Sampling saproxylic beetles: lessons from a 10-year monitoring study     

Petri Martikainen  Lauri Kaila 《Biological conservation》2004,120(2):171-181

We sampled saproxylic beetles using trunk window traps in two birch-dominated forests in Finland during 1990-1999. The sampling scheme, 10 traps attached to living fruiting bodies of Fomes fomentarius growing on dead birches, remained unchanged in both forests throughout the study period. Beetles belonging to 32 selected families were identified every year, whereas all species were identified during the last 4 years. Total number of identified individuals was 40,294 and number of species 583, of which 258 were saproxylic (dependent on dead wood). Species richness of rare and threatened saproxylic beetles in the samples varied a lot between the years and did not fluctuate synchronously between the forests. Variation between years was smaller when all saproxylic species were pooled together and some abundant species fluctuated synchronously in the two forests. Similarity indices and DCA-ordination did not generally suggest decreasing similarity between samples with increasing temporal isolation. Incidence-based similarities of common saproxylic species within and between forests and years were high (means 0.7-0.8), whereas those of rare saproxylics were roughly 50% smaller and much more variable. More than 75% of the common saproxylic species found during the entire 10-year period were detected already after 3 years of sampling but accumulation of rare and threatened species was much slower. Our results suggest that: (1) occurrence of rare and threatened species in samples is much less predictable than that of common species and, e.g. reserve selection based on rarities should be made cautiously; (2) estimation of total number of threatened species in a forest is very difficult, because such species accumulate slowly in the samples; (3) samples from different years can be comparable in certain cases.  相似文献   

Why conservation reserves should not always be concentrated in riparian areas: A study of ground-dwelling beetles in wet eucalypt forest     

Susan C. Baker  Alastair M.M. Richardson 《Biological conservation》2006,133(2):156-168

Reserve corridors in production forestry landscapes are frequently concentrated in riparian areas. This study describes the numerical response of ground-dwelling beetles to increasing distance from streams, with the aim of evaluating the effectiveness of such a bias in reserve allocation. Patterns in abundance and diversity of epigaeic beetles were quantified at four first order streams in wet eucalypt forest in Tasmania, Australia. The depth and pattern of beetles’ riparian response varied between streams. Commonly trapped beetles were less abundant near to three of the four streams, and the numerical response model differed in each case. Species richness of common beetles was also lower near one of the streams. Pooled abundance and richness of rare species did not vary in response to the riparian-upslope transition. No riparian or upslope specialist species were identified among the most commonly collected species. Compared to upslope habitat, the riparian-upslope transition encompassed greater variability in species composition without actually increasing overall richness. The study findings demonstrate the need for ecosystem-specific data to optimize reserve placement, since the results were not predicted from general vegetation patterns, ecological theory, or the widely held assumption that riparian areas support greater abundance and diversity of organisms than adjacent upslope areas. Reserves encompassing more upslope habitat are recommended to complement those located in riparian areas.  相似文献   

Patterns of amphibian diversity in Brazilian Amazonia: conservation implications     

Claudia Azevedo-Ramos  Ulisses Galatti 《Biological conservation》2002,103(1):103-111

A literature survey was conducted to determine the amphibian diversity and distribution in Brazilian Amazonia. Patterns of endemisms and similarity of fauna between localities were also addressed. Twenty-eight inventories were found for the region, the majority localized in areas with easier access by road or river. A minimum of 163 amphibian species was recorded for Brazilian Amazonia. Although many species are endemic to the Amazonian lowlands as an entity, the patterns of species uniqueness among sites suggested low endemic distribution within the lowlands of the Amazon Basin. The mean similarity between localities varied from low to intermediate (mean=0.40), indicating that the Brazilian Amazonia is characterized by distinctive assemblages of amphibians throughout its extension. Localities further apart had lower similarity. No threatened species were recorded. These results contribute to determine priority areas for new inventories and establishment of conservation units. We suggest that areas next to the Amazon deforestation frontier should be prioritized for new studies due to the high rate of alteration and potential loss of species. Additionally, studies on amphibian population dynamics are few in Brazilian Amazonia and more of them should be emphasized to help to draw a better picture of the status of amphibians in this region.  相似文献   

Forest structure, composition, and tree diversity response to a gradient of regeneration harvests in the mid-Cumberland Plateau escarpment region, USA     

Callie Jo Schweitzer  Daniel C. Dey 《Forest Ecology and Management》2011,262(9):1729-1741

