Pattern analysis in landscape ecology: progress, challenges and outlook

Landscape pattern indices or landscape metrics, an important means in landscape pattern analysis, has resulted in the prosperity of landscape ecology. However, landscape pattern analysis was criticized recently for its poor correlation with ecological processes. In this paper, the current situation and challenges in landscape pattern analysis was elaborated, and the future of landscape pattern analysis was discussed. We believe that the landscape metrics is still the main method in spatial pattern analysis, and is important for landscape ecology. However, there are 3 challenges in landscape pattern analysis: (1) how to develop new methods by integrating explicit ecological sense in landscape pattern analysis? (2) How to link landscape pattern and ecological processes? (3) How to apply the theory of “matrix-patch-corridor” to practice? In future, 5 issues are to be addressed: (1) to develop a methodology to describe landscape pattern in a dynamic manner; (2) to explore the ecological sense of landscape pattern using a series of landscape metrics; (3) to develop new methods for landscape pattern analysis related to ecological processes; (4) to conduct landscape pattern analysis at multi-dimensions; (5) to explain the relationship between landscape pattern and ecological processes by multi-scale pattern analysis.     

Ecosystems patterns and dynamics in Haihe river basin

Research on ecosystems patterns and dynamics is critical for understanding the regional problems of resources and environment. In this study, based on the technology of RS and GIS, the composition, patterns and dynamics of the ecosystems in Haihe river basin during 1990–2005 were analyzed using landscape indices including the area of average patches, aggregation index and Shannon–Weaver diversity index. According to the development situation of economy and society in Haihe river basin, some driving factors for dynamics of ecosystems patterns were concluded based on correlation analysis. Results showed that the ecosystems patterns in Haihe river basin changed greatly from 1990 to 2005. The area of urban and grassland increased, but farmland, forest and wetland decreased. As for landscape indices, the area of average patches, value of aggregation index, clump index and diversity index all increased, indicating the trend of evenness for the whole ecosystems. Growth of population, economy growth together with urbanization and policy were the main driving factors for dynamics of ecosystem pattern in this basin.     

Ecosystems patterns and dynamics in Haihe river basin

Research on ecosystems patterns and dynamics is critical for understanding the regional problems of resources and environment. In this study, based on the technology of RS and GIS, the composition, patterns and dynamics of the ecosystems in Haihe river basin during 1990–2005 were analyzed using landscape indices including the area of average patches, aggregation index and Shannon–Weaver diversity index. According to the development situation of economy and society in Haihe river basin, some driving factors for dynamics of ecosystems patterns were concluded based on correlation analysis. Results showed that the ecosystems patterns in Haihe river basin changed greatly from 1990 to 2005. The area of urban and grassland increased, but farmland, forest and wetland decreased. As for landscape indices, the area of average patches, value of aggregation index, clump index and diversity index all increased, indicating the trend of evenness for the whole ecosystems. Growth of population, economy growth together with urbanization and policy were the main driving factors for dynamics of ecosystem pattern in this basin.     

Changing perspectives on biodiversity conservation: from species protection to regional sustainability

Biodiversity is the basis for ecosystem goods and services that provide for human survival and prosperity. With a rapidly increasing human population and its demands for natural resources, landscapes are being fragmented, habitats are being destroyed, and biodiversity is declining. How can biodiversity be effectively conserved in the face of increasing human pressures? In this paper, Ⅰ review changing perspectives on biodiversity conservation, and discuss their relevance to the practice of biodiversity conservation. The major points include The notion of balance of nature is a myth rather than a scientific concept; the theory of island biogeography is useful heuristically but flawed practically; the SLOSS debate is intriguing in theory but irrelevant in reality; the concept of minimum viable population and population viability analysis are useful, but technically inefficient and conceptually inadequate; metapopulation theory is mathematically elegant but ecologically oversimplistic; and integrative perspectives and approaches for biodiversity conservation are needed that incorporate insights from landscape ecology and sustainability science. Ⅰ further discuss some key principles for regional conservation planning, and argue that the long-term success of biodiversity conservation in any region will ultimately depend on the economic and social sustainability of that region. Both research and practice in biodiversity conservation, therefore, need to adopt a broader perspective of sustainability.     

