Plant diversity declines with recent land use changes in European Alps

Against a background of increasing land use intensification on favorable agricultural areas and land abandonment on less arable areas in the Alps, the aim of this investigation was to detect whether and how 10 differently used types of grassland can be distinguished by site factors, plant species composition, and biodiversity. By using a very large number of vegetation surveys (936) that were widely distributed in the Central Alps, site parameters and species composition of the different land use types were compared by discriminant analyses and various biodiversity indices. Results showed that land use is a significant factor affecting the development of different grassland communities with site factors playing a subordinate, yet important role. The 10 land use types studied can be clearly differentiated from one another by single species as well as by species composition. Our study found that the number of plant communities along with the number of species decreases constantly and significantly with increasing land use intensity and on abandoned land. For example, on average, extensively used meadows have more than three times as many species as intensively used meadows. Further, the most even distribution of species (Evenness index) is reached in intensively used meadows, whereas on pastures and abandoned land, some species become dominant forcing other species to recede. The results confirm that due to current trends in agriculture, such as land abandonment and land use intensification, plant diversity in the Alps is decreasing considerably.     

Scale-dependent effects of land use on plant species richness of mountain grassland in the European Alps

Traditionally managed mountain grasslands in the Alps are species‐rich ecosystems that developed during centuries of livestock grazing. However, changes in land use including fertilisation of well accessible pastures and gradual abandonment of remote sites are increasingly threatening this diversity. In five regions of the Swiss and French Alps we assessed the relationship between land use, soil resource availability, cover of the unpalatable species Veratrum album, species richness and vegetation composition of mountain grasslands across four spatial scales ranging from 1 to 1000 m². Mean species richness and the increase in the number of species with increasing area were lower in intensively grazed, fertilised pastures than in traditional pastures or in abandoned pastures. Species composition of abandoned pastures differed from that of the other management types. Plant species richness was influenced by different factors at different spatial scales. At the 1 m² scale, plant species richness was negatively related to soil nitrate and influenced by the cover of V. album, depending on land use: species richness and cover of V. album were negatively correlated in abandoned pastures, but positively correlated in fertilised grasslands. At the 1000 m² scale, a negative effect of fertilization on richness was evident. These results indicate that at small scales species richness in mountain grasslands is determined by competition for light, which should be more important if nutrient availability is high, and by positive and negative interactions with unpalatable plants. In contrast, species richness at the large scale appears to be mainly influenced by land use. This result emphasizes the importance of studying such inter‐relationships at multiple scales. Our study further suggests that the maintenance of the traditional land use scheme is crucial for the conservation of plant species richness of mountain pastures as both intensification and abandonment changed species composition and reduced plant species diversity.     

Tree line shifts in the Swiss Alps: Climate change or land abandonment?

Questions: Did the forest area in the Swiss Alps increase between 1985 and 1997? Does the forest expansion near the tree line represent an invasion into abandoned grasslands (ingrowth) or a true upward shift of the local tree line? What land cover / land use classes did primarily regenerate to forest, and what forest structural types did primarily regenerate? And, what are possible drivers of forest regeneration in the tree line ecotone, climate and/or land use change? Location: Swiss Alps. Methods: Forest expansion was quantified using data from the repeated Swiss land use statistics GEOSTAT. A moving window algorithm was developed to distinguish between forest ingrowth and upward shift. To test a possible climate change influence, the resulting upward shifts were compared to a potential regional tree line. Results: A significant increase of forest cover was found between 1650 m and 2450 m. Above 1650 m, 10% of the new forest areas were identified as true upward shifts whereas 90% represented ingrowth, and we identified both land use and climate change as likely drivers. Most upward shift activities were found to occur within a band of 300 m below the potential regional tree line, indicating land use as the most likely driver. Only 4% of the upward shifts were identified to rise above the potential regional tree line, thus indicating climate change. Conclusions: Land abandonment was the most dominant driver for the establishment of new forest areas, even at the tree line ecotone. However, a small fraction of upwards shift can be attributed to the recent climate warming, a fraction that is likely to increase further if climate continues to warm, and with a longer time‐span between warming and measurement of forest cover.     

