Distribution of Exotic Plants along Roads in a Peninsular Nature Reserve

To examine the influence of roads on the spread of invasive exotic plants, we studied six species on a peninsular nature reserve. Three species were noxious invasives that we believed to be actively spreading; one of these (goatgrass, Aegilops triuncialis) was a major problem weed that recently invaded the reserve. The other three were ubiquitous and long-established exotics. Based on the idea that roads act as corridors for the spread of weeds, we predicted that the abundances of the three noxious invasives would decline along the roads from the base to the tip of the peninsula, while the abundances of three long-established species would not. However, the only species to show a base-to-tip decline in abundance along the peninsula was a long-established species (oat grass, Avena fatua), and a field experiment showed that habitat suitability could explain this pattern. We did find that the abundance of the invasive A. triuncialis declined with increasing distances from the edges of roads, suggesting that roads act as sources of weed propagules into adjacent grasslands. Our results add support to the idea that roads act as disturbances that promote invasive species, but not to the concept that roads act as corridors for the flow of invasive propagules into new landscapes.     

Food of introduced pumpkinseed sunfish: ontogenetic diet shift and seasonal variation

The pumpkinseed sunfish Lepomis gibbosus introduced into Lake Banyoles (Spain) were predominantly littoral but there was a tendency of large fish to use deeper zones. Their diet was dominated by littoral macrobenthos, particularly amphipods ( Echinogammarus sp.). There was ontogenetic variation in the diet, with small young-of-the-year (L_F<4 cm) feeding on several littoral microcrustaceans, especially the cladoceran Ceriodaphnia reticulata , whereas larger fish shifted to a freshwater shrimp ( Atyaephyra desmaresti ), snails and damselfly larvae. Seasonal variation in diet was linked to resource availability, with consumption of fish eggs and plant debris in spring and summer. In autumn, pumpkinseeds were partially zooplanktivores, preying on the cladoceran Daphnia longispina. The diet of pumpkinseeds in Lake Banyoles and other Iberian populations shows less molluscivory than North American populations. The potential ecological impact of this successful exotic species involves mainly predation on fish eggs and molluscs.     

Biogeographical zonation of the western Iberian peninsula on the basis of the distribution of earthworm species

We used TWINSPAN and CANOCO to investigate the biogeography of the western Iberian Peninsula on the basis of the distribution of earthworms among ninety areas of Galicia, Portugal, Asturias, León, Zamora, Salamanca, Cáceres, Badajoz and Huelva. This part of Iberia is clearly divisible into a Eurosiberian Region in the north and west and a Mediterranean Region in the south and east. For earthworm faunas, however, the limit between these regions is considerably further south than is conventionally accepted on the basis of Rivas Martinez's (1987) vegetation-type classification. Species character- istic of the Eurosiberian Region include Dendrobaena madeirensis, D. octaedra, Allolobophora caliginosa and various species of the genus Lumbricus . Within this region the earthworm fauna of Asturias is clearly distinct from that of Galicia and northern Portugal. Species characteristic of the Mediterranean Region include Allolobophora caliginosa , A. chlorotica and A. rosea , but inventories from this region are most easily identified by the absence or scarcity of those species characteristic of the Eurosiberian Region. Many areas show intermediate characteristics between the two major regions, and in some cases one region 'intrudes' into the other.     

Structure of Benthic Diatom Assemblages from a Mangrove Environment in a Mexican Subtropical Lagoon1

The taxonomic list and the structure of benthic diatom assemblages occurring in fine sediments (silt and sand) from the mangrove forest of the Balandra lagoon in Baja California Sur, Mexico was determined based on seasonal samplings for one year. Assemblage structure was analyzed using several ecological indices for estimating diversity (H'), dominance (REDI), equitability, and similarity. A total of 230 diatom taxa were identified and include 109 new records for the Baja California peninsula coast. Taxa representative of highly productive and hypersaline environments were common. Assemblages were characterized by a few abundant species and many uncommon or rare taxa. High diatom diversity estimates at all sampling sites during all seasons suggest that diatom assemblages in sediments of the Balandra lagoon represent a quasi-pristine environment.     