Conservation-oriented restoration—a two for one method to restore both threatened species and their habitats

There is an urgent need for a new conservation approach as mere designation of protected areas, the primary approach to conserving biodiversity, revealed its low conservation efficiency and inability to cope with numerous challenges faced by nature in the Anthropocene. The paper discusses the new concept, which proposes that ecological restoration becomes an integral part of conservation planning and implementation, and is done using threatened plant species that are introduced not only into locations where they currently grow or grew in the recent past, but also into suitable locations within their potential distribution range. This new concept is called conservation-oriented restoration to distinguish it from the traditional restoration. Although the number of restoration projects focusing on recreation of once existing natural habitats is instantly growing, the majority of ecological restoration projects, in contrast to conservation-oriented restoration, have predominantly utilitarian goals, e.g.improvement or air quality, erosion control or soil replenishment. Conservation-oriented restoration should not be seen as an alternative either to the latter, or to the conservation dealing with particular threatened species(species-targeted conservation). These three conservation approaches, traditional ecological restoration, species-targeted conservation, and conservation-oriented restoration differ not only in broadly defined goals and attributes of their targets, but also in the types of ecosystems they are applicable to, and complement each other in combating global deterioration of the environment and biodiversity loss.     

广西农作物种质资源遗传多样性

This paper is about PLEC,but also about small farmers and biodiversity . Until a very few years ago, all agriculture was supposed to be the enemy of biodiversity . Now it is better understood that some areas managed by small farmers contain almost as much biodiversity as the wild. This diversity, (Wood and Lenne 2000).Even in regard to the wild itself,ecological thinking has now swung away from the old view that the richest biodiversity occurs in ecosystems that have had a long period of undisturbed evolution toward acli maxstate. Since the late 1970s it has been forcefully argued that disturbances may be essential to the creation and maintenance of plant and animal diversity (eg. Zimmerer and young 1998).     

Conservation-oriented restoration—a two for one method to restore both threatened species and their habitats

There is an urgent need for a new conservation approach as mere designation of protected areas, the primary approach to conserving biodiversity, revealed its low conservation efficiency and inability to cope with numerous challenges faced by nature in the Anthropocene. The paper discusses the new concept, which proposes that ecological restoration becomes an integral part of conservation planning and implementation, and is done using threatened plant species that are introduced not only into locations where they currently grow or grew in the recent past, but also into suitable locations within their potential distribution range. This new concept is called conservation-oriented restoration to distinguish it from the traditional restoration. Although the number of restoration projects focusing on recreation of once existing natural habitats is instantly growing, the majority of ecological restoration projects, in contrast to conservation-oriented restoration, have predominantly utilitarian goals, e.g.improvement or air quality, erosion control or soil replenishment. Conservation-oriented restoration should not be seen as an alternative either to the latter, or to the conservation dealing with particular threatened species(species-targeted conservation). These three conservation approaches, traditional ecological restoration, species-targeted conservation, and conservation-oriented restoration differ not only in broadly defined goals and attributes of their targets, but also in the types of ecosystems they are applicable to, and complement each other in combating global deterioration of the environment and biodiversity loss.     

