Selection of diurnal roosts by red bats (Lasiurus borealis) in an intensively managed pine forest in Mississippi

Forest managers are increasingly expected to incorporate biodiversity objectives within forest landscapes devoted to timber production. However, data on which to base management recommendations for bats within these systems are limited. Although the red bat (Lasiurus borealis) is a widespread and common species in temperate forests of North America, little is known of its ecology within intensively managed pine (Pinus spp.) forests of the southeastern United States. Diurnal roost sites of red bats may be limiting on industrial pine forests due to a lack of large hardwoods within managed stands. Therefore, we investigated selection of day roosts by red bats at multiple spatial scales during June–September 2000 and May–August 2001 in an intensively managed pine landscape in east-central Mississippi, USA. We captured bats using 4-tier mist nets placed over water and attached 0.47–0.54 g radiotransmitters to captured red bats (n = 46). We located day roosts of red bats (n = 141 roosts of 27 bats) for the life of the transmitters. Red bats roosted in 16 species of hardwood trees (70% of day roosts) and loblolly pine (Pinus taeda; 30% of day roosts). In contrast to other studies in the southeastern United States, red bats roosted in pine trees and in midstory hardwood trees. Within thinned pine stands, red bats tended to prefer roost trees with a denser subcanopy and higher basal area as compared to random sites. Stand-level characteristics appeared more important than individual tree characteristics in choice of diurnal roosts. Except for adult males, logistic regression models of roost sites of red bats had high (≥79%) correct classification rates. Day roost site requirements of red bats may exhibit greater plasticity than previously thought. On our study area, intensive forest management appears compatible with diurnal roost needs of this species.     

The R. R. Reynolds Research Natural Area in Southeastern Arkansas

The R. R. Reynolds Research Natural Area is a 32-ha pine-hardwood forest in southeastern Arkansas, U.S.A., that originated from diameter-limit cutting of the virgin forest before 1915. In 1935, these 32 ha were reserved from timber management. Between 1937 and 1993, eight inventories were taken of all living trees > 9-cm DBH, using 2.5-cm DBH classes within three species groups: Pinus spp., Quercus spp., and other hardwoods. In 1994, all standing dead snags of pines and hardwoods > 9-cm DBH were inventoried by 2.5-cm DBH classes. During 56 years, thc overstory pine-hardwood ratio remained stable in terms of relative basal area, but pine density decreased with a commensurate increase in hardwood density. In 1993, pines represented 63% of basal area but only 23% of stem density. Just before the 1993 inventory, a pine bark-beetle infestation developed on the area, and within one year the pines lost about 2.5 m2/ha in basal area and had 180% more snags than were contributed by hardwoods. The overstory pine component is decreasing in density as a result of natural senescence and the allogenic effects of bark beetles. Hardwood species are expected to eventually dominate the forest because shade-intolerant pine regeneration will not develop to maturity beneath the closed hardwood canopy which can be altered only by catastrophic natural disturbances or anthropogenic intervention.     

The role of herbicide in savanna restoration: Effects of shrub reduction treatments on the understory and overstory of a longleaf pine flatwoods

Woody plant encroachment is a threat to savanna ecosystems worldwide. By exploiting differences in the physiology and seasonality of herbaceous species and encroaching hardwoods, herbicides can be used to control woody shrubs in savannas without causing lasting harm to desirable vegetation. We applied three herbicides and one tank mix to control shrubs following removal of the slash pine (Pinus elliottii Engelm.) canopy and replanting with container-grown longleaf pine (Pinus palustris Mill.) seedlings in a mesic-wet savanna in the southeastern USA. The herbicides tested were imazapyr, sulfometuron methyl, hexazinone, and a hexazinone + sulfometuron methyl tank mix. 4 years after application, no negative effects on understory species richness, diversity, evenness, or community composition were evident in any of the herbicide treatments. Oaks (Quercus spp.), one of the dominant shrub genera on the study site, were resistant to sulfometuron methyl, and this herbicide was therefore ineffective both as a pine release treatment and for enhancing herbaceous species cover. Imazapyr was the most effective treatment overall, leading to significant improvements in longleaf pine seedling growth and also enhancing herbaceous species cover. Both hexazinone and the hexazinone + sulfometuron methyl tank mix provided some seedling growth and understory enhancement as well. In particular, the tank mix significantly increased wiregrass cover relative to the control. Shrubs resprouted quickly following a dormant-season prescribed fire in the fifth year after treatment, indicating that herbicide-related increases in herbaceous cover may be lost if an aggressive prescribed fire program is not implemented.     

