The relatively small succulent flora of the part of Ecuador considered here includes some 25 species of Cactaceae (Madsen 1989), about 4 poorly understood species of Echeveria (currently being studied for the Flora of Ecuador project) and the endemic Peperomia graveolens. Of the Cactaceae, 8 species are endemic and of these Armatocereus brevispinus, Cleistocactus leonensis, and Espostoa frutescens are rare and restricted to the Rio Catamayo valley (together with some other, non-endemic succulents), and Weberocereus rosei, known from only 2 natural sites in Chimborazo and Cañar Provinces, is regarded as endangered (Hunt 1992) and is not included in any protected area. Likewise, there appear to be no reserves that would afford any protection to the species restricted to the aforementioned Catamayo valley. The non-endemic Melocactus peruvianus has apparently become extinct in south-western Ecuador, but is widespread and thought to be abundant in neighbouring Peru.
The part of Peru included here has the largest but least understood succulent plant flora in South America and, in the Americas, in terms of succulent plant diversity Peru is second only to Mexico. The following discussion utilises the annotated checklist of the flowering plants of Peru (Brako and Zarucchi 1993), which accepts 247 taxa* of Cactaceae (accepted and provisionally accepted species mainly according to Hunt 1992), 75 per cent said to be endemic; 26 species of Portulacaceae, 35 per cent endemic (especially Cistanthe); 20 species of Crassulaceae (Tillaea and introductions excluded), 50 per cent endemic; and one non-endemic succulent Bromeliaceae, Deuterocohnia longipetala. In addition, of the many species of Peperomia known from Peru, at least 10 are succulent (3 endemic), and there are various endemic Nolana spp., but it is uncertain which of these qualify as succulents. There appear to be no endemic Aizoaceae or Agavaceae.
It is unclear whether any of Peru's endemic succulents are included within the few protected areas indicated in WCMC (1992).
* At least 13 taxa of Cactaceae are almost certainly synonyms and 3 spp. have been recorded in error (see Neoporteria), while a further 16 represent interspecific or intergeneric hybrids.
At generic level the following are endemic and emphasise the importance of the Andean Region (especially subdiv. I-II): Calymmanthium (1-2 spp., Andean I); Lasiocereus (2 spp., genus of uncertain taxonomic status, Andean I-II); Matucana (22 spp., various only provisionally accepted, Amazonian and Andean I-III); Mila (1-3 spp., Andean I-II and Coastal, probably not threatened); Oroya (1-3 spp., Andean II-III); Rauhocereus (1 sp., Coastal).
As the Table 3.19 indicates, the Amazonian Region of Peru appears to be the least important in terms of succulents, and the majority of the species it holds and its endemics are found in close proximity to the adjacent Andean I subdivision and do not relate to the vast Amazonian Region in the sense of Takhtajan (see above). There is no information available on the conservation status of succulent plants from this region.
Subdivisions I and II of the Andean Region of Peru (500-3500 m altitude) are extremely rich in succulent plant species, and on average two thirds of these are endemic. These subdivisions include dry vegetation with conspicuous, large-shrubby or treelike cacti from the genera Armatocereus, Browningia, Cleistocactus, Corryocactus, Echinopsis, Espostoa, Haageocereus, and all of which are credited with numerous species (Hunt 1992; Brako and Zarruchi 1993). The lower-growing, endemic genus Matucana also has the majority of its species in subdivisions I and II. The number of species in these genera will possibly be reduced by 50 per cent or more once proper taxonomic studies are accomplished, but the level of endemism is
Browningia candelaris, Quebrada Tinaja, Peru.
likely to remain high. As in the case of the previous Peruvian region, very little is known of the conservation status of succulents in these subdivisions, but shifting agriculture and especially overgrazing by livestock, which are inhibiting regeneration of species such as the tree forming cactus Browningia candelaris (Anderson and Kattermann, pers. comm. 1994), may be placing some species in danger.
Andean subdivision III, i.e. land above 3500 m altitude, is less rich in succulent species than that at lower Andean elevations and, as might be expected, the taxa it includes are markedly different. Highly specialised, alpine species from the cactus genera Echinopsis (Eobivia), Matucana, Oreocereus, Oroya, Neowerdermannia, and Opuntia are complemented by various endemic Echeveria and Cistanthe species, most of whose ranges commence in the Andean II subdivision. Endemism is slightly lower, at about 59 per cent, but there may be taxa at risk, at least in the drier parts of south-eastern Peru, where agricultural practices similar to those described for the high Andes of Bolivia are assumed to occur (see below, especially with reference to Neowerdermannia).
In terms of numbers, with 49 species the Coastal Region of Peru is the third most important of the five subdivisions recognised here, but has the second highest ratio of endemics (71.4 per cent). However, it is the part where most of Peru's human population is located. The Region is divisible into two basic zones, the southern, fog-influenced 'lomas' (which represent a continuation of the Chilean Coastal Fog Desert, see below), and the northern Sechura Desert, which is contiguous with the dry southwestern corner of Ecuador. According to recent observations, habitat alteration, through urban expansion and overgrazing, is a serious problem in areas where water availability permits the establishment of human settlements. The seasonal 'garua' or coastal fog supports annual grasses and other temporary vegetation. Livestock are transported to coastal areas to graze upon these ephemeral plants and nurse plants and juvenile cacti are severely impacted in some areas (Anderson, pers. comm. 1994).
The Andean part of Bolivia can be subdivided into three zones, the high Andes to the west and the lower inter-andean valleys to the east (which descend until the Chaco is reached) and, partly between these and expanding to the north, the very humid Yungas forest.
