Twentieth-century decline of large-diameter trees in Yosemite National Park,California, USA     

J.A. Lutz  J.W. van Wagtendonk  J.F. Franklin 《Forest Ecology and Management》2009

Studies of forest change in western North America often focus on increased densities of small-diameter trees rather than on changes in the large tree component. Large trees generally have lower rates of mortality than small trees and are more resilient to climate change, but these assumptions have rarely been examined in long-term studies. We combined data from 655 historical (1932–1936) and 210 modern (1988–1999) vegetation plots to examine changes in density of large-diameter trees in Yosemite National Park (3027 km²). We tested the assumption of stability for large-diameter trees, as both individual species and communities of large-diameter trees. Between the 1930s and 1990s, large-diameter tree density in Yosemite declined 24%. Although the decrease was apparent in all forest types, declines were greatest in subalpine and upper montane forests (57.0% of park area), and least in lower montane forests (15.3% of park area). Large-diameter tree densities of 11 species declined while only 3 species increased. Four general patterns emerged: (1) Pinus albicaulis, Quercus chrysolepis, and Quercus kelloggii had increases in density of large-diameter trees occur throughout their ranges; (2) Pinus jeffreyi, Pinus lambertiana, and Pinus ponderosa, had disproportionately larger decreases in large-diameter tree densities in lower-elevation portions of their ranges; (3) Abies concolor and Pinus contorta, had approximately uniform decreases in large-diameter trees throughout their elevational ranges; and (4) Abies magnifica, Calocedrus decurrens, Juniperus occidentalis, Pinus monticola, Pseudotsuga menziesii, and Tsuga mertensiana displayed little or no change in large-diameter tree densities. In Pinus ponderosa–Calocedrus decurrens forests, modern large-diameter tree densities were equivalent whether or not plots had burned since 1936. However, in unburned plots, the large-diameter trees were predominantly A. concolor, C. decurrens, and Q. chrysolepis, whereas P. ponderosa dominated the large-diameter component of burned plots. Densities of large-diameter P. ponderosa were 8.1 trees ha⁻¹ in plots that had experienced fire, but only 0.5 trees ha⁻¹ in plots that remained unburned.  相似文献   

A generic model of thinning and stand density effects on forest growth, mortality and net increment     

Oskar Franklin  Kentaro Aoki  Rupert Seidl 《Annals of Forest Science》2009,66(8):815-815

? For assessing forest thinning effects at large (i.e. continental) scale, data scarcity and technical limitations prevent the application of localized or individual-based thinning models.

? Here we present a simple general framework to analyze and predict the effects of thinning on growth and mortality, including the following stand density development. The effects are modeled in relative terms so that the model can be parameterized based on any thinning experiment that includes an unthinned control, regardless of site conditions and stand age.

? The model was tested against observed thinning effects on growth and mortality from five temperate and boreal species (all species pooled r ² = 0.51). It predicted a maximum increase in net stem biomass increment of 16% and a reduction in density-related mortality of 75% compared to un-thinned conditions at stand densities of around 70% of the maximum (increment optimal density).

? A sensitivity analysis revealed overlapping ranges of near optimal density (net increment within 95% of optimal) among all tested species, suggesting that one thinning scenario can be used for many species. The simple and general formulation of thinning effects based on only five parameters allows easy integration with a wide range of generic forest growth models.

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Sheep fed with banana leaf hay reduce ruminal protozoa population     

Cláudio Eduardo Silva Freitas  Eduardo Robson Duarte  Dorismar David Alves  Isabel Martinele  Marta D’Agosto  Franciane Cedrola  Angélica Alves de Moura Freitas  Franklin Delano dos Santos Soares  Makenzi Beltran 《Tropical animal health and production》2017,49(4):807-812

