nearest neighbor data showed clear patterns of kin association beyond the mother-last kid bond. The adult male interacted most often with the regular keepers, the subordinate female and the oldest subadult female. Interactions with the females consisted mostly of herding and sexual behaviors, while those with keepers were almost exclusively competitive/aggressive. While most findings paralleled those from studies of wild chamois, no study has previously reported long-lasting associations among kin.     

A soil heat and water transfer model to predict belowground grass rhizome bud death in a grass fire

Question: Grasses often resprout from surviving belowground buds following a fire in which aboveground matter is consumed. We used a soil heat and water transport model to present a general method for determining the potential mortality of rhizome buds due to fire for three tallgrass species (Andropogon gerardii, Sorghastrum nutans, and Panicum virgatum). Methods: Soil heating was described by physical processes that include heat conduction through the soil and heating and evaporation of soil water. We considered the following factors: soil moisture, texture, mineral thermal conductivity, maximum surface temperature, and fire residence time. Simulated soil temperature profiles were combined with measured belowground bud distributions to determine the proportion of buds expected to be heated to lethal temperatures under various conditions. Location: Wisconsin, USA. Results: Lethal temperatures for buds do not occur below ～2 cm, and at least 30% of rhizome buds remain below lethal temperatures, even under extreme conditions. Conclusions: The model explains the possible mechanisms for grass belowground rhizome bud survival in fires. Changes in fire and soil conditions do not notably impact soil temperatures and rhizome bud survival.     

Phosphorus Accumulation in Saint Lawrence River Watershed Soils: A Century-Long Perspective

Understanding historical patterns of soil phosphorus (P) accumulation is critical to management of water quality across agricultural landscapes. To address the effects of long-term agricultural P management on soil P accumulation in the Saint Lawrence River sub-basin (574,000 km²), we calculated cropland P budgets at decadal intervals from 1901 to 2001 for the sub-basin and its tributary watersheds. Agricultural census data were used to estimate P inputs in the form of fertilizer and manure, and outputs (P removed in harvested crops). The resulting balances indicate the potential magnitude of P accumulation in cropland soils. Cropland P surpluses occurred in the sub-basin in each decade of the past century, with the rate of accumulation increasing after 1951 due to more widespread use of P fertilizers and manure. The largest annual P surplus occurred in 1981 (42,000 Mg y⁻¹), followed by a decline in the rate of accumulation to almost half that level by 2001 (24,850 Mg y⁻¹) as a result of improved management of agricultural P. Comparison of the cumulative P surpluses estimated for the entire 20th century with measured soil P data indicates a strong linear relationship between these watershed P budgets and the average soil P content across the sub-basin (R ² = 0.712, P < 0.0001). These results support the view that historical land management can have important ecological legacies.     

Stream chemistry and hydrologic pathways during snowmelt in a small watershed adjacent Lake Superior

In regions with airborne contaminants and large snowpacks, there is concern over the impact that snowmelt chemical pulses — periods of sharp increase in meltwater solute concentration — could have on aquatic resources during spring runoff. A major variable in determining such an effect is the flow path of snowmelt solutes to the stream or lake. From December 1988, to late April 1989, the quality and quantity of precipitation, snowmelt, soil solution and streamwater were measured in a 176-ha gauged watershed on the south shore of Lake Superior. The main objectives were to (1) examine the change in flow path meltwaters take to the stream during distinct winter and spring hydrologic periods, (2) quantify ecosystem-level ion budgets prior to, during, and following snowmelt, and (3) examine if streamwater chemistry might be a sensitive indicator of change in ecosystem flow paths. Prior to peak snowmelt, groundwater made up 80% of stream discharge. During peak snowmelt, the groundwater level rose to the soil surface resulting in lateral water movement through near-surface macropores and as overland flow. Near the end of snowmelt, melt-waters exerted a piston action on deeper soil solution again increasing its relative contribution to streamwater discharge. Net groundwater drawdown during the study resulted in streamwater discharge about equal to precipitation inputs. Unfrozen soils and brief mid-winter thaws resulted in steady snowmelt throughout early and mid-winter. The snowpack lost > 50% of most ions prior to the period of major snowmelt and high stream discharge in late March and early April. Snowmelt and streamwater NO₃ ^– and NH₄ pulses occurred before the period of overland flow and peak streamwater discharge (April 4–24). During overland flow, stream discharge of total N, P, DOC, and AI peaked. Nutrient budgets computed for distinct hydrologic periods were much more helpful in explaining ecosystem pathways and processes than were changes in solute concentration. For the study period, watershed base cation (C_B) discharge was 23 times input and SO₄ ^2– discharge exceeded input by 42%. H⁺ was the most strongly conserved ion with output < 0.2% of input. Also conserved were NH₄ ⁺ with only 1.4% of input leaving the ecosystem and NO₃ ^– with output equal to 9.4% of input.     

