Socio-ecological implications of modifying rotation lengths in forestry

The rotation length is a key component of even-aged forest management systems. Using Fennoscandian forestry as a case, we review the socio-ecological implications of modifying rotation lengths relative to current practice by evaluating effects on a range of ecosystem services and on biodiversity conservation. The effects of shortening rotations on provisioning services are expected to be mostly negative to neutral (e.g. production of wood, bilberries, reindeer forage), while those of extending rotations would be more varied. Shortening rotations may help limit damage by some of today’s major damaging agents (e.g. root rot, cambium-feeding insects), but may also increase other damage types (e.g. regeneration pests) and impede climate mitigation. Supporting (water, soil nutrients) and cultural (aesthetics, cultural heritage) ecosystem services would generally be affected negatively by shortened rotations and positively by extended rotations, as would most biodiversity indicators. Several effect modifiers, such as changes to thinning regimes, could alter these patterns.     

Replacing monocultures with mixed-species stands: Ecosystem service implications of two production forest alternatives in Sweden

Whereas there is evidence that mixed-species approaches to production forestry in general can provide positive outcomes relative to monocultures, it is less clear to what extent multiple benefits can be derived from specific mixed-species alternatives. To provide such insights requires evaluations of an encompassing suite of ecosystem services, biodiversity, and forest management considerations provided by specific mixtures and monocultures within a region. Here, we conduct such an assessment in Sweden by contrasting even-aged Norway spruce (Picea abies)-dominated stands, with mixed-species stands of spruce and birch (Betula pendula or B. pubescens), or spruce and Scots pine (Pinus sylvestris). By synthesizing the available evidence, we identify positive outcomes from mixtures including increased biodiversity, water quality, esthetic and recreational values, as well as reduced stand vulnerability to pest and pathogen damage. However, some uncertainties and risks were projected to increase, highlighting the importance of conducting comprehensive interdisciplinary evaluations when assessing the pros and cons of mixtures.     

Placental transfer of polychlorinated biphenyls, their hydroxylated metabolites and pentachlorophenol in pregnant women from eastern Slovakia

The aim of the present study was to understand the placental transfer of polychlorinated biphenyls (PCBs), specific hydroxylated PCB metabolites (OH-PCBs), and pentachlorophenol (PCP) in blood serum, in a birth cohort from eastern Slovakia. During the period 2002-2004, cord blood specimens were collected in parallel with maternal specimens from women delivering in the two eastern Slovak districts of Michalovce and Svidnik/Stropkov. A total of 92 pairs of mother-cord specimens at delivery were selected for this study. 4-OH-CB107, 3-OH-CB153, 4-OH-CB146, 3'-OH-CB138, 4-OH-CB187, and 4'-OH-CB172 were quantified. The median concentrations of Sigma(17)PCBs, Sigma(6)OH-PCBs, and PCP in cord serum were 0.92, 0.33, and 0.69 ng/g wet wt., respectively and highly correlated with the corresponding maternal serum levels (correlations were R(2)=0.61, 0.78, and 0.82, respectively). The median cord to mother ratios of the Sigma(17)PCBs, Sigma(6)OH-PCBs, and PCP were 0.18, 0.75, and 1.10, respectively. The median ratio of the Sigma(6)OH-PCBs to the Sigma(17) PCBs in the cord serum was 0.38 from wet weight based concentrations, which was about four times higher than the ratio of these compounds in maternal serum (0.09). PCP was more abundant than any PCB or OH-PCB congener measured in cord serum. The higher cord to maternal ratios of OH-PCB metabolites as compared with the parent compounds suggests either a higher placental transfer rate or greater metabolism in the fetus as compared with the maternal compartment. These findings are consistent with their preferential binding to TTR that can cross the placenta. The cord to maternal ratio varies by congener (e.g., 4-OH-CB107=0.58, 4-OH-CB146=0.74, 3'-OH-CB138=1.01).     