The impact of land abandonment on the plant diversity of olive groves

We investigated the effect of woody species’ encroachment on plant diversity changes with regard to vascular plants and bryophytes in traditional olive groves of the Maremma Regional Park (Tuscany, Italy) and assessed cross-taxon correlation between these two taxa. We classified the olive groves into four land use types, representing different successional stages. To describe the evenness of species distribution within a community, we plotted rank-abundance diagrams for each taxon and each land use type. The relationship between the number and cover of vascular plants, therophytes, bryophytes, colonists and phanerophytes in each plot was examined using linear regression. The effects of land use type on vascular plant and bryophyte richness and assemblages were assessed by permutational uni- and multivariate analysis of variance. The congruence in species composition between the two taxa was evaluated using Procrustes analysis. The number of vascular plants, bryophytes and therophytes decreased linearly with increased phanerophyte species cover. The number of species belonging to Thero-Brachypodietea progressively decreased throughout succession. Rank-abundance diagrams and multivariate analysis showed differences between the land use types, which were statistically significant for vascular plants between the traditional olive groves and the other land use types, and for bryophytes between the traditional olive groves and woodlands. PROTEST analysis and NMDS graphs showed a correlation between vascular plant and bryophyte communities. The results suggested that conservation measures are needed in the study area in order to ensure both the maintenance of traditional olive groves of conservation interest and high levels of environmental heterogeneity.     

Golden Eagle Aquila chrysaetos density and productivity in relation to land abandonment and forest expansion in the Alps

Land abandonment and afforestation are causing considerable forest expansion in the Alpine chain, with consequent loss of Alpine pastures, the main foraging habitat for Golden Eagles Aquila chrysaetos. A population of 46 pairs of Golden Eagles was systematically surveyed between 1984 and 1989 in the central-eastern Italian Alps. We measured the amount of woodland within the potential hunting range of 36 pairs. Nearest-neighbour distance was correlated positively with the extent of woodland within the potential hunting range. Productivity was not significantly affected by the amount of woodland within the potential for-aging range. At current rates of forest expansion, such data suggest a 5–9% density decline in the next 20 years. However, increasing food supply and decreasing human persecution could be masking current effects of habitat loss.     

The role of landuse and natural determinants for grassland vegetation composition in the Swiss Alps

The Alps provide a high habitat diversity for plant species, structured by broad- and fine-scale abiotic site conditions. In man-made grasslands, vegetation composition is additionally affected by the type of landuse. We recorded vegetation composition in 216 parcels of grassland in 12 municipalities representing an area of 170×70 km in the south-eastern part of the Swiss Alps. Each parcel was characterized by a combination of altitudinal level (valley, intermediate, alp), traditional landuse (mown, grazed), current management (mown, grazed, abandoned), and fertilization (unfertilized, fertilized). For each parcel we also assessed the abiotic factors aspect, slope, pH value, and geographic coordinates, and for each municipality annual precipitation and its cultural tradition. We analysed vegetation composition using (i) variation partitioning in RDA, (ii) cover of graminoids, non-legume forbs, and legumes, and (iii) dominance and frequency of species. Species composition was determined by, in decreasing order of variation explained, landuse, broad-scale abiotic factors, fine-scale abiotic factors, and cultural tradition. Current socio-economically motivated landuse changes, such as grazing of unfertilized former meadows or their abandonment, strongly affect vegetation composition. In our study, the frequency of characteristic meadow species was significantly smaller in grazed and even smaller in abandoned parcels than in still mown ones, suggesting less severe consequences of grazing for vegetation composition than of abandonment. Therefore, low-intensity grazing and mowing every few years should be considered valuable conservation alternatives to abandonment. Furthermore, because each landuse type was characterized by different species, a high variety of landuse types should be promoted to preserve plant species diversity in Alpine grasslands.     

