【CASK EFFECT】0910F阅读全方位锻炼--越障【SCI】 1-8

tuziduiduiUID: 2599524

【CASK EFFECT】0910G阅读能力基础自测（速度、难度、深度、越障、真题、RAM）
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【CASK EFFECT】0910F阅读全方位锻炼--越障【SCI】汇总贴
https://bbs.gter.net/thread-982020-1-1.html

规则：0 u, r. g$ C/ d+ [4 f5 C

我每天贴出1000字左右的一篇文字7 j) N0 Q, Q- ]( V4 E

没有别的要求，只要大家坚持读完就可以

如果你能坚持一个月，你会发现自己的阅读进化了~
[注]9 K7 C8 w4 {" L
1、直接在电脑屏幕面前做，虽然GRE阅读是在纸上考，但是这个过程会遏制你做笔记，同时给你的阅读造成视觉障碍，也就是把难度训练和抗干扰训练同步结合，增加效率（初期会很累，但是既然大家想要成为高手，那么就别对自己太温柔）

Today's Topic: VEGETATION ANALYSIS

Located along the western seaboard of Ireland, the Burren is one of the largest expanses of limestone karst in Europe and is renowned for its unique flora, which includes arctic alpine and Mediterranean species growing together, an occurrence found nowhere else in the world (Webb and Scannell 1983). The study area is part of the Atlantic biogeographical region of Europe (Roisin 1969), andit has a temperate, oceanic climate characterised by mild, wet winters and cool, moist summers. It is subject to few frosts, but can be prone to severe periods of reduced water availability in the summer months (Osborne et al. 2003). These environmental and edaphic features have contributed to the extant floral assemblage. The arctic alpine species, particularly Gentiana verna and Dryasoctopetala, may be relicts from the glaciations (Hill et al. 2004). These two species’ distributions have also been described as European arctic montane and circumpolar arctic montane, respectively (Preston and Hill 1997). The Mediterranean species (e.g. Neotinea maculata; also called Mediterranean Atlantic (Prestonand Hill 1997)) may be surviving because of the reduced water availability experienced during the summer months (Clabby and Osborne 1994; Jeffrey 2003). Highrain fall causes leaching and acidification of the thin soils, and this further enriches the floral diversity of the Burren area, which, together with Connemara,contains up to 82% of the Irish flora (Webb and Scannell 1983).

The traditional land use is grazing, predominantly by cattle, although sheep were also significant grazers in the past. Grazing usually occurs only in the winter in the Burren uplands, due to the mild climate and nutritious grazing on these limestone grasslands (Haughton 1953). During the summer the cattle are moved down to the more-productive pastures. In recent times, however, due to depopulation and changes in agricultural policies, there has been a relaxation of grazing pressure in the Burren (Dunford and Feehan 2001). Other contributory factors include a switch to heavier and more productive animal breeds, as well as an increased reliance on supplementary feeding, so that grazing pressure is reduced (Dunford and Feehan 2001). In turn, this has contributed to a rapid expansion of scrub in recent times (The Heritage Council 2006), and this is encroaching on to the species-rich limestone grasslands and heaths for which the area is famous. This is not just an Irish problem (Bohnsack 2000): it is also occurring more widely in Europe in extensive grazing systems (Rejmanek and Rosen 1992;Dzwonko and Loster 1998).

Despite the importance of the Burren flora, classification of Burren plant communities has been piecemeal and superficial. There are many reasons for this. Being sucha heterogeneous landscape with a paucity of clear-cut ecological boundaries,many of the communities merge and interdigitate, particularly the grassland and heath communities. Also, because of the intimate mixture of usually quite widely separated species assemblages, such as arctic_alpine and Mediterranean species,the community types found in the Burren do not fit neatly into any existing classification.

As these grassland and heath habitats make up the largest part of the area and are of unique conservation interest due to their species richness, diversity and unusual species combinations, there is a need for a more-comprehensive study of their vegetation.This has become more pressing in recent times, due to the changing grazing practices mentioned earlier. Other changes in land use, such as the reclamation of Burren grasslands, which involved bringing in topsoil and subsequent fertilisation (Drew and Magee 1994), and the change from haymaking to silage,which, in a karstic region with thin soils, affects groundwater quality (Drew 1996),have also impacted on the vegetation, but these are now of minor significance.As most of the Burren is now protected under European law as a suite of Special Areas of Conservation (SACs), good baseline assessment and long-term monitoring are now practical and pressing requirements (Bohnsack 2000).

GENERAL BACKGROUND TO PHYTOSOCIOLOGY OF GRASSLANDS AND HEATHS IN IRELAND
The first description of Irish limestone grasslands was made by Braun-Blanquet and Tu¨xen (1952), who placed them into the class Festuco_Brometea, the dry, calcareous grassland class found throughout Europe. The alliance Brometalia describes the base rich central- and west-European grasslands, and the sub-alliance Mesobromion (Braun-Blanquet and Moor1938) represents the limestone and chalk grasslands of the British Isles and is well-represented in the Burren. Two sub-alliances have been described: the Eu_Mesobromenion and the Seslerio_ Mesobromenion (Oberdorfer 1957). The former is characteristic of eskers and moraines and stable landward dunes in the west of Ireland. It lacks the boreo-temperate Sesleria caerulea. The Seslerio_Mesobromenion sub-alliance is thought to be the most remarkable of all Irish grasslands, with such arctic_alpine species as Dryas octopetala found at sea level. This association has not been found outside of the Burren, and it has affinities with the class of alpine grasslands called Seslerietea variae. The association Asperulo_Seslerietumwithin Seslerio_Mesobromenion was reclassified, being originally classed as subassociations within the Eu_Mesobromenion (Shimwell 1971).

