Los sitios arqueológicos de altura en el Centro Oeste Argentino y Chile Central se caracterizan por estar localizados en ambientes altoandinos, presentar recintos pircados, cerámica afín a complejos culturales de la cuenca Maipo-Mapocho de Chile Central, evidencias de caza de camélidos y procesamiento de plantas silvestres y cultivadas. En este trabajo se presenta el estudio antracológico de dos sitios ubicados en el Área Natural Protegida Laguna del Diamante (3.200 m snm), con evidencias de ocupación humana entre 2.100 años aP y tiempos históricos. Para caracterizar cuali-cuantitativamente el registro antracológico de LD-S2 y LD-S4 se utilizaron métodos estándar. Se identificaron siete taxa vegetales. Las estrategias de manejo de plantas leñosas detectadas estuvieron orientadas a la recolección de maderas locales (familia Asteraceae y Adesmia sp.), junto con otras de pisos altitudinales inferiores, tanto de Chile Central (Acacia aff. caven, Persea lingue y Quillaja saponaria) como de Argentina (Prosopis aff. alpataco), así como de un taxón que crece en ambos flancos cordilleranos (Ochetophila sp.). Los resultados obtenidos se integraron con estudios previos sobre fuentes y artefactos de obsidiana y análisis isotópicos y cerámicos. Todos muestran un acceso predominante de sociedades de la cuenca cordillerana del río Maipo a Laguna del Diamante.

The effects of photoperiod and temperature on the translocation of triclopyr {[1(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid}, picloram (4-amino-3,5,6-trichloropicolinic acid) and 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] were studied on tanoak [Lithocarpus densiflorus (Hook. & Arn.) Rehd.], snowbush ceanothus (Ceanothus velutinus Dougl.), bigleaf maple (Acer macrophyllum Pursh), bean (Phaseolus vulgaris L. var. ‘Red Kidney’) and barley (Hordeum vulgare L. var. CM-67). Isolation of 14C and analysis for the radioactive herbicides revealed little metabolism of the herbicides. Regardless of herbicide or plant species herbicide movement was greatest under warm temperature and long day conditions. Among the herbicides tested, 14C associated with triclopyr was the most mobile in each species. Each herbicide moved readily in the symplast but root applications of each herbicide revealed limited apoplastic mobility.

The objective of this work was to evaluate resprouting features and mortality in Cerrado woody plants after annual controlled fires (in 1998, 1999 and 2000) in a campo sujo area (an open savanna physiognomy) of 2500 m2 at the Reserva Ecológica do IBGE, Brasília-DF, Brazil. The area was protected against fire for 23 years prior to the fires. All plants of the woody layer with diameter larger than 2.0 cm at 30 cm from soil level were tagged and identified. At about one year after each controlled fire the damage type and the number of basal and underground sprouts for each individual were recorded. Stem diameter and height were measured for each marked sprout. A total of 1307 sprouts were tagged and measured. The main impact of fire on resprouting was a decrease in the number of new sprouts after each controlled fire: 684 sprouts after the first burning to 248 after the third burning. Mortality of sprouts was 34.8% and 37.8% after the 1999 and 2000 fires. A decrease in the number of sprouts with a diameter smaller than 1.0 cm after the successive fires was also observed, indicating that fires at one-year intervals resulted in alterations in the structure of the woody vegetation in the area. The species mortality rates were higher after the first controlled fire. However, it seems that there is no relation between sprouting capacity and species survival. The species that show mortality rates lower than 10% also showed a variety of sprouting capacity.

Most studies on the effects of tanniferous plants on nematodes have examined forages but have neglected the woody plants. Therefore, in vitro effects of extracts from 3 woody plants (Rubus fructicosus, Quercus robur, Corylus avellana) have been tested on trichostrongyles and compared to sainfoin, a legume forage. Because some in vivo results indicated that the effects of tannins differed depending on the parasitic species and/or stages, the effects were measured on 3rd-stage larvae (L3) and adult worms of Teladorsagia circumcincta, Haemonchus contortus and Trichostrongylus colubriformis. The effects of plant extracts varied according to the plant sources, the parasite species and stages. For the woody plants, significant inhibitory effects were obtained on both stages of abomasal species. Results for T. colubriformis were more variable. Effects of sainfoin extracts were significant on T. colubriformis and H. contortus L3, and on abomasal adult worms. In order to assess the implications of tannins, polyethylene glycol (PEG), an inhibitor of tannins, was added to hazel tree, oak and sainfoin extracts. Without PEG, significant inhibitory effects on L3 and adult worms were confirmed. After addition of PEG, the larval migration and motility of adult worms were restored in most cases. These results confirm variations in effects depending on factors related to plants or parasites and suggest that tannins are partly responsible for the effects.

Although the honey fungus (Armillaria mellea) is notorious as a common soil-borne pathogen and no woody plant appears completely immune to attack, it is frequently supposed by gardeners and others that some non-woody plants are less susceptible. Few herbaceous plants are inspected for this pathogen, and this may have limited our understanding of its epidemiology.

An appendix is available for this article which was not included in the print edition of the Journal. The appendix may be found at the rear of the full text, PDF version of the article.

A popular conceptual model asserts that shade tolerance is characterized by morphological and physiological traits that enhance the net rate of carbon capture in low light. We tested this model by quantitatively reviewing growth, leaf lifespan, CO2 exchange and morphological data from 76 studies on woody seedlings grown under conditions of low light. Data were placed into three tolerance categories (intolerant, intermediate, tolerant), two light categories (less than 4% and 4–12%) and two leaf phenology categories (broad-leaved evergreen and winter deciduous). For both evergreen and deciduous groups, intolerant species had traits conferring greater growth potential than tolerant species in both light categories. These traits included greater leaf mass ratio, leaf area ratio, specific leaf area and mass-based photosynthetic rates above light compensation. However, in 0–4% light, growth rates were similar for intolerant and tolerant species, because low light together with higher respiration rates for intolerant species limited the expression of their growth potential differences. Deciduous and evergreen intolerant species were similar in many respects. However, both intermediate and tolerant deciduous species had markedly lower leaf mass ratios and higher root mass ratios than intermediate and tolerant evergreen species. In addition, deciduous species and intolerant evergreens must cope with as much as sixfold higher leaf turnover rates than tolerant evergreen species. Thus, rather than maximizing growth rates in low light, tolerant evergreen species minimize biomass loss through long leaf lifespans and low respiration rates. Tolerant deciduous species also minimize biomass losses by minimizing whole-plant respiration rates but they accomplish low biomass turnover though low leaf mass ratio and not low leaf turnover rates. Furthermore, unlike most tropical evergreens, tolerant deciduous species can gain large fractions of their total growing season carbon during short periods when the overstory is leafless and then allocate this carbon to storage (as reflected by high root mass ratios) rather than new leaves. In conclusion, we found no support for the low-light-enhanced carbon capture model of shade tolerance as viewed strictly from the perspective of physiological growth capacity. This can be explained by the disadvantages to net growth and survival of maintaining a high growth potential at low light, because high growth potential results in greater rates of whole-plant respiration, tissue turnover, herbivory and mechanical damage and in decreased storage. Thus, shade tolerance can be characterized by traits that maximize survival and net growth, where net growth includes losses to all agents.