Are higher taxa adequate surrogates for species-level assemblage patterns and species richness in stream organisms?

We examined the utility of using genera and families as surrogates of species-level assemblage patterns. We assessed cross-taxonomic level congruence, as well as taxonomic structure-environment and taxon richness-environment relationships in stream macroinvertebrate and diatom data surveyed across Finland. A number of interesting and important findings emerged from our analyses. For both macroinvertebrates and diatoms, species richness was strongly correlated with genus and family richness, and similarities in assemblage structure between species-, genus- and family-level matrices were also significant and relatively strong. For macroinvertebrates, the key environmental variables for assemblage structure and taxon richness remained the same irrespective of taxonomic level. For diatoms, however, the environmental variables related to variation in diatom taxon richness varied between taxonomic data sets, while determinants of assemblage structure remained largely the same. For macroinvertebrates, relatively similar amounts of variation in assemblage structure and taxon richness for species-, genus-, and family-level data were accounted for by the environmental variables, shared environmental and spatial variables, spatial variables, and total variation explained. By contrast, for diatoms, these components of variability differed somewhat between taxonomic levels. Our results suggest that, for macroinvertebrates, even family-level data could be used in rapid biodiversity assessments, where the objective is to examine biodiversity patterns and rank sites according to their conservation value in our study region. Families might also perform well in this task in other regions that are characterized by low faunal species diversity, but the situation is likely to be different for regions with higher species diversity. Although weaker than the relationships in macroinvertebrate data, species-level data for diatoms also showed rather similar patterns to genus- and family-level data. However, due to the low number of diatom families, it is likely that families do not provide enough variability in biodiversity patterns. Thus, for diatoms, genus-level data could perhaps be more efficient than family-level data in correlating with species-level data and portraying assemblage patterns for conservation purposes.     

Long-term recovery of stream habitat structure and benthic invertebrate communities from in-stream restoration

Headwater streams channelized for water transport of timber in Finland are being restored to their pre-channelization state. The primary motivation is the enhancement of sport fisheries, but restoration probably has profound impacts also on other stream organisms. We assessed how such “single-goal” restorations affect benthic macroinvertebrate communities. We revisited the streams sampled by Laasonen et al. [Aquatic Conservation: Marine and Freshwater Ecosystems 8 (1998)] in the early 1990s when the streams had been recently restored. In 1997, the recovery period of these streams ranged from 4 to 8 years. Habitat structure among the stream types represented a distinct recovery gradient, with streams restored 1 month before sampling and natural streams being the endpoints of a gradient in moss cover (highest in natural, lowest in recently restored streams). Channelized streams supported a characteristic set of indicator species, whereas shifts in species composition between restored and natural streams were more gradual. Macroinvertebrate communities in unmodified streams changed little between the two surveys, whereas communities in restored streams had undergone considerable changes. In-stream restoration is an unpredictable disturbance, to which stream biota cannot have any evolved responses. Therefore, the relatively rapid recovery of habitat structure and macroinvertebrate communities in restored streams is encouraging. However, long-term monitoring of benthic communities in both restored and natural streams is needed to assess whether restoring rivers by these techniques will enhance the recovery of benthic biodiversity in boreal streams.     

Long-term response of spring flora to chronic herbivory and deer exclusion in Great Smoky Mountains National Park, USA

Chronic herbivory by white-tailed deer (Odocoileus virginianus Zimmerman) can have profound impacts on the function and structure of forest ecosystems. We examined the combined influence of intense herbivory associated with a deer population eruption and chronic herbivory by the post eruption population on the spring flora of Cades Cove, Great Smoky Mountains National Park. During the 1970s the deer population reached a peak of 43 deer per km², from which it has slowly declined in recent decades. To examine the influence of intense herbivory, we compared the abundance and flowering rates of early flowering plants in Cades Cove to a nearby reference site with similar bedrock geology, vegetation, and disturbance history but contrasting history of deer abundance. Our results suggest that significant changes (p ? 0.05) in the diversity, evenness, and species richness of the spring flora occurred during the eruptive phase. Trillium spp. and other liliaceous species appeared to be disproportionately impacted. Comparisons between control and exclosure plots established after the deer population eruption indicate that recovery has been largely restricted to species that were able to persist under intense herbivory. These species have increased in number in exclosures, suggesting continued impacts by deer on the plant community outside the exclosures. Little to no recolonization by browse sensitive species was observed. Consequently, to restore the natural diversity of early flowering plants once present in Cades Cove, active restoration may be necessary in addition to maintaining deer densities below current levels.     

Estimating Fine-Root Production and Mortality in the Biomass Plantations

Loblolly pine (Pinus taeda L.), silver maple (Acer saccharinum L.), and cottonwood (Populus deltoides Bartr.) are short-rotation woody crops with potential use for biomass plantations. The study of fine-root production and mortality in these intensively managed crops is important to understand carbon and nutrient cycling in these systems. We used minirhizotrons to measure monthly fine-root production and mortality of each species in a biomass plantation during the second growing season in Collins, Arkansas, USA. Images were taken and digitized on a monthly basis from March 2008 to February 2009 to calculate volumes and were converted into dry-weight biomass. Data analysis showed that net fine-root production varied among the species and the time of year. Loblolly pine had significantly greater net fine-root production and mortality than others. Overall fine-root production was greatest during fall months, whereas fine-root mortality showed no seasonal difference.     