Ivimey-Cook and Proctor (1966)were the first to attempt to classify Burren habitats as a whole. Within these habitats, they identified a range of limestone and mesotrophic grasslands andheaths. Firstly, they described the Centaureo_Cynosuretum (Braun-Blanquet andTu¨xen 1952), pastures on well-drained sites over the Carboniferous shales south of the Burren. They also recognised Centaureo _Cynosuretum on thin, clayey,drift-derived soils in the Burren itself, interdigitating imperceptibly with limestone soils, forming intermediate types between the two extremes. They noted that Braun-Blanquet and Tu¨xen (1952) created a Thymus drucei sub-association to cater for this intermediate formation in western Ireland, but they disagreed with this classification, considering it to be too general. Within the limestone grasslands they recognised three types relevant to this study. Firstly, the Dryasoctopetala_Hypericum pulchrum association (Braun-Blanquet and Tu¨xen 1952), whichoccurs widely throughout the Burren and is very species-rich. Ivimey-Cookand Proctor also recognised a variation on this theme in their Empetrum nigrum_Epipactisatrorubens nodum on steep, high, exposed slopes. A third type was recognised as the Antennaria dioica_Hieracium pilosella nodum, which was found over drift soils. The limestone heaths they recognised were essentially derived from the Dryasoctopetala_Hypericum pulchrum association and the Antennaria dioica_Hieraciumpilosella nodum, but Calluna vulgaris replaced Dryas octopetala. Another heath community recognised was the Arctostaphyllos uva ursi_Dryas octopetala nodum,which occurs at altitudes over 200m and also contains, significantly, Juniperus communis.

From phytosociological studies conducted on lowland Irish grasslands in the early 1970s (O’Sullivan 1982), the upland calcareous grasslands were assigned to a unique sub-alliance called the Seslerio_Mesobromion.This disagreed with Ivimey- Cook and Proctor’s classification, which placed the same community in the Mesobromion erecti. Within this alliance the Dryas octopetala_Hypericumpulchrum association was considered to be the commonest grassland association in the Burren (O’Sullivan 1982). However, this also included variations with Calluna vulgaris on more-leached soils, giving it the appearance of a heath.

The heaths are less studied and less easily defined within the Burren context. A general European classification may be applied using the classes Calluno_Ulicetea (dry,calcareous heath), Oxycocco_Sphagnetea (wet heath) and Carici rupestris_ Kobresietea bellardii/Loiseleurio_Vaccinietea (montane heath) (Fossitt 2000).

The habitats studied here may also be aligned to EU Annex I habitats, which form the Natura 2000 complex of protected habitats or SACs in Europe (European Commission 1999). The calcareous grasslands fall into the categories ‘seminatural dry grasslands and scrub facies on calcareous substrates (Festuco_Brometalia) (priority type for important orchid sites) 6210’ and ‘Juniperus communis formations on heaths or calcareous grasslands, 5130’. Some of the heath communities may fall under the categories ‘European Dry Heaths, 4030’, ‘Alpine and Boreal heaths, 4060’ and, again, ‘Juniperus communis formations on heaths or calcareous grasslands, 5130’.

As can be seen from the above, classification of Burren grasslands and heaths has been complex and has spanned a long time period. This study seeks to further elucidate the classification of grasslands and heaths in the Burren and to provide up-to-date information on the correlation of these groups with their management. Former classifications have aligned heath-like vegetation with grasslands. In an attempt to clarify the situation, the ambiguity between a heath and a grassland in the Burren context has been addressed by enforcing a25%- cover rule as a way of separating out heaths and grasslands, with heaths having more than 25% cover of dwarf shrubs (Fossitt 2000). The rationale for this was based mainly on prior field experience. From that standpoint,vegetation classification was carried out to further clarify the composition of grasslands and heaths of high conservation value in the Burren.

The objective of this study was firstly to describe the grassland and heath vegetation of conservation interest in the Burren using well established vegetation-description techniques. A second aim was to correlate the vegetation data with environmental and management factors. This work is part of a larger study involving the use of satellite imagery to identify the spatial location of habitats likely to be of conservation value within the Burren region (Parr et al. 2006),and to investigate the correlation between these classifications and the vegetation classes defined by image analysis. Both of these methods were employed with a view to monitoring long-term change in the Burren landscape.Only data from the vegetation analysis are presented here.

cjluUID: 2448066

标记一下 表明看过了^^

dairymanUID: 2683905

植被分类？这个limestone我还刚看过，石灰岩嘛
高兴啊

lghscuUID: 2552043

这篇的分类实在是太复杂了！！！

还好结尾部分比较通俗！

qisaimanUID: 2703629

mark it

solosandraUID: 2889127

表示云里雾里扫完了..表示只有结尾有点懂...T T

solosandraUID: 2889127

看的迷迷糊糊..只知道大意是在说burren的以前的分类不好现在换了比较好的
专有名词果然好多..