Addressing nonresponse bias in forest inventory change estimation using response homogeneity classifications

Estimating amounts of change in forest resources over time is a key function of most national forest inventories(NFI). As this information is used broadly for many management and policy purposes, it is imperative that accurate estimations are made from the survey sample. Robust sampling designs are often used to help ensure representation of the population, but often the full sample is unrealized due to hazardous conditions or possibly lack of land access permission. Potentially, bias may be imparted to the sample if the nonresponse is nonrandom with respect to forest characteristics, which becomes more difficult to assess for change estimation methods that require measurements of the same sample plots at two points in time, i.e., remeasurement. To examine potential nonresponse bias in change estimates, two synthetic populations were constructed: 1) a typical NFI population consisting of both forest and nonforest plots, and 2) a population that mimics a large catastrophic disturbance event within a forested population. Comparisons of estimates under various nonresponse scenarios were made using a standard implementation of post-stratified estimation as well as an alternative approach that groups plots having similar response probabilities(response homogeneity). When using the post-stratified estimators, the amount of change was overestimated for the NFI population and was underestimated for the disturbance population, whereas the response homogeneity approach produced nearly unbiased estimates under the assumption of equal response probability within groups. These outcomes suggest that formal strategies may be needed to obtain accurate change estimates in the presence of nonrandom nonresponse.

Genome sequencing and population genomics modeling provide insights into the local adaptation of weeping forsythia

Understanding the genetic basis underlying the local adaptation of nonmodel species is a fundamental goal in evolutionary biology.In this study,we explored the genetic mechanisms of the local adaptation of Forsythia suspensa using genome sequence and population genomics data obtained from specific-locus amplified fragment sequencing.We assembled a high-quality reference genome of weeping forsythia(Scaffold N50=7.3 Mb)using ultralong Nanopore reads.Then,genome-wide comparative analysis was performed for 15 natural populations of weeping forsythia across its current distribution range.Our results revealed that candidate genes associated with local adaptation are functionally correlated with solar radiation,temperature and water variables across heterogeneous environmental scenarios.In particular,solar radiation during the period of fruit development and seed drying after ripening,cold,and drought significantly contributed to the adaptive differentiation of F.suspensa.Natural selection exerted by environmental factors contributed substantially to the population genetic structure of F.suspensa.Our results supported the hypothesis that adaptive differentiation should be highly pronounced in the genes involved in signal crosstalk between different environmental variables.Our population genomics study of F.suspensa provides insights into the fundamental genetic mechanisms of the local adaptation of plant species to climatic gradients.

Fuel characteristics, loads and consumption in Scots pine forests of central Siberia

Forest fuel investigations in central and southern Siberian taiga of Scots pine forest stands dominated by lichen and feather moss ground vegetation cover revealed that total aboveground biomass varied from 13.1 to 21.0 kg/m 2.Stand biomass was higher in plots in the southern taiga,while ground fuel loads were higher in the central taiga.We developed equations for fuel biomass(both aerial and ground)that could be applicable to similar pine forest sites of Central Siberia.Fuel loading variability found among plots is related to the impact and recovery time since the last wildfi re and the mosaic distribution of living vegetation.Fuel consumption due to surface fi res of low to high-intensities ranged from 0.95 to 3.08 kg/m 2,that is,18–74%from prefi re values.The total amount of fuels available to burn in case of fi re was up to 4.5–6.5 kg/m 2.Moisture content of fuels(litter,lichen,feather moss)was related to weather conditions characterized by the Russian Fire Danger Index(PV-1)and FWI code of the Canadian Forest Fire Weather Index System.The data obtained provide a strong foundation for understanding and modeling fi re behavior,emissions,and fi re eff ects on ecosystem processes and carbon stocks and could be used to improve existing global and regional models that incorporate biomass and fuel characteristics.

