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PubMed2026

Tree Killer, Qu'est-ce Que C'est? Insights From Forest Pathogen Genomes.

Forests are central to planetary health but are increasingly challenged by emerging diseases driven by climate change, global trade, and anthropogenic disturbance. Despite the apparent resilience of long-lived, genetically diverse tree hosts, forest ecosystems have repeatedly experienced landscape-level pathogen-driven transformations. Advances in genomics, transcriptomics, and functional biology have transformed our understanding of how fungal and oomycete pathogens interact with their hosts across a continuum of lifestyles, from saprotrophy and necrotrophy to biotrophy. Here, we synthesize insights from comparative and population genomics and functional studies across diverse forest pathosystems to examine the traits that characterize successful tree pathogens. We highlight how lifestyle plasticity, adaptations to woody tissues, vector-mediated transmission, and biotrophic stealth enable pathogens to colonize perennial hosts and persist over long temporal scales. We further examine how genome plasticity, hybridization, and horizontal gene transfer generate adaptive potential that often outpaces host evolutionary responses under current environmental change. Finally, we discuss emerging genomic tools, including biosurveillance, machine learning-based classification, and genome editing, that are beginning to link genotype to phenotype and inform assessments of disease risk. By integrating genomic, ecological, and evolutionary perspectives, this review outlines general principles governing forest pathogen success and identifies priorities for future research aimed at improving understanding, early detection, and management of forest diseases in a changing world.

Trees↗
PubMed1988

Threatened biotas: "hot spots" in tropical forests.

The mass-extinction episode underway is largely centered on tropical forests, insofar as they contain at least half of all Earth's species and they are being depleted faster than any other biome. But species distributions and depletion patterns are anything but uniform throughout the biome. This paper identifies 10 areas that a) are characterized by exceptional concentrations of species with high levels of endemism and b) are experiencing unusually rapid rates of depletion. While these "hotspot" areas comprise less than 3.5% of remaining primary forests, they harbor over 34,000 endemic plant species (27% of all plant species in tropical forests and 13% of all plant species worldwide). They also feature 700,000 endemic animal species and possibly several times more. Unfortunately, they appear likely to lose 90% of their forest cover as soon as the end of the century or shortly thereafter, causing the extinction of almost 7% of Earth's plant species and at least a similar proportion of animal species, this occurring in only 0.2% of Earth's land surface. By concentrating on such areas where needs are greatest and where the pay-off from safeguard measures would also be greatest, conservationists can engage in a more systematized response to the challenge of large-scale extinctions impending in tropical forests.

Conservation of Natural Resources↗
PubMed1990

Neuropeptide immunoreactivity and choline acetyltransferase activity in the mouse urinary bladder following inoculation with Semliki Forest Virus.

The effect of Semliki Forest Virus, a known central demyelinating agent and a proposed model for multiple sclerosis, on the innervation of the mouse urinary bladder has been examined 3, 6, 9 and 12 weeks after inoculation. Three weeks after Semliki Forest Virus inoculation, vasoactive intestinal polypeptide content of the bladder was reduced and the density of vasoactive intestinal polypeptide-immunoreactive nerves was decreased in the smooth muscle, but not in the mucosa. Choline acetyltransferase activity and neuropeptide Y and substance P content was normal, as was the pattern of innervation by acetylcholinesterase-containing and neuropeptide Y- and substance P-immunoreactive nerve fibres. Six weeks after Semliki Forest Virus inoculation, the choline acetyltransferase activity was significantly reduced. Between 6 and 9 weeks the level of vasoactive intestinal polypeptide in the bladder of Semliki Forest Virus-infected mice significantly increased, so that at 9 weeks it was higher than the control value. However, by 12 weeks both choline acetyltransferase activity and vasoactive intestinal polypeptide content were normal. At this time, the substantial age-related increase in substance P content of the bladder was more pronounced in the Semliki Forest Virus-treated animals. Thus there are transitory changes in the innervation of the mouse bladder by vasoactive intestinal polypeptide-containing and cholinergic nerve fibres after exposure to a central demyelinating agent which may reflect changes in bladder dysfunction seen in multiple sclerosis patients.

