Effects of area and isolation of woodland patches on herbaceous plant species richness across Great Britain

Richness of Ancient Woodland Indicator plant species was analysed in 308 woodland patches that were surveyed during the Countryside Survey of Great Britain carried out in 1998. The Countryside Survey recorded vegetation plots and landscape structure in 569 stratified 1 km sample squares and developed a remotely-sensed land cover map of the UK. Using these datasets, we tested the hypothesis that Ancient Woodland Indicator species richness in woodland fragments was limited by patch area, shape and spatial isolation and that woodland patches located in the lowland region of Great Britain would respond differently than those in the upland region. The variation in Ancient Woodland Indicator species richness in the British lowlands (n = 218) was mainly explained by patch area and two measures of connectivity, the length of hedgerows and lines of trees in the 1 km square and the area of woodland within 500 m of the vegetation plot. By contrast, variation in Ancient Woodland Indicator species richness in the British uplands (n = 90) was related to Ellenberg scores of the vegetation communities sampled – a surrogate for habitat quality – and no significant effect of spatial structure was detected. It therefore appears that the degree of fragmentation of woodland in the British lowlands limits the distribution of Ancient Woodland Indicator species, while in the uplands, failed colonisation is a matter of habitat quality rather than a result of landscape structure.This revised version was published online in May 2005 with corrections to the Cover Date.     

Assessing the sustainability of cropping systems in single- and multi-site studies. A review of methods

The multiple new challenges facing agriculture require the development of innovative cropping systems with high environmental, economic and social performances. Many research programmes are currently focusing on the design of such cropping systems. Some include the multicriteria assessment of cropping systems by diverse methods and approaches. Some of these research programmes are supported by experimental or farmers’ networks, generating new opportunities for data analysis and raising new research and methodological questions. In this article, we provide an overview based on a review of 56 articles, comparing the various methods for sustainability assessment in single- and multi-site studies. Articles were classified according to three characteristics: (i) their objectives, (ii) the study design (single- vs. multi-site), (iii) the type of system assessed (fictitious vs. real). Our analysis was structured around four items: (i) the variables used to describe cropping systems and production situations and the use of these variables in the assessment process, (ii) the criteria and associated indicators assessed, (iii) the methods used to explore multiple aspects of the performance of cropping systems, (iv) the use of reference values. We identified key points to be taken into account in multi-site studies. The application of the proposed guidelines to experimental networks should facilitate the identification of high-performance cropping systems and the identification of the drivers of cropping system performance.     

Habitat fragmentation in an urban environment: large and small fragments support different arthropod assemblages

We investigated the effects of fragmentation due to urbanisation on the species composition and functional roles of ants, beetles, spiders, flies and wasps. The study was conducted in 21 fragments of heath and woodland in south-eastern Australia classed as either ‘small’ (? 4 km²) or ‘large’ (? 80 km²). Arthropods were pitfall-trapped and identified to family or genus and morphospecies and microhabitat characteristics were recorded. Large fragments did not support more species per unit area than small fragments for most arthropods, although there were more species of ants per sampling unit in small than large woodland fragments, mainly due to a higher frequency of generalist species in smaller fragments. Large and small habitat fragments contained different assemblages of spiders, wasps and ants, indicating that predators and parasitoids are affected more strongly than other trophic groups. Arthropod assemblages within larger fragments where grids were furthest apart were less similar than those within smaller fragments where grids were closer together in woodland, but not in heath. The responses of arthropods to fragmentation suggest that, in addition to effects of reduced area and proximity to the urban matrix, changes in fire regimes and the degradation of habitats resulting from urbanisation, may have a role in altering arthropod assemblages, particularly affecting those species belonging to higher trophic levels. Management goals for urban remnants should identify mechanisms for controlling fire and anthropogenic disturbance such that they closely resemble the levels of these factors in larger fragments.     

