Influence of individual tree characteristics,spatial structure and logging history on tree-related microhabitat occurrence in North American hardwood forests

Background:Tree-related microhabitats(hereafter,"TreMs")are key components of forest biodiversity but they are still poorly known in North American hardwood forests.The spatial patterns of living trees bearing TreMs(hereafter,"TreM-trees")also remain to be determined.As logging practices can lead to a loss of TreM-trees and of their associated biodiversity,it is essential to identify the factors explaining TreM occurrence to better integrate them into forest management.We therefore inventoried TreMs in 40.5-ha survey strips in northern hardwood forests in Quebec,Canada,while recording the spatial location of each tree.Two strips were located in unmanaged oldgrowth forests,and 2 were in forests managed under selection cutting.All 4 stands were dominated by sugar maple(Acer saccharum Marsh.)and American beech(Fagus grandifolia Ehrn.).Beech bark disease,an exotic pathology,was observed in all the strips.Results:Large diameter at breast height and low tree vigor were the main characteristics explaining the presence of TreMs at the tree scale.TreM-trees presented slight spatial aggregation patterns.These aggregates,however,were not well-defined and were generally constituted by a large number of trees bearing few different types of TreMs.Two TreM classes(broken branch or top and woodpecker lodge)also presented a spatial aggregation.Logging practices had no significant effect on TreM occurrence.Beech bark disease increased the frequency of senescent beeches.The impact of this pathology on TreMs was however mitigated by the small size of infected trees and probably by the short time elapsed since its appearance.Conclusion:The factors explaining the presence and abundance of TreMs on trees has so far been little studied in North American hardwood forests.Our results highlight that TreM-tree characteristics in the surveyed forests are consistent with those of previous studies conducted in other forest types and regions(e.g.,Europe or Northwestern America).To our knowledge,this study is also the first to identify a spatial aggregation of TreM-trees and of specific TreM classes.It will be nevertheless necessary to determine whether the small impact of logging activities we observed results from current or past management practices.

Balancing timber production and habitat conservation of Okinawa Rails(Gallirallus okinawae): Application of a harvest scheduling optimization model in subtropical forest in Okinawa, Japan

Finding the right balance between timber production and the management of forest-dependent wildlife species,present a difficult challenge for forest resource managers and policy makers in Okinawa,Japan.A possible explanation of this can be found in the unique nature of the forest management area which is populated with various kinds of rare and endangered species.This issue has been brought to light as a result of the nomination of northern Okinawa Island in 2018 as a candidate for World Natural Heritage site.The nomination has raised public awareness to the possibility of conflicting management objectives between timber extraction and the conservation of habitat for forest-dependent wildlife species.Managing exclusively for one objective over the other may fail to meet the demand for both forest products and wildlife habitat,ultimately jeopardizing the stability of human and wildlife communities.It is therefore important to achieve a better balance between the objective of timber production and conservation of wildlife habitat.Despite the significance of this subject area,current ongoing discussions on how to effectively manage for forest resources,often lack scientific basis to make sound judgement or evaluate tradeoffs between conflicting objectives.Quantifying the effect of these forest management activities on wildlife habitat provides useful and important information needed to make forest management and policy decisions.In this study we develop a spatial timber harvest scheduling model that incorporates habitat suitability index(HSI)models for the Okinawa Rail(Gallirallus okinawae),an endangered avian species found on Okinawa,Japan.To illustrate how the proposed coupling model assembles spatial information,which ultimately aids the study of forest management effects on wildlife habitat,we apply these models to a forest area in Okinawa and conduct a simple simulation analysis.

Variation in abundance and habitat relationship of three understory insectivorous birds in a disturbed landscape of Neotropical dry forest of Colombia

Background:Evaluating relationships between avian populations and their habitat is important for understanding the biology of these species and for management decisions that improve the effectiveness of restoration practices.We investigated how habitat variation along a disturbance gradient affected the abundance of three insectivorous bird species,White-bellied Antbird(Myrmeciza longipes),Barred Antshrike(Thamnophilus doliatus),and Pale-breasted Spinetail(Synallaxis albescens)in a Neotropical dry forest remnant in central Colombia.Methods:The study area,which is located in Magdalena Valley,is under ecological restoration after the construction of the“El Quimbo”hydroelectric dam,with a gradient of habitat conditions,from relatively advanced secondary growth to recently disturbed areas.We conducted bird surveys and quantified the habitat conditions from June 2018 to June 2019.We compared the relative abundance of the birds among the three zones with increasing disturbance and modeled the relationship between the bird abundance with the micro-and landscape-habitat conditions,with Poisson generalized linear model regression.Results:The relative abundance of the three bird species varied according to the habitat features and disturbance level.The abundance of White-bellied Antbirds was higher in forests and thickets than shrubland fragments;Barred Antshrike was more abundant in shrubland and thickets than in forest fragments,and Pale-breasted Spinetail had the highest abundance in shrubland and the lowest in forest fragments.The abundance of both White-bellied Antbird and Pale-breasted Spinetail did not differ among zones with different levels of disturbance,while the abundance of Barred Antshrike decreased in zones with more disturbance.Conclusions:There were significant differences in the habitat relationships of the three understory insectivorous species along the disturbance gradient,although these species were within the same trophic group.These bird species preferred different stages of habitat succession and responded to different habitat and landscape features.Increasing forest fragment areas and decreasing the amount of edge would be useful restoration priorities for these and other similar avian species in this study area.