Animals↗
PubMed1988

Decree No. 88-103 setting the functions of the Minister of Waters and Forests, 27 January 1988.

This Decree sets forth the functions of the Minister of Waters and Forest of the Ivory Coast. Among other things, the Minister is to take the initiative in developing activities relating to the conservation, renewal, and management of the State's forests; defining a national reforestation plan; controlling the exploitation of forest products; and protecting the soil, water, and vegetation by using rational methods to preserve the climate, to fight erosion and fires, to restore natural vegetal cover, and to ensure that natural resources last. Decree No. 88-104 of 27 January 1988 sets forth the organization of the Ministry of Waters and Forests. Among the divisions of the Ministry are the Directorate for Conservation of the State Forests and for Reforestation and the National Committee to Defend and Fight against Fires (Journal Officiel de la Republique de Cote d'Ivoire, No. 7, 18 February 1988, pp. 62-64).

Africa↗
PubMed1998

Forests without primates: primate/plant codependency.

Detailed studies of primates and fruiting trees have illustrated that these groups of organisms are involved in a very complex set of interactions, with primates relying on fruiting trees as important food resources and fruiting trees relying on frugivores for seed dispersal. Human activities that influence either primate seed dispersal or fruit production have the potential of having unanticipated effects on the other interactants. Here we evaluate what is known and what we still need to learn to evaluate the long-term consequences of disrupting the interactions between primates and tropical forest trees. We do this by first assessing the potential importance of primates at dispersing the seeds of tropical forest trees. Second, we consider possible consequences of hunting primates on recruitment in tropical tree communities. Third, we address the converse by considering the impacts of decreasing resource availability for primates through either logging or through the extraction of nontimber forest products. Finally, we provide a case study from Kibale National Park, Uganda, that contrasts seedling recruitment in 20 forest fragments in which primate seed dispersers have been dramatically reduced with seedling recruitment in areas that have an intact frugivore community. In comparison to the intact forest, the fragments had lower seedling density and fewer species of seedlings. Furthermore, a greater proportion of the seedlings were from small-seeded species that might not require primates for their dispersal, since they probably can be dispersed by small birds. All of these considerations suggest that disrupting the complex interactions between primates and fruiting trees can potentially have negative and possibly cascading effects on ecosystem processes.

Animals↗
PubMed2000

Foraging ecology of the mountain monkey (Cercopithecus l'hoesti): implications for its evolutionary history and use of disturbed forest.

We present the first systematic field study on the feeding ecology of the mountain monkey (Circopithecus l'hoesti), a semi-terrestrial guenon. We compare our results with findings from a concurrent study of blue monkeys (C. mitis doggetti, which have an overlapping home range) conducted over ten months in the Nyungwe Forest Reserve, Rwanda. The mountain monkeys spent 35% of observation time feeding on terrestrial herbaceous vegetation. Thirty-five fruit and seed species comprised 42% of their diet, and invertebrates composed 9%. They spent 38% of observation time on the ground and 27% of observation time in canopy trees. Individuals were observed for equivalent proportions of time foraging on the ground for herbs and in canopy trees for fruits. Although mountain monkeys primarily foraged in undisturbed open areas, they also used disturbed open habitats for this purpose. Synthesizing our results with Pleistocene forest history and C. l'hoesti evolutionary history, we suggest that, although these monkeys readily use disturbed forest for herb foraging, they are a forest-adapted species which has adopted a terrestrial lifestyle to exploit the abundant herb layer common to montane forests.

Animals↗
PubMed2001

Eight hundred-year-old human remains from the Ituri tropical forest, Democratic Republic of Congo: the rock shelter site of Matangai Turu Northwest.