Effectiveness of basal area for estimating canopy cover of ponderosa pine

Basal area is commonly used as a measure of canopy cover when describing overstory-understory relationships in forest ecosystems. We evaluated basal area and a number of other biotic and abiotic variables from 61 stands along the Rocky Mountain Front Range to establish whether this procedure has scientific merit and ascertain whether other models might provide a more precise estimator. Only basal area was correlated to overstory canopy and that relationship broke down above a canopy cover of 60%. Quadratic and piecewise linear models both provided an adequate fit of data over all stands sampled, however, the latter was regarded as better because (1) it reflected the straight-line relationship found below 60% canopy cover and (2) it objectively estimated the change-over point from a positively correlated model to one of no correlation. Basal area explained about 83% of the variation in canopy cover in both models.     

灵空山主要森林类型枯落物生物量及持水性能

通过对太岳灵空山四种主要森林类型 :油松纯林、辽东栎林、松栎混交林、油落桦栎混交林的枯落物生物量及其持水性能的调查分析 ,总结出不同森林类型的生物量、最大持水量、分解率的大小排序。为研究森林的水土保持、水源涵养功能以及进一步综合评价该区的森林生态功能提供了科学依据     

我国马尾松林经营现状及近自然育林探索

马尾松是我国南方主要造林用材树种,在满足国内木材需求和维持生态安全中发挥着重要作用。随着我国社会进入生态文明新时代,对森林的利用形式发生了改变,传统的马尾松林经营模式已无法满足人们对其提供多种生态服务的需要,必须寻求新的马尾松林经营模式。近自然育林以培育结构复杂、物种丰富、功能多样的森林群落为目标,是满足人们对森林多种需求的有效途径。文中综述了我国马尾松林经营现状及近自然育林理念在马尾松林经营中的探索应用,并提出马尾松林未来经营方向。     

Probability models for pine twisting rust (Melampsora pinitorqua) damage in Scots pine (Pinus sylvestris) stands in Finland

Factors affecting the probability that pine twisting rust (Melampsora pinitorqua) damage occur in a Scots pine (Pinus sylvestris) stand were analysed using the 7th Finnish National Forest Inventory data (NFI7) from southern Finland in 1977–1983. The inventory was based on systematic sampling. The NFI7 data was measured in clusters, each of which consisted of 21 sample plots. In addition to the stand and site characteristics measured for forest management planning purposes, the data included records of damage by pine twisting rust and occurrence of aspens (Populus tremula, the other host plant of the pathogen) in the stands. Two multilevel logit models were developed for predicting the overall probability of pine twisting rust damage and the probability of severe pine twisting rust damage. Site and stand characteristics were used as explanatory variables in the models. Residual variance in the models was studied on the inventory crew, cluster and year levels. The occurrence of aspens and site fertility were the most important factors increasing the probability that pine twisting rust damage will occur in a stand. The damage probability also decreased with increasing effective temperature sum calculated for the location. The overall damage probability was equally high on peatlands and on mineral soil if there were aspens in the stand. If, however, there were no aspens in the stand, the probability of damage was higher on mineral soils than on peatlands. In addition, the overall probability was lower in naturally regenerated stands than in planted or sown stands, and it decreased with increasing mean age of pines. In both models, the residual variance was significant on the both the inventory crew and the cluster levels.     