顽拗型种子贮藏和脱水过程中碳水化合物、脂肪和蛋白质的生化变化(英文)

顽拗型种子通常不能干燥到较低含水量或贮藏较长时间而不受伤害。导致这一问题的生化机制因属不同甚至同一属中的种不同而异。笔者测定了栎属、槭属和七叶树属顽拗型种子在室温下贮藏或干燥过程中的生化变化。虽然贮藏脂肪组成的变化是不确定的,但膜脂肪和蛋白质的结构以及蔗糖含量发生了变化。用两份白橡树种子在室温下贮藏12 d的实验表明,脱水样品的蔗糖含量发生很大变化,而保持水分的样品中蔗糖含量变化很小。因此,保持水分种子的蔗糖用于正常的生长和发育,而干燥种子的蔗糖则用作糖保护剂。尽管如此,蔗糖的存在也许能保护干燥橡实的细胞膜不致破裂,但蔗糖不能保持橡实的生活力。

Axial compressive behavior of Moso Bamboo and its components with respect to fiber-reinforced composite structure

Bamboo is a unique fiber-reinforced bio-composite with fibers embedded into a parenchyma cell matrix.We conducted axial compression tests on bamboo blocks prepared from bottom to top,and from inner to outer portions of the culm.The apparent Young’s modulus and compressive strength of whole thickness bamboo blocks exhibited slight increases with increasing height along the culm,due to slight increases of fiber volume fraction(Vf)from 28.4 to 30.4%.Other blocks showed a significant increase in apparent Young’s modulus and strength from the inner to outer part of the culm wall,mainly owing to a sharp increase of Vf from 17.1 to 59.8%.With a decrease of fiber fraction volume there was a transition from relatively brittle behavior to very ductile behavior in bamboo blocks.Results indicated that stiffness and strength of bamboo was primarily due to fiber in compression,and ductility of bamboo was provided by the parenchyma cell matrix acting as a natural fiber-reinforced composite.

Host-environment mismatches associated with subalpine fir decline in Colorado

Subalpine fir decline （SFD） has killed more trees in Colorado＇s high elevation forests than any other insect or disease problem. The widespread nature of this disorder suggests that the cause involves climatic factors. We examined the influence of varying combinations of average annual temperature and precipitation on the incidence and distribution of SFD. Climatic transition matrices generated in this study indicate that most healthy trees are found in climatic zones with moderate to low temperatures and high precipitation; whereas, SFD occurs mostly in zones of moderate temperatures and moderate precipitation. The contrasting distributions define an environmental mismatch. Forests matched with favorable climatic conditions thrive; those that are mismatched can become vulnerable to decline disease.

Thinning and in-stream wood recruitment in riparian second growth forests in coastal Oregon and the use of buffers and tree tipping as mitigation

Many aquatic habitats in coastal Oregon have been impacted by historic land use practices that led to losses of in-stream wood and associated degraded fish habitats. Many of these streams are now bordered by stands of dense second growth forests（30–80 years） that are incorporated into riparian buffer zones with low wood recruitment and storage. Thinning in riparian zones is one management option to increase the rate of large tree growth and eventually larger in-stream wood, however, it raises concern about impacts on current wood recruitment, among other issues. Using a forest growth simulation model coupled to a model of in-stream wood recruitment, we explore riparian management alternatives in a Douglas-fir plantation in coastal Oregon. Alternatives included：（1） no treatment,（2） single and double entry thinning, without and with a 10-m buffer, and（3） thinning combined with mechanical introduction of some portion of the thinned trees into the stream（tree tipping）. Compared to no treatment, single and double entry thinning on one side of a channel, without a 10-m buffer, reduce cumulative instream wood volume by 33 and 42 %, respectively, after100 years（includes decay）. Maintaining a 10-m buffer reduces the in-stream wood loss to 7 %（single entry thin）and 11 %（double entry）. To completely offset the losses of in-stream wood in a single entry thin（on one or both sides of the stream）, in the absence or presence of a 10-m buffer,requires a 12–14 % rate of tree tipping. Relative to the notreatment alternative, cumulative in-stream wood storage can be increased up to 24 % in a double-entry thin with no buffer by tipping 15–20 % of the thinned trees（increased to 48 % if thinning and tipping simultaneously on both sides of the stream）. The predicted increases in in-stream wood that can occur during a thin with tree tipping may be effective for restoring fish habitat, particularly in aquatic systems that have poor habitat conditions and low levels of in-stream wood due to historic land use activities.

A global review of the ecological significance of symbiotic associations between birds and fungi

Symbiotic associations between mammals and fungi have been well documented and are widely regarded as vital to ecosystem functions around the world.Symbioses between birds and fungi are also ecologically vital but have been far less thoroughly studied.This manuscript is the first to review a wide range of symbiotic associations between birds and fungi.We compile the largest list to date of bird species reported to eat fungi(54 bird species in 27 families)and follow up with a discussion of these symbioses and suggestions for how future studies can determine the prevalence of associations between birds and fungi.We review the importance of fungi for cavity-excavating birds and show that at least 30 bird species in three families form varying levels of associations with fungi for cavity excavation.We also review the use of fungal rhizomorphs in nest construction and show that 176 bird species in 37 families use fungal material in their nests.All of these interactions have wide-reaching ecosystem implications,particularly in regard to fungal dispersal and biogeography,plant health,ecosystem function,bird nutrition/fitness and bird behaviour.