Upland hardwood stands on mesic, escarpment-oriented sites on the Cumberland Plateau region of northeastern Alabama provide a myriad management opportunities. Stands are primarily managed for Quercus, but the high species diversity allows for management that targets multiple species. Stand composition is unique in that dominant species include shade tolerant species such as Acer saccharum, intermediate tolerant Quercus spp. and Carya spp., and intolerant Liriodendron tulipifera. Three replications of five levels of disturbance were created to assess species compositional changes; disturbances included three levels of harvest intensity, a mid-story herbicide treatment, and a control. After eight growing seasons, there were no discernable differences in species richness, diversity or evenness. Importance values based on relative basal area and relative density also changed little, except for clearcuts where L. tulipifera greatly increased. An initial gradient in basal area, canopy cover, and light created by harvesting or thinning dissipated following five growing seasons. Options exist for future stand management, including promoting two-aged or uneven-aged systems. Maintenance of Quercus will require additional tending.  相似文献   

Canopy cover and groundlayer vegetation dynamics in a fire managed eastern sand savanna     

Marlin Bowles  Steven ApfelbaumAlan Haney  Susan LehnhardtTom Post 《Forest Ecology and Management》2011,262(11):1972-1982

Savanna vegetation is characterized by high and variable ground layer species richness regulated by functional group interactions with fire regimes and canopy cover. Frequent fire selects for C4 grasses and prairie forbs in canopy openings and C3 graminoid species and shade-adapted forbs and shrubs in canopy shade. Frequent fire also maximizes heterogeneity in partial canopy cover and species richness across the full canopy gradient. However, few studies have linked fire induced change in tree canopy cover with groundlayer vegetation dynamics in relation to this model. In 1986 and in 2007, we measured canopy cover and sampled groundlayer vegetation in 1 m² plots along 53 transects at the Tefft Savanna, a fire managed 197 ha eastern sand savanna with strong canopy cover and elevation gradients. We analyzed temporal change in canopy cover and groundlayer vegetation, correlating percent change in canopy cover with change in ground layer functional groups. After 20 years of burning at 3 fires/decade, elevation accounted for 62% of the variation in an NMS ordination of groundlayer vegetation. However, canopy cover, which averaged 24-86% in 2007, had a significant secondary effect on the ordination. Five vegetation types classified by TWINSPAN varied significantly in elevation and canopy cover. Woody vegetation comprised 8 of the 12 species with greatest niche breadths, and tended to predominant in woodland or forest, where tree cover averaged 50% or more. Forbs had greater richness in savanna, which averaged less than 30% canopy cover. The C3 sedge Carex pensylvanica was the dominant graminoid species under woodland canopy cover, and was co-dominant with the C4 grasses Andropogon scoparius and Sorghastrum nutans under savanna canopy cover. As in other savannas, N-fixing species sorted across shade and canopy openings, and heterogeneity among transects was maximized at mid-canopy cover. Over time, canopy cover decreased up to 50%, creating more open savanna conditions at mid to high elevations. This decrease was associated with a 20-100 % increase in species richness and was significantly correlated with increasing richness and cover of C4 grasses and summer flowering prairie and woodland forbs. These results support a canopy cover model of fire-maintained savanna vegetation, with greater abundance of C4 grasses and prairie forb species associated with lower canopy cover, greater heterogeneity at mid-canopy cover, and species richness maximized across the light gradient. They also indicate that decreasing canopy cover caused by repeated burning increases species richness and abundance of C4 and prairie forb species.  相似文献   

Tree plantations on farms: Evaluating growth and potential for success     

Jefferson S. Hall  Brian E. Love  Eva J. GarenJacob L. Slusser  Kristin SaltonstallShane Mathias  Michiel van BreugelDiogenes Ibarra  Edward W. BorkDean Spaner  Mark H. WishnieMark S. Ashton 《Forest Ecology and Management》2011,261(10):1675-1683