High Andes. A large part of Bolivia is situated in the region where the high Andes divide and expand into two major mountain chains with the altiplano between (the 'nudo andino' or Andean knot). The altiplano is a large plateau surrounded and cut through by volcanic, metamorphic, or in many cases sedimentary mountains, the latter having habitats most seriously affected from the conservation standpoint. The rainfall is greater towards the northern end of this area and permits dense human settlements to exist despite the high elevations of the region (3000-5000 m). The main activity is traditional subsistence agriculture, most produce being consumed locally, and heavy machinery is used only in a few places where there are wider plains of clayey soil. Most cultivation takes place on steep slopes, which are sometimes terraced. The farmers collect the many stones from the small fields (average minimum of 100 m2), piling them up at the field edges, having first removed all the natural vegetation of scattered shrubs, grasses, other herbs and cacti. Then the men take the ox-plough to the field and are followed by the rest of the family who plant crops such as potatoes, broad beans, corn, and Chenopodium quinoa. Each field is used for one year then left fallow for 3-7 years, or less if the locality is highly populated. The summer rains expose the clay surface which is then eroded by the wind during the dry winter season. A good example of this agricultural system is the sedimentary plateau at 5000 m elevation near the airport at La Paz. In this region, which presumably continues into the dry Andes of adjacent Peru, all the vegetation is strongly affected by human activity. The traditional agricultural techniques continue to expand into new areas. The perennial vegetation disappears leaving only shortlived herbs and shrub seedlings. The cacti, which are virtually the only succulents of the region, almost disappear. If one estimates the density of cacti per square metre, in a hectare plot about 10,000 plants are destroyed
Lepismium bolivianurn, known only from the Yungas forests of Depto. La Paz, Bolivia.
during clearance. If there is an increase of 1000 plots each year, then an annual destruction of 10 million cacti can be imagined. The genera with species most affected by this are Echinopsis (Lobivia, Mediolobivia), Opuntia (Maihueniopsis and the Airampo Group), Corryocactus, Parodia, Rebutia, and Weingartia. Many of their Bolivian species are endemics.
Another disturbing development in the high Andes of Bolivia is the planting of Eucalyptus to provide wood which is locally in shortage. On the stony slopes where it is not possible to grow other crops the trees are planted only two metres apart over large areas of land, such as can be seen near Sucre. The shade cast by these plantations kills all the low-growing native vegetation including cacti such as Echinopsis (Lobivia) spp. and endemic Rebutia (Sulcorebutia) spp. Also of special concern is the status of Neowerdermannia vorwerkil, a widespread species at high altitudes in northern Argentina, Bolivia, and probably Peru (TV. peruviana), whose swollen underground stem is harvested at certain times of year as a substitute for potatoes. It can even be found for sale in local markets. Despite its wide distribution and relative abundance it may soon become endangered unless its cultivation can be encouraged, as recently proposed during a course on Cactaceae at the University of La Paz (by W. Hoffmann et aL). The same university is currently in the early stages of establishing a botanic garden, which should help in the ex situ conservation of some of the cacti threatened in this region. At present (1994) it does not have facilities for the cultivation of the smaller globular cacti, but has planted some of the larger-growing species (Metzing, inlitt.).
Not all human activities in this region result in a negative influence on the cactus flora. Disturbance or clearance of the natural vegetation sometimes increases the abundance of particular species by reducing competition, e.g. Opuntia spp., the larger Echinopsis spp. etc., and, in degraded Prosopis woodland, columnar cacti including Oreocereus may become more abundant.
Yungas. This narrow band of rain forest extends along the eastern slopes from the central Bolivian Andes northwards into Peru and is notable mainly for endemic representatives of the primarily epiphyic Cactaceae tribe Rhipsalideae, namely Lepismium crenatum, L. lorentzianum, L. micranthum, L. miyagawae, L. monacanthum, L. paranganiense, L. incachacanum, L. bolivianum, Rhipsalis cuneata, and R. goebeliana. The conservation status of these cannot be determined at present, but most are known from only one or very few localities. Some have been seen recently (e.g. R. cuneata), while others await recollection (e.g. L. miyagawae).
Dry Inter-andean valleys. East of the altiplano at altitudes of 1000-2500 m there is a dry vegetation which shares some characteristics with the Chaco. Columnar cactus forests, known as cardonales, are found in the drier parts of this zone, which has a much lower density of human population than the higher region to the west. Habitat modification is limited to river valleys and includes primitive cattle ranching (with consequent soil erosion through trampling) and forestry plantations. In addition, some of the natural forest on the drier slopes is being cleared for charcoal production, all these pressures being of concern to conservationists studying locally endemic macaw species (M.B. Christiansen, pers. comm.). Treelike and shrubby, endemic cacti commonly represen ted in this forest include Cleistocactus patviflorus, C. samaipatanus, Corryocactus pulquinensis, Harrisia tetracantha, Neoraimondia herzogiana, Opun tia cochabambensis, Pereskia diaz-romeroana, and P. weberiana. These and other, non-endemic species (e.g. the epiphytic Lepismium ianthothele) may not be under serious threat at present, but the status of more restricted endemics, such as Samaipaticererrs corroan us, Yungasocereus inquisivensis, Echinopsis (Lobivia) caineana, Gymnocalycium riograndense, Parodia mairanana (P. compressa), and Espostoa (Vatricania) guentheri (Rio Grande drainage system), needs to be monitored. The first two are monotypic genera, while the last-named follows river valleys where cultivation is more prevalent.
The Andes of north-western Argentina comprise the western Cordillera del Limite and the southern extension of the Cordillera Real of Bolivia, which, as in the latter country, surround the altiplano plateau or Puna. Altitudes range from 500 to 5000(-6950) m, but succulents are absent from the higher parts, where cold is too intense, their altitudinal limit reaching 5000 m in Jujuy in the north, but down to c. 2500 m in San Juan, and less than 1000 m at the southernmost part, to the south of Mendoza, where the climate becomes increasingly wet.
Although succulent species are numerous and many are endemic, relatively few seem to be of conservation concern on present knowledge. On stony slopes in the
Blossfeldialiliputana in habitat on cliff in north-west Argentina.
Eriosyce aurata after commercial collection in habitat, northern Chile.
Puna, the attractive, white-woolly, non-endemic Oreocereus trollii was formally collected for sale elsewhere in the country as a decorative garden plant, but this has largely stopped with the realisation that most plants soon die. Specimens growing near to roads are still collected by inexperienced tourists, but it remains abundant in less accessible areas. Other succulents from this habitat, such as Anacampsews kurtzii and Parodia maassii, are either very common or too insignificant to attract attention from collectors.