Size-dependent flight capacity and propensity in a range-expanding invasive insect

For capital-breeding insects,all resources available for adult metabolic needs are accumulated during larval feeding.Therefore,body size at adult eclosion represents the total energetic capacity of the individual.For female capital breeders,body size is strongly correlated with lifetime fecundity,while in males,body size,which correlates with fitness,is less understood.In capital-breeding species with wingless,flightless,or dispersal-limited females,flight potential for male Lepidoptera has important implications for mate-finding and may be correlated with body size.At low population densities,failure to mate has been identified as an important Allee effect and can drive the success or failure of invasive species at range edges and in species of conservation concern.Th capital-breeding European subspecies of Lymantria dispar(L.),was introduced to North America in 1869 and now ranges across much of eastern North America.In L.dispar,females are flightless and mate-finding is entirely performed by males.We quantified male L.dispar flight capacity and propensity relative to morphological and physiological characteristics using fixed-arm flight mills.A range of male body sizes was produced by varying the protein content of standard artificial diets while holding other dietary components constant.Wing length,a proxy for body size,relative thorax mass,and forewing aspect were all important predictors of total flight distance and maximum speed.These results have important implications for mate-finding and invasion dynamics in L.dispar and may apply broadly to other capital-breeding insects.

Taxonomy of Pseudolagarobasidium(Polyporales,Basidiomycota)

Pseudolagarobasidium(Polyporales,Basidiomycota)is a small,monophyletic genus of crustose,wood-inhabiting fungi with spines and a saprobic,endophytic,or parasitic habit.Seven species are accepted in the genus including two new species,P.belizense from Belize and P.pusillum from Australia.Sequence analysis of the internal transcribed spacer of the ribosomal RNA gene places P.belizense in a monophyletic clade with P.acaciicola and an undescribed foliar endophyte.New combinations proposed include P.modestum for Irpex modestus Berk.,P.pronum for Hydnum pronum Berk.&Broome which is an earlier name for P.calcareum,and P.venustum for Radulodon venustus Hjortstam&Ryvarden.Irpex colliculosum Berk.&Broome from Sri Lanka is conspecific with P.subvinosum.Two species,Sistotrema ochroleucum and Radulum concentricum are not accepted in Pseudolagarobasidium.Pseudolagarobasidium is compared with Radulodon and similar genera.A key to the species of Pseudolagarobasidium is provided.

A review of potential conservation and fisheries benefits of breaching four dams in the Lower Snake River(Washington,USA)

Abundances of important and imperiled fishes of the Snake River Basin continue to decline.We assessed the rationale for breaching the four lower Snake River Basin dams to prevent complete loss of these fishes,and to maximize their likelihood of recovery.We summarize the science surrounding Sockeye Salmon(Oncorhynchus nerka),Chinook Salmon(O.tshawytscha),steelhead(O.mykiss),Bull Trout(Salvelinus confluentus),White Sturgeon(Acipenser transmontanus),and Pacific Lamprey(Entosphenus tridentatus).From this,we drew ten conclusions:(1)development of the Columbia River System(including the Snake River Basin)has converted mainstem rivers into reservoirs,altering fish behavior and survival;(2)most populations currently record their lowest abundance;(3)the Columbia River System dams reduce productivity of diadromous fishes in the highest-quality spawning grounds that could buffer against future climate dynamics;(4)past actions have done little to reduce impacts or precipitate recovery;(5)the Columbia River System constrains survival and productivity of salmon,steelhead and Bull Trout;(6)Snake River Basin salmon and steelhead remain at high extinction risk;(7)eliminating migration impediments and improving mainstem habitats are essential for maintaining genetic diversity and improving Bull Trout persistence;(8)the lower Snake River Basin dams preclude passage of adult White Sturgeon,constraining gene flow and recruitment;(9)the lower Snake River Basin dams impede dramatically passage of adult and juvenile Pacific Lamprey,and(10)Snake River Basin Pacific Lamprey is at high risk of extirpation.Breaching the four lower Snake River Basin dams is an action likely to prevent extirpation and extinction of these fishes.Lessons from the Columbia River System can inform conservation in other impounded rivers.