Post-mining policies and practices in the Eastern USA coal region

Surface coal mines prior to 1950 in the USA were generally left without any reclamation.As government regulations advanced since then,mine operators were required to backfill the area and plant grasses or trees.After the federal Surface Mining Control and Reclamation Act(SMCRA)was passed in 1977 in the USA,mine operators were required to conduct pre-mining analyses of the site and to designate a land use that could be achieved after mining.Successful reclamation,as needed to satisfy today’s societal demands,requires engineering,design,and purposeful reconstruction of the full mining disturbance,not just its surface,and control of waters leaving the mine site.Effective reclamation on modern American coal mines is fully integrated with the mining operation.A suitable and effective postmining land use that is sustainable for future generations is crucial to the long-term success and profitability of the mining business and to the future economic benefits of the landowner.Accepted post-mining land uses in the USA are:(1)prime farmland,(2)hay land and pasture,(3)biofuel crops,(4)forestry,(5)wildlife habitat,and(6)building site development.Policies and regulations for each post-mining land use were developed and practices to achieve successful and sustainable land uses were established.Post-mining conditions should provide ecosystem services and produce lands capable of supporting societal needs in the future.

Predisposing factors’effects on mortality of oak (Quercus) and hickory (Carya) species in mature forests undergoing mesophication in Appalachian Ohio

Background:Mature oak(Quercus spp.)and hickory(Carya spp.)trees are gradually being replaced by more shadetolerant tree species across the eastern U.S.,likely due to fire suppression and increased precipitation.Oaks and hickories are highly valuable to wildlife;therefore,studying their mortality patterns can provide information on the longevity of habitat quality for many animal species.Oak mortality has most often been studied following large oak decline events,but background mortality rates in forests with aging oak and hickory canopies warrant equal attention,especially in the context of widespread oak and hickory regeneration failure.Methods:We studied background mortality rates of five oak and one hickory species over a 23–25 year time period(1993–1995 to 2018),using 821/20th hectare permanent plots on the Marietta Unit of the Wayne National Forest in southeastern Ohio.We calculated mortality rates based on remeasurement of individual trees for white oak(Quercus alba),chestnut oak(Quercus montana),northern red oak(Quercus rubra),black oak(Quercus velutina),scarlet oak(Quercus coccinea),and pignut hickory(Carya glabra).For each of these species other than scarlet oak,we also modeled the relationships of mortality probability with a priori topographic,soil,stand structural,and individual tree covariates,using a mixed-effects logistic regression framework.Results:The species with the highest mortality rate was scarlet oak(61.3%),followed by northern red oak(41.4%),black oak(26.7%),pignut hickory(23.9%),white oak(23.4%),and chestnut oak(19.1%).In our models,northern red oak mortality was associated with more mesic slope positions,shallower solums,more acidic soils,and older stand ages.Pignut hickory and chestnut oak mortality rates were associated with higher basal areas on the plot,while white oak mortality showed the opposite pattern.Conclusions:Our data suggest that red oak subgenus trees in mature forests of our area will become increasingly uncommon relative to white oak subgenus trees,as the result of higher mortality rates likely related to the shorter lifespans of these species.Particularly vulnerable areas may include more mesic topographic positions,shallower or more acidic soil,and older stands.Since maintaining oak subgenus diversity is beneficial to wildlife diversity in the eastern U.S.,managers in areas with extensive mature mixed-oak forests could choose to favor the red oak subgenus when conducting silvicultural treatments.

Born from a Flood: The Salton Sea and Its Story of Survival

The Salton Sea is a terminal lake located in the deepest point of the topographically closed Salton Trough in southeastern California. It is currently the largest lake in area in the state. It was created by a flooding event along the Colorado River in 1905-1907, similar to the way historical floods over past centuries created ephemeral incarnations of ancient Lake Cahuilla in the same location. Its position at the center of today＇s Imperial Valley, a hot and arid locale home to some of the most productive irrigated agricultural lands in the United States, has ensured its ongoing survival through a delicate balance between agricultural runoff, its principal form of input, and vast evaporation losses. Nevertheless, its parallel role as a recreational resource and important wildlife habitat, established over its first century of existence, is threatened by increasing salinity decreasing water quality, and reduced water allocations from the Colorado River that feeds the valley＇s agriculture. The Salton Sea faces an increasingly uncertain future that will be influenced by reduced water imports from the Colorado River, demands for additional water sources to support farming and energy industries in the valley, and needs to stabilize the lake salinity, maintain recreational resources, and preserve what have become important ecosystems and wildlife habitats.