区域土地资源可持续利用评价指标体系的研究

从土地利用系统的角度,分析土地资源可持续利用的标准.构建了区域土地资源可持续利用指标体系的基本框架,其指标体系包括目标层、准则层、分目标层、指标层4个层次,并对各指标层进行说明。     

绥中干旱分析

利用绥中县1956-2012年气象资料,采用统计分析方法,对近57年绥中的干旱状况进行分析,并对此提出了相应的防御对策。结果表明,在57年中,绥中共发生春旱27年,严重春旱15年;共发生伏旱30年,严重伏旱21年;共发生秋吊19年,严重秋吊12年;共发生春夏连旱14年,伏秋连旱13年,春旱、伏旱和秋吊同时出现的三季连旱8年。     

Bryophytes as potential indicators of forest integrity

Forest integrity has been proposed as one conservation endpoint that integrates desirable characteristics such as natural biodiversity, stand structure and continuity. Although its defining criteria are still under discussion, any surrogates must effectively represent or predict their status, and be easier to measure than the criteria themselves. Bryophytes have been proposed as such surrogates, because they are important components of forest integrity, and considerable research indicates that some groups are sensitive to the changes associated with specific forest management regimes. The objectives of this paper are (1) to review the issues in determining indicators of forest integrity, including desirable qualities in such indicators, (2) to review the state of knowledge concerning bryophytes as components of forest integrity (i.e. their responses to forest management practices), and (3) to assess bryophytes as potential indicators of forest integrity, in terms of both qualities desirable in indicators and our understanding of bryophyte response patterns. Although bryophytes possess some characteristics that suggest potential indicator value, many challenges prevent their reliable application. I highlight key areas in which research is required to identify operational bryophyte indicators of forest integrity. Along with a standardized protocol to select and calibrate such indicators, we urgently require strategic research to compile data on undisturbed reference forests on which to base selection of endpoints; species-specific ecological tolerances, with consideration of complex interactions; mechanisms of response to disturbance, with consideration of temporal aspects; population viability thresholds; and recruitment effects on community assembly. Whether we succeed in finding bryophyte indicators of forest integrity, this research would also provide the data to monitor and interpret the integrity of the bryophyte community.     

Root parameters of forest trees as sensitive indicators of acidifying pollutants: a review of research of Japanese forest trees

The root parameters of forest trees can be indicators of a changing environment. We summarize the results of root studies with regard to the effects of acidifying pollutants, especially soil acidification and aluminum toxicity, on various root parameters of Japanese forest trees under experimentally controlled conditions. All root parameters such as biomass, morphology, nutritional status, and physiology can be regarded as indicators, because, under laboratory conditions, root responses occur prior to the responses in the aboveground parts. However, considering the conditions of forest sites, the nutritional status and physiological changes are better indicators of soil acidification and Al stress than the biomass and morphological response. The currently available data suggest that the most important indicator is the Ca/Al molar ratio in roots of Japanese tree species. In order to predict and detect the initial effects of soil acidification, we postulate that the specific root response to the Ca/Al molar ratio of tree roots should be considered as a parameter for use in long-term forest monitoring sites.     

Exploring the limitations of pathophysiological indicators used for targeted selective treatment in sheep experimentally infected with Haemonchus contortus

