Colonization in an abandoned East-Mediterranean vineyard

Abstract. Previous studies on secondary succession in abandoned agricultural land in the Mediterranean area were carried out by the chronosequence method, including data from different sites. A unique opportunity to study secondary succession arose from a situation in which different parts of one homogeneous East-Mediterranean vineyard were abandoned for 5, 8, 15 and 35 yr, and did not suffer from any disturbance subsequently. Most of the perennial species that colonized the abandoned vineyard were fleshy fruited species, which apparently were dispersed by birds from the surrounding maquis into the vineyard. These bird-dispersed species were the first to be established, and were the dominant plant group according to dispersal modes. The abandoned vine plants and their supporting columns provided the birds with perching and feeding sites, enhancing the arrival of bird-dispersed species regardless of their life forms. Under these conditions the most important attribute that affected vegetation dynamics was seed dispersal mode. Trees were among the first to colonize in the vineyard, implying that no facilitation was needed for their establishment. Annual plant species were the only species to disappear during succession. Almost all perennial species which had arrived persisted in the vineyard, and no replacement of perennial species was found. The rate of succession was rapid, as expressed by the short time (8–15 yr) needed for the stabilization of species composition, for growth to average height of late succession trees, and for reaching high cover of the invading perennial species in the abandoned vineyard. The secondary succession described above differs from that in the western Mediterranean by the absence of perennial species replacement and its rapid rate. The possible causes are discussed.     

内蒙古哈民忙哈遗址废弃情境观察与分析

哈民忙哈遗址位于科尔沁沙地腹心地带,是迄今在西辽河以北地区发现的最重要的史前聚落遗址。本文全面考察2010~2014年发掘的44座房址的废弃情境,将它们分为三种类型。不同类型房址体现的不同废弃行为方式,分别对应灾难性、不预期返回和预期返回三种废弃模式。科尔沁沙地脆弱的生态环境促使人们采取流动性居住方式、依赖多元化的生计方式,从而形成了不预期返回和预期返回废弃模式。但这种人地关系的短暂平衡仍然潜伏着危机,当一系列因素耦合作用时,酿成了一场可怕的灾难,导致聚落形成最后阶段的灾难性废弃模式。     

Changes of traditional agrarian landscapes and their conservation implications: a case study of butterflies in Romania

Global biodiversity is decreasing as a result of human activities. In many parts of the world, this decrease is due to the destruction of natural habitats. The European perspective is different. Here, traditional agricultural landscapes developed into species-rich habitats. However, the European biodiversity heritage is strongly endangered. One of the countries where this biodiversity is best preserved is Romania. We analyse the possible changes in Romania's land-use patterns and their possible benefits and hazards with respect to biodiversity. As model group, we used butterflies, whose habitat requirements are well understood. We determined the ecological importance of different land-use types for the conservation of butterflies, underlining the special importance of Romania's semi-natural grasslands for nature conservation. We found that increasing modern agriculture and abandonment of less productive sites both affect biodiversity negatively — the former immediately and the latter after a lag phase of several years. These perspectives are discussed in the light of the integration of Romania into the European Union.     

Changes of species richness pattern in mountain grasslands: abandonment versus restoration

Changes in plant species richness at various spatial scales were investigated by manipulative experiment in mountain grasslands. The aim of the research was to compare changes in species richness in newly abandoned sites and sites where restoration measures were applied after 20 years of abandonment. The plots were located in two vegetation types with different moisture regime. Species richness decreased significantly after abandonment, mainly at the finest spatial scale of 10 × 10 cm. There was significant increase of species richness on restored sites, but it was apparent mainly at a larger scale. However, even 4 years of regular mowing were not sufficient to restore species richness to the level typical for traditionally managed grasslands in the region. No significant difference was found in the performance of the 2 contrasting vegetation types (wet and dry) in relation to management measures. A significant difference in scale-dependent species richness was only observed. The dry type had a steeper species-area curve, with a lower number of species at the finest spatial scale. According to the results of the experiment, mountain grasslands are very vulnerable habitats, losing their conservation value quickly after abandonment. Restoration is possible due to an extensive species pool in the region, but return to the original species richness at all spatial scales is quite a long process.     