The dry valleys of the lower Prepuna botanical province have an abundance of succulents from the families Bromeliaceae (Abromitiella, Deuterocohnia, Dyckia), Cactaceae (including the endemic Eriosyce subsect. Pyrrhocactus with 5 spp.), Crassulaceae, Piperaceae (Peperomia) and Portulacaceae, and there are vegetation types dominated by succulents including treelike forms (e.g. Echinopsis pasacana). A remarkable, highly specialised, dwarf cactus is Blossfeldia liliputana, but this, like most species, is not significantly threatened by human influences, and even more local taxa, such as Sedum jujuyense (endemic) and Xenia vulcanensis (also known from southern Bolivia), are safe, inhabiting very steep slopes. Other local endemics include Parodia chrysacanthion, P. penicillata, and P. nivosa, the last-named requiring regular monitoring since a road passes through the only locality known.
There is a special conservation problem in the mountains of Tucuman and northern Catamarca, where broad plains have been cleared for the production of seed potatoes, the region being free of potato virus. This has caused the destruction of numerous populations of the endemic Echinopsis (Lobivia/Soehrensia) bruchii, E. schreiteri (L. stilowiana), and Gymnocalycium baldianum. Fortunately each of these is also found on adjacent stony slopes that are unsuitable for potato culture, but our knowledge is incomplete and it cannot be ruled out that there are other, more threatened species restricted to the plains favoured for this kind of agriculture. Species that are abundant on stony ground unsuitable for cultivation and which can definitely be stated to be out of danger include: Denmoza rhodacantha, Echinopsis (Trichocereus) angelesiae, E. (T.) candicans, E. (T.) thelegonoides, and E. leucantha.
(Region de Coquimbo northwards). This part of Chile comprises two types of habitat, the Coastal Fog Desert with irregular winter rainfall and the montane desert far inland with summer rainfall, the two being separated by the essentially lifeless Atacama Desert.
Coastal Fog Desert. This is very important in terms of endemic taxa, with more than 65 species, and it was the subject of a conservation field survey sponsored by WWF-US (Anderson et al. 1990). Amongst the Cactaceae (ibid.: 18-19; Hunt 1992) the remarkable genus Copiapoa, with about 25 species, is endemic, and the treelike genus Eulychnia (6 spp.) is almost endemic (1 sp. in S Peru). Other cactus taxa with endemic species are Eriosycc (Neoporteria), with 18 spp. restricted to the region (Kattermann 1994), Echinopsis (Trichocereus) (6 spp.), and Haageocereus (1 sp.), and there is also the taxonomically isolated Opuntia miquelii. Representatives of other families are Montiopsis and Cistanthe (Calandrinia pro parte, Portulacaceae) with 10 or more
Copiapoa desertorum plants uprooted, Chile.
Discocactus zehntneri ssp. boomianus, CITES Appendix I cactus known from only three populations.
mostly endemic spp., Deuterocohnia chrysantha (Bromeliaceae, endemic), Euphorbia lactiflua, Oxalis carnosa, 0. gigantea, and 0. succulenta, and various highly succulent Nolana spp. Vegetation in this region is very patchy and is represented by small green islands interspersed with extensive barren areas, their distribution depending on how much moisture deposition from the fog (locally termed 'Camanchaca') takes place, which in turn depends on local land relief, height and steepness of coastal bluffs, and direction of the deep dry valleys ('quebradas'). Almost every one of these 'quebradas' has a distinct and characteristic vegetation, with some endemic species probably restricted to one 'quebrada' only. The most up to date, comprehensive study about phytogeography, climatology, and ecology of this region was published by Rundel et al. (1991). However, the flora of the Coastal Fog Desert, known to be extremely rich in endemic species, remains poorly studied.
Hoffmann and Flores (1989) and Hunt (1992) assign IUCN conservation status categories to the above Cactaceae and Bromeliaceae, but these were reinterpreted by Anderson et al. (1990) and in general the though many are Rare, are not considered to be seriously under threat in view of the remoteness of the area and generally limited human influence. However, there are important exceptions to this, notably as a consequence of mining and associated ore treatment activities, goat grazing, rubbish dumping, local harvesting as timber, and commercial and amateur collection for the succulent plant hobby. The species affected, all of them cacti and regarded as Vulnerable or Rare, are as follows: Copiapoalaui (Rare, one of the smallest of all cacti and therefore intensively searched for by collectors near Esmeralda); C. megarhiza (Rare and insufficiently known, but certainly Endangered in the locality surveyed in 1990 at Paipote, near Copiap6, due to very heavy pollution from ore processing); C. rupestris (Rare, and apparently now extinguished at its northernmost site, north of Taltal, by collecting for the horticultural trade); Eriosyce laui (Vulnerable, from mining subsidence destroying its montane habitat south of Tocopilla); E.(Neoporteria) (Vulnerable, from rubbish dumping and urban spread in the vicinity of Huasco); E. occulta (Vulnerable and now apparently extinct through over-collection at the type locality near Taltal, the more southern of its two known sites); E. heinrichiana ('N. jussieui') and E. senilis ssp. clquiensis ('N. nidus') (Rare/Vulnerable through overgrazing by goats in the region of La Serena); Eulychnia iquiquensis (Vulnerable - all populations known in northern Chile are dying and there is no regeneration perhaps due to climatic changes leading to greater aridity); Eulychnia sp. indet. (Vulnerable, Paposo/Taltal region, where affected by acid fumes from ore processing and local extraction for timber). Eriosyce aurata (E. sandillon), a widespread Chilean endemic ranging into Central Chile, is sometimes collected for planting in local gardens and may be vulnerable where it occurs near large towns, e.g. in the La Serena area. Echinopsis glauca, Eulychnia aricensis, and Haageocereus australis are possibly Rare/Vulnerable but insufficiently known taxa.
Uebelmannia pectinifera ssp. flavispina, Minas Gerais, Brazil. CITES Appendix I.
which may not be regenerating due to the same climatic changes as are affecting Eulychnia iquiquensis.