Dominant species and ecosystem gas exchange in temperate grassland under different land use patterns

在内蒙古温带草原围封、放牧和割草3种处理下的样地内, 对生态系统尺度和大针茅(Stipa grandis)、冷蒿(Artemisia frigida)、羊草(Leymus chinensis) 3种优势种植物叶片尺度上的气体交换和水分关系进行了测定, 对比研究了植物碳水对环境的响应。结果表明, 在优势种单株尺度和生态系统尺度上, 大气-植被CO₂交换因草地利用方式的不同而具有不同的表现。在生态系统层面, 放牧样地的群落净CO₂气体交换量和总初级生产力都与围封样地和割草样地有差异, 群落总初级生产力受生态系统呼吸的影响。在放牧处理下, 群落净CO₂气体交换量日变化表现为生态系统对碳的吸收, 而围封和割草则以碳释放为主。单叶光合速率出现负值并随时间推移而恢复的现象, 应是植物对干旱高温、高光照的特殊反应。生态系统水分利用效率没有明显不同, 但各样地的蒸散能力有趋势上的变化; 对于同种植物, 放牧样地植物单叶水分利用效率的日变化波动幅度最大, 围封样地最小。     

不同利用方式对红壤坡地微生物多样性和硝化势的影响

采集了中国科学院桃源农业生态试验站红壤坡地农田、自然恢复林和茶园土壤样品,采用末端限制性酶切片段长度多态性分析(T.RFLP)技术分析土壤细菌、古菌、氨氧化细菌(AOB)和氨氧化古菌(AOA)的多样性,采用好气培养法测定不同土壤的硝化势,研究不同土地利用方式对微生物多样性和硝化势的影响.结果表明:土壤AOB和AOA多样性指数差异不显著,且在3种不同土地利用方式中呈现相同的趋势,均为农田=茶园>自然恢复林;通过RDA分析发现,不同利用方式造成土壤理化性状的改变是影响土壤AOA和AOB群落结构的主要原因;好气培养法测得不同土壤硝化势农田最高,茶园次之而自然恢复林最低;相关性分析显示,硝化势与细菌16S rRNA、AOA和AOB amoA基因多样性指数呈显著正相关,其中与AOA amoA基因关系最为密切;总体来说,红壤坡地不同利用方式改变了土壤细菌、古菌、AOA和AOB的多样性,土壤AOB和AOA积极参与了土壤的硝化过程,且AOA在氨氧化微生物群落生态功能中占有重要地位,AOA比AOB与硝化势的关系更为密切.     

Seasonal variations in nitrogen mineralization under three land use types in a grassland landscape

Soil nitrogen (N) mineralization is an important component of the N cycling process in ecosystems. In this study, we assessed the seasonal patterns of net soil N mineralization and nitrification using an intact soil core incubation method in the upper 0–10 cm soil layer in three representative land use types. These included a fenced steppe, an abandoned field and a crop field in a grassland landscape of Inner Mongolia, China. The study was conducted from September 2004 to August 2005. Our results demonstrate marked seasonal variations in inorganic N pools, net nitrogen mineralization and net nitrification. Net N mineralization was higher in the crop field than in the fenced steppe and the abandoned field. Daily rates of N mineralization and nitrification during the growing season were approximately twice their corresponding mean annual rates. Accumulative mineralization and nitrification of N during the growing season accounted for about 90 and 85% of that measured for the entire year. Rates of mineralization and nitrification were positively correlated with soil bulk density, but negatively correlated with soil pH. Net N mineralization and nitrification were strongly regulated by land use, precipitation, soil water and temperature.     

