. The Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGAN2.1) is a modeling framework for estimating fluxes of biogenic compounds between terrestrial ecosystems and the atmosphere using simple mechanistic algorithms to account for the major known processes controlling biogenic emissions. It is available as an offline code and has also been coupled into land surface and atmospheric chemistry models. MEGAN2.1 is an update from the previous versions including MEGAN2.0, which was described for isoprene emissions by Guenther et al. (2006) and MEGAN2.02, which was described for monoterpene and sesquiterpene emissions by Sakulyanontvittaya et al. (2008). Isoprene comprises about half of the total global biogenic volatile organic compound (BVOC) emission of 1 Pg (1000 Tg or 1015 g) estimated using MEGAN2.1. Methanol, ethanol, acetaldehyde, acetone, α-pinene, β-pinene, t-β-ocimene, limonene, ethene, and propene together contribute another 30% of the MEGAN2.1 estimated emission. An additional 20 compounds (mostly terpenoids) are associated with the MEGAN2.1 estimates of another 17% of the total emission with the remaining 3% distributed among >100 compounds. Emissions of 41 monoterpenes and 32 sesquiterpenes together comprise about 15% and 3%, respectively, of the estimated total global BVOC emission. Tropical trees cover about 18% of the global land surface and are estimated to be responsible for ~80% of terpenoid emissions and ~50% of other VOC emissions. Other trees cover about the same area but are estimated to contribute only about 10% of total emissions. The magnitude of the emissions estimated with MEGAN2.1 are within the range of estimates reported using other approaches and much of the differences between reported values can be attributed to land cover and meteorological driving variables. The offline version of MEGAN2.1 source code and driving variables is available from http://bai.acd.ucar.edu/MEGAN/ and the version integrated into the Community Land Model version 4 (CLM4) can be downloaded from http://www.cesm.ucar.edu/ .

/pdf/the-model-of-emissions-of-gases-and-aerosols-from-nature-4abxgaax5t.pdf

The model of emissions of gases and aerosols from nature version 2.1 (MEGAN2.1): An extended and updated framework for modeling biogenic emissions

The Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGAN2.1): an extended and updated framework for modeling biogenic emissions

Forest management, coarse woody debris and saproxylic organisms: Fennoscandian boreal forests as an example

Conifers are long-lived organisms, and part of their success is due to their potent defense mechanisms. This review focuses on bark defenses, a front line against organisms trying to reach the nutrient-rich phloem. A major breach of the bark can lead to tree death, as evidenced by the millions of trees killed every year by specialized bark-invading insects. Different defense strategies have arisen in conifer lineages, but the general strategy is one of overlapping constitutive mechanical and chemical defenses overlaid with the capacity to up-regulate additional defenses. The defense strategy incorporates a graded response from 'repel', through 'defend' and 'kill', to 'compartmentalize', depending upon the advance of the invading organism. Using a combination of toxic and polymer chemistry, anatomical structures and their placement, and inducible defenses, conifers have evolved bark defense mechanisms that work against a variety of pests. However, these can be overcome by strategies including aggregation pheromones of bark beetles and introduction of virulent phytopathogens. The defense structures and chemicals in conifer bark are reviewed and questions about their coevolution with bark beetles are discussed.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-8137.2005.01436.x

Anatomical and chemical defenses of conifer bark against bark beetles and other pests.

The role of pheromones, kairomones, and allomones in the host selection and colonization behavior of bark beetles

The diversity in different groups of obligate saproxylic beetles was related to ecological variables at three levels of spatial scale in mature spruce-dominated forest. The variables were connected to: (i) decaying wood, (ii) wood-inhabiting fungi, (iii) the level of disturbance, (iv) landscape ecology, and (v) vegetational structure. Several strong relationships were found at medium (1 km2) and large scales (4 km2), while only weak relationships were found at a small scale (0.16 ha; 1 ha=104 m2). This may be explained by the local variations in habitat parameters and the high mobilities of many beetle species. Factors connected to decaying wood and wood-inhabiting fungi were clearly the most important factors at all scale levels. In particular, the variables diversity of dead tree parts, number of dead trees of large diameter and number of polypore fungi species increased the species richness of many groups and increased the abundance of many species. Eight species were absent below a certain density of decaying wood per 1 or 4 km2. Former extensive cutting was a negative factor at large scale, probably because of decreasing recolonization with increasing distance to the source habitats. Thinning reduced the diversity of species associated with birch. The development of guidelines favouring the diversity of saproxylic beetles are discussed below.

What factors influence the diversity of saproxylic beetles? A multiscaled study from a spruce forest in southern Norway

The spruce bark beetle, Ips typographus Linnaeus (Coleoptera: Scolytidae), is the most destructive scolytid in the coniferous forests of the palaearctic region. In Europe, outbreaks may lead to the destruction of millions of Norway spruces [Picea abies (Linnaeus) Karsten], its principal host tree. In Northeastern Asia a subspecies, Ips typographus Linnaeus f. japonicus Niijima, may cause severe damage to spruces in the group P. jezoensis (Siebold and Zuccarini) Carriere sensu lato.

The Spruce Bark Beetle of Eurasia

The distribution of bark beetles in the Nordic countries.

During the period 1971-81 there were severe outbreaks of the bark beetle Ips typographus in southern Norway that damaged trees equivalent to 5 million cubic metres of timber. The outbreaks were caused partly by an extensive windblow and partly by drought. Trap trees were used until 1979, when pheromone-baited traps were introducted as part of an extensive control program. The various aspects of this program are outlined and problems of scientific, technological, economical-administrative and informative character are discussed. Possible explanation for the decline of the epidemic after 1980 is presented and the main conditions which must be fulfilled for achieving successful mass trapping of insect pests are listed.

The recent Ips typographus outbreak in Norway ‐ experiences from a control program

Thanasimus formicarius (L.) responds to racemic ipsdienol and ipsenol and less to (S)-cis-verbenol. All three are pheromone components in several bark beetles of the genusIps. Synergistic effects appeared when the components were combined. Methylbutenol alone, the specific pheromone component ofIps typographus, elicited no response, but synergestic effects appeared when methylbutenol was combined withcis-verbenol and ipsdienol. The sympatric speciesThanasimus femoralis (Zett.) responds to (S)-cis-verbenol, while ipsdienol and ipsenol synergize the response.

Alf Bakke

Papers

What factors influence the diversity of saproxylic beetles? A multiscaled study from a spruce forest in southern Norway

The Spruce Bark Beetle of Eurasia

The distribution of bark beetles in the Nordic countries.

The recent Ips typographus outbreak in Norway ‐ experiences from a control program

Kairomone response inThanasimus predators to pheromone components ofIps typographus.