Conservation-oriented restoration—a two for one method to restore both threatened species and their habitats

There is an urgent need for a new conservation approach as mere designation of protected areas, the primary approach to conserving biodiversity, revealed its low conservation efficiency and inability to cope with numerous challenges faced by nature in the Anthropocene. The paper discusses the new concept, which proposes that ecological restoration becomes an integral part of conservation planning and implementation, and is done using threatened plant species that are introduced not only into locations where they currently grow or grew in the recent past, but also into suitable locations within their potential distribution range. This new concept is called conservation-oriented restoration to distinguish it from the traditional restoration. Although the number of restoration projects focusing on recreation of once existing natural habitats is instantly growing, the majority of ecological restoration projects, in contrast to conservation-oriented restoration, have predominantly utilitarian goals, e.g.improvement or air quality, erosion control or soil replenishment. Conservation-oriented restoration should not be seen as an alternative either to the latter, or to the conservation dealing with particular threatened species(species-targeted conservation). These three conservation approaches, traditional ecological restoration, species-targeted conservation, and conservation-oriented restoration differ not only in broadly defined goals and attributes of their targets, but also in the types of ecosystems they are applicable to, and complement each other in combating global deterioration of the environment and biodiversity loss.     

Sex and season explain spleen weight variation in the Egyptian mongoose

The Egyptia n mon goose (Herpestes ichneumon Linn aeus, 1758) is a medium-sized car nivore that experienced remarkable geographic expansion over the last 3 decades in the Iberian Peninsula. In this study, we investigated the association of species-related and abiotic factors with spleen weight (as a proxy for immunocompete nee) in the species. We assessed the relationship of body con dition, sex, age, seas on, and envir onmental conditi ons with splee n weight established for 508 hunted specimens. Our results indicate that the effects of sex and season outweigh those of all other variables, including body condition. Spleen weight is higher in males than in females, and heavier spleens are more likely to be found in spring, coinciding with the highest period of investment in reproduction due to mating, gestation, birth, and lactation. Coupled with the absence of an effect of body condition, our findi ngs suggest that splee n weight variation in this species is mostly influe need by lifehistory traits linked to reproduction, rather than overall energy availability, winter immunoenhancement, or energy partitioning effects, and prompt further research focusing on this topic.     

Ecological dynamic model of grassland and its practical verification

Based on the physico-biophysical considerations, mathematical analysis and some approximate formulations generally adopted in meteorology and ecology, an ecological dynamic model of grassland is developed. The model consists of three interactive variables, i.e. the bio-mass of living grass, the biomass of wilted grass, and the soil wetness. The major biophysical processes are represented in parameterization formulas, and the model parameters can be determined inversely by using the observational climatological and ecological data. Some major parameters are adjusted by this method to fit the data (although incomplete) in the Inner Mongolia grassland, and other secondary parameters are estimated through sensitivity studies. The model results are well agreed with reality, e.g., (i) the maintenance of grassland requires a minimum amount of annual precipitation (approximately 300 mm); (ii) there is a significant relationship between the annual precipitation and the biomass of living grass; and (iii) the overgrazing will eventually result in desertification. A specific emphasis is put on the shading effect of the wilted grass accumulated on the soil surface. It effectively reduces the soil surface temperature and the evaporation, hence benefits the maintenance of grassland and the reduction of water loss in the soil.     

黑河上游天然草地蝗虫空间异质性与分布格局

蝗虫空间分布格局是物种长期适应自然的结果,是蝗虫与环境、蝗虫之间关系的反映,有助于理解蝗虫发生学的环境背景。采用地统计学方法,在黑河上游山区天然草地研究了微生境影响下的蝗虫空间格局与异质性。结果表明:该区域5种优势种蝗虫的半变异函数模型均为非线性模型,表现为聚集分布;不同种类蝗虫样点之间空间依赖的范围为2.29—24.59 m;在蝗虫种群总异质性中随机部分引起的空间异质性占15.77%—88.64%。受食性和栖息地选择的影响,蝗虫种群形成了片状和斑块状的分布格局;尺度依赖性使蝗虫分布格局趋于多元化和繁杂化的特点,不同蝗虫种群之间相互交错嵌插,同种蝗虫高低值呈非均匀扩散,整体上形成了均衡性与互补性的斑块镶嵌结构,这种分布格局反映了蝗虫对生境和气候变化的多元适应性结构。     