Spatial ecology of the European wildcat in a Mediterranean ecosystem: dealing with small radio-tracking datasets in species conservation

Despite some populations of European wildcat Felis silvestris in central Europe are stable or increasing, the Iberian subpopulation is in decline and is listed as 'vulnerable'. In Portugal, little is known about wildcat populations, making conservation policies extremely difficult to define. Furthermore, the secretive behaviour of these mammals, along with low population densities, make data collection complicated. Thus, it is crucial to develop efficient analytical tools to interpret existing data for this species. In this study, we determine the home-range size and environmental factors related to wildcat spatial ecology in a Mediterranean ecosystem using a combined analysis of habitat selection and maximum entropy (Maxent) modelling. Simultaneously, we test the feasibility of using radio-tracking locations to construct an ecologically meaningful distribution model. Six wildcats were captured and tracked. The average home-range size (MCP95) was 2.28 km² for females and 13.71 km² for one male. The Maxent model built from radio-tracking locations indicated that the abundance of the European rabbit Oryctolagus cuniculus and limited human disturbance were the most important correlates of wildcat presence. Habitat selection analysis revealed that wildcats tend to use scrubland areas significantly more than expected by chance. A mosaic of scrublands and agricultural areas, with a higher proportion of the former, benefits wildcat presence in the study area; however, species distribution is mainly constrained by availability of prey and resting sites. The Maxent model validation with camera-trapping data indicated that highly adequate model performance. This technique may prove useful for recovering small radio-tracking datasets as it provides a new alternative for handling data and maximizing the ecological information on a target population, which can then be used for conservation planning.     

Natural and human-mediated factors in the recovery and subsequent expansion of the Purple swamphen Porphyrio porphyrio L. (Rallidae) in the Iberian Peninsula

Instances of range contraction and population decline in bird species in Europe are more common than cases of recovery following decline. Here we report on the recovery and expansion processes of an endangered bird species in Europe, the purple swamphen (Porphyrio porphyrio L., Rallidae), with special reference to the Iberian Peninsula, its main distribution area in Western Europe. After a drastic decline during the first half of the 20th century, which restricted its range to a few areas in southern Spain, the Iberian population has recovered. Currently, the species occurs in a range similar to the one it had at the beginning of the 20th century, and has even colonized new areas. These processes seem to be the result of both human-mediated (effective protection of the species and suitable habitats; success of reintroduction programs as expansion focuses of birds colonizing nearby and distant regions [>300 km] wetlands) and natural factors (inter- and intra-seasonal cycles of wet and dry years). Thus, we found a significant relationship between rainfall and bird abundance and productivity, suggesting that such inter- and intra-seasonal cycles may have significant effects on demographic parameters that could be related to the expansion process. Finally the species shows remarkable adaptability, as proven by data on breeding success in recently colonized areas and the ability to breed shortly after reintroduction. We hypothesize that saturation of breeding habitats in established areas, a reasonable habitat continuity and favorable environmental conditions, and protection have facilitated the dispersion of birds.     

Colonization history of Mallorca Island by the European rabbit,Oryctolagus cuniculus,and the Iberian hare,Lepus granatensis (Lagomorpha: Leporidae)

The Mediterranean islands have a long history of human‐mediated introductions resulting in frequent replacements of their fauna and flora. Although these histories are sometimes well documented or may be inferred from paleontological studies, the use of phylogenetic and population genetic reconstruction methods provides a complementary perspective for answering questions related to the history of insular species. In the present study, we infer the colonization history of Mallorca (Balearic Islands) by the European rabbit (Oryctolagus cuniculus) and the Iberian hare (Lepus granatensis) using sequence variation of the mitochondrial DNA control region from continental and insular specimens (total of 489 sequences). Additionally, the taxonomic identity of Mallorcan L. granatensis was confirmed using a diagnostic nuclear marker. For both Mallorcan rabbits and hares, genetic diversity was comparable to the continental populations, suggesting the introduction of multiple lineages. Two Mallorcan haplogroups were found in hares, which likely correspond to two introduction events. Rabbits from Mallorca were identified as belonging to the subspecies Oryctolagus cuniculus cuniculus, and may have been originated both from Iberian and French populations. The molecular estimates of the timing of the colonization events of the Mallorcan lagomorphs are consistent with human‐mediated introductions by early settlers on the islands. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 748–760.     