Spatial and temporal variation of soil solution chemistry and ion fluxes through the soil in a mature Norway Spruce (Picea abies (L.) Karst.) stand

In this study we investigated the spatial and temporal variation in soil solution chemistry and of water and ion fluxes through the soil in a forest ecosystem. Our aim was to evaluate the relevance of these variations for the accuracy of average areal soil solution concentrations and ion fluxes with seepage at 90 cm depth.Twenty spatially distinct subcompartments of approximately 1 m² were established within a mature stand of Norway spruce and ceramic suction lysimeters were installed at depths of 20, 35 and 90 cm. A tensiometer was placed close to each suction lysimeter, and one throughfall sampler was established for each subcompartment.Soil solution samples were analysed for major ions (H⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺, Mn²⁺, Fe³⁺, Al³⁺, Cl^-, NO ₃ ^- , SO ₄ ^2- . We calculated water fluxes for each subcompartment separately by a numeric simulation of the soil water flux close to the lysimeters. The ion fluxes at each lysimeter were calculated by multiplying the simulated water fluxes with the ion concentrations on a fortnightly base. Averaging these 20 independent ion fluxes gave the areal average flux and an estimate of its statistical accuracy. The spatial variation of ion concentrations in the soil solution was high with coefficients of variance ranging from 5% to 128%. Part of the spatial variation was related to stem distance. Temporal variation of the concentrations was less than spatial for most ions. The spatial variation of water and ion fluxes with seepage was also substantial; for example the fluxes of SO ₄ ^2- -S calculated for each subcompartment ranged from 21 to 119 kg ha^-1 yr^-1, with an arithmetic average of 47 kg ha^-1 yr^-1. For H₂O, Mg²⁺, Cl^-, and SO ₄ ^2- , the spatial heterogeneity of seepage fluxes was largely explained by the heterogeneity of throughfall fluxes. No such relationship was found for nitrogen.Despite using 20 replicates, the 95% confidence intervals of the average annual areal fluxes with seepage were found to be 20–30% for most ions.     

Energy budgets and risk-sensitive foraging in starlings

The effect of energy budget on risk-sensitive foraging was assessedin a laboratory experiment using starlings (Sturnus vulgaris).Subjects chose between two options offering the same mean amountof food per trial, but differing in variance: a "fixed" optiongave 5 units food in every trial, and a "variable" option gave2 or 11 units food with probabilities 2/3 and 1/3, respectively.We manipulated energy budgets by controlling the cumulativeamount of food received by each bird at the end of a day. Inone treatment (positive budget) individuals were allowed toeat at the level of their own ad-libitum daily consumption,while for the other (negative budget), food was rationed toprovoke a steady drop in body weight during the experimentalperiod. No subject was allowed to drop below 80% of its ad libitumbody weight. Contrary to predictions from the "energy budgetrule" and contrary to reported results of some other studies, starlingssignificantly preferred the "fixed" option irrespective of energybudget conditions. Our results support the view that persistentrisk aversion for food amounts and risk proneness for food delaysare the norm, and shifts in risk attitude according to energybudget are exceptions. Several algorithms, which may have evolvedto maximize energetic pay off between variable food sources,can produce this trend as a side effect. We discuss two of thesealgorithms: (1) maximization of local (per trial) rate as opposedto global rate of gains, with longer handling time for largerrewards, and (2) choosing larger rewards and smaller delayssubject to Weber's law in the memory for the parameters of eachfood supply.     

Periphyton production in an Appalachian river

Periphyton primary production was measured by ¹⁴C uptake on natural substrates in two sections of the New River, Virginia, U.S.A. Production ranged from 6.71 ± 0.43 mg C g^–1 h^–1 in summer to 1.47 ± 0.22 mg C g^–1 h^–1 in late autumn in the hardwater reach and from l.90 ± 0.10 mg C g^–1 h^–1 to 0.12 ± 0.08 mg C g^–1 h^–1 in the softwater reach. Production in the hardwater reach was 3–5 times greater than in the softwater reach and significantly correlated with dissolved inorganic carbon (DIC) concentration (r² = 0.506). No significant correlation was found between periphyton production and photosynthetically active radiation (PhAR). Extrapolation of periphyton production to a 135 km reach of the New River yielded an estimated annual input of 2 252 T AFDW from this source. Estimates of allochthonous (excluding upstream contributions) and aquatic macrophyte inputs to this same reach were 64 T AFDW and 2 001 T AFDW, respectively. While periphyton is not a large source of organic matter, its high food quality and digestibility make it an important component of the New River energy dynamics.