A ciliate protozoa suppression can reduce methane production increasing the energy efficiency utilization by ruminants. The physicochemical characteristics of rumen fluid and the profile of the rumen protozoa populations were evaluated for sheep fed banana leaf hay in replacement of the Cynodon dactylon cv. vaqueiro hay. A total of 30 male sheep were raised in intensive system during 15 days of adaptation and 63 days of experimental period. The animals were distributed in a completely randomized design that included six replicates of five treatments with replacement levels (0, 25, 50, 75, and 100%) of the grass vaquero for the banana leaf hay. Samples of fluid were collected directly from the rumen with sterile catheters. Color, odor, viscosity, and the methylene blue reduction potential (MBRP) were evaluated and pH estimated using a digital potentiometer. After decimal dilutions, counts of genus protozoa were performed in Sedgewick Rafter chambers. The averages of pH, MBRP, color, odor, and viscosity were not influenced by the inclusion of the banana leaf hay. However, the total number of protozoa and Entodinium spp. population significantly decreased at 75 and 100% inclusions of banana leaf hay as roughage.  相似文献   

Gender discrimination and its impact on income,productivity, and technical efficiency: evidence from Benin     

Florent M. Kinkingninhoun-Mêdagbé  Aliou Diagne  Franklin Simtowe  Afiavi R. Agboh-Noameshie  Patrice Y. Adégbola 《Agriculture and Human Values》2010,27(1):57-69

This paper examines the occurrence and impact of gender discrimination in access to production resources on the income, productivity, and technical efficiency of farmers. Through an empirical investigation of farmers from Koussin-Lélé, a semi-collective irrigated rice scheme in central Benin, we find that female rice farmers are particularly discriminated against with regard to scheme membership and access to land and equipment, resulting in significant negative impacts on their productivity and income. Although women have lower productivity, they are as technically efficient as men. The findings suggest that there is considerable scope for improving the productivity of women through increasing their access to production resources.  相似文献   

Refrigerated Gas Storage of Fruit. V. Conference,Doyenné du Comice and Williams’ Bon Chrétien Pears     

Franklin Kidd  Cyril West 《The Journal of Horticultural Science and Biotechnology》2013,88(4):243-276

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Spotting and Other Effects on Apples in Storage Due to Volatile Products from Ripe Apples of Other Varieties Stored with Them     

Franklin Kidd  Cyril West 《The Journal of Horticultural Science and Biotechnology》2013,88(3):7-279

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The specific gravity,mealiness, and flavor of baked Maine potatoes as related to fungicide treatment     

Elizabeth F. Murphy  Reiner Bonde  Franklin E. Manzer 《American Journal of Potato Research》1963,40(2):35-46

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The effect of sward height on responses of mini-swards of perennial ryegrass/white clover to slurry application     

P. S. Wightman  M. F. Franklin  & D. Younie 《Grass and Forage Science》1997,52(1):42-51

The influence of sward height at the time of slurry application on sward responses to slurry was investigated using perennial ryegrass ( Lolium perenne )/white clover ( Trifolium repens ) mini-swards under greenhouse conditions. Pig slurry, cattle slurry and a fertilizer control were applied either to: swards cut 1 d before slurry application to heights of 2, 4 or 8 cm (CH2, CH4 or CH8); or to swards cut to 4 cm with regrowth intervals of 1, 4 or 8 d before slurry application (RI1, RI4 and RI8). Scorch, smother and growth of marked clover stolons and grass tillers were monitored after slurry application. Dry-matter yields of both species were recorded over two harvests. Electrolyte leakage from leaves was used to assess leaf damage. Both slurries increased leakage, which was greatest from clover leaves, with biggest increases caused by pig slurry. Yield responses to slurry application varied with plant species and sward height. Reduced grass growth after slurry application to long swards (CH8, RI4, RI8) was probably caused by greater smother. In short swards (CH2), grass leaf growth was not depressed following slurry application but grass yields were reduced. Ammonia volatilization losses may have been greater in both long and short swards, contributing to yield reductions. Yield responses to slurry were greatest in swards cut to 4 cm, 1 d before application.  相似文献   

Report of Potato Virus Investigations Committee     

Franklin Manzer  W. J. Hooker  N. S. Wright  James Munro 《American Journal of Potato Research》1961,38(10):361-362

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The rate and amount of absorption of maleic hydrazide by potato tubers     

Everett W. Franklin  Everett C. Lougheed 《American Journal of Potato Research》1964,41(7):191-195

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