Influence of sulfometuron methyl on conifer seedling root development

On three sites in coastal northwestern Oregon, USA, seedling root and shoot development were assessed for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and western red-cedar (Thuja plicata Donn ex D. Don) container seedlings under varying sulfometuron methyl (Oust XP^®) herbicide application treatments. Treatments consisted of application of 0.16 kg active ingredient (ai) ha^?1 as a site preparation in fall 2003, a release application in fall 2004, or a control treatment with no application. Seedlings were planted in winter 2004 and measurements recorded in summer 2004, winter 2005, and summer 2005. During first season growth, western red-cedar seedlings showed the greatest negative impact to site preparation compared to the control with overall average new root length outside the root plug reduced by 67%. Significant reductions in root length also occurred for western hemlock (47%) and Douglas-fir (40%) seedlings. About 9 months after the release treatment, and 21 months after the site preparation application, there were no significant differences between treatments for any measured parameter. These findings suggest that seedlings under the site preparation treatment recovered from initial damage incurred to the root system. Lack of seedling response under the release treatment may be the result of opposing influences from the herbicide application associated with seedling phytotoxicity and enhanced seedling development resulting from effective vegetation control. Although our study was limited to 21 months following planting, reduced vegetation cover in the site preparation and release treatments suggests that these treatments may benefit future seedling growth.     

Performance and nutrient dynamics of holm oak (<Emphasis Type="Italic">Quercus ilex</Emphasis> L.) seedlings in relation to nursery nutrient loading and post-transplant fertility

Holm oak (Quercus ilex L.) seedlings were exponentially (E) nutrient loaded using incremental increases in fertilizer addition or conventionally (C) fertilized using a constant fertilizer rate during nursery culture. The fertility treatments (mg N plant⁻¹) were control (0), 25E, 100E, and 100C. Subsequently, 1-year-old plants were transplanted under simulated soil fertility gradients in a greenhouse to evaluate effects of nutrient loading and post-transplant fertility on seedling performance. Post-transplant fertility consisted of fertilizing plants at two rates (0 vs. 200 mg N plant⁻¹). A water-soluble fertilizer 20-20-20 was supplied in both nursery and post-transplant experiments. Nutrient loading increased plant N content by 73% in 100E and by 75% in 100C relative to controls, although no significant differences were detected between constant and exponential fertilization regimes at the 100 mg N plant⁻¹ rate. When transplanted, nutrient loading promoted post-transplant root growth relative to shoot, implicating potential to confer competitive advantage to loaded holm oak seedlings after trans-planting. In contrast, post-transplant fertility increased new shoot dry mass by 140% as well as N, P and K content relative to controls. Results suggest that holm oak seedlings can be successfully nutrient loaded in the nursery at higher fertility rates, improving its potential to extend new roots, but alternative fertilization regimes and schedules that better fit nutrient availability to the growth rhythm and conservative strategy of this species must be tested.     

Occurrence of <Emphasis Type="Italic">Bursaphelenchus mucronatus</Emphasis> (Nematoda; Aphelenchoididae) in France and association with <Emphasis Type="Italic">Monochamus galloprovincialis</Emphasis> (Coleoptera: Cerambycidae)

As a consequence of the recent introduction of the pine wood nematode Bursaphelenchus xylophilus in Portugal, nematodes of the genus Bursaphelenchus were looked for in various French pine forests, in trees attacked by Monochamus galloprovincialis, the vector insect of B. xylophilus, and in the insects themselves. Trap trees were felled in 12 localities distributed all over the country. Nematodes were extracted from transversal stem discs; insects emerging from the trap trees were studied. B. hellenicus, B. leoni, B. mucronatus and B. sexdentati were isolated, but not B. xylophilus. The presence of B. mucronatus and the absence of B. xylophilus were confirmed by molecular markers. B. mucronatus was isolated from several regions with an average prevalence of 19%. The infestation of M. galloprovincialis by B. mucronatus reached 26.7%. The wide distribution of B. mucronatus in France could have an effect on the extension of B. xylophilus in a case of an introduction.     

