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Forest Ecology and Management
Elsevier Science
Forest Ecology and Management

Elsevier Science

0378-1127

Forest Ecology and Management/Journal Forest Ecology and ManagementSCIISTPEIAHCI
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    Contrasting effects of eucalyptus, pine and oak plantations on nest predation risk in Mediterranean grasslands

    Faria, JoaoSanchez-Oliver, Juan S.Beja, PedroMoreira, Francisco...
    13页
    查看更多>>摘要：Large scale afforestation (i.e., establishment of forests on farmland, grassland and other land not previously forested) is increasingly regarded as a cost-effective option to mitigate climate change by promoting carbon sequestration. However, this strategy can have negative biodiversity impacts, potentially causing the loss and fragmentation of open habitats of conservation value, as well as edge effects that can extend well beyond forest boundaries. Mitigating impacts of afforestation programs thus requires a detailed understanding of the mechanisms whereby they affect biodiversity, particularly where new plantations are established close to areas important for open habitat species. Here, we examined how afforestation with oak, pine or eucalyptus trees, commonly planted in Mediterranean Europe, may have distinct effects on nest predation risk of grassland birds in southern Portugal. We used artificial nests with quail eggs and camera traps to: (i) identify nest predators and estimate predation risk of ground-nesting birds in grasslands adjacent to oak, pine and eucalyptus plantations across a distance gradient (0 m to 300 m) from the plantation edge; and (ii) examine how predation risk was influenced by avian predator abundance, sward height and vegetation clearing for photo monitoring (nest-site manipulation), and their interactions with plantation type. Carrion crow was by far the main egg predator identified, followed by Montagu's harrier, raven and magpie. Overall, nest predation risk and predator abundance were higher around eucalyptus plantations, compared to either pine or oak plantations. Predation decreased with increasing sward height, but this effect was less noticeable when vegetation around nests was cleared. In pine and oak plantations, predation risk was slightly higher close to edges, and decreased with distance from the edge. Conversely, in eucalyptus plantations predation was lower close to edges, and increased with distance to edges. Distance effects around eucalyptus plantation were, however, absent in manipulated nests. Overall, results show that afforestation with different tree species has distinct impacts on predation risk of artificial nests in Mediterranean farmland. This is probably a consequence of an increasing structural complexity of the plantations, from oak to eucalyptus, driven by differences in tree growth rates and undergrowth cover. These findings suggest that farmland afforestation should favour agro-forest plantations with slow growing species (oak and pine) to mitigate negative effects on breeding grassland birds in adjacent open habitats.
      原文链接:
    • NSTL
    • Elsevier

    Identifying conifer mortality induced by Armillaria root disease using airborne lidar and orthoimagery in south central Oregon

    Oblinger, Brent W.Bright, Benjamin C.Hanavan, Ryan P.Simpson, Mike...
    14页
    查看更多>>摘要：Armillaria root disease causes tree stress and mortality worldwide, including in conifer forests of western North America. Armillaria-induced tree mortality is slower than other disturbances, such as fire, but persistent over time, and therefore difficult to detect across large areas. Hence methods to detect Armillaria-affected trees and identify infested stands are of great value to forest managers. We used high-density light detection and ranging (lidar), high-resolution aerial orthoimagery, and associated field observations to map individual tree health across an Armillaria-affected forest dominated by Abies in south central Oregon. The lidar point cloud was segmented into individual tree objects (polygons representing tree crown extents as viewed from nadir), for which lidar metrics and spectral metrics derived from orthoimagery were computed. Lidar-detected tree objects were paired with 150 field-observed trees with corresponding health measurements, and a random forest classifier was developed that separated trees into: 1) asymptomatic; 2) live, Armillaria-infected; 3) recently killed (>50% of red needles remaining); and 4) dead (<50% of dead needles remaining) classes with 83% accuracy using lidar and spectral metrics. The classifier was applied to map individual tree health status for 290,964 tree objects across the 1257-ha study area. Approximately 20% of trees were classified as unhealthy including live, infected and 4% of trees were classified as recently killed or dead. We created hotspot maps using the Getis-Ord Gi* statistic and analyzed clustering of tree health spatial patterns using Ripley's L statistic. Hotspot maps effectively identified clusters of live unhealthy trees and tree mortality; unhealthy and dead trees were found to be significantly spatially clustered at distances of 100-2500 m. We created a dead tree density grid, which we coupled with a lidar-derived canopy gap grid to identify sites and stands affected by root disease. Canopy openings were mapped using a canopy height model with a minimum opening area of > 202 m2. Clusters of mapped dead trees (excluding recently killed trees) intersecting canopy gaps were used to detect sites with root disease-induced mortality. Twenty-seven stands containing long-term plots from previous studies were evaluated for the presence of root disease-induced mortality. All 27 stands were correctly identified with conifer mortality induced by root disease. This approach for detecting dead trees intersecting canopy openings induced by root disease can aid in: i) prioritizing subsequent field data collection; ii) planning silvicultural prescriptions; and iii) assessing management expectations for snags and wildlife habitat where root disease-induced mortality is altering stand structure.
      原文链接:
    • NSTL
    • Elsevier

    Excelling the progenitors: Breeding for resistance to Dutch elm disease from moderately resistant and susceptible native stock