Moisture and soil texture effects on soil CO2 efflux components in southeastern mixed pine forests

Monitoring soil CO₂ efflux rates and identifying controlling factors, such as forest composition or soil texture, can help guide forest management and will likely gain relevance as atmospheric CO₂ continues to increase. We examined soil CO₂ efflux and potential controlling factors in managed mixed pine forests in southwestern Georgia. Soil CO₂ efflux was monitored periodically in two stands that differed in soil texture in 2001 and 2002, and in six additional stands in 2003. We also monitored controlling factors: soil temperature, moisture, organic layer mass, and A layer depth. Soil moisture and CO₂ efflux varied with soil texture differences among the stands. As expected, soil temperature had a strong influence on soil CO₂ efflux. Soil moisture, organic layer mass, and A layer depth also were correlated with soil CO₂ efflux during periods of water stress, but these relationships differed with soil texture. Forest management activities can alter components of soil CO₂ efflux, including soil carbon pools, temperature, and moisture; understanding the underlying variation of these components and resultant CO₂ efflux over soil types can help guide management toward desired forest carbon balance trends in southeastern mixed pine forests.     

广西龙桥林区不同植被类型水文效益的研究

1985～1987年,在广西龙桥林区,对杉木、马尾松人工纯林和柠檬桉与马尾松人工混交林,以及天然灌木草本群落4种不同植被类型对降水的截留、地表径流及调蓄功能等水文效益进行测定,结果表明,对降水的截留效果以马尾松林为最好,混交林次之,杉木林较差,在同一植被类型的不同层次,以乔木层的截留量占绝对优势;对减少地表径流和延缓洪峰的效果,以层次结构较为复杂的混交林最佳。在同一植被类型内部结构特征的诸因子中,活地被物层的总盖度和草本层的生物量,是影响地表径流的主导因子:植被土壤对降水的调蓄功能,以混交林为最好。其他3种植被类型差异不大。说明在山地防护林建设中,营造针阔叶混交林,使其形成复层林,并保护好灌木草本层和死地被物层,对增强森林的调蓄能力具有重要的意义。     

Relationships between insect diversity and habitat characteristics in plantation forests

A methodological approach to the identification of biodiversity indicators in commercial forest stands is illustrated by analysis of the relationships between syrphid (hoverflies) and carabid (ground beetles) community composition and diversity, and stand structure and field layer vegetation. Data were collected from 12 commercial forest sites encompassing a range of climatic conditions and different crop types (Scots pine, Sitka spruce, Norway spruce and Corsican pine) across the UK. Comparisons were also made between unmanaged semi-natural Scots pine woods and Scots pine plantations. For both syrphids and carabids, no differences in species richness and diversity were recorded between semi-natural stands and plantations; one rare syrphid considered to be restricted to semi-natural pine stands was also found in spruce. Syrphid species diversity and richness was higher in southern spruce sites than in the northern sites. Northern sites had distinctive carabid communities, as did sites in the New Forest, a large ancient woodland in southern England. Of the measured habitat variables, vertical stand structure showed the best correlation with species richness and diversity of both carabids and syrphids. Richness and diversity were less in stands with high vertical cover values for canopy layers. Stands with higher field layer cover supported greater syrphid diversity, but lower carabid diversity. Measures of stand structure could be used as potential indicators of syrphid and carabid diversity, but additional habitat parameters also need to be tested.     