An ecosystem report on the Panama Canal: monitoring the status of the forest communities and the watershed

In 1996, the Smithsonian Tropical Research Institute and the Republic of Panama's Environmental Authority, with support fromthe United States Agency for International Development, undertook a comprehensive program to monitor the ecosystem of the Panama Canal watershed. The goals were to establish baselineindicators for the integrity of forest communities and rivers. Based on satellite image classification and ground surveys, the2790 km² watershed had 1570 km² of forest in 1997, 1080 km² of which was in national parks and nature monuments. Most of the 490 km² of forest not currently in protected areas lies along the west bank of the Canal, and its managementstatus after the year 2000 turnover of the Canal from the U.S. to Panama remains uncertain. In forest plots designed to monitorforest diversity and change, a total of 963 woody plant specieswere identified and mapped. We estimate there are a total of 850–1000 woody species in forests of the Canal corridor. Forestsof the wetter upper reaches of the watershed are distinct in species composition from the Canal corridor, and have considerably higher diversity and many unknown species. Theseremote areas are extensively forested, poorly explored, and harbor an estimated 1400–2200 woody species. Vertebrate monitoring programs were also initiated, focusing on species threatened by hunting and forest fragmentation. Large mammals are heavily hunted in most forests of Canal corridor, and therewas clear evidence that mammal density is greatly reduced in hunted areas and that this affects seed predation and dispersal. The human population of the watershed was 113 000 in 1990, and grew by nearly 4% per year from 1980 to 1990. Much of this growth was in a small region of the watershed on the outskirts of Panama City, but even rural areas, including villages near and within national parks, grew by 2% per year. There is no sewage treatment in the watershed, and many towns have no trashcollection, thus streams near large towns are heavily polluted. Analyses of sediment loads in rivers throughout the watershed did not indicate that erosion has been increasing as a result ofdeforestation, rather, erosion seems to be driven largely by total rainfall and heavy rainfall events that cause landslides.Still, models suggest that large-scale deforestation would increase landslide frequency, and failure to detect increases inerosion could be due to the gradual deforestation rate and the short time period over which data are available. A study of runoff showed deforestation increased the amount of water fromrainfall that passed directly into streams. As a result, dry season flow was reduced in a deforested catchment relative to aforested one. Currently, the Panama Canal watershed has extensive forest areasand streams relatively unaffected by humans. But impacts of hunting and pollution near towns are clear, and the burgeoningpopulation will exacerbate these impacts in the next few decades.Changes in policies regarding forest protection and pollution control are necessary.     

Bacteria Degrading PCBs and CBs Isolated from Long-Term PCB Contaminated Soil

Bacteria able to degrade polychlorinated biphenyls (PCBs) and chlorobenzoic acids (CBs) were isolated from soil that had been contaminated with PCBs for 15–30 years. Contaminated soil in which PCB content ranged between 10–470 mg/kg was naturally vegetated with different plants including ash (Fraxinus excelsior), birch (Betula pendula), black locust (Robinia pseudoacacia), Austrian pine (Pinus nigra) and goat willow (Salix caprea) trees as well as a variety of grasses and forbs. Bacteria able to use biphenyl as a sole source of carbon and energy were found in the root zone of all plants, but occurred in the largest numbers beneath pine and black locust. Bacteria able to degrade chlorobenzoic acids were isolated from the same location contaminated with PCBs. Strains that were taxonomically identified by 16S rDNA as Pandoraea were able to use 2-CB, 3-CB, 2,3-CB, 2,5-CB as sole carbon sources, and the strain Arthrobacter utilised 4-CB.     

Nonideal breeding habitat selection: a mismatch between preference and fitness

The selection of breeding sites in heterogeneous habitats should ideally be based on cues closely reflecting habitat quality and thus predicting realized individual fitness. Using long-term population data and data on territory establishment of male Northern Wheatears (Oenanthe oenanthe), we examined whether territory characteristics linked to individual fitness (reproductive performance and survival) also were linked to territory preference. Breeding territories varied in their physical characteristics and their potential effects on reproductive performance, and this variation among territories was correlated from one year to the next. Of all measured territory characteristics (from the focal and the previous year) only territory field layer height predicted individual fitness, i.e., reproductive performance was higher in territories with permanently short rather than growing field layers. Territory preference, instead, was only linked to the size of territory aggregations, i.e., males settled earlier at territory sites sharing borders with several adjacent sites than at those with few or no adjacent sites. This mismatch between territory characteristics linked to fitness and those linked to territory preference was not explained by site fidelity or compensated for by the different fitness components measured. Because the results were not in agreement with an ecological trap scenario, where poor habitats are preferred over high-quality habitats, our results suggest a more general case of nonideal habitat selection. Whereas nonideal selection with respect to territory field layer height may be explained by its poor temporal predictability within the breeding season, the preference for territory aggregations is still open to alternative adaptive explanations. Our study suggests that nonideal habitat selection should be investigated by direct estimates of preferences (e.g., order of territory establishment) and their links to habitat characteristics and fitness components. Furthermore, we suggest that the probability of establishing a territory needs to be included as a factor influencing patterns of habitat selection.