An Analysis of Growth of Oil Palms under Nursery Conditions: I. Establishment and Growth in the Wet Season

Growth of oil palm seedlings over the period 2–31 weeksafter planting in the nursery was studied using growth-analysistechniques. Curves of the Gompertz type were fitted to the basicdata of plant dry weight and leaf area, and from the equationsof the fitted curves, net assimilation rate (E_A), relative growth-rate(Rw), and relative leaf growth-rate (R_A) were calculated. The low values of E_A (0.16-0–31 g/dm²/week) and Rw (1.4–2.2per cent./per day) confirm earlier work on oil palm seedlings.The time trend of increasing E_A and R_W over the period studiedis associated with steadily increasing solar radiation overthe second half of the period. Leaf-area ratio is markedly affected by transplanting, and asthis unbalance of leaf area/total dry weight has been shownto be associated with low rates of EA in seedlings, it is suggestedthat the low values of E_A and R_W in the first half of the experimentalperiod are due to the effect of transplanting. These findings are discussed in relation to current nurserypractice.     

Using Resource Selection Functions to Improve Estimation of Elk Population Numbers

Abstract: Stratification is commonly used to improve sampling efficiency of aerial surveys of ungulate populations with strata typically based on a priori information, such as preflight animal observations or vegetation attributes as surrogates for animal densities. We evaluated the usefulness of stratifying survey units for elk (Cervus elaphus) in the Rocky Mountain foothills of Alberta, Canada, using a resource selection function (RSF). We compared precision and design efficiency (DEFF) of population estimates from stratification approaches based on an RSF model to the past approach using amount of forest cover. We used a sample of telemetry relocations taken over a 3-year period from 165 elk, rarified to times of the day and months of the year when aerial surveys are conducted, to develop the RSF. We then used the top RSF model, based on Akaike's Information Criterion, to derive the average RSF value for an 8-km² survey unit. Using survey data from the first year, we evaluated binning schemes to define RSF-oriented strata based on poststratification and showed that Jenks natural breaks in the RSF values provided the greatest improvement in DEFF and increased precision, compared to 2 other stratification schemes. We then used this approach with data from 2 additional surveys to find that stratification by RSF consistently improves relative precision and design efficiency of elk population estimates, whether we employ pre- or poststratification. Where a RSF is available it could be used as a surrogate for animal densities when conducting stratified sampling for population surveys.     

In the Way of Development: Indigenous Peoples, Life Projects, and Globalization

In the Way of Development: Indigenous Peoples, Life Projects, and Globalization. Mario Blaser, Harvey A. Feit, and Glenn McRae, eds. New York: Zed Books, 2004. 362 pp.     

How useful are the recommended counts and indices in the systematics of the Octopodidae (Mollusca: Cephalopoda)

A morphological dataset based on 14 standard counts and indices was constructed for 68 specimens comprising 12 species of octopuses. This was used to construct distance matrices based on morphological characters. These matrices were compared with genetic distance matrices compiled during molecular phylogenetic analyses of the same 12 species using four mitochondrial and two nuclear genes. Mantel tests showed that there was significant congruence between the phenetic and genetic matrices, suggesting that the genetic signal is reflected in the morphological data set. Matrices of geographical distance were constructed for the 12 species based on the latitude, longitude, and depth of capture of 1726 individuals. These matrices never showed significant congruence with genetic data or with morphological data. Multivariate analysis of the morphological dataset suggests that these counts and indices, traditionally used for discriminating between species in cephalopods, do not show great discrimination at species level, but provide excellent discrimination at the generic level, and, as such, might be useful for resolving the generic placement of some problematic taxa. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 205–218.     

Mitochondrial genomes in the Hymenoptera and their utility as phylogenetic markers

Abstract.  In this study, we assessed the ability of mitochondrial genome sequences to recover a test phylogeny of five hymenopteran taxa from which phylogenetic relationships are well accepted. Our analyses indicated that the test phylogeny was well recovered in all nucleotide Bayesian analyses when all the available holometabolan (i.e. outgroup) taxa were included, but only in Bayesian analyses excluding third codon positions when only the hymenopteran representatives and a single outgroup were included. This result suggests that taxon sampling of the outgroup might be as important as taxon sampling of the ingroup when recovering hymenopteran phylogenetic relationships using whole mitochondrial genomes. Parsimony analyses were more sensitive to both taxon sampling and the analytical model than Bayesian analyses, and analyses using the protein dataset did not recover the test phylogeny. In general, mitochondrial genomes did not resolve the position of the Hymenoptera within the Holometabola with confidence, suggesting that an increased taxon sampling, both within the Holometabola and among outgroups, is necessary.     

Responses of lotic periphyton to pulses of phosphorus: P‐flux controlled growth rate

1. The response of stream periphyton to the addition of limiting nutrients has been the focus of many studies. However, the influence of pulsed nutrient additions has not previously been examined. This study investigates the biomass accrual and physiological responses of phosphorus‐limited lotic periphyton to hourly phosphate fluxes. 2. Two pulsing experiments were conducted: (i) a variable flux trial that compared variable hourly P‐fluxes, delivered either continuously at different concentrations or at the same concentration but in pulses of differing duration per hour and (ii) a constant flux trial that compared periphyton responses at a set hourly P‐flux but delivered in pulses of varying concentration and duration. 3. Growth response and alkaline phosphatase activity during the variable flux experiment showed that periphyton responds to the hourly integrated flux of phosphorus, regardless of whether the nutrient is supplied in short concentrated pulses or continuously at much lower concentrations. 4. The constant flux experiment examined the pulse period required to attain maximum biomass for a given phosphorus flux. Periphyton response to 5‐min pulses of phosphate per hour approximated the maximum biomass as that attained when the same hourly flux was added continuously. Compared with the control, there was also a substantial increase in biomass with pulses of only 1 min each hour. These results demonstrate that the hourly average phosphate concentration to which periphyton communities are exposed is paramount in determining P‐limited growth dynamics. 5. Species composition was not significantly different among treatments in each experiment; however, the design was to evaluate monotonic response with increasing phosphorus flux and species diversity may not respond monotonically. The data are therefore preliminary but suggest the need to determine if species diversity is generally lower when there are brief pulses of phosphate. Unlike pulse experiments that mimic lentic situations, nutrient additions were not used to completion and species success and composition was more dependent on their ability to acquire limiting nutrients rapidly rather than on their ability to take up nutrients at the lowest concentration.