Landscape context determinants to plant diversity in the permanent meadows of Southern European Alps

In the Southern Alps, the role of landscape context on meadows plant diversity was evaluated using a multi-model information theoretic approach and five competing hypotheses of landscape context factors: habitat quality (H1), matrix quality (H2), habitat change (H3), matrix quality change (H4) and topography-environmental conditions (H5)- measured at three spatial scales (125, 250 and 500 m). Shannon diversity index and species richness represented plant diversity obtained in 34 plots (100 m² size). Landscape context affected plant diversity measures differently. Matrix quality change at larger scale (500 m) was the most supported hypothesis explaining Shannon diversity index, while species richness responded mostly to topography-environmental conditions in the immediate surroundings (125 m). No effects of present-day habitat and matrix quality (H1 and H2) were found. Matrix quality change affected positively Shannon diversity index through an effect of landscape neighbourhood context on farming management practices. Due to the importance of exposure and inclination of slopes, topography-environmental conditions influenced species richness mostly through energy-driven processes and farming management strategies. In terms of scale, matrix quality change was the strongest hypothesis explaining Shannon diversity index at all scales, while the underlying process affecting species richness changed with scale (H5 or H3). Overall, landscape context explained only 25–28 % of the variation in plant diversity, suggesting that landscape management may support biodiversity conservation when comprised in a global strategy including farming practices. In the study area, change in landscape diversity may be a good indicator for Shannon diversity index and south-eastern facing meadows should be preserved.     

Loss of functional diversity under land use intensification across multiple taxa

Land use intensification can greatly reduce species richness and ecosystem functioning. However, species richness determines ecosystem functioning through the diversity and values of traits of species present. Here, we analyze changes in species richness and functional diversity (FD) at varying agricultural land use intensity levels. We test hypotheses of FD responses to land use intensification in plant, bird, and mammal communities using trait data compiled for 1600+ species. To isolate changes in FD from changes in species richness we compare the FD of communities to the null expectations of FD values. In over one-quarter of the bird and mammal communities impacted by agriculture, declines in FD were steeper than predicted by species number. In plant communities, changes in FD were indistinguishable from changes in species richness. Land use intensification can reduce the functional diversity of animal communities beyond changes in species richness alone, potentially imperiling provisioning of ecosystem services.     

沈阳市东部土地利用格局变化

以沈阳市东部１９７６～１９８９年的历史航空像片为基础,以地理信息系统（ＧＩＳ）技 术为手段,分析土地利用的空间格局及其变化．结果表明,针叶林、水田平均嵌块体大小增 加,旱地、落叶林、灌丛平均嵌块体大小减少;分数维值略有增加．预示嵌块体形状逐步复 杂化;多样性指数、均匀性指数增加．优势度和蔓延度指数由原来的１．６３２７和８９．２０２２分 别减少到１．３２２６和８８．２７４４,说明景观嵌块体的空间分布趋于均匀,嵌块体的聚集分布状 况将随时间的推移逐步分散化．此外．本文对沈阳东部土地利用格局变化的原因进行了剖 析．     

High diversity and regional endemism in land snails of eastern Tanzania

In February/March 1995 we collected land snails (including slugs) at 12 stations in eastern Tanzania. A total of 571 person-hours yielded 9174 snails assigned to 159 morpho-species. The richest two sites each (<4ha of uniform forest) had 50 species (Amboni Cave) and 48 species (near Amani, Usambaras), nearly as great as the most species-rich sites known in the world; sieving of litter and soil would probably yield more species. In lowland (coastal) forests, both diversity and endemism seemed to decrease from north to south. Most snail species were found within only one of four coastal or one montane geographic regions, indicating substantial regional endemism. Only one species (Achatina fulica) appeared in all five regions, and 84% of all other species were found in only one (61%) or two regions (23%). The predatory streptaxids comprised about half the species and a third of the individuals at the Usambara site, an extremely high ratio of carnivores. Small snails (< 5mm greatest adult shell dimension) – many of which are probably undescribed species – comprise a substantial proportion of Tanzanian molluscan diversity; more surveys are needed, especially because of human pressures on the few forest patches remaining.     