Plant species cover,frequency, and biomass: Early responses to clearcutting,burning, windrowing,discing, and bedding in Pinus elliottii flatwoods

Pinelands in a 49 ha naturally-regenerated, mature flatwoods forest in north Florida were clearcut harvested in the fall of 1978, site prepared by burning, shearing and piling, discing, and bedding, and planted to slash pine (Pinus elliottii) in 1979. Three vegetation surveys were conducted: one prior to harvest in the summers of 1977 and 1978, and two subsequent to planting in the summers of 1980 and 1981.Cover and frequency of all plant species encountered were assessed on permanent transects. Foliage biomass by species was assessed by destructive sampling of distinct subplots within permanent plots. The aim was to assess plant species cover, frequency, and biomass responses to the forest operations imposed.Pine was eliminated as a dominant genus by harvesting. Planted pines were a fast increasing, but not dominant, component of the vegetation at 2 years of age. Previously dominant shrubs were severely reduced — often by approximately two orders of magnitude. Indeed, woody species were severely reduced: woody cover from 151 to 12% of surface area at plantation age 2 years; woody biomass from 6223 to 521 kg/ha.Conversely, herbaceous species were substantially increased: herbaceous cover from 38 to 51% of surface area at 2 years; herbaceous biomass from 382 to 1439 kg/ha. Thus, a predominantly woody ecosystem was converted to a predominantly herbaceous one for 2 years following planting.There was little change in plant species richness as a result of forest operations. Plant diversity changes were mixed the 1st year but diversity substantially increased the 2nd year. Comparisons with a companion study (Conde et al., 1983) suggest that, while increases in diversity following maximum site preparation may lag increases following minimum site preparation, cover, frequency, and biomass diversity all converge to common values after 2 years despite disparity in treatments.     

Impacts of economic reforms on rural forestry in China

This paper addresses the effects of economic transition policies on forestry in China. The effects of de-collectivization and market liberalization on the forest land area and timber harvest are studied using panel data from four provinces covering the period 1978–1995. Fixed effects ordinary least squares models for forest land cover and annual harvests per hectare are estimated, allowing for differences across provinces and prefectures in northern and southern China. The results show that land tenure reform in general has had a positive effect on forest land expansion, but the absolute size of the effects varies from province to province. The positive impact of the reform on timber harvesting has not taken place at the cost of forest land cover. The claim that market liberalization leads to over-harvesting of forest resources in developing countries is not supported by our results.     

不同天然林分对灌木植物多样性的影响

在黑河市平山林场选取环境条件(如坡度、坡向、郁闭度等)相似的阔叶混交林、落叶松阔叶林、红松阔叶林3种森林群落类型样地灌木进行分析的结果表明,红松阔叶林的Gleason指数、Shannon-Wiener指数、Simpson指数都较大,其物种丰富度和多样性均较高;毛榛子为各林分类型下灌木层的主要物种。     

The Impact of Hardwood Line-Planting on Tree and Amphibian Diversity in a Secondary Subtropical Wet Forest of Southeast Puerto Rico

The impact on tree and amphibian diversity of line-planting of tropical hardwoods—mahogany (Swietenia macrophylla × S. mahagoni) and mahoe (Hibiscus elatus)—was studied in a secondary subtropical wet forest of Puerto Rico. Common coqui (Eleutherodactylus coqui) and melodious coqui (E. wightmanae) are the most frequent frog species; forest coqui (E. portoricensis) is less abundant. Although relative abundance means were slightly greater in the undisturbed forest and during the wet season, differences were not statistically significant suggesting that line-planting did not significantly affect amphibian diversity. The line-planted areas had a slightly higher, but not statistically significant diversity, richness, and evenness of tree species than the unplanted forest. Multi-response permutation procedure (MRPP) showed statistically significant community composition differences between line-planting and control plot trees (T = ?5.89, A = .86; p < .001). But mean similarity among plots in both the line-planted and control plots was relatively low at less than 50% of shared species, indicating high diversity of vegetation in the overall forest area. Canopy cover by tree species greater than 3 cm in dbh was much higher in the undisturbed forest but this difference may be reduced as the young line-planted hardwoods mature. Forest enrichment through line-planting of valuable timber species in secondary subtropical wet forest does not significantly affect tree diversity.     

