Wardle et al. (Brevia, 2 May 2008, p. 629) reported that fire-derived charcoal can promote loss of forest humus and belowground carbon (C). However, C loss from charcoal-humus mixtures can be explained not only by accelerated loss of humus but also by loss of charcoal. It is also unclear whether such loss is related to mineralization to carbon dioxide or to physical export.

The canopy of many central African forests is dominated by light-demanding tree species that do not regenerate well under themselves. The prevalence of these species might result from ancient slash-and-burn agricultural activities that created large openings, while a decline of these activities since the colonial period could explain their deficit of regeneration. To verify this hypothesis, we ...

BACKGROUND Long-term vegetation changes in hyper-arid areas have long been neglected. Mortality, recruitment and change in populations of the ecologically and culturally important and drought persistent Acacia tortilis and Balanites aegyptiaca are therefore estimated in the Eastern Desert of Egypt, and are related to the primary agents of change, water conditions and human intervention. METHO...

Wittke et al. (1) present evidence of a major cosmic impact at the onset of the Younger Dryas (YD) episode, including some markers found in the top of the well-known Usselo marker horizon (UH). This finding is contrary to our extensive radiocarbon dating effort from this horizon (2), which shows that the UH at Aalsterhut postdates the onset of the YD. Furthermore, Wittke et al. (1) misinterpret...

We report the discovery in Lake Cuitzeo in central Mexico of a black, carbon-rich, lacustrine layer, containing nanodiamonds, microspherules, and other unusual materials that date to the early Younger Dryas and are interpreted to result from an extraterrestrial impact. These proxies were found in a 27-m-long core as part of an interdisciplinary effort to extract a paleoclimate record back throu...

A protocol for in vitro cloning of mature plants of Citrus limon using nodal shoot segments has been developed. Three to four shoots were induced per axillary meristems on MS medium amended with 9 μM BAP. Repeated transfer of the initial explants for up to six passages on MS medium [having 50% of the original concentrations of NH4NO3 and KNO3, and supplement of 250 mg L (NH4)2SO4] with 0.22 μM ...

A protocol was established for mass clonal propagation of Phalaenopsis amabilis cv. 'Golden horizon' through in vitro culture of young leaf segments from mature plant. Explants were cultured on half strength Murashige and Skoog (1/2 MS) medium supplemented with N6-benzyladenine (2.0 mg l-1), a-naphthaleneaceetic acid (0.5 mg l-1), 2% (w/v) sucrose, 10% (v/v) coconut water, 2 g l-1 peptone and 1...

A novel method of shoot regeneration from immature floral buds along with inflorescence axis in C. borivilianum, a rare medicinal herb is described. Using this explant, axenic cultures were established with very less contamination (10%). MS medium with 2 mg l(-1) kinetin and 0.1 mg l(-1) 2, 4-dichlorophenoxyacetic acid proved to be the best for multiple shoot induction. Maximum number (35) of s...

In vitro mass production of C. suaveolens (Lindl.) Hook, an endangered orchid with its snowy white flowers having horticultural potential was accomplished through immature seed culture, and subsequent plant regeneration. The developmental stage of the immature seeds and nutrient media significantly influenced the germination frequency. Seeds at 13 months after pollination cultured on 3% sucrose...

OBJECTIVE To analyze the efficiency of labeling impalpable breast lesions with inert charcoal suspension; to evaluate the morphological alterations associated with its use and to determine whether the use of charcoal labeling hampers the diagnostic interpretation of the pathologist. METHODS Was evaluated a total of 135 cases of impalpable breast lesions previously labeled with charcoal suspen...