Marshall, Craig D.Maerz, John C.Larsen-Gray, Angela L.Chamberlain, Michael J....
7页
查看更多>>摘要：Private working forest landscapes provide wildlife habitat and understanding how species interact with these landscapes is critical to identifying conservation opportunities. The gopher tortoise (Gopherus polyphemus; hereafter, tortoise) is a species endemic to the Coastal Plain ecoregion of the southeastern United States, with private working pine (Pinus spp.) forests encompassing a substantive portion of area within the species' range. Although private working pine forests contain tortoises, uncertainty exists about how tortoises use these landscapes. Specifically, there is limited information regarding tortoise habitat associations within these landscapes relative to current forest management practices. Therefore, we used radio telemetry data from 55 adult tortoises collected over 3 years to estimate resource selection within a private working forest landscape dominated by planted loblolly pine (Pinus taeda) stands in the Upper Coastal Plain ecoregion of Georgia, USA. The strongest predictor of resource selection by tortoises was proximity to permanently open areas, specifically a utility rightof-way and areas adjacent to unpaved forest roads and, to a lesser extent, areas of higher elevation containing soils suitable for tortoises. On our study area, we identified permanently open areas as an important landscape component to adult tortoises. Although adult tortoises persist within these landscapes, more work is needed to understand tortoise recruitment in private working pine forest landscapes.
查看更多>>摘要：Quantifying spatio-temporal variation in forest microclimate is important to understand the habitat associations of some species, identify potential refugia, and manage forests in a changing climate. We quantified relationships between microclimatic conditions and stand age using a detailed case study of the Mountain Ash (Eucalyptus regnans) forests in south-eastern Australia. We deployed sensor buttons to capture data on day-time and nighttime seasonal (Julian Day) temperature profiles in even-aged stands that were 12-years-old, 30-40-years-old, ~82-95-years-old, and 200+-years-old. We constructed Bayesian generalised linear models (GLMs) to quantify the main and interacting effects of stand age and topographic factors and foliage cover on seasonal profiles for: median, maximum and variability in day-time and night-time temperature.& nbsp;The most parsimonious model for median day-time temperature included a main effect of midstory and overstory cover, both of which were inversely related to median day-time temperature. The most parsimonious model for median night-time temperature measures included an additive effect of forest age and seasonality. Temperatures for the youngest forests (that were 12-years-old) were different from other age classes and were characterised by the lowest median and minimum night-time temperatures.& nbsp;The most parsimonious model for day-time maximum temperature and day-time interquartile range included an interaction between forest age and Julian day. Day-time maximum temperatures were warmest in 12-year-old forest. The coolest maximum day-time temperatures in summer were generally in old growth stands (200+ -year-old). The greatest variability in maximum day-time temperatures was in 12-year-old forest whereas, in general, old growth stands experienced the least variable day-time temperatures. Our sensor data also showed that old growth forests were characterised by fewer days above 30, 35 and 40 degrees than 12-year old forest. Our empirical data contain compelling evidence that the youngest forests were characterised by the hottest day-time temperatures, the coldest night-time temperatures, and the most variable day-time and night-time temperature regimes. Age class differences in stand structure (e.g. canopy height, prevalence of large old trees and dense wet understorey) may explain stand age related seasonal differences in local microclimatic conditions.
Aleksic, Jelena M. M.Mataruga, MilanDanicic, VanjaCvjetkovic, Branislav...
9页
查看更多>>摘要：Studying how genetic diversity is transmitted between generations is critical for assessing the survival prospects of fragmented forest tree populations. This is especially urgent in the case of rare, endangered species that are at high risk of extinction and/or exceptionally susceptible to climate change, and are thus to be prioritised for conservation initiatives. We performed the first assessment of gene flow patterns by parentage analysis in the IUCN red-listed Serbian spruce [Picea omorika (Pan.c.) Purk.], within a Genetic Conservation Unit (GCU) which was exposed to fire disturbance 30 years ago. Parentage analysis was based on assigning the parentage of 104 juveniles to all the adult trees (48) present in the 2.8 ha population. All individuals were genotyped at 11 highly informative nuclear microsatellite markers. We found that fire disturbance triggered natural regeneration, usually poor to absent in Serbian spruce, and boosted pollen immigration (66%), which is reported as rather modest among undisturbed populations of this species. Seed immigration was absent, coherently with what was previously hypothesised for natural, undisturbed populations. Thus, the immigration of new gametes into the studied Serbian spruce population was accomplished exclusively through pollen gene flow, at a rate sufficient to counteract, at least in the short term, genetic drift. Furthermore, the abundant post-disturbance pollen immigration most likely accounts for the lack of fine-scale spatial genetic structure (SGS) in the juvenile cohort, contrary to the SGS observed in the adult cohort which is amongst the strongest ever recorded in anemophilous forest tree species. Finally, as generally found in forest trees, individual reproductive success was uneven among individuals, with 25% of local adults siring 70% of the sampled juveniles. Our results on post-disturbance gene flow patterns in the only Serbian spruce population with reportedly abundant regeneration complement the outcomes of previous genetic studies while providing essential information for the dynamic management and conservation of this rare and endangered species severely threatened by climate warming. Tracking the temporal development of gene flow parameters and the consequences of gene flow on genetic diversity are two cornerstones of future forest genetic monitoring programs, which are particularly important for GCUs. In particular, monitoring the genetic diversity of forest regeneration is deemed as the key for understanding changes that otherwise would remain mostly untraceable in long-lived organisms such as forest trees.