我国雷州半岛典型农田大气氮沉降

近一个半世纪以来,粮食和能源需求导致活性氮创造的急剧增加,从而导致各种活性氮的排放及其沉降的增加。氮沉降引起土壤酸化,水体富营养化,及敏感生态系统植物多样性的丧失等不良生态效应。因此定量不同生态系统氮沉降量对于确定该地区生态系统安全及氮循环有重要意义。南方地区氮沉降已有较多研究,主要集中于湿沉降的研究,选取雷州半岛地区典型农田综合研究了大气氮素的干湿沉降。结果表明:大气活性氮浓度NH3、HNO3、NO2、pNH+4和pNO-3浓度分别为5.62、0.88、3.16、3.30、2.02μg N/m3。采用欧洲氮沉降监测网的氮干沉降速率估算了大气氮干沉降量为17.6 kg N hm-2a-1。大气降雨NO-3-N浓度为(0.86±0.36)mg N/L,NH+4-N浓度为(1.11±0.68)mg N/L,大气降雨无机氮含量冬季最高,夏季最低。大气无机氮年湿沉降总量为25.3 kg N/hm2。湿沉降NH+4-N和NO-3-N,干沉降NH3、HNO3、NO2、pNH+4、pNO-3分别占沉降量的30.8%、28.0%、23.7%、5.4%、2.8%、3.9%、5.4%。湿沉降NH+4和干沉降NH3在氮沉降中占主导地位显示氮肥施用导致的NH3挥发对大气活性氮浓度及氮沉降的显著贡献。鉴于研究可观的氮沉降量(总沉降量42.9 kg N hm-2a-1),其向农田的养分的输入不容忽视;氮沉降对该地区水体,自然生态系统的环境影响需要受到重视。     

基于植物区系的雷州半岛天然林群落树种特征研究

传统涉及植物区系和重要值的研究思路通常先分析该地区的植物区系组成,然后再分析该区域某个区系中某个优势种的重要值。该种思路存在未能完全同时反映不同区系不同植物物种参与群落构建和其在群落中的地位等缺陷。为了解决上述问题,构建物种群落指数,以雷州半岛天然季雨林的木本植物为对象开展研究。基于雷州半岛8个区域的80个20 m×20 m固定样地的实测数据,通过植物区系+重要值的方式构建物种群落指数开展研究。(1)湛江云脚村群落、湛江湖光岩、雷州鹰峰岭、雷州足荣村、徐闻双洋村、廉江高桥和廉江谢鞋山皆以热带区系分布为主导,数值皆大于0.8以上。廉江根竹嶂地理位置特殊,以9区系东亚和北美洲间断分布为主,数值接近0.5。(2)第2区系树种在雷州半岛群落树种组成和构建中处于优势地位,最高值为0.4261,朴树和鹅掌柴为优势种;第3区系树种和第6区系树种处于劣势地位;第4区系树种处于优势地位,最高值为0.3339,橄榄为优势种;第5区系树种处于优势地位,最高为0.3787,阴香和樟树为优势种;第7区系树种在雷州半岛地区群落内分布较为均衡,普遍适应各个样地。本研究表明,雷州半岛地区带有明显的热带性区系特征;物种群落指数能够较好的体现雷州半岛样地各个区系树种在植物群落组成的特征。     

辽东半岛的旧石器文化

辽东半岛旧石器研究可追溯至20世纪30年代, 但较大的进展则在70年代以后所取得。迄今为止, 包括以庙后山石器工业和营口金牛山人类化石为代表的旧石器早期、以海城小孤山下层石器工业为代表的旧石器中期和以海城小孤山中层石器工业、骨角制品和前阳人类化石为代表的旧石器晚期组成的辽东旧石器文化发展序列已经初步建立起来。从古生态环境和石器技术、类型学而言, 辽东半岛旧石器文化和华北同期文化存在密切的联系。