Little is known about human prehistory in the central African lowland tropical forest due to a paucity of archaeological evidence. Here we report results from our archaeological investigations of a late Holocene site in the northeast Congo Basin, with emphasis on a single skeleton from the rock shelter site of Matangai Turu Northwest, in the Ituri Forest, Democratic Republic of Congo. The skeleton dates from approximately 810 BP (1235 calibrated AD) and is associated with Later Stone Age lithics, animal bone and shell remains from wild taxa, fruit endocarps from forest trees, phytoliths from tropical forest plants, Late Iron Age ceramics, and a single iron artifact. Phytolith analysis indicates that the habitat was dense tropical forest, without evidence of domesticated food.

Adult↗
PubMed2002

Management of old landfills by utilizing forest and energy industry waste flows.

The lack of landfill capacity, forthcoming EU waste disposal and landfill management legislation and the use of non-renewable and energy intensive natural resources for the end-treatment of old landfills increase pressures to develop new landfill management methods. This paper considers a method for the end-management of old landfills in Finland, which is based on the utilization of forest and paper industry waste flows, wastes from paper recycling (de-inking) and wastes from forest industry energy production. Fibre clay wastes from paper mills, de-inking sludges from de-inking of recovered waste paper and incineration ash from forest industry power plants serve to substitute the use of natural clay for the building of landfill structures for closed landfills. Arguably, this method is preferable to existing practices of natural clay use for landfill building, because it (1) substitutes non-renewable natural clay, (2) consumes less energy and generates less CO2 emissions than the use of natural clay, and (3) eliminates considerable amounts of wastes from paper production, paper consumption and from forest industry energy production. Some difficulties in the application of the method are considered and the waste flow utilization is incorporated into a local forest industry recycling network.

Aluminum Silicates↗
PubMed1981

Effect of fire on soil microorganisms in a Meghalaya pine forest.

The effect of man-made fire on soil microbial population in a natural subtropical pine forest eco-system, was studies. a nearly fifty years old pine (Pinus kesiya Royle) forest was cut and burnt in March 1977. Another half of this pine forest was left uncut and unburnt. Microbial population was destroyed completely just after the burning and recolonization occurred after some days. Bacteria and actinomycetes were found to be the first colonizers followed by fungi. Burning initiated better growth and higher population of bacteria after two or three showers. Bacterial population was highest in July in burnt and in May in unburnt forest. Maximum fungal population in burnt site was recorded in July while it was highest in april and May in unburnt site. Penicillium spp., Cladosporium sp. and Trichoderma sp. were found to be first colonizing fungi just after the burning. In unburnt forest eco-system Absidia sp., Trichoderma sp., Fusarium sp. and Penicillium spp. were found to be dominant.

Bacteria↗
PubMed2003

Geographic analysis of forest health indicators using spatial scan statistics.

Geographically explicit analysis tools are needed to assess forest health indicators that are measured over large regions. Spatial scan statistics can be used to detect spatial or spatiotemporal clusters of forests representing hotspots of extreme indicator values. This paper demonstrates the approach through analyses of forest fragmentation indicators in the southeastern United States and insect and pathogen indicators in the Pacific Northwest United States. The scan statistic detected four spatial clusters of fragmented forest including a hotspot in the Piedmont and Coastal Plain region. Three recurring clusters of insect and pathogen occurrence were found in the Pacific Northwest. Spatial scan statistics are a powerful new tool that can be used to identify potential forest health problems.

Animals↗
PubMed2003

Allocation of river flows for restoration of floodplain forest ecosystems: a review of approaches and their applicability in Europe.