This part of Chile includes the established Pan de Azúcar and Fray Jorge National Parks (WCMC 1992) and another of considerable size under consideration since 1985 in the region of Paposo (north of Taltal). These areas could protect a considerable number of the succulents found in the region, and the more so if recommendations of the Anderson et al. (1990) report for the modest enlargement of the more northern parks are carried out. This would give protection to additional species currently just outside park limits (amongst these the Rare Copiapoa rupestris and C. desertorum from south of Taltal, a second population of the rare C. laui, and two Copiapoa sp. nov. from Quebrada Botija, 70 km north of Paposo). However, one problem to be resolved in the Pan de Azucar National Park is the increasing population of Guanacos (from 17 to >300 in the period 1983-1990), which graze upon the tuberous rootstocks of the geophytic cacti.
Montane Desert. Phytogeographically the Montane Desert is almost completely separated from the Coastal Fog Desert. The cacti there (no other succulents are known for this region) have affinities to those from the adjoining Andean countries. At lower elevations (between c. 20003000 m) there seems to be no regeneration of any cactus population at present, which may be due to climatic changes. The conservation status of the cacti from the region has been assessed by Hoffmann and Flores (1989). The vulnerable taxa they identify are: Browningia candelaris, Oreocereus (Arequipa) australis (endemic), 0. (A.) hempeliana, Haageocereus fascicularis (endemic), Neowerdermannia chilensis, Echinopsis atacamensis (endemic, but perhaps conspecific with E. pasacana from Argentina), E. uebelmannianai (endemic), and Opuntia conoidea (endemic). The taxonomic and therefore conservation status of all Opuntia taxa from the region remains unclear. All cactus populations from the higher elevations (>3000 m) seem to be out of danger. Corryocactus brevistylus and Neowerdermannia chilensis, assessed by Hoffmann and Flores as Vulnerable, are widespread and there is no evidence that N. chilensis is collected for human consumption as occurs with N. vorwerkii in Bolivia. In this part of Chile the Lauca National Park and some other Reserves have been established (WCMC 1992), but these include none of the threatened species.
The Brazilian Region
This vast region is further divisible on a country/vegetational basis as follows:
Four major vegetational areas are recognised here, in order of their importance for succulent plants. The largest succulent genera, each with 15 or more endemic species,
Melocactus pachyacanthus ssp. viridis, known only from two sites surrounded by agricultural fields, northern Bahia, Brazil. Endangered.
are Dyckia, Encholirium, Pilosocereus, Rhipsalis, and Melocactus (Smith and Downs 1974; Zappi 1994; Barthlott and Taylor 1995; Taylor 1991b). Only recently has the importance and plight of Brazilian succulents been specifically addressed by that country's authorities, with the proposal to place various endangered cacti on Appendix I of CITES. However, the most serious problem at present is the almost complete lack of reserves to protect the many rare and endemic terrestrial (rather than epiphytic) succulents from the dry parts of north-east and south-east Brazil, and from the rocky East Brazilian Highlands, which rise out of the dry zone.
Eastern Brazil. This area includes the seasonally dry, deciduous thorn forests ('caatinga' and 'agreste') and associated highlands ('campos rupestres') of northeastern Brazil, plus rock outcrops in the savannas ('cerrados') of the central/eastern parts of the adjoining states of Tocantins and Goias, and, going south into south-eastern Brazil, dry areas and campos rupestres in the states of Minas Gerais (excluding the extreme west and south-west) and Espirito Santo (inland valleys and inselbergs only). This area is home to about 100 broadly defined Cactaceae species (90 per cent endemic, including 10 endemic genera, Taylor and Zappi, ined.), c. 80 more narrowly defined, ± succulent species of Bromeliaceae, represented by Encholirium (endemic, c. 20 spp.) and numerous species of Dyckia (c. 90 per cent endemic), and many, mostly weedy and inadequately understood Portulaca and Talinum taxa, besides a few succulents from other families.
Of special conservation concern are endemic species of the cactus genera Discocactus (6 spp., 5 endemic), Uebelmannia (endemic, 3 spp.), and Melocactus (M. conoideus, M. deinacanthus, M. glaucescens, M. paucispinus), which are Critically Endangered, Endangered, or Vulnerable and have been placed on Appendix I of CITES to afford them protection from the export trade. Most of these endemics are known from only one or very few localities, where the populations number between less than ten to at most 500 individuals. Discocactus horstii, D. placentifomis, D. pseudoinsignis, D. zehntneri ssp. boomianus, Melocactus glaucescens, M. paucispinus (both known from only two or three small sites each), and all Uebelmannia spp. (U. buiningii Critically Endangered, cf. Braun and Esteves Pereira 1988) are threatened primarily by trade, including regular collection of plants for seed production, or of seeds in habitat for wholesale export in large quantities. Discocactus bahiensis and Melocactus deinacanthus (the latter with only two populations known) are more seriously threatened by agricultural development, and both the former and D. zehntneri ssp. zehntneri had their ranges and numbers significantly reduced by inundation from the Represa de Sobradinho, a huge dam lake created in the 1970s on the Sao Francisco River (Bahia/Pernambuco). Repeated commercial collecting was only partly responsible for the decline of Melocactus conoideus, a species Critically Endangered due to the extraction of the quartz gravel in which it grows, and threatened with extinction at its type and only known locality above the expanding city of Vitoria da Conquista, southern Bahia (Taylor 1992). Some documented plants still exist in cultivation and could be used to effect its reintroduction to the wild, should attempts to find new populations near its original habitat fail. The tall columnar species, Micranthocereus dolichospermaticus (from karstic Bambui limestone outcrops of difficult access in south-west Bahia), has attractive young seedlings appreciated by the horticultural trade and may be in danger from the practice of felling mature individuals to facilitate the collection of seed for wholesale export. Export of seed is not controlled for CITES Appendix II species such as this, which deserves further investigation in habitat to determine if it should be proposed for Appendix I listing.