Simultaneous prediction of the development of loblolly pine and woody competitors in young plantations

A system for examining the effects of hardwood density and cover of herbaceous components on mean size in newly established loblolly pine plantations was developed using a site preparation study located in the piedmont province of Georgia (USA). Multispecies density models were derived to predict the sum of crown heights for eight important hardwood species using both the current or age 1 number of rootstocks and herbaceous vegetation to account for intra- and interspecific effects. The predicted sums of crown heights for the woody species were then used as predictors of mean height, diameter, and volume for loblolly pine. A seemingly unrelated regression procedure was used to compensate for correlations in error components within each system of equations that result from using predicted crown heights as regressor variables. The effects of varying sweetgum density and andropogon cover on the inter-related components of the systems based on current and age 1 competition were examined for mean height and mean diameter of the planted loblolly pines. The cumulative impacts of associated vegetation on loblolly pine growth and the relative sensitivity of height and diameter to competing vegetation were demonstrated.     

辽东山区不同森林类型土壤改良效益分析

辽宁东部山区是辽宁省浑河、太子河等主要河流的发源地和集水区,为辽宁省中南部工农业生产和人民生活用水提供保障。通过对该地区柞树林、杂木林、落叶松林、红松林、油松林等5种主要森林类型的林下枯落物层积累、土壤的物理化学性质等方面进行比较分析,研究结果表明:阔叶林在土壤改良、涵养水源方面较针叶林好,因此,在辽东山区营林时应多营建阔叶林或针阔混交林。     

亚热带几种森林类型下土壤的理化性质

在福建省邵武市卫闽林场，在本底条件一致的同龄杉木林、马尾松林、天然阔叶林及杉阔混交林林下土壤进行了野外调查和室内分析，结果表明，土壤容量重为天然阔叶林〈杉阔混交林〈马尾松林〈杉木林；总孔隙度和最大含水量为天然阔叶林〉杉阔混交林〉杉木林〉马尾松林；〈０．００１细微颗粒百分含量为阔叶林〈杉阔混交林〈杉木林〈马尾林；土壤ＰＨ伙阔叶林〉杉阔混交林〉马尾松林〉杉木林，速效Ｐ，速率Ｋ，全Ｎ和有机质含量均为阔叶     

Yellow pine regeneration as a function of fire severity and post-burn stand structure in the southern Appalachian Mountains

We used pre- and post-burn fire effects data from six prescribed burns to examine post-burn threshold effects of stand structure (understory density, overstory density, shrub cover, duff depth, and total fuel load) on the regeneration of yellow pine (Pinus subgenus Diploxylon) seedlings and cover of herbaceous vegetation in six prescribed-fire management units located within western Great Smoky Mountains National Park (GSMNP) in east Tennessee, USA. We also evaluated the utility of the Keetch-Byram Drought Index (KBDI) as a predictor of post-burn stand and fuel conditions by comparing post-burn stand variables for different ranges of KBDI (23-78; more wet, and 328-368; more dry). We found that yellow pine seedlings were effectively absent in post-burn forests until overstory density was reduced over 40%, understory density was reduced over 80%, and post-burn shrub cover was 10% or less. We also observed that a reduction in total fuels of 60% and a post-burn duff layer depth of less than four cm were required for successful regeneration of yellow pine. Total herbaceous species cover exhibited near identical responses with increased cover following an 80% reduction in understory density and a post-burn duff depth of less than 4 cm. We observed strong positive relationships between high KBDI values and burn severity, changes in forest structure, reductions in fuels, and post-burn yellow pine reproduction. We observed continuous recruitment of yellow pine seedlings 5 years after fire in high KBDI burns while low KBDI burns showed little change in yellow pine density through time. An intense outbreak of the southern pine beetle (SPB; Dendroctonus frontalis) occurred within 2 years of our high KBDI burns and reduced shading resulting from overstory mortality likely enhanced the survival of yellow pine seedlings. The results of this study provide targets for the application of prescribed fire to restore yellow pine in the southern Appalachians. Continued research and monitoring will help determine how prescribed fire can best be applied in combination with other disturbance agents such as SPB to perpetuate yellow pine forests.