Floodplain forests are flood-dependent ecosystems. They rely on well-timed, periodic floods for the provision of regeneration sites and on tapered flood recession curves for the successful establishment of seedlings. These overbank flood events are described as "regeneration flows." Once floodplain forest trees are established, in order to grow they also require adequate, although variable, river stage levels or "maintenance flows" throughout the year. Regeneration flows are often synonymous with flood flows and only occur periodically. There is a disparity between this need for varied interannual flows over the decadal time frame and the usual annual cycle of flow management currently used by most river management agencies. Maintenance flows are often closer to established minimum flows and much easier to provide by current operational practices.A number of environmental flow methodologies, developed in North America, Australia, and South Africa are described in this review. They include the needs of the floodplain environment in the management and allocation of river flows. In North America, these methodologies have been put into practice in a number of river basins specifically to restore floodplain forest ecosystems. In Australia and South Africa, a series of related "holistic approaches" have been developed that include the needs of floodplain ecosystems as well as in-channel ecosystems. In most European countries, restoration of floodplain forests takes place at a few localized restoration sites, more often as part of a flood-defense scheme and usually not coordinated with flow allocation decisions throughout the river basin. The potential to apply existing environmental flow methodologies to the management of European floodplain forests is discussed.

Conservation of Natural Resources↗
PubMed2003

Decision support for road system analysis and modification on the Tahoe National Forest.

The United States Forest Service is required to analyze road systems on each of the national forests for potential environmental impacts. We have developed a novel and inexpensive way to do this using the Ecosystem Management Decision Support program (EMDS). We used EMDS to integrate a user-developed fuzzy logic knowledge base with a grid-based geographic information system to evaluate the degree of truth for assertions about a road's environmental impact. Using spatial data for natural and human processes in the Tahoe National Forest (TNF, California, USA), we evaluated the assertion "the road has a high potential for impacting the environment." We found a high level of agreement between the products of this evaluation and ground observations of a TNF transportation engineer, as well as occurrences of road failures. We used the modeled potential environmental impact to negatively weight roads for a least-cost path network analysis to 1573 points of interest in the forest. The network analysis showed that out of 8233 km of road analyzed in the forest, 3483 km (42%) must be kept in a modified road network to ensure access to these points. We found that the modified network had improved patch characteristics, such as significantly fewer "cherry stem" roads intruding into patches, an improved area-weighted mean shape index, and larger mean patch sizes, as compared to the original network. This analysis system could be used by any public agency to analyze infrastructure for environmental or other risk and included in other mandated analyses such as risks to watersheds.

Conservation of Natural Resources↗
PubMed2004

Influence of woody debris on channel structure in old growth and managed forest streams in central Sweden.

Anecdotal information suggests that woody debris have had an important channel-forming role in Swedish streams and rivers, but there are few data to support this view. We identified 10 streams within near-natural and 10 streams within managed forest landscapes in central Sweden, and quantified their channel characteristics and content of woody debris. All pieces of woody debris greater than 0.5 m in length and greater than 0.05 m in base diameter were included. The near-natural forests were situated in reserves protected from forest cutting, whereas the managed forests had previously faced intensive logging in the area adjacent to the stream. The two sets of streams did not differ in general abiotic characteristics such as width, slope, or boulder cover, but the number of wood pieces was twice as high and the wood volume almost four times as high in the near-natural streams. This difference resulted in a higher frequency of debris dams in the near-natural streams. Although the total pool area did not differ between the two sets of streams, the wood-formed pools were larger and deeper, and potentially ecologically more important than other pools. In contrast to what has been believed so far, woody debris can be a channel-forming agent also in steeper streams with boulder beds. In a stepwise multiple regression analysis, pool area was positively and most strongly related to the quantity of woody debris, whereas channel gradient and wood volume were negatively related. The frequency of debris dams increased with the number of pieces of woody debris, but was not affected by other variables. The management implications of this study are that the wood quantity in streams in managed forests would need to be increased if management of streams will target more pristine conditions.

Conservation of Natural Resources↗
PubMed2004

Land-use systems and resilience of tropical rain forests in the Tehuantepec Isthmus, Mexico.