The driest zone of eastern Brazil, namely the 'caatinga' and its ecotones with Atlantic Forest to the east (known as 'agreste'), dry forests to the south (in Minas Gerais and Espirito Santo) and savannas ('cerrados') to its west (Maranhao to Goias), represents a severely disturbed ecosystem (Andrade-Lima 1981), which has been subject to forest clearance for agriculture over more than two centuries. However, in general many succulents have probably suffered less than most other plants as a consequence of their frequent occurrence on rock
Espostoopsisdybowskii, Bahia, Maracas, Brazil.
outcrops unsuitable for cultivation or livestock grazing. Thus, many species of succulent Bromeliaceae (Dyckia, Encholirium), Coleocephalocereus, various Pilosocereus, and some Melocactus (e.g. M. ernestii, M. orcus) have significant populations in places dominated by gneiss/granite inselbergs, which are probably at less risk from habitat modification unless situated near expanding towns. Of those cacti that are not mainly restricted to rock outcrops, the least threatened are those which seem able to regenerate when their forest habitat is cut over. These include Cereus jamacaru, Pereskia grandifoliu.P. bahiensis, and P. stenantha, and all are also conserved by their use in the form of impenetrable livestock fences or as hedges surrounding homesteads, both within and sometimes outside their natural ranges. A few very widely distributed endemic cacti which inhabit little-utilised or sufficiently diverse habitats are probably not at risk, even though their numbers may have dropped significantly, e.g. Facheiroa squamosa, Harrisia adscendens, Opun tia inamoena, Pilosocereus gounellei ssp. gouneliei and P. pachycladus s.l. However, other, mostly wide-ranging succulents that are mainly found growing in the soil of the caatinga-agreste, or on exposed rocks more or less level with the floor of the surrounding thorn forest, have suffered considerable reductions in their distributions and abundance through forest clearance. Endemic cactus species affected in this way, whose ranges now appear to be strongly fragmented, include Arrojadoa penicillata, A. rhodan tha, Brasilicereus phaeacan thus, Cereus albicarrlis,
Coleocephalocereus goebelianus, Melocactus salvadorensis, M. zehntneri, Opuntia palmadora, Pereskia aureiflora, Pseudoacan thocereus brasiliensis, Pilosocereus ca tingicola s.l., P. floccosus ssp. quadricostatus, P. flavipulvinatus, P. glaucochrous, P. pentaedrophorus s.l., Stephanocereus leucostele, Tacinga braunii, and T. funalis. Although most of these are unlikely to become seriously threatened in the immediate future, regular monitoring is essential if some are not to become endangered in the longer term. The same applies to some locally abundant and spectacular caatinga bottle-trees or 'barrigudas' from the Bombacaceae (Cavanillesia arborea, Ceiba insignis s.l, C. jasminodora and Ceiba sp. indet. [SW Bahia]), whose habitats have decreased sharply, especially in southern Bahia, adjacent Minas Gerais and drier parts of western Espirito Santo.
Of more urgent concern are Melocactus azureus ssp. azureus and M. pachyacanthus, which have smaller ranges and are restricted to local low-lying outcrops of limestone, whose vegetation gets destroyed when the surrounding caatinga forest is cleared for cultivation. These taxa should be classified as Endangered on the basis of their known populations (see Taylor 1991b: 40-41), but further field studies are needed in the remoter parts of northern Bahia state, where additional and less disturbed habitats could exist.
Other succulents from the caatinga, whose native populations may be threatened, include the complex of species allied with Euphorbia phosphorea, certain members of the Cucurbitaceous genus Apodanthera (e.g. A. succulenta, A. congestiflora), Dioscorea basiclavicaulis, and Marsdenia sessilifolia, but, unfortunately, little is known about their conservation status, although some appear to be Rare or of restricted distribution (Rizzini 1989, Jeffrey 1992, Rizzini and Mattos-Filho 1992). Even if succulents found on raised rock outcrops within the caatinga are generally at less risk from agricultural development etc., some, and particularly those close to roads or human settlements, are at risk from the quarrying of stone for building materials. Those found only on limestone outcrops are probably most at risk (viz. Encholirium [3 spp. indet. cited by Andrade-Lima 1977: 191], Facheiroa cephaliomelana s.l., Melocactus azureus ssp. ferreophilus, M. levitestatus, Micranthocereus dolichospermaticus, M. estevesii, Pilosocereus albisummus, P. densiareola tus, P. diersianus, P. Hexibilispinus, P. floccosus, P. gounellei ssp. zehntneri, Opuntia saxatilis, 0. estevesii), but gneiss, granite, and other crystalline rocks are also quarried and, if this should take place at the site(s) of one of the very local taxa, extinction could be sudden (e.g. Marsdenia megalantha [Mun. Iramaia, BA], Encholirium sp. nov. [Mun. Tanhagu, BA], Coleocephalocereus purpureus, Espostoopsis dybowskii, Melocactus deinacanthus, Opuntia werneri). 0. werneri is already threatened at one of its localities through granite quarrying (Rui Barbosa, BA) and the other species are each known from only one or two localities.
The few and mostly relatively small protected areas within the vast caatinga zone are as follows:
• Parques Nacionais Serra de Capivara (includes
Pilosocereus piauhyensis) and Sete Cidades (both in Piaui state),
. Estagao Ecologica de Serido (Rio Grande do Norte),
• Reserva Ecologica Raso da Catarina (NE Bahia),
• Reserva Biologica Federal da Serra Negra
. Areas de protegao ambiental da Serra de Baturite (Ceara) and Gruta dos Brejies/ Vereda do Romao Gramacho (Bahia, includes Melocactus azureus), . Estagao Ecologica Federal de Aiuaba (Ceara).