Identifying which sheep to treat as part of a Targeted Selective Treatment approach to gastro-intestinal nematode control relies entirely on the efficacy of the indicators. Indicators such as FAMACHA© (anaemia), DISCO (diarrhea) and reductions in weight gains were designed specifically to reflect those sheep experiencing symptomatic consequences of infection. Using the gastro-intestinal nematode Haemonchus contortus as a model species, this study explored the utility and sensitivity of these indicators under controlled experimental conditions on 63 adult sheep. The potential effect of sheep with different H. contortus resistance phenotypes on indicator efficacy was compared in three different phenotypes, i.e. high (Blackbelly females), medium (Blackbelly rams) and low resistance (Romane rams). The potential effect of the H. contortus isolate on indicator efficacy was also explored by using four different isolates, with varying anthelmintic resistance capacities, to infect the sheep. We limited the study to the first month of infection to evaluate the interest of these indicators as an early predictive means for controlling infection. The pathophysiological indicators FAMACHA© and DISCO do not reflect infection intensity based on Faecal Egg Counts, nor do reductions in weight gains. FAMACHA© was however a good indicator of anaemia with strong correlations to haematocrit. There was little agreement among the three indicators to identify the same animals in need of treatment and even combining them did not increase their predictive value of infection intensity or relative host damage from infection. The indicator sensitivity was influenced by the H. contortus isolate and sheep resistance phenotype in which they were tested. One isolate was poorly infective but induced high levels of anaemia (FAMACHA©) and diarrhea (DISCO) compared to the three others. The FAMACHA© and DISCO had higher values in the sheep group with a medium resistance phenotype (Blackbelly rams) indicating higher levels of damage compared to the high and low resistance phenotypes. We conclude that there is no ‘one size fits all’ approach to the use of indicators for Targeted Selective Treatment and the indicators should be calibrated to farm-specific conditions to increase their efficacy.     

Bark beetle community structure under four ponderosa pine forest stand conditions in northern Arizona

We studied the bark beetle guild (Coleoptera: Scolytidae) in the ponderosa pine forests of northern Arizona to explore if the species assemblages and relative abundance differ between managed and unmanaged stands. Four stand conditions were assessed: (1) unmanaged stands with high tree density, (2) thinned stands, (3) thinned and burned (with prescribed fire) stands and (4) stands that had been burned by stand replacing wildfires. The study was conducted in the ponderosa pine forests of the Coconino Plateau, northern Arizona. For several decades this area has been relatively free of bark beetle outbreaks despite the current overstocked condition of many stands. We found that a similar species assemblage composed of Dendroctonus frontalis, D. brevicomis, D. valens, D. approximatus, D. ponderosae, and Ips pini occurred across all four stand conditions over 3 years of study. The population levels of all these species were endemic across all stand conditions. The non-aggressive D. approximatus and D. valens were indicator species for thinned and unmanaged stands, respectively, but this was not consistent among years. The ambrosia beetle Gnathotrichus sp. and the bark beetle predator Enoclerus sp. consistently indicated stands burned by wildfire. In addition to our field experiment, we analyzed the historical pattern of attacks of bark beetles in our area of study. Our findings suggest that the pattern of attack of D. brevicomis (the only Dendroctonus species for which attacks have been reported) and Ips spp. has been through scattered small infestations in groups of 1–10 trees. Whereas small infestations by Ips spp. are increasing, those for D. brevicomis are decreasing. Although we agree that the high density stands in northern Arizona are in an “unhealthy” condition, our results do not show that they were supporting large bark beetle outbreaks. Our results challenge the theoretical assumptions about the relationship between stand structure, tree resistance and bark beetle performance.     

The impact of mowing as a management strategy for wet meadows on spider (Araneae) communities

Meadows are often managed by mowing to prevent succession and brushwood encroachment. This management practice is efficient to maintain plant diversity, but the effect on arthropod groups is less well known. We sampled spiders in the Grande Cariçaie (Switzerland), a site of nature conservation importance, in two types of wet meadows, an unmanaged site and one 2-years-old mown conditions. Numbers of individuals for the most abundant families, diversity measures, and indicator taxa were compared among vegetation and treatment types. The results indicate that the less mobile spiders and species linked to litter or dead reeds, including rare species, are reduced by mowing. Present management consists in triennial mowing of 2-4 ha non-contiguous sectors. We investigate the conflict between the need to mow the meadows to maintain them, and the negative effect of mowing on spider communities. We therefore propose a new management scheme aimed at maintain the vegetation while lessening its negative effects on spider communities by providing refuges.