Land-cover types were analyzed for 1970, 1990 and 2000 as the bases for determining land-use systems and their influence on the resilience of tropical rain forests in the Tehuantepec Isthmus, Mexico. Deforestation (DR) and mean annual transformation rates were calculated from land-cover change data; thus, the classification of land-use change processes was determined according to their impact on resilience: a) Modification, including land-cover conservation and intensification, and b) Conversion, including disturbance and regeneration processes. Regeneration processes, from secondary vegetation under extensive use, cultivated vegetation under intensive use, and cultivated or induced vegetation under extensive use to mature or secondary vegetation, have high resilience capacity. In contrast, cattle-raising is characterized by rapid expansion, long-lasting change, and intense damages; thus, recent disturbance processes, which include the conversion to cattle-raising, provoke the downfall of the traditional agricultural system, and nullify the capacity of resilience of tropical rain forest. The land-use cover change processes reveal a) the existence of four land-use systems (forestry, extensive agriculture, extensive cattle-raising, and intensive uses) and b) a trend towards the replacement of agricultural and forestry systems by extensive cattle-raising, which was consolidated during 1990-2000 (DR of evergreen tropical rain forest = 4.6%). Only the forestry system, which is not subject to deforestation, but is affected by factors such as selective timber, extraction, firewood collection, grazing, or human-induced fire, is considered to have high resilience (2 years), compared to agriculture (2-10 years) or cattle-raising (nonresilient). It is concluded that the analysis of land-use systems is essential for understanding the implications of land-use cover dynamics on forest recovery and land degradation in tropical rain forests.

Agriculture↗
PubMed2002

Changes in biomass, productivity and decomposition along topographical gradients under different geological conditions in tropical lower montane forests on Mount Kinabalu, Borneo.

We have examined how the structure and function of a forest ecosystem change with topography (lower-slope versus ridge) and how the changes are modified by nutrient availability depending on geological substrate (Quaternary and Tertiary sedimentary rocks and ultrabasic rock) in the tropical montane rain forests of Mt. Kinabalu (Borneo) where climate is humid and aseasonal. Reflecting the difference in site age and parent rock, the pool size of soluble-P and inorganic-N in topsoil decreased from Quaternary sedimentary >Tertiary sedimentary >ultrabasic rock on the lower-slope, and they decreased from the lower-slope to the ridge on all substrates. Forest structural attributes [stature, above-ground biomass, and leaf area index (LAI)] decreased in the order of Quaternary sedimentary >Tertiary sedimentary >ultrabasic rock in association with soil nutrients on the lower-slopes, and decreased upslope consistently on each of the three substrates. Functional attributes [above-ground net primary productivity (ANPP) and decomposition rate] demonstrated similar patterns to structure. ANPP significantly correlated with LAI among the six sites, while net assimilation rate (ANPP divided by LAI assuming an even productivity between above vs below-ground system) was nearly constant. Therefore, ANPP could be explained primarily by LAI. Topographical change in LAI could be explained by leaf mass per area (LMA) combined with stand-level leaf biomass. LMA increased upslope on all substrates in association with the decrease in individual leaf area. Stand-level leaf biomass decreased upslope on all substrates but the Tertiary sedimentary rock. Our study demonstrated that topography and geological substrates interactively affected forest structure and processes. The effect of topography on forest structure and processes was greater on nutrient-rich substrates than on poor substrates, and the effect of geological substrate was greater on lower-slopes than on ridges.

Biomass↗
PubMed2003

Use of forest corridors by boreal Xestia moths.