关于蝗虫多样性与草原生态系统可持续发展的若干科学问题

蝗虫多样性既是草原生态系统演化的产物 ,反过来也影响着草原生态系统的结构与功能。蝗虫多样性状况与草原生态系统的持续发展有着密切的关联 ,这其中的科学问题包括 :(1 )蝗虫多样性及其空间变异机理 ;(2 )蝗虫多样性对草原生态系统过程的影响 ;(3 )蝗虫多样性空间格局与草原生态系统演化中的自然和人文因素的关联 ;(4 )蝗虫种群暴发的多样性阈值与草原生态系统的调控 ;(5 )蝗虫多样性和稳定性与草原生态系统的健康等。深入发掘生物多样性所包含的科学内涵 ,将一个物种的多样性与生态系统的结构和功能耦合起来研究 ,从重要物种蝗虫的生物多样性入手 ,深入探讨草原生态系统的持续发展问题 ,将为减少或减轻我国西部草原蝗灾发生提供科学的支持     

中国北方草地蝗虫学研究概况

<正> 就目前所知,我国严重为害草地的害虫约计40余种(田畴等,1988),其中主要为蝗虫类。其为害遍布我国北方草地。仅在内蒙古,每年发生面积约500～1000万亩,在为害严重的局部地区其虫口密度达200头/m~2。蝗虫的大发     

Range restricted grasshoppers better conserved in a terrestrial zone than in a riparian zone

Riparian zones (RZs) functionally connect aquatic and terrestrial ecosystems, and have azonal and geographically widespread plant communities that differ from those of the neighboring terrestrial zone (TZ). Although well studied botanically, RZs are not well understood in terms of their terrestrial insect diversity, including grasshoppers. The Cape Floristic Region (CFR) is a global biodiversity hotspot with small rocky rivers running through highly diverse sclerophyllous vegetation. It has high levels of endemism among many taxa, including grasshoppers, making it ideal for testing the effect of azonal vegetation on grasshopper assemblages of the RZ, and determining whether conservation efforts should be focused on the RZ as well as the TZ. We determine grasshopper dispersion patterns along the RZ of an important CFR river, and compare these patterns with those of the TZ to understand the habitat occupancy relative to 27 environmental variables of the zones and geographical distribution of the grasshoppers. Forty percent of individuals we collected were CFR endemics. We found only weak differences in the grasshopper assemblages between the RZ and TZ, apparently driven by deep history, complex geomorphology, stressful environmental conditions, a diverse vegetation and land mosaic, and probable high predator pressure. There were two groups: large-sized, well-flighted, geographically widespread generalists that were overall more abundant in the RZ than TZ, and small, flightless or poorly-flighted, vegetation-specialists which are narrow-range endemics adapted to both RZ and TZ, but still more abundant in the TZ. We conclude that although the vegetation of this riparian zone may require some special conservation attention, this is not so for the grasshoppers which overall are best conserved in the TZ.     

Influence of a large late summer precipitation event on food limitation and grasshopper population dynamics in a northern Great Plains grassland

The complex interplay between grasshoppers, weather conditions, and plants that cause fluctuations in grasshopper populations remains poorly understood, and little is known about the ecological processes that generate grasshopper outbreaks. Grasshopper populations respond to interacting extrinsic and intrinsic factors, with yearly and decadal weather patterns and the timing of precipitation all potentially important. The effects of initial and increasing grasshopper densities on grasshopper survival and reproductive correlates were examined at a northern mixed-grass prairie site through manipulations of grasshopper densities inside 10-m2 cages. High-quality grass growth occurred after a 9.1-cm mid-August rain. Reduced proportional survival was apparent in the two higher density treatments before the rain, indicative of food-limited density-dependent mortality. However, the large late summer rainfall event mediated the effects of exploitative competition on demographic characteristics because of the high-quality vegetation growth. This led to weaker effects of food limitation on survival and reproduction at the end of the experiment. The results indicate a direct link between weather variation, resource quality and grasshopper population dynamics led to a severe grasshopper outbreak and show that infrequent large precipitation events can have significant effects on population dynamics. Additional research is needed to examine the importance of infrequent large precipitation events on grasshopper population dynamics in grassland ecosystems.     