These can offer protection to only few and mostly the widespread species noted above, since, unfortunately, there are currently no significant protected areas in the southern part of the caatingas zone (central-S Bahia to N Minas Gerais), where higher species diversity and endemism is matched by a most disturbing level of habitat destruction (mainly for agriculture and charcoal production). One of the most important areas needing protection amongst the southern caatinga-agrestes is the middle section of the Rio Jequitinhonha valley (i.e.
to Jacinto) in north-eastern Minas Gerais, where a remarkably rich assortment of succulent plants exists (Rizzini and Mattos-Filho 1992), including many endemic and potentially threatened cactus species (Taylor and Zappi 1992). Another promising site for protection, with a comprehensive range of southern caatinga cacti, including the rare Espostoopsis dybowskii, is situated to the east of the village of Porto Alegre, on the north bank of the Rio de Contas, Mun. Maracas, Bahia. Other sites need to be identified for the conservation of succulent taxa characteristic of the deep soils and Bambui limestone outcrops in the valley of the Sao Francisco River (especially for Bombacaceae and columnar Cactaceae). One such would be the massive raised outcrop south of the town of Iuia on the east bank of the river (Bahia), which, besides some spectacular bottle-trees of Cavanillesia and Ceiba growing around its base, has two very local endemics (Facheiroa estevesii, Opuntia estevesii) restricted to the rock itself. Other sites should be found on the west side of the river, where further endemics, such as the aforementioned Micron thocereus dolichospermaticus and Facheiroa cephaliomelana, are located.
The East Brazilian Highlands, with their mosaic of 'campo rupestre' and 'cerrado' vegetation (Giulietti and Pirani 1988; Zappi and Taylor 1994: 77), represent the least modified of the environments considered under the present heading of eastern Brazil. However, they have as many if not more endemic succulent species than the caatingas-agrestes just discussed, and many are of extremely local occurrence and therefore potentially at risk. Widespread and mostly common, non-threatened exceptions include Cottendorfia florida, Cipocereus minensis ssp. minensis, Leocereus bahiensis, Melocactus bahiensis, M. concinnus, Pilosocereus aurisetus ssp. aurisetus, Micranthocereus purpureus, and Stephanocereus luetzelburgii, the latter two endemic to the extensive uplands of the Chapada Diamantina, Bahia, and also found within its national park (Mucuge-Lencois).
Utilisation of the campos rupestres is limited to cattle grazing, with associated burning to induce regrowth, and local extraction of some plants, e.g. Eriocaulaceae (dried flower export trade — a serious conservation issue), orchids, and Vellozia spp., and there is also limited disturbance caused by small scale mining for gold and precious stones. Some parts where cerrado vegetation is more abundant are being cut over for the production of charcoal and later converted into Eucalyptus plantations, especially in Minas Gerais state, where this activity is one of the factors threatening Uebelmannia spp. and Cipocereus crassisepalus. The burning for cattle grazing does affect some native populations of succulents, but the regular collection of plants, and nowadays more especially of seed? of certain rare cacti may be cause for greater concern.
In addition to some of the CITES Appendix I taxa noted above, the following campo rupestre / cerrado cacti are known from only one or two small populations, or at best have a very localised range which does not include any kind of designated protected area (cf. Taylor and Zappi,ined.): Arrojadoa dinae (especially the rare variant known as A. eriocaulis), Arthrocereus rondonianus, Brasilicereus markgrafii, Cipocereus bradei, C. crassisepalus, C. laniflorus (sp. nov. ined.), C. pusUliflorus, Melocactus violaceus ssp. ritteri, Micranthocereus albicephalus, M. ciuriazureus, M. polyanthus, M. streckeri, M. violaciflorus, Pilosocereus vilaboensis, P. aurisetus ssp. aurilanatus, and P. fulvilanatus ssp. fulvilanatus and rosae.
Similarly restricted taxa located within protected areas are rather few: Arrojadoa bahiensis (Parque Nacional Chapada Diamantina, Bahia), Cipocereus minensis ssp. pleurocarpus (Parque Nacional da Serra do Cipo, Minas Gerais), Arthrocereus melanurus ssp. nov. (Parque Estadual de Ibitipoca, MG) and Pilosocereus rupicola (Estagao Ecologica da Serra de Itabaiana, Sergipe). If extended slightly to its west, the first-listed would include a second population of the remarkable A. bahiensis. The last-named Pilosocereus is possibly endangered or even extinct, but has not been investigated in habitat in recent times. The Serra da Piedade (Mun. Caete, MG) is not a designated protected area, but a site of religious significance, which has a population of Arthrocereus glaziovii, a specialised species restricted to rocks very rich in iron ('canga'), many of its former habitats having disappeared through ore extraction. It is also the type and only known locality for Dyckia simulans. Numerous, other, little-known species of Dyckia and some Encholirium are recorded from various serras in central and eastern Goias and especially from the regions of Diamantina, the Serra do Cipo and serras further south in Minas Gerais state.
Melocactus violaceus, on the coast of Bahia, Brazil, threatened by tourist developments.
These deserve further study in the field to determine their taxonomic and conservation status. A peculiar and cactus, found in the sandy cerrados bordering on the caatinga and campo rupestre zones, from western Bahia to central-eastern Minas Gerais, is Cereus It is widespread but of erratic occurrence and much of its habitat is being destroyed by charcoal producers, so its status needs to be monitored carefully.
Locations where new protected areas are needed to assist the conservation of the above listed rarities, including the earlier discussed CITES Appendix I cactus taxa, are as follows and are listed in the Action Proposals.
Atlantic Forest. This comprises the coastal rain forest ('Mata Atlantica' in its strictest sense) and sandy littoral dunes ('restingas') of north-eastern Brazil and their extensions southwards, where the former broadens and merges with the planalto forests of south-eastern and southern Brazil, reaching the northern part of Rio Grande do Sul state. The area, which is very humid, has a high diversity of epiphytic cacti from the tribe Rhipsalideae, but, as is now well known, only a small fraction of the original forest remains. Endemic Rhipsalideae include the horticulturally and economically important genera Schlwnbergera (6 spp.) and Hatiora (5 spp.). A few very widespread or regionally common taxa, such as the epiphytic Hatiora salicornioides f. salicornioides, Lepismium cruciforme, L. houlletiannm, L. warmingianum, Rhipsalis floccosa, R. lindbergiana, R. teres, R. elliptica, and R. cereuscula, and the non-ep'phvtes Brasiliopuntia brasiliensis, Opuntia monacantha, Cereus fernambucensis, Pilosocereus arrabidae, and P. brasiliensis are probably to be regarded as at low risk, but the remaining Brazilian endemic species are of conservation concern to varying degrees. For example, the wideranging but erratically occurring restinga taxa, Melocactus violaceus ssp. violaceus and margaritaceus, are threatened at various points in their ranges by touristic developments and other forms of urban expansion. Particular species diversity 'hot spots' are found in southern Espirito Santo state (between Domingos Martins and the Serra do Caparao) and around and between the great cities of Rio de Janeiro and Sao Paulo, various taxa being endemic to very small areas. The flora of southern Espirito Santo is poorly understood, but includes a recently described species of Christmas Cactus, Schlumbergera kautskyi (known from only two or three small sites), and the remarkable, red flowered Rhipsalis hoelleri. Other species are represented by disjunct populations, often at their northern limits, such as Hatiora salicomioides f. cylindrica, Rhipsalis cereoides, R. pilocarpi R. campos-portoana, and Schlumbergera microsphaerica (the latter two within the boundaries of the Parque Nacional do Caparao).