Interest in native species is growing across the tropics as reforestation of degraded lands becomes more widespread. In this study four tree species native to Panama - Cedrela odorata, Pachira quinata, Samanea saman, and Tabebuia rosea - were grown on rural farms at two dry tropical sites in Panama for up to five years. Survivorship and growth data at these “on-farm” trials are compared to data recorded from nearby experimental or “species selection” trial sites and evaluated in terms of soil fertility and management. Participant farmers were also asked about their interest in planting trees in general as well as their interest in 61 species grown in the species selection trial.Although, on-farm survivorship was variable and generally lower than that found on the species selection trial, one species (S. saman) experienced high and consistent survivorship. High survivorship combined with growth data from farms at both sites for this species suggests it would be a good candidate for extension projects working with rural farmers. Survivorship of other species appears more sensitive to farmer management and/or local site conditions. Generally lower growth on the Los Santos farms as compared to the species-selection trial is attributed to the lower soil fertility (plant available P) at the on-farm sites compared to the species selection trial. In contrast, only one species - P. quinata - had a growth variable found to be significantly lower between the on-farm and species selection trial sites in Rio Hato. C. odorata, P. quinata T. rosea can all be used in on-farm conditions with consideration to specific site and management conditions.By 2009, approximately 80% of the farmers planting trees still wished to participate in tree planting activities. All of the farmers no longer wishing to continue with the project expressed slow growth rates of trees as a principal reason. All but one of these farmers had growth rates for his/her trees markedly below those of the species selection trial nearby. Some farmers wishing to continue had very high mortality rates (>70% for all species), suggesting non-tangible benefits for participating in project activities. Other species that were not tested on-farm but grew well in the species-selection trials and were of interest to local farmers are discussed.As long as specific site and management conditions are carefully considered, data from species selection trials can be useful in informing tree planting projects with rural farmers; however, care should be taken to manage expectations.  相似文献   

广东潮州凤凰山次生林物种多样性及群落优势种的研究     

钟小山  徐瑞晶  黄川腾  莫惠芝  曾宪锋  庄雪影 《广东林业科技》2011,27(4):19-26

应用样方调查法,研究分析了广东潮安凤凰山省级自然保护区内2片保护状态较好的次生林群落的植物组成和物种多样性特点.在两个面积为1200 m2的调查样方内,共记录了112种维管植物,隶属于48科77属.次生林优势科为茜草科、山茶科和樟科.乔木层优势种为阿丁枫(Altingia chinensis)、尖叶假蚊母树(Disty...  相似文献   

What is the impact of Impatiens glandulifera on species diversity of invaded riparian vegetation?     

Martin Hejda 《Biological conservation》2006,132(2):143-152

Effect of invasion by Impatiens glandulifera (Balsaminaceae) on the community characteristics and species composition of invaded riparian communities was studied at six rivers in the Czech Republic. Two approaches were used: space for time substitution approach, i.e., comparing invaded and uninvaded sites under the same habitat conditions, and removal of the invader from experimental plots. Differences in the number of species, Shannon diversity index H′ and evennes J were compared between invaded and uninvaded plots. Uninvaded plots of the comparative study harboured by 0.23 more species per 16 m², and had higher value of H′ and J, calculated with species covers as importance values; however only the difference in J was marginally significant (p = 0.04). Other effects were not significant, indicating that once I. glandulifera is removed, communities recover without any consequences for species diversity. Multivariate analysis did not reveal any effect of invasion on the species composition in terms of species presence but their cover hierarchies changed after the invasion, as I. glandulifera became dominant at the expense of tall native nitrophilous dominants. It is concluded that I. glandulifera exerts negligible effect on the characteristics of invaded riparian communities, hence it does not represent threat to the plant diversity of invaded areas. This makes it very different from other Central European invasive aliens of a similar performance.  相似文献   

Effects of grassland abandonment, restoration and management on butterflies and vascular plants     

Erik Öckinger  Anna K. Eriksson  Henrik G. Smith 《Biological conservation》2006,133(3):291-300

When semi-natural pastures are abandoned, specialized grassland species are lost as a consequence of succession. As a counter-measure, previously abandoned grasslands may be restored by clearing shrubs and trees and re-introducing grazing livestock. In order to examine the effects of this type of habitat restoration, we compared species richness of plants and of specialized plants thought to be dependent on continuous management and species richness and abundance of butterflies and red-listed butterflies in 12 sets of matched continuously managed, abandoned and restored grassland in southern Sweden. We found no differences in species richness or abundance between the three grassland types. There were, however, some negative effects of abandonment. The number of management-dependent plants decreased with increasing cover of trees and shrubs, and in restored sites species richness of all groups decreased with increasing cover of trees and shrubs before restoration. Also the present management significantly affected both butterflies and plants. Species richness of both groups increased with increasing vegetation height and differed between sites depending on the species of grazers, with negative effects of sheep compared to cattle or horses. Our study indicates that for grassland management to be efficient, the restoration actions should mainly be directed towards sites where the post-abandonment succession has not proceeded too far.  相似文献   

天然甜槠林物种多样性的研究   总被引：1，自引：0，他引：1  

陈禄春 《亚热带水土保持》2006,18(1):19-21

本文运用物种多样性、物种丰富度、物种均匀度等分析方法对福建省周宁县天然甜槠林的群落组成进行研究。结果表明:甜槠群落物种多样性指数和均匀度值均较大,群落结构复杂、物种丰富。研究结果为保护该地域森林植被提供了理论依据。  相似文献