Environmental determinants of geographic butterfly richness pattern in eastern China

A long-standing task for ecologists and biogeographers is to reveal the underlying mechanisms accounting for the geographic pattern of species diversity. The number of hypotheses to explain geographic variation in species diversity has increased dramatically during the past half century. The oldest and the most popular one is environmental determination. However, seasonality, the intra-annual variability in climate variables has been rarely related to species richness. In this study, we assessed the relative importance of three environmental hypotheses: energy, seasonality and heterogeneity in explaining species richness pattern of butterflies in Eastern China. In addition, we also examined how environmental variables affect the relationship between species richness of butterflies and seed plants at geographic scale. All the environmental factors significantly affected butterfly richness, except sampling area and coefficient of variation of mean monthly precipitation. Energy and seasonality hypotheses explained comparable variation in butterfly richness (42.3 vs. 39.3 %), higher than that of heterogeneity hypothesis (25.9 %). Variation partitioning indicated that the independent effect of seasonality was much lower (0.0 %) than that of energy (5.5 %) and heterogeneity (6.3 %). However, seasonality performed better in explaining butterfly richness in topographically complex areas, reducing spatial autocorrelation in butterfly richness, and more strongly affect the association between butterflies and seed plants. The positive relationship between seed plant richness and butterfly richness was most likely the result of environmental variables (especially seasonality) influencing them in parallel. Insufficient sampling may partly explain the low explanatory power of environmental model (52.1 %) for geographic butterfly richness pattern. Our results have important implications for predicting the response of butterfly diversity to climate change.     

基于生态系统服务功能的中国北方草地及农牧交错带区划

以北方草地和农牧交错带草地类型区域分异为基础,重点考虑不同草地类型的生态系统服务功能,在综合分析了北方草地和农牧交错带生态环境基本特征的基础上,确定了草地生态功能区划的原则、依据、方法及命名,然后在"3S"技术的支持下,将北方草地和农牧交错带分为北方草原区、北方荒漠区和农牧交错区3个一级区及10个二级区,对各个功能区的区域范围、主要生态环境问题、主要的生态服务功能及为了功能区的保护与可持续发展而需要采取的措施都进行了详细论述。区划结果对认识北方草地与农牧交错带不同草地类型生态系统服务功能的重要价值,对草地资源的合理利用和农业生产的合理布局、对生态环境保护与建设规划及对维护区域生态安全、实现区域的可持续发展都具有重大意义。     

The geographical and environmental determinants of genetic diversity for four alpine conifers of the European Alps

Climate is one of the most important drivers of local adaptation in forest tree species. Standing levels of genetic diversity and structure within and among natural populations of forest trees are determined by the interplay between climatic heterogeneity and the balance between selection and gene flow. To investigate this interplay, single nucleotide polymorphisms (SNPs) were genotyped in 24 to 37 populations from four subalpine conifers, Abies alba Mill., Larix decidua Mill., Pinus cembra L. and Pinus mugo Turra, across their natural ranges in the Italian Alps and Apennines. Patterns of population structure were apparent using a Bayesian clustering program, STRUCTURE, which identified three to five genetic groups per species. Geographical correlates with these patterns, however, were only apparent for P. cembra. Multivariate environmental variables [i.e. principal components (PCs)] were subsequently tested for association with SNPs using a Bayesian generalized linear mixed model. The majority of the SNPs, ranging from six in L. decidua to 18 in P. mugo, were associated with PC1, corresponding to winter precipitation and seasonal minimum temperature. In A. alba, four SNPs were associated with PC2, corresponding to the seasonal minimum temperature. Functional annotation of those genes with the orthologs in Arabidopsis revealed several genes involved in abiotic stress response. This study provides a detailed assessment of population structure and its association with environment and geography in four coniferous species in the Italian mountains.