Grasshoppers affect grassland ecosystem functioning: Spatial and temporal variation

Using experiments and monitoring, we find that grasshoppers in a grassland ecosystem impact ecosystem functioning (nutrient cycling and primary production) in different ways among sites in the ecosystem. Experiments conducted over many years at two sites (21 and 15 years, respectively) with the same grasshopper and plant species demonstrated that grasshoppers increased nitrogen availability (N) and consequently annual plant production (ANPP) at one site, and decreased N and consequently ANPP at the other site. Comparing the two sites, N increased on average by 8% and up to 21.6%, and resulting ANPP increased on average by 18.6% and up to 33.3%. Grasshoppers increase N and ANPP by preferentially feeding on slower decomposing plants, and the opposite occurs by preferentially feeding on faster decomposing plants. Monitoring 20 random sites in the ecosystem, grasshoppers consistently increased N and ANPP over 3 years at 40% of sites, consistently decreased N and ANPP at 35% of sites, and sometimes increased and decreased N and ANPP at 25% of sites. Therefore, grassland grasshoppers, and insects in many ecosystems, may strongly affect ecosystem functioning.     

Effects of large herbivore grazing on grasshopper behaviour and abundance in a meadow steppe

1. Adaptive phenotypic plasticity has been a major subject in evolutionary ecology, but how a species' behaviour may respond to certain environmental change is still not clear. In grasslands worldwide, large herbivores are increasingly used as a tool for grazing management, and occur to interact with grasshoppers that dominate grassland insect communities. Previous studies have been well-documented about grazing effects on diversity and abundance of grasshoppers. Yet, how grazing may alter grasshopper behaviour, and potential effects on their abundance remains elusive. 2. We conducted a field experiment by manipulating grazing using sheep, cattle, and their mix to examine the behavioural responses and abundance of the grasshoppers (Euchorthippus unicolor) to grazing in a Leymus chinensis-dominated grassland. 3. Results showed that the grasshoppers spent less time on feeding and resting on grasses, but more time on switching and resting on forbs under cattle grazing and mixed grazing with cattle and sheep. In contrast, the grasshoppers spent more time on feeding but less time on switching and resting on forbs under sheep grazing. The behavioural changes were also potentially linked to grasshopper abundance in the context of grazing management. 4. The responses of grasshopper behaviour and abundance to grazing may be largely triggered by altered vegetation and microclimates. Such behavioural flexibility of grasshoppers must be considered when large herbivores are recognised as a management tool for influencing grasshopper abundance, and grazer species should be paid more attention both individually and jointly for better grassland conservation.     

Grasshopper (Orthoptera: Acrididae) communities respond to fire,bison grazing and weather in North American tallgrass prairie: a long-term study

Because both intrinsic and extrinsic factors influence insect population dynamics, operating at a range of temporal and spatial scales, it is difficult to assess their contributions. Long-term studies are ideal for assessing the relative contributions of multiple factors to abundance and community dynamics. Using data spanning 25 years, we investigate the contributions of weather at annual and decadal scales, fire return interval, and grazing by bison to understand the dynamics of abundance and community composition in grasshopper assemblages from North American continental grassland. Each of these three primary drivers of grassland ecosystem dynamics affects grasshopper population and community dynamics. Negative feedbacks in abundances, as expected for regulated populations, were observed for all feeding guilds of grasshoppers. Abundance of grasshoppers did not vary in response to frequency of prescribed burns at the site. Among watersheds that varied with respect to controlled spring burns and grazing by bison, species composition of grasshopper assemblages responded significantly to both after 25 years. However, after more than 20 years of fire and grazing treatments, the number of years since the last fire was more important than the managed long-term fire frequency per se. Yearly shifts in species composition (1983–2005), examined using non-metric multidimensional scaling and fourth-corner analysis, were best explained by local weather events occurring early in grasshopper life cycles. Large-scale patterns were represented by the Palmer Drought Severity Index and the North Atlantic Oscillation (NAO). The NAO was significantly correlated with annual mean frequencies of grasshoppers, especially for forb- and mixed-feeding species. Primary grassland drivers—fire, grazing and weather—contributing both intrinsic and extrinsic influences modulate long-term fluctuations in grasshopper abundances and community taxonomic composition. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Yaks and sheep trigger different changes in the grasshopper assemblages of the Qilian Mountains via differentially altering plant assemblages