Further south the diversity of epiphytic and epilithic Rhipsalideae increases markedly along the coast and in the Serra do Mar westwards from Cabo Frio (RJ), where also an isolated member of tribe Cereeae, Pilosocereus ulei, is narrowly endemic on coastal rocks. Rhipsalis pentaptera, a species relatively common in cultivation, is presumed to be extinct in the wild, since its only recorded native site is within what is now the city of Rio de Janeiro (at Praia da Gavea). Other rare and probably vulnerable (but inadequately studied) species of Rhipsalideae from the region of Rio de Janeiro include Rhipsalis pacheco-leonis, R. cereoides, R. mesembryanthemoides, and
Rhipsalis pentaptera, almost extinct in the wild at the only known site within the city of Rio de Janeiro.
Schlumbergera orssichiana. Rhipsalis burchellii is known for certain only from the metropolitan region of Sao Paulo, and a substantial part of its presumed former habitat appears to have been either destroyed completely or severely affected by industrial pollution. Hatiora herminiae and H. epiphylloides are each known from only two relatively small areas of montane cloud forest between Rio and Sao Paulo and should be classified as endangered due to forest clearance, even though they are at least partly found within protected areas (the former in the Parque Estadual Campos do Jordao, SP, the latter in the Parques Nacionais do Itatiaia, RJ/MG, and Serra da Bocaina, RJ/SP). Other species of Rhipsalideae from this part of the Atlantic Forest and montane forest zones appear to have greater ranges, but are infrequent, disjunct or seldom observed. These include Hatiora salicornioides f. cylindrica, Rhipsalis neves-armondii, R. graudi flora, R. pilocarpa, R. clavata, R. pulchra, Schlumbergera tmncata, S. russelliana, and S. opuntioides. Protected areas that include or probably include one or other of these species are the Parques Nacionais da Floresta da Tijuca and da Serra dos Orgaos (RJ), the Parques Estaduais de Ilha Grande (RJ), de Ibitipoca (MG), de Campos do Jordao and de Picinguaba (SP), and the Reservas Biologicas de Poqo das Antas, de Paranapiacaba, da Jureia, Ilhabela and that proposed for the Serra do Japi (SP).
Destruction of the Atlantic Forest has been greatest in north-eastern Brazil, where only 5-10 per cent remains and, therefore, our knowledge of the flora is correspondingly fragmentary. It is quite possible that epiphytic Cactaceae from here have become extinct before discovery and description. In Paraiba and Pernambuco remnants of this forest include the 'brejos' on higher land away from the coast, where the watersheds are important for the human populations living below them. Such forests are currently being studied and as part of an Anglo-Brazilian initiative (Plantas do Nordeste), with great emphasis being placed on the need to preserve these floristic refuges which, inter include disjunct populations of cactus epiphytes, such as Lepismium cruciforme and Rhipsalis crispatu.
Further south, in coastal Bahia (up to 100 km inland), between the capital Salvador and Belmonte to the south, where annual rainfall is generally in excess of 1750 mm, there are occasional records of various species of Rhipsalideae, indicating a once rich centre of diversity including Hatiora salicornioides f. cylindricu, Rhipsulis paradoxa ssp. septentrionalis, R. baccifera ssp. hileiabaiana., R. russellii, and R. oblonga. With so little forest remaining it seems reasonable to assume that here all of these are threatened to a greater or lesser extent, even ifPsome may benefit irom protection in local reserves, such as the Reserva Biologica Federal de Una (south of Ilheus).
Also part of the Brazilian north-east, is the Archipelago of Fernando de Noronha, a Federal Environment Protection area. These Atlantic islands are home to at least one endemic cactus, Cereus insularis (a relative of the Brazilian coastal C. fernambucensis), which seems adequately protected at present. A second species, or perhaps a form of the first, is C. ridleii, which has not been seen since its original collection in the 1950s and may now be extinct. It is no longer in cultivation, so far as is known.
Some of the best-preserved Atlantic Forest and coastal habitats are those found in southern Brazil, in the states of Parana, Santa Catarina, and northern Rio Grande do Sul, between sea level and almost 2000 m. Here a wide variety of Rhipsalideae could be protected if deforestation can be controlled. These include the horticulturally important Easter Cacti, Hatiora gaertneri and H. rosea (its range includes Parque Nacional de Sao Joaquim, SC), which are characteristic of Araucaria forest, the peculiar Rhipsalis dissimilis (a widespread but infrequent SE Brazilian lithophyte protected in the Parque Estadual Vila Velha, Parana), and the forest epiphytes Rhipsalis trigona, R. paradoxa, R. pulvinigera, R. puniceodiscus, R. pachyptera, and R. campos-portoana. There are also at least 11 endemic and 5 non-endemic Dyckia spp., all of unknown conservation status. In the western part of southern Brazil, in the drainage of the Rio Parana, the situation is rather different, much of the humid and savanna forest having been cleared for agriculture. Fortunately, there are no endemic succulents known from this vegetation, which extends westwards into eastern Paraguay, where it is better preserved.
Besides those mentioned already, protected areas in the species-rich Atlantic slopes of southern Brazil include the Parque Nacional de Superagui and the Federal Environmental Protection Area and Ecological Station of (Parana), which probably include at least some epiphytic taxa. Non-endemic succulents found in the forested and coastal parts of southern Brazil that are probably out of danger include Cereus hildmannianus and Lepismium lumbricoides.