Restoration of a multi-species seabird colony

Nesting herring and great black-backed gulls (Larus argentatus and Larus marinus) were removed from a recently abandoned tern (Sterna sp.) colony through a combination of poisoning and shooting. Following gull control, all three species of tern that had nested in the colony prior to the arrival of the gulls returned and nested in increasing numbers. In addition to the restoration of the terns, removal of the gulls led to colonization and/or significant increases in populations of four other seabirds. Gull numbers were greatly reduced by initial poisoning efforts, but continued immigration from surrounding colonies has required an on-going program of shooting to eliminate territorial birds nesting in areas utilized by terns and other species. In situations calling for active management we advocate rapid, focused intervention, and stress the importance of inter-organizational cooperation, and an active program of public education.     

Quantifying plant species diversity in a Natura 2000 network: Old ideas and new proposals

Assessing the effects of the spatial components on species diversity in a network of protected areas represents an important step for assessing its conservation “capacity”. A clear evaluation on how α-, β-, and γ-diversity are partitioned among and within spatial scales can help to drive manager decisions and provide method for monitoring species diversity. Moving from these concepts, a probabilistic sample of plant species composition was here applied for quantifying plant species diversity within the Sites of Community Importance (SCIs) of the Natura 2000 network in the Siena Province. All analyses were performed separately for all species and those species defined as “focal” (included in regional, national or continental “red” lists). The results indicated that species richness of the SCIs differed from one location to another one independently from the sampling efforts. Diversity partitioning indicated that most of the flora diversity within the network was given by larger-scale β-diversity, i.e. the differences in species composition among SCIs. β-diversity was then decomposed in two components: β_Area (due to the differences in area among SCIs) and β_Replacement (due to the compositional differences across SCIs). β_Area was particularly important for all species, while β_Replacement was the most important factor for focal species. The consequent implications for monitoring and nature conservation strategies are discussed.     

Net ecosystem exchange, evapotranspiration and canopy conductance in a riparian forest

The ecosystem fluxes of mass and energy were quantified for a riparian cottonwood (Populus fremontii S. Watson) stand, and the daily and seasonal courses of evapotranspiration, CO₂ flux, and canopy conductance were described, using eddy covariance. The ecosystem-level evapotranspiration results are consistent with those of other riparian studies; high vapor pressure deficit and increased groundwater depth resulted in reduced canopy conductance, and the annual cumulative evapotranspiration of 1095 mm was more than double the magnitude of precipitation. In addition, the cottonwood forest was a strong sink of CO₂, absorbing 310 g C m⁻² from the atmosphere in the first 365 days of the study. On weekly to annual time scales, hydrology was strongly linked with the net atmosphere-ecosystem exchange of CO₂, with ecosystem productivity greatest when groundwater depth was ∼2 m below the ground surface. Increases in groundwater depth beyond the depth of 2 m corresponded with decreased CO₂ uptake and evapotranspiration. Saturated soils caused by flooding and shallow groundwater depths also resulted in reduced ecosystem fluxes of CO₂ and water.     

Gene flow after inbreeding leads to higher survival in deer mice

We test the ability of gene flow to alleviate the deleterious effects of inbreeding in a small mammal, the deer mouse (Peromyscus maniculatus). After three generations of sib-sib mating, individuals from three lines of mice were either subject to further inbreeding or were mated with an outbred individual. Subsequently, these mice, plus a control line, which were first generation (F₁) mice from unrelated individuals kept in captivity for the same duration as the treatment lines, were released into isolated pens in a forest in western Montana. Survival of individual mice was recorded. Survival models that allowed variation in breeding treatments were well supported, whereas models explaining variation in line, or release location were not well supported. Survival was highest for offspring of the outcross group, intermediate for the inbred animals, and lowest for the control group. This suggests that the introduction of migrants can reduce inbreeding depression, as theory predicts. We also show limited evidence for purging of deleterious recessive alleles that can cause inbreeding depression. While purging may have occurred, the demographic cost was non-trivial as 5 of 8 of our inbred mouse lines went extinct during the inbreeding process.     

Endangered economic species of Indian desert

The economically important, naturally occurring species of the Indian desert was surveyed on the basis of the perception of local plant scientists. About one-fourth of the total 84 taxa were seen to be facing varying stages of risk. Of these, 17 species and 8 botanical varieties are endemic to Indian desert. Eighteen species in Bikaner, 21 in Jaisalmer and 19 in Jodhpur divisions were reported to be at risk. Factors responsible for the loss of species diversity have been discussed and appropriate strategies have been suggested for their conservation.     

