Can plantations develop understory biological and physical attributes of naturally regenerated forests?

With an increasing proportion of natural forests being replaced by plantations, there is a need to determine their potential to fulfill ecological purposes other than wood production. This study evaluated the extent to which deciduous and coniferous plantations develop understory attributes comparable to those of naturally regenerated stands. A functional group approach was used to synthesise species responses in terms of their ecological traits. Multivariate analyses of ecological traits revealed 16 emergent groups that shared common traits associated with a similar life history strategy. Responses of these groups, understory structure, and understory environmental conditions to plantation types and stand stages were analyzed and compared to naturally regenerated stands. Clear associations of trait responses to stand developmental stages and plantation types emerged. Light-demanding and wind-dispersed species groups were associated with early-successional stages, while woody groups, ferns and ant-dispersed spring-flowering herbs were associated with late-successional stages. Analyses also revealed an indicator group associated with old naturally regenerated forest. The understory functional groups and environmental conditions of deciduous plantations converged toward those of old naturally regenerated forests. However, understory structure in deciduous plantations remained poorly developed and richness of the indicator group was low compared to unplanted stands. Conifer plantations, currently the most common plantation type in the northern hardwood biome, showed a completely different pathway of understory development. Modifications to current plantation management practices are proposed to help recreate or maintain natural understory biological and physical attributes

A Tunguska Sized Airburst Destroyed Tall el‑Hammam a Middle Bronze Age City in the Jordan Valley Near the Dead Sea

We present evidence that in ~ 1650 BCE (~ 3600 years ago), a cosmic airburst destroyed Tall el-Hammam, a Middle-Bronze-Age city in the southern Jordan Valley northeast of the Dead Sea. The proposed airburst was larger than the 1908 explosion over Tunguska, Russia, where a ~ 50-m-wide bolide detonated with ~ 1000× more energy than the Hiroshima atomic bomb. A city-wide ~ 1.5-m-thick carbon-and-ash-rich destruction layer contains peak concentrations of shocked quartz (~ 5–10 GPa); melted pottery and mudbricks; diamond-like carbon; soot; Fe- and Si-rich spherules; CaCO(3) spherules from melted plaster; and melted platinum, iridium, nickel, gold, silver, zircon, chromite, and quartz. Heating experiments indicate temperatures exceeded 2000 °C. Amid city-side devastation, the airburst demolished 12+ m of the 4-to-5-story palace complex and the massive 4-m-thick mudbrick rampart, while causing extreme disarticulation and skeletal fragmentation in nearby humans. An airburst-related influx of salt (~ 4 wt.%) produced hypersalinity, inhibited agriculture, and caused a ~ 300–600-year-long abandonment of ~ 120 regional settlements within a > 25-km radius. Tall el-Hammam may be the second oldest city/town destroyed by a cosmic airburst/impact, after Abu Hureyra, Syria, and possibly the earliest site with an oral tradition that was written down (Genesis). Tunguska-scale airbursts can devastate entire cities/regions and thus, pose a severe modern-day hazard

Species diversity and diversity profiles: concept, measurement, and application to timber and range management

The concepts and use of several diversity assessments are presented and applied to a practical situation. Burning, mechanical methods of site preparation, and cattle grazing are common disturbances in forests of the South. Their influence on plant diversity indices are examined in a longleaf-slash pine forest of north Florida. Species richness, Shannon's index, and Simpson's index showed increases in diversity shortly following burning and site preparation and a trend toward pre-treatment conditions after 6 years. Deferred-rotation grazing systems had no influence. Comparative diversity profiles showed similar trends but were more informative by providing both qualitative and quantitative information. These techniques are useful for assessing community responses to management practices, that is, they are effective methods for understanding the impacts of forest management and range management practices on plant community structure and succession.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Vegetation Response to Prescribed Fire in a North Florida Flatwoods Forest

Selected naturally regenerated flatwoods forests were burned in preparing a large, long-term study of the effects of several multiple use management practices on forest vegetation and wildlife. Early effects of burning on understory vegetation are reported here. Fire reduced woody understory coverage (from 72 to 66% of surface area), and increased herbaceous species frequency (from 60 to 81%) and herbaceous standing biomass (from 124 to 245 kg/ha). Graphical analyses show an increase in herbaceous species diversity as a result of burning.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Understory Biomass Response to Microsite and Age of Bedded Slash Pine Plantations

Understory standing crop biomass was studied on three culturally imposed microsites (bed, furrow, and flat) bedded slash pine (Pinus elliottii) plantations in north Florida. Biomass was clipped in the late spring of 1977 on plantations 2, 5, and 10 years old and separated into five classes: grass, forb, sedge, shrub, and litter (including standing dead). After an initial abundance following site preparation sedges and forbs dropped to relatively low levels within the first 5 years of plantations development. Grasses were the dominant live vegetation in two-year-old plantations. Shrubs became dominant by the fifth year and remained so through the 10th year. Litter, as a result of the lack of cultural treatments designed to remove accumulated dead vegetation, was the major biomass class (more than 8,000 kg/ha by the fifth year following pine establishment). Total live understory biomass increased from the second to the fifth year after which it decreased. Grass standing crop biomass was highest on the flats, lowest in furrows. Hence, forage inventories should be stratified by microsite. Prescribed burning on a properly managed cattle operation may prevent high accumulations of litter while effectively improving the availability of palatable forage. Forage may also be increased by decreasing the proportion of land occupied by the less productive microsites, namely the furrows and beds.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Herbage Capacitance Meter: an Evaluation of Its Accuracy in Florida Rangelands

This paper reports results of regression analyses of the use of a capacitance meter to estimate herbage weight. Estimation of dry weights was found to be as accurate as estimation of green weights. Analysis of covariance for three factors, site, season of year, and year of data collection, showed only season significantly (P<.01) affected the relationship between herbage weight and meter reading. Simple linear regressions were compared to natural logarithmic regressions. Logarithmic regressions were found to be better predictors of herbage weight as determined by Furnival's Index. Winter and spring proved to be the best time to use the capacitance meter, probably due to decreased effect of moisture fluctuations on the meter's performance.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202