查看更多>>摘要：Decades of expansion of industrial resource extraction in boreal forests have resulted in the legacy of thousands of kilometers of linear features (seismic lines, forest roads) that have fragmented several wildlife habitats. The decommissioning of anthropogenic linear features and the restoration of suitable habitat are top priorities for the recovery of several species at risk, among which, the threatened populations of boreal caribou (Rangifer tarandus caribou). However, the decommissioning of linear features found in caribou range is expensive, and determining which characteristics make them more beneficial to caribou predators and competitors could assist in prioritizing those that may be most critical for boreal caribou habitat restoration. We thus aimed to determine how fine-scale forest road characteristics influence their use by gray wolf (Canis lupus), black bear (Ursus americanus), moose (Alces americanus) and caribou. We used camera traps and generalized linear mixed models to test the effect of road-scale characteristics on the use of forest roads by wolves, bears and moose while also considering largerscale covariates. Wolves had a greater probability of using roads that were surrounded by wetlands and had a low lateral cover density. For bears, the intensity of use was lower on 20+ year-old roads when compared to 0-10-year-old roads, and higher on roads surrounded by coniferous stands. Moose intensity of use was higher on 11-20-year-old roads and lower on 30+ year-old roads, and decreased on roads surrounded by clearcuts and with a lower number of deciduous stems growing on them. We could not test for caribou use as we did not capture enough events. Nevertheless, by showing which forest roads are more used by caribou predators (wolves and bears) and its apparent competitor (moose), our study highlights the importance of considering both road-scale characteristics and the landscape context in which roads are built to prioritize the most detrimental roads to caribou conservation and guide efficient restoration efforts of its habitat.
Campbell, Joshua W. W.Grodsky, Steven M. M.Milne, Marc A. A.Vigueira, Patrick...
9页
查看更多>>摘要：Prescribed burns and understory thinnings are forest management practices aimed at reducing fuel loads to lessen wildfire threat in the Southern Appalachians, USA. Spiders play a critical role in forest ecosystems by controlling insect populations and providing an important food source for vertebrates. We used pitfall and colored pan traps to investigate how abundance, species richness, and diversity of spiders differed among three fuel reduction treatments administered repeatedly over a 15-year period and untreated controls. Additionally, we examined how spiders responded to one round (before and after) of fuel reduction treatments. We established treatments within the 15-year period as follows: mechanical understory removal (twice; M), prescribed burning (four times; B), mechanical understory removal followed one year later by high-severity prescribed burns and three subsequent burns (MB), and untreated controls (C). Our study period (2014-2016) occurred after multiple prescribed burns and two rounds of mechanical understory removal had occurred. Salticidae and Lycosidae were the two most commonly collected spider families in Southern Appalachian hardwood forests. Generally, we found increased spider abundances within all fuel-reduction treatments compared to controls. Individual spider families and species showed variable responses to treatments, but abundance of several spider families was greater in one or more fuel-reduction treatments than in controls. Additionally, abundance of several spider families and hunting/web building guilds (webs built for hunting purposes or defense) exhibited yearly differ-ences to the last round of fuel-reduction treatments. Overall, our results suggest that changes in the overstory and understory of a forest are important drivers of regional spider abundance and assemblages, and forest man-agement practices that modify forest structure can dramatically alter spider abundance and richness, usually in a positive manner.
Harrington, Timothy B. B.Peter, David H. H.Marshall, David D.DeBell, Dean S....
13页
查看更多>>摘要：In the Pacific Northwestern USA, concerns regarding impacts of forest harvesting on visual quality, wildlife habitat, and carbon management have prompted evaluations of alternative silvicultural regimes for coast Douglas-fir (Pseudotsuga menziesii var. menziesii). Research was initiated in 1998 near Olympia WA USA to conduct long-term comparisons among six silvicultural regimes: clearcut (harvest all trees), two age (harvest all except 38 mature trees ha(-1)), patches (harvest 20% of the area in 0.6-2.0 ha tracts), groups (harvest 20% of the area in 0.1-0.5 ha tracts), thinning (reduce stand density to 45% of the biological maximum for Douglas-fir), and a non-treated control. Harvested areas in the first four regimes were planted with Douglas-fir seedlings. This report focuses on tree regeneration and stand productivity during the first decade of the study. Fifth year height of planted Douglas-fir was greater in the clearcut regime (1.8 m) than in the patches and groups regimes (1.1-1.2 m). Fifth year tree regeneration in the clearcut and two-age regimes was dominated by Douglas-fir (80-86% of seedlings), but regeneration in the patches and groups regimes was composed of a mixture of conifer and hardwood species. Ten-year periodic annual increment (PAI) in Douglas-fir ingrowth volume was greater in the clearcut regime (1.4 m(3) ha(-1) yr(1)) than in the control (0.1 m3 ha(-1) yr(1)), whereas ingrowth volume PAI of other conifer species was greater in the two-age regime (0.4 m3 ha(-1) yr(-1)) than in the control (0.0 m3 ha(-1) yr(-1)). Tree regeneration responses indicated increasing abundance of shade tolerant species in the non-clearcut regimes, especially western hemlock (Tsuga heterophylla). Fifth year cover of the vine, California blackberry (Rubus ursinus), in the clearcut regime (21%) was over four times that in the control (5%). Ground disturbance in the clearcut regime reduced 5th-year height of the shrubs, salal (Gaultheria shallon) and red huckleberry (Vaccinium parvifolium), by 40-50% compared to the control. Ten-year volume PAI of Douglas-fir was linearly related to post-harvest stand basal area (r2 = 0.94), and the relationship did not vary significantly among the three replicate sites. During the first decade of the study, Douglas-fir regeneration and stand productivity differed among silvicultural regimes because of post-harvest variation in stand edge competition, species composition of tree seedlings and ingrowth, and residual stand density.
NSTL
Elsevier