Managing predation on ground-nesting birds: The effectiveness of nest exclosures

Ground-nesting birds have declined world-wide, probably partly due to high nest predation. A non-lethal method for decreasing predation uses protective cages at nests. Tests have mainly looked at the effect of such nest exclosures on hatching success and adult predation, but several additional aspects need to be explored for a comprehensive evaluation of this conservation technique. Here, we test the effect of nest exclosures in two common European shorebirds: northern lapwing (Vanellus vanellus) and redshank (Tringa totanus), measuring hatching success, incubation length, hatching synchrony, hatchability, partial clutch loss, chick condition, and adult predation. In both species, protected nests had higher hatching success than unprotected nests. Taking into account incubation time, nest abandonment, hatchability and partial clutch loss, protected nests still hatched more young than unprotected controls. In lapwings, but not in redshanks, protected nests were incubated longer, but this did not impair the condition of lapwing chicks. Protected redshanks suffered increased predation on incubating adults, which often sit on the nest until a predator is close by. Our results emphasize the need for caution in the use of nest exclosures, particularly in redshanks and other species with similar incubation behaviour. Exclosures can, however, be a useful management tool in shorebirds that leave their nest early, when an approaching predator is still far away.     

Observed and modelled distributions of channel and gully heads—with examples from SE Spain and Belgium

In soil erosion by overland flow, sediment discharge is driven by discharge and gradient against the resistance of the soil and vegetation. The form of the relationship, which is taken as a sum of power law terms, may then be inferred from several data sources: (1) ephemeral gully head location, (2) permanent channel head location, (3) slope profile form, (4) consistency with evolutionary models and (5) erosion plot data. The paper focuses on (1) to (4), in order to understand how far these data constrain the form of the dependence on discharge and gradient. Field data from mapping a set of ephemeral gully heads after storms show a weak inverse relationship between channel head gradient and catchment area, which flattens towards an upper threshold gradient of about 25%. These relationships are compared with those theoretically obtained for a range of sediment transport laws which have been previously used, and which are analysed to forecast both overall slope profile form and the location of stream heads. The theory predicts that the location of ephemeral gully heads produced in a single storm will differ from the long-term average stream head location. There is a fairly good relationship between theoretical and observed locations, associated with the form of the sediment transport law. For a single event, the location depends on storm magnitude which cannot be well defined from the data sets, creating a spread of data with an envelope curve defined for the largest events. The empirically acceptable sediment transport equations have also been used to analyse families of slope profiles in a small area, and used within a landscape evolution model to generate landscapes which are compatible with those observed in the field, and provide confirmation of the long-term viability of the expressions obtained to forecast the direction, style and rates of landscape evolution in response to land use or climate drivers.     

云南彝族农户庭园系统生物多样性研究——以云南省武定县永兆村为例

对云南省武定县永兆村彝族农户庭园生物多样性系统研究发现,该村农户庭园中生物种类109种,其中蔬菜占33.0％,经济林果占21.1％,饲养动物占14.7％,且随历史的变化其生物种类而变化;不同生物种类在农户庭园中出现的频率不同,出现频率在90％以上的有13种;农户庭园中生物品种为1-7个,物种丰富度为3.21-7.67,且随庭园结构层次的增加其物种丰富度指数也相应增大。     

Diversity of heterotrophic aerobic cultivable microbial communities of soils treated with fumigants and dynamics of metabolic, microbial, and mineralization quotients

A combination of molecular and classical techniques was used to study the composition, structure, diversity, and dynamics of an aerobic heterotrophic cultivable bacterial community isolated from five different soil samples treated with the fumigant agent 1,3-dichloropropene (1,3-D) and further subjected to nitrogen–phosphorous–potassium (NPK) fertigation (F), amendment (C ₂ and C ₄), and NPK fertigation plus amendment (F + C) in two different periods (May and July). The restriction and sequence analysis of 16S rDNA from 189 isolates revealed a very high percentage (94%) of Gram-positive bacterial isolates, most of which (83%) belonging to the genus Bacillus. The degree of intraspecific genetic diversity was high, as shown by random amplified polymorphic DNA analysis. These data seem to be related with the increase in microbial biomass C (C _mic) content and the decrease in the total organic C (C _org) and metabolic quotient (qCO₂) values, especially in amended soils (C ₂, C ₄) where soil microflora mineralized the organic matter of the added fertilizers. In a short term, it is suggested that the presence of very high percentage of Gram-positive bacteria might be related to the ability of these bacteria to form spores so as to be resistant to fumigants rather than being the result of a selective pressure in the predominance of microbial species with a set of genes involved in biodegradation of 1,3-D. Stefano Mocali and Donatella Paffetti contributed equally to this work.     

生物多样性与生态农业

根据数十年在云南所做的试验以及目前国际研究动态,阐述了生物多样性与生态农业之间的关系,生物多样性与农业生态系统的诸多功能如生产力、稳定性及病虫害发生等有密切的关系,故生物多样性对生态农业及农业可持续发展具有极其重要的意义。     

泉州市生物多样性保护工程建设对策

简述了福建省泉州市独特的地理气候特征及丰富的生物多样性资源,泉州市建设生物多样性总体目标及“九五”规划和保护工程建设现状,并提出“十五”期间进一步广泛开展生物多样性保护和野生动植物保护宣传,实施规范管理,扩大保护规模,加强湿地保护和建设,开展科学研究等对策。