Growth,biomass partitioning,and water-use efficiency of a leguminous shrub (<Emphasis Type="Italic">Bauhinia faberi</Emphasis> var. <Emphasis Type="Italic">microphylla</Emphasis>) in response to various water availabilities

Responses of the endemic leguminous shrub Bauhinia faberi var. microphylla, to various soil water supply regimes were studied in order to assess water stress tolerance of seedlings. Two-month-old seedlings were grown under water supply regimes of 100, 80, 60, 40, and 20% water field capacity (FC), respectively, in a temperature and light-controlled greenhouse. Plant height and leaf number were measured monthly over a 4-month period, while water use (WU), water-use efficiency (WUE), leaf relative water content (RWC), biomass production and its partitioning were recorded at the end of the experiment. Seedlings exhibited the greatest biomass production, height, basal diameter, branch number, leaf number, and leaf area when soil content was at 100% FC, and slightly declined at 80% FC. These parameters declined significantly under 60% FC water supply, and severely reduced under 40 and 20% FC. RWC, WU and WUE decreased, while the ratio of root mass to stem mass (R:S) increased in response to decreasing water supply. Water stress caused leaf shedding, but not plant death. The results demonstrated that B. faberi var. microphylla seedlings could tolerate drought by reducing branching and leaf area while maintaining a high R:S ratio. However, low dry mass and WUE at 40 and 20% FC suggested that the seedlings did not produce significant biomass under prolonged severe water deficit. Therefore, before introducing B. faberi var. microphylla in vegetation restoration efforts, water supply above 40% FC is recommended for seedlings to maintain growth.     

Community participation in a social forestry program in Central Java,Indonesia: the effect of incentive structure and social capital

A new social forestry program has been implemented in Java to overcome encroachment of state forests. In this program, the state and local communities jointly manage the state forests and share the benefits of increased forest resource stock and flow as a result of the management. This article aims to investigate the complete incentive structure of the social forestry program and how the incentive structure changes community member participation in forest management. Property rights transfers and economic analyses were employed to analyze the incentive structure. We conclude that although incomplete, the transfer of rights from the state to the community members is a useful approach toward establishing an effective incentive structure and provides a net gain to the community members. The extent of community participation, however, depends not only on the incentive structure but also on the social capital that exists in the community.     

Examining disadoption of gum arabic production in Sudan

Gum arabic production in Sudan has developed over the years in a well-established traditional bush-fallow system in which the gum tree (Acacia senegal) is rotated with annual crops. Following the Sahel drought, the gum area has suffered from deforestation and gum production has declined. Several programs have been developed to stimulate gum production; however, many original adopters have disadopted gum production and the bush-fallow system. In this paper we apply a logit model to study the decision-making behavior of farmers in west Sudan and to identify the socio-economic factors influencing disadoption of gum production and gum agroforestry system. Variables that measure farmer’s wealth were found significant in explaining the disadoption behavior. Off-farm work was also found to positively influence the disadoption decision. Results show that a higher level of income from annual crops decreases the probability of disadoption, which suggests that annual crops and gum production do not compete but rather complement each other within the farm household economy. Therefore, policy measures aiming to boost the production of annual crops in the region might reduce seasonal labor migration and accordingly stimulate gum production.

The power of knowledge: information transfer and açaí intensification in the peri-urban interface of Belém,Brazil

Academic scholarship and development paradigms promote non-timber forest products (NTFPs) as potential options to link environmental conservation with sustainable economic development objectives for rural communities worldwide. The açaí berry (Euterpe oleracea) is a native palm found in forest ecosystems of northern Brazil and historically extracted and sold in regional markets. Recent increases in national and international açaí demand have resulted in dramatic price increases. Management decisions on a local producer level reflect trends not typically associated with traditional NTFPs as future production and income expectations increase. This case study draws on research conducted in peri-urban communities in close proximity to Belém, Brazil. The work draws links between recent açaí intensification trends in upland areas and information pathways that are contributing to this pattern. This paper argues that external information sources regarding land use choices are prioritized over local knowledge and market indicators which previously have been described as drivers for intensification processes of NTFPs. This qualitative analysis highlights the power structures that influence information sharing and in turn, land use choices on a community level. The results of this analysis are important for NTFP intervention initiatives focused on risk management for smallholders. Finally, this study is a useful complement for ecological studies currently being conducted on intensification processes of non-timber forest products.     

Influence of neutral inorganic chlorides on primary and secondary char formation from cellulose

The influence of various alkali and alkaline earth metal chlorides (LiCl, NaCl, KCl, MgCl₂, and CaCl₂) on primary and secondary char formation from cellulose was studied at 400°C. Secondary char was formed through carbonization of the volatile products. All chlorides increased the primary char yield while decreasing the secondary char formation, and this situation was promoted in the order of alkaline earth Mg, Ca, alkali Li > alkali Na, K. Levoglucosan yield also decreased along with the secondary char yield. These results indicate that the reduced formation of volatile levoglucosan was related to the decreasing yield of secondary char. A model experiment at 250°C revealed that these chlorides, especially the two alkaline earth metals, had catalytic action on the polymerization of levoglucosan, which serves to reduce the formation of volatile levoglucosan.     

Changes in the N and P concentrations,N:P ratios,and tannin content in <Emphasis Type="Italic">Casuarina equisetifolia</Emphasis> branchlets during development and senescence

Changes in the N and P concentrations, N:P ratios, and tannin content in Casuarina equisetifolia branchlets across a coastal gradient were studied at Chishan Forestry Center of Dongshan County, Fujian Province, China. (1) Total phenolics and protein precipitation capacity in young branchlets was significantly higher than in mature and senescent branchlets across a coastal gradient; extractable condensed tannin content was higher in young and mature branchlets than in senescent branchlets. Whereas protein-bound condensed tannins increased with senescence, fiber-bound condensed tannins fluctuated without a consistent pattern; (2) N and P concentrations at various stages of branchlet development across a coastal gradient followed the same order: young branchlets > mature branchlets > senescent branchlets; N:P ratio of young branchlets was the lowest, and increased with maturity and senescence across a coastal gradient; phosphorus resorption efficiency was significantly higher than nitrogen resorption efficiency among corresponding coastal gradients in response to P deficiency (high N:P ratio), but nutrient resorption efficiency was influenced by coastal gradients; (3) significant linear relationships between total phenolics and nutrient contents indicated that polyphenolics had a potential effect on nutrient cycling.     

Effect of planting stocktype and cultivation treatment on the establishment of Norway spruce on cutaway peatlands

In order to determine the effect of stocktype and cultivation treatment on the field performance (survival and growth) and physiological status of Picea abies in cutaway peatlands, small bare-root, large bare-root and containerised seedlings were planted in a deep ploughed and a control site. Survival after 2 years was good across all treatment (>90%) except for the large bare-root seedlings growing in the control site (84%). For all the morphological characteristics assessed in this study, there was no significant interaction between stocktype and cultivation treatment indicating that the growth response to site cultivation was not stocktype dependent. After two growing seasons, all Norway spruce seedlings performed better in the deep ploughed site and displayed also better nutritional and physiological status. Regardless of cultivation treatment, mean height, diameter and volume increment were significantly smaller for the large bare-root seedlings while the small bare-root seedlings displayed the greatest growth rates. In order to promote early height growth in container and small bare-root stock, large diameter is important. Other initial characteristics such as foliar nitrogen content may also have a strong influence on first year field performance. The physiological status of the seedlings during the first year after outplanting was assessed using chlorophyll fluorescence (CF) measurements. CF measurements detected a higher level of stress for the large-bare root stock (low Fv/Fm). On the other hand, small bare-root stock displayed highest maximum potential photochemical activity which corresponded to greatest growth rates. Container seedlings demonstrated higher capacity for photosynthetic electron transport during the first five months after planting suggesting that they recovered from planting stress quicker and optimised better light interception and utilization than bare-root stock. It can be concluded that intensive management systems including deployment of best-adapted stocktype and site cultivation can be used to enhance early height growth of Norway spruce on cutaway peatlands.