We studied movements of the noctuid moths Xestia speciosa and X. fennica in a fragmented forest landscape including old-growth spruce forest corridors in eastern Finland. We individually marked and released 1,796 adults of the habitat generalist X. speciosa and 683 individuals of X. fennica, which prefers old-growth spruce forests. Moths were recaptured with 60 sugar-bait traps that were placed within habitat corridors, in the non-habitat matrix and in surrounding old-growth forest patches. Both species favoured the corridors during their movements and tended to avoid entering the matrix. We analysed recapture rates and movements of the recaptured moths. Results suggest that X. speciosa moves longer distances than X. fennica. Though corridors clearly canalized movements by both species, the impact of old-growth forest corridors at the larger landscape scale was less clear in X. fennica. Movement behaviour of the two sexes differed more than that of the two species.

Animals↗
PubMed2004

Diversity of arbuscular mycorrhizal fungi across a fragmented forest in Panama: insular spore communities differ from mainland communities.

It is now understood that alterations in the species composition of soil organisms can lead to changes in aboveground communities. In this study, we assessed the importance of spatial scale and forest size on changes in arbuscular mycorrhizal fungal (AMF) spore communities by sampling AMF spores in soils of forested mainland and island sites in the vicinity of Gatun Lake, Republic of Panama. We encountered a total of 27 AMF species or morphospecies, with 17, 8, 1 and 1 from the genera Glomus, Acaulospora, Sclerosystis, and Scutellospora, respectively. At small scales (<100 m2), we found little evidence for spatial structuring of AMF communities (decay of Morisita-Horn community similarity with distance). However, at large spatial scales, we found that the AMF spore community of a mainland plot was more similar to other mainland plots several kilometers (>5) away than to nearby island plots (within 0.7 km). Likewise, most island plots were more similar to other island plots regardless of geographic separation. There was no decay in AMF species richness (number of species), or Shannon diversity (number of species and their spore numbers) either with decreasing forest-fragment size, or with decreasing plant species richness. Of the six most common species that composed almost 70% of the total spore volume, spores of Glomus "tsh" and G. clavisporum were more common in soils of mainland plots, while spores of Glomus "small brown" and Acaulospora mellea were more abundant in soils of island plots. None of these common AMF species showed significant associations with soil chemistry or plant diversity. We suggest that the convergence of common species found in AMF spore communities in soils of similar forest sizes was a result of forest fragmentation. Habitat-dependent convergence of AMF spore communities may result in differential survival of tree seedlings regenerating on islands versus mainland.

Analysis of Variance↗
PubMed2004

Thuja plicata exclusion in ectomycorrhiza-dominated forests: testing the role of inoculum potential of arbuscular mycorrhizal fungi.

The ability of trees dependent on arbuscular mycorrhizal (AM) fungi to establish in ectomycorrhizal forests is unknown. On northern Vancouver Island, Canada, there are sharp boundaries between mixed red cedar (Thuja plicata)-hemlock (Tsuga heterophylla) (CH) stands, and stands of hemlock and amabilis fir (Abies amabilis) (HA). We tested differences in AM colonization of red cedar between ectomycorrhiza-dominated (HA) stands and stands containing red cedar (CH), across a range of light levels. We used a soil bioassay approach to determine whether there was sufficient AM fungal inoculum in the HA tree stands to colonize red cedar seedlings. Seeds of hemlock and red cedar were sown in forest floor samples collected from the two types of forests, and shade treatments ranging from < 1 to 53% of full sunlight were imposed. After 6 months, seedling survival and root and shoot biomass were quantified, and red cedar seedlings were sampled for AM fungal colonization. Hemlock survival and growth did not differ between soil types, suggesting there was no substrate-associated limitation to its establishment in either forest type. Red cedar colonization by AM fungi was significantly correlated with light levels in CH soils but arbuscular mycorrhizas were absent in roots of red cedar seedlings grown in HA soil. Red cedar survival and relative growth rate were significantly greater in the CH than in HA soil; higher growth was due primarily to greater shoot growth in CH soils at high light levels. The low soil inoculum potential for red cedar in ectomycorrhiza-dominated stands may account for the virtual exclusion of red cedar seedlings from these forests.

Abies↗