Floristic and life form diversity in post-pasture successions on a Mediterranean island (Corsica)

The landscapes of the French island of Corsica are the result of thegrazing tradition which has always occupied a pivotal position in the island'seconomy. Furthermore, in the last fifty years, a reduction in the pressure fromhuman activity has lead to changes in plant cover. This article intends tostudythe evolution of dynamic mechanisms during the secondary successions and theeffect of changes in vegetation on plant diversity. Our study was based on asimultaneous study of 375 plots carried out between May and September from 1996to 1998. We studied the floristic composition of each stage both qualitatively(life form, adaptive strategy and seed dispersal mode) and quantitatively(species richness, equitability, Shannon index). The results show a change inspecies and environmental conditions, with a progressive move from heliophilicgrassland and low shrub species with an S or SR strategy, anemochoric and withahigh tolerance for soil quality to a final stage of dense forest composed ofcompetitive (C or CS) zoochoric or barochoric phanerophytes. Moreover, theturning point in Corsica in terms of floristic diversity lies between 20 and 55years after land abandonment. Successions are due to a series of rapidinteractions. Thus, when a site is given reserve or protected area status, weneed to take into account the fact that it will evolve according to thebiological traits of the species. From a research point of view, we need tolookat process diversity and the role of each of the species present during thesuccessions.     

The effect of the expansion of the clonal grass Calamagrostis epigejos on the species turnover of a semi‐arid grassland

Question: How does the dominance of Calamagrostis epigejos influence species turnover of a grassland? Location: Loess grassland at the foothills of Bükk Mountains, Hungary (47°54’ N., 20°35’ E). Methods: Presence/absence of vascular plants and different performance attributes of C. epigejos were recorded in a plot‐subplot system between 2002 and 2005. Appearance and disappearance rates of grassland species were calculated for pairs of consecutive years. 1. Mean appearance and disappearance rates were compared in grassland plots dominated by C. epigejos and in plots free from this species, based on Monte Carlo randomization. 2. Mean appearance rates were assessed for categories of C. epigejos performance and their confidence intervals were calculated via Monte Carlo randomization. For two performance variables (percentage cover and shoot number) analyses were performed at two spatial scales. Results: 1. C. epigejos.‐dominated plots differed from unaffected ones by significantly lower appearance rates. 2. Change in appearance rates was best explained by differences in percentage cover of C. epigejos. Coarse‐scale C. epigejos performance had a closer correspondence with appearance rate change than fine‐scale performance. Low level C. epigejos performance enhanced appearance rate compared to intact stands, while high level performance decreased it, regardless of the choice of performance measure. Conclusions: C. epigejos lowers species number by hindering reappearance of species of the original grassland. This is best explained by the increased shading effect at the coarse scale. The marked non‐linear initial enhancement in appearance rate, however, can also be taken as an early sign of future species loss.     

撂荒年限对陕北黄土区山地枣林深层土壤有机碳的影响

以陕西省延安市延川县齐家山红枣试验示范基地不同撂荒年限山地枣林(Ziziphus jujuba Mill.)为研究对象,采用空间代替时间的方法,研究该地区0～340 cm土壤有机碳的分布特征以及撂荒年限对有机碳分布的影响.结果显示:研究区土壤有机碳含量及有机碳储量具有明显的表聚现象;不同撂荒年限土壤有机碳储量差异显著,...     

Structural analysis of woody species in Mediterranean old fields

Abstract

The study analyses the changes in vegetation structure and composition within a sere of secondary succession at Pantelleria Island (Sicilian Channel, Italy). It aims to show that not only phytosociological data but also structural parameters, like woody species’ height and spatial distribution indices are useful to describe and interpret renaturation processes. Woody species structure was recorded on abandoned terraces, both on north-facing and on south-facing slopes. Relevés were made in fallows representing five different stages of succession. The pace of succession, measured through the analysis of woody species cover, basal area, height distribution and spatial indices, resulted quite rapid: already after 50 years of abandonment terraces are covered by dense maquis communities. Our study also revealed that different plant species or groups prevail during colonisation dynamics, mostly depending on exposition, a factor which strongly influences also the speed of colonisation by woody species. In this case study, human activity seems to be unnecessary to accelerate the process of renaturation, except in some unfavourable contexts. Species turnover rate, biodiversity value, and structural evolution along progressive succession must be taken into account in nature management and conservation policies of terraced landscapes, which are nowadays one of the most endangered landscape types throughout the Mediterranean area.