1. The Qilian Mountains represent one of the key livestock‐raising grasslands in China. The two main herbivore species raised in this area – yaks and sheep – are of critical economical value. Grasshoppers compete with these animals for available nutrients, creating multifaceted relationships between livestock, grasshoppers and plants. A clear understanding of such relationships is lacking and is urgently needed to guide conservation efforts. 2. This study aims to document the effects of yak and sheep grazing on grasshopper assemblages and to elucidate the underlying mechanisms of such effects. 3. It is shown here that yaks and sheep impact grasshopper assemblages differently. Grasshopper assemblages exhibited lower density, biodiversity, richness, and evenness of distribution in yak‐grazed pastures than in grazing‐free grasslands. Sheep‐grazed pastures exhibited a dramatically divergent picture, with elevated density, biodiversity and richness, and a slightly decreased evenness of distribution. Grasshoppers were generally larger in grazed pastures than in grazing‐free grasslands, especially in yak‐grazed plots. 4. The present study suggests that differences between yak and sheep pastures in plant assemblage structure and plant traits are probably the underlying forces driving the differences in grasshopper assemblage structure and grasshopper traits, respectively. 5. The study shows that the grasshopper habitat indicator species differ between yak and sheep pastures, raising the possibility that such indicators can be used to monitor grassland usage and degradation in the Qilian Mountains. 6. These results provide novel insights into the dynamic interactions of common domesticated herbivore species, grasshoppers and plants in Qilian Mountains, which augment current knowledge and may ultimately lead to better conservation practices.     

Review of the Methods Frequently Used to Estimate the Abundance of Orthoptera in Grassland Ecosystems

Ecologists have quantified Orthoptera (grasshoppers and crickets) density in a wide variety of conservation studies. Objective determination of Orthoptera population size is possible using mark-release recapture techniques but these are time-consuming and of little use for all but the smallest scale studies. Therefore, a wide range of sampling techniques have been devised to quantify population density and the most commonly used methods include sweep netting and quadrat counts. It is the aim of this paper to critically review studies that have used these techniques and to provide useful suggestions for non-specialists on which method may be most applicable to their study site. This paper reviews a selection of the extensive literature reporting studies estimating the abundance of grasshoppers (Acrididae) in a wide range of grassland ecosystems. Where possible, studies on bush-crickets (Tettigoniidae) and crickets (Gryllidae) are included reflecting their overall contribution to assemblage diversity in grassland ecosystems and to highlight the need for further investigations of sampling efficiency on these two under-researched families.The most rapid and inexpensive sampling methods, such as quadrat and transect counts, involve ‘flushing’ grasshoppers from the sward. These techniques are fairly accurate in short, open swards (<50 cm sward height) where grasshopper densities are low (<2 adults per m²). At higher population densities (>2 adults per m²), methods which require the capture of grasshoppers such as box quadrats and sweep netting may be more appropriate. Sampling grasshopper populations in taller vegetation (>50 cm sward height) is more problematic as the efficiency of many techniques may be reduced by vegetation structure. Methods such as timed counts can be used at low densities (<2 adults per m²) and night trapping might be most applicable where high numbers of grasshoppers are present (>2 adults per m²).There is an urgent need for development of a standardised sampling technique that can produce comparable data from studies with a wide variety of observers in grasslands with differing vegetation structures and grasshopper densities.