    Dominguez, JorgeMacaya-Sanz, DavidGil, LuisMartin, Juan A....
    10页
    查看更多>>摘要：Under the continuous pressure of Dutch elm disease (DED) in Europe, increasing the genetic diversity of Ulmus minor trees resistant to Ophiostoma novo-ulmi is a priority for the species conservation and reintroduction. In this work we screened 121 U. minor genotypes for resistance to O. novo-ulmi under field experimental conditions. The genotypes had been previously obtained through controlled crosses between two moderately resistant (dams) and one susceptible (sire) genotypes. After two years of artificial inoculations with O. novo-ulmi, transgressive resistance was present but not prevalent, and a moderate relation was found between tree growth and susceptibility. Heritability estimates of DED resistance endorse significant genetic control and higher estimates for experimental blocks with milder symptoms. Three genotypes excelled for their high DED resistance, showing average foliage wilting values below 30% after the two years of inoculations. The genetic fingerprint, leaf phenology and morphology, and ornamental traits of these three genotypes were evaluated to facilitate their identification and use by stakeholders. Nuclear microsatellite profiling displayed unique barcodes for each genotype, ensuring traceability of the plant material. Morphological and phenological traits of the three genotypes are quite similar and fall within the species standards. In base of these results, three new native genotypes are proposed as basic materials for elm reintroduction in Western Europe.
      原文链接:
    • NSTL
    • Elsevier

    Managing forests for old-growth attributes better promotes the provision of ecosystem services than current age-based old-growth management

    Barros, Luizmar de AssisVenter, MichelleElkin, CheVenter, Oscar...
    14页
    查看更多>>摘要：Old-growth forests with complex structural attributes and large trees are rapidly transformed to more homogenous secondary forests through logging, reducing ecosystem services such as carbon storage, water provision and biodiversity. In British Columbia (BC), Canada, a century of logging resulted in strong pressures in the perceived dichotomy of conserving or logging the remaining old-growth. There is an urgency to determine if the current conservation policy for old-growth forests (e.g. old-growth management areas OGMAs) primarily based on stand age is adequate to protect old-growth structural attributes and their ecosystem services (ES) while leaving opportunities for timber harvesting within timber harvesting tenures. We applied a systematic conservation planning tool (PrioritizR) to design and evaluate attribute-based old-growth reserves as an alternative to the current age-based OGMAs, in a Community Forest (123,695 ha), managed primarily for timber. Old-growth, timber, carbon, tree diversity, and water services were mapped using Aerial Laser Scanning (ALS), and field measurements were used to ground truth with the random forest machine-learning algorithm. Then, "PrioritizR " was used to identify optimal reserve's networks for age, old-growth attribute, carbon, water, and a combination thereof. We found that the attribute-based old-growth reserves had significantly higher ESs provisioning than the age-based OGMAs. In addition, tradeoffs with timber harvesting were reduced when we simultaneously prioritized old-growth attributes and water values. Finally, while timber harvesting affects the provision of ESs by up to 11.8% ES loss for each 1% timber harvested (-283,150 m3 of timber), an increase in the area used for old growth conservation did not affect priority areas for timber harvesting until 22.6% of the study area was set aside (-30,316 ha) (more than threefold increase of the current OGMAs' area, 8,611 ha). Such results indicate that the conservation of old-growth via attribute-based OGMAs can help maintain the provision of multiple ESs in the landscape, including sustainable timber harvesting.
      原文链接:
    • NSTL
    • Elsevier

    The dynamics of Mauritia flexuosa (Arecaceae) recalcitrant seed banks reveal control of their persistence in marsh environments

    Salvador, Higor FernandoMazzottini-dos-Santos, Hellen CassiaDias, Daiane SouzaAzevedo, Alcinei Mistico...
    14页
    查看更多>>摘要：Mauritia flexuosa is a neotropical palm associated with marsh environments, having supra-annual fruiting and producing recalcitrant and dormant seeds. We sought to characterize the soil seed banks (SSB) of this species, determine the effects of edaphic and climatic factors on the dynamics of its SSB, and evaluate the influence of permanence in the bank on seed structure and physiology. Newly dispersed and SSB (established more than two years earlier) seeds were collected from four natural populations in the Brazilian Cerrado biome. Evaluations of seeds, embryos, and young plants defined 20 indicators of SSB dynamics that were correlated with 17 physical and chemical soil attributes. Biometric, biomechanical, cytological and physiological evaluations were made in newly dispersed and SSB seeds. Despite producing recalcitrant seeds, Mauritia flexuosa forms persistent SSB in humid environments, and this is the first in-depth report on this topic for angiosperms. Persistence in SSB is affected by predator and pathogen attacks, without the direct influence of physical or chemical soil attributes. Permanence in the SSB does not affect seed viability, as they have great homeostatic capacities, involving water retention and oxidative stress control. Dormancy levels decrease in the SSB, related to increased temperature sensitivity and embryo growth, promoting gradual positive output via germination. Persistent SSB contribute to the reproductive success of M. flexuosa and must be considered in the management of natural populations, as they can contribute to the recovery of degraded areas and, on the other hand, require monitoring of soil moisture, which is essential for its maintenance.
      原文链接:
    • NSTL
    • Elsevier