The third and fourth areas of extra-amazonian Brazil comprise the plant communities mainly composed of grasses etc. ('campos') of southernmost Brazil (Rio Grande do Sul state) and the savannas or 'cerrados' of Central-western Brazil. The relatively smaller succulent floras of these two areas and the perceived threats have much in common with those of eastern Paraguay, eastern Bolivia, and Uruguay, as discussed below.
Campos. The 'campos' of Rio Grande do Sul are important for the high number of endemic and non-endemic but probably threatened taxa belonging to the Cactaceae-Notocacteae, i.e. the genera Parodia (Notocactus) and Frailea, and tribe Trichocereeae (Gymnocalycium). There are also two endemic species of Dyckia (Bromeliaceae), their conservation status Unknown. Other succulents are representatives of widespread elements characteristic of the floras of Argentina and Paraguay and probably not at serious risk as species, e.g. Cereus aethiops, Echinopsis spp., Pereskia nemorosa, and Lepismium lumbricoides (an epiphyte). As explained below, under Uruguay, the habitats of many of the endemic and threatened Notocacteae arc rocky outcrops amongst agricultural land, much of the terrain being cultivated for arable crops or grazing pasture. Exceptions include the Parque Nacional Aparados da Serra, situated at the northern border of the state with part inside adjacent Santa Catarina, and including the habitats of the endemic Parodia haselbergii and P. graessneri, which are presumed to be adequately protected. The conservation status of most of the remaining 40 or so Parodia (Notocactus) taxa (many of doubtful taxonomic standing), c. 15 Frailea and 4 Gymnocalycium spp. (2 endemic), which are concentrated in the southern part of Rio Grande do Sul, needs to be determined. However, some populations are known to be very small and illegal collection to satisfy the demand for novelties by hobbyists in Europe and elsewhere is certainly taking place. There appear to be no other officially designated, protected areas including Notocacteae/ Trichocereeae in Rio Grande do Sul.
Western cerrados. The 'cerrado' in the states of Mato Grosso, Mato Grosso do Sul, Goias, the western parts of south-eastern Brazil and easternmost Bolivia (Santa Cruz) comprise open savanna woodlands on oligotrophic (strongly weathered and leached) soils and included rocky outcrops, inselbergs and uplands, such as the Chapada dos Guimaraes (Mato Grosso). The altitude varies between 300-1500 m and rainfall is in excess of 1000 mm per annum with high average temperatures for most of the year. This area has very few endemic succulents, including 8 poorly known species of Dyckia and only 5 botanically distinct species of cacti: Arthrocereus spinosissimus, Cereus adelmarii, C. saddianus, Echinopsis hammerschmidii, and Frailea chiquitana (the latter two are Bolivian endemics found on inselbergs in the ecotonal region between the 'cerrado' and Amazonian forests), all of whose conservation status is inadequately known (the Arthrocereus may benefit from any protection afforded by its location inside the Parque Nacional da Chapada dos Guimaraes). Widespread cactus taxa include the highly variable Discocactus heptacanthus s.l. and Pilosocereus machrisii s.l. (both fragmented into numerous ill-defined microspecies by some authors), besides a treelike species of Cereus found on calcareous outcrops, whose identity is uncertain at present (C. calcirupicola ?), C. bicoloi (botanical affinity uncertain) and the shrubby C. euchlorus (= Praecereus sp.). One or more Opuntiu spp., Cleistocactus horstii (? = C. baumannii), Frailea cataphracta s.l. (including F. matoana, EW according to Hunt 1992), Cereus (Mon villea) kroenleinii, Gymnocalycium anisitsii, G. marsoneri (G. matoense), Harrisia guelichii (Cereus balansae), Pereskia sachawsa, Jacaratia corumbensis, Dyckia ferox, D. microcalyx. and Deutercohnia meziana also occur, but have the major parts of their ranges in adjacent Paraguay. Although the fireswept 'cerrados' are not noted for succulent plants, there may be reason for concern about the status of even the widespread taxa in this large geographical area, and especially taxa restricted to calcareous soils and rocks, which are at greater risk from habitat conversion. Large scale farming operations, for both arable (especially soybean) and livestock, are modifying the environment and local assessments of the likely effects on succulent plant populations are needed. In easternmost Bolivia this environment has been used for cattle grazing for more than 200 years and is now being cultivated in some areas. The seasonally inundated region of the Pantanal (Brazil), which includes raised rocky areas where succulents are found, is currently benefitting from ecotourism and may thus be less at risk from agricultural development.
This subdivision includes two of the three vegetational areas of Paraguay (Esser 1982; Metzingl994), namely the valley of the Rio Paraguay and the part of Paraguay to its east, and the north-eastern Provinces of Misiones and Corrientes from Argentina. The succulents of this area are almost exclusively Cactaceae and Bromeliaceae (Dyckia spp.) and many of these are also found in the adjacent parts of central-western and southern Brazil (see above). According to Metzing (see also references to Esser 1984a, b cited therein) some of the cacti of eastern Paraguay are seriously affected by agricultural practices, including the destruction of protective nurse-plant shrubs by fire, and the same threats apply in north-eastern Argentina, where forest clearance is more accentuated. Genera with one or more species affected in this way include Cereus, Opuntia, Pereskia, Gymnocalycium, and Harrisia, some of which include endemics whose conservation status needs further investigation (e.g. G. mesopotamicum, H. hahniana, the first-named known from a single, flat, rock outcrop where grazing occurs). More specific problems are noted below.
Between 30 and 35 species of Cactaceae are known from this region, of which the following are endemic to Paraguay and have been assigned regional conservation status categories by Metzing (1994), who believes they deserve to be included on Appendix I of CITES: Frailea knippeliana (Rare, only 2 localities), Gymnocalycium paraguayense (Endangered, only 2 small populations, which could be quickly eliminated by collecting and are currently affected by livestock grazing); 'G. fleischerianum' (Endangered, ± 5 localities known, affected by tourism, house construction etc.) and Parodia (Notocