Detection of vegetation degradation on Swedish mountainous heaths at an early stage by image interpretation

Mountainous vegetation in general, and especially in subpolar regions, is sensitive, compared to vegetation in lowland areas, as mountainous vegetation has low resilience and low productivity. Mountainous areas have been perceived as being sensitive to mechanical damage. Quick methods with a high degree of accuracy are needed for the monitoring of mountainous areas and for planning the sustainable use of resources. The aim was i) to investigate if the dry dwarf shrub heath on hummocky moraine in the southern part of the mountains with a maritime climate and in open areas used for summer grazing, is susceptible to change; and ii) to test if high-resolution IKONOS-2 satellite data can, with a high degree of accuracy, be used for detection, and for quantification and mapping of erosion patches in montane vegetation. In which case, these data can substitute color infrared aerial photos for the early detection of changes. For the detection of changes, visual interpretations on high-quality printouts of IKONOS-2 satellite images from 2000 and of color infrared aerial photographs from 1975 were carried out and the results compared. Interpretations were verified in the field. The results show that for the period 1975-2000, erosion was in process on and around wind heaths, indicating that the wind heath and surrounding dry dwarf shrub heath in this landscape type of hummocky moraine are sensitive to mechanical damage by trampling and grazing, and thus susceptible to change. Most of the wind heaths and changes found were small (50-1000 m2). The results show that it is possible to detect, with good accuracy, detailed changes in the size and distribution of erosion patches and wind heaths by visual interpretation in single images of IKONOS-2 data. This implies that for monitoring these kinds of changes, these high-resolution (4 x 4 m pixel resolution) satellite data can substitute for color infrared aerial photographs.     

Public participation in water resources management: stakeholder voices on degree, scale, potential, and methods in future water management

The European Water Framework Directive puts strong emphasis on stakeholder and public participation in water management. Several practical questions regarding who should be involved, why, when, and how still remain unanswered. This paper investigates stakeholders' own experiences and views of increased public participation in water management. The article also explores the potential for increasing levels of participation by forming catchment committees with representation from stakeholder groups and through the use of various practical methods for participation. For both these aspects of participation, the views, expectations, and apprehensions of different stakeholder groups involved in nutrient loss management are investigated. Stakeholder opinions were collected by inviting representatives from five stakeholder groups within the R?nne? catchment in southern Sweden to a catchment dialog process.     

Lights and shadows: growth patterns in three sympatric and congeneric sponges (Ircinia spp.) with contrasting abundances of photosymbionts

The life-history traits of long-lived benthic littoral invertebrates remain poorly understood. In this study, we analysed patterns of growth in three abundant sublittoral sponges from the western Mediterranean Sea, chosen for their close phylogenetic relatedness, sympatric distribution, and contrasting amounts of photosymbionts: high in Ircinia fasciculata, lower in I. variabilis, and absent in I. oros. Sponge area, perimeter, number of oscula, and epibiont abundance were quantified from in situ digital images taken monthly for 1.5 years and volumetric growth rates were calculated from empirical area–volume relationships. Volumetric growth rates were different among species and coherent with the photosymbiont abundance: high in I. fasciculata (40.03 ± 4.81 % year^?1, mean ± SE), low in I. variabilis (5.65 ± 6.11 % year^?1), and almost nil in I. oros (?0.04 ± 3.02 % year^?1). Furthermore, a marked seasonality was observed in the first two species, with greater growth during the warm season. The high growth rates of I. fasciculata were likely fuelled by symbiont-derived photosynthates and required to compete in the well-lit, algal-dominated habitats this species prefers. In contrast, I. variabilis and I. oros tended to dwell in shaded habitats, where competition from slow-growing invertebrates is intense, and featured lower growth rates. The flattened morphology and lower circularity of I. variabilis indicates a capacity for adaptation to any space that is freed, while I. oros had less oscula and was more massive and circular, suggesting a strategy of passive occupation and minimisation of biological interactions. The results show that even congeneric species living sympatrically can achieve important biomass using different growth and substrate occupation strategies.     

Meligethes aeneus pollen-feeding suppresses, and oviposition induces, Brassica napus volatiles: beetle attraction/repellence to lilac aldehydes and veratrole

Insect pollination and pollen feeding can reduce plant volatile emissions and future insect floral attraction, with oviposition having different effects. Meligethes aeneus F. (Coleoptera: Nitidulidae), is a pollen-feeding pest beetle of oilseed rape, Brassica napus L. (Brassicaceae). We measured plant VOC emission over 72 h from two types of 24 h M. aeneus exposure to B. napus: pollen feeding vs. flower bud injury and oviposition. The most abundant constitutive volatile organic compounds (VOCs), lilac aldehydes A (LA A) & B (LA B) and veratrole (VER), had 30–40 % reductions from M. aeneus pollen-feeding exposure at 24 h and 50–90 % reductions by 72 h, with greater reductions after bud injury and oviposition. Linalool (LIN), a common herbivore-induced plant volatile (HIPV), emission did not change at 24 h, but was induced six- to sevenfold 48 h after both exposure treatments. By 72 h, LIN had even greater (tenfold) induction after bud injury and oviposition, but no induction from pollen feeding. Three common HIPVs (β-caryophyllene, = βCAR (E)-β-farnesene = EβFAR, and (Z)-β-ocimene = ZβOCI) were progressively induced up to 2.5-fold 72 h after floral bud injury and oviposition. We assayed M. aeneus adult behavioral responses to LA A and B, and VER. Both M. aeneus sexes were attracted to higher concentrations than single plant constitutive emission for these VOCs, but avoided much higher doses. Progressive LA A and B, and VER, emission reductions might help plants (e.g., B. napus) to avoid future interactions with pollen-feeding pest herbivores (e.g., M. aeneus). After bud injury and oviposition, HIPV induction could help plants deter future oviposition and/or attract natural enemies to deposited eggs.     

Costs and benefits of capsaicin-mediated control of gut retention in dispersers of wild chilies

A fundamental way in which animal-dispersed plants can influence the viability and distribution of dispersed seeds is through control of retention time in the guts of dispersers. Using two species of wild chilies and their dispersers, we examined how chemical and physical properties of fruits and seeds mediate this interaction. Capsicum chacoense is polymorphic for pungency, occurs in Bolivia, and is dispersed mostly by elaenias. Capsicum annuum is not polymorphic, occurs in Arizona (USA), and is dispersed mostly by thrashers. We first tested whether capsaicin, the substance responsible for the pungency of chilies, affects gut retention time of seeds in primary dispersers. Capsaicin slowed gut passage of seeds but did so in a manner that differed greatly between bird species because the constipative effects of capsaicin occurred only after an 80-minute time lag. Elaenias in Bolivia held only 6% of C. chacoense seeds for > 80 minutes, whereas thrashers in Arizona held 78% of C. annuum seeds for > 80 minutes. Next we examined the effects of retention time on seed viability and germination. Increased retention resulted in a greater proportion of seeds germinating in C. annuum, had no effects on non-pungent C. chacoense, and had negative effects on pungent C. chacoense. These divergent effects are explained by differences in seed coat morphology: seed coats of pungent C. chacoense are 10-12% thinner than those of the other two types of seeds. Thus, longer retention times damaged seeds with the thinnest seed coats. In C. annuum, seed viability remained high regardless of retention time, but germination increased with retention, suggesting a role for scarification. Thus, in C. annuum, fruit chemistry appears well matched with seed morphology and disperser physiology: capsaicin extends gut retention for most seeds, resulting in greater seed scarification and higher germination rates. Increased retention of pungent C. chacoense seeds is detrimental, but because the primary consumers have short retention times, capsaicin slows only a small proportion of seeds, minimizing negative effects. These results illustrate the importance of context in studies of fruit secondary metabolites. The same chemical can have different impacts on plant fitness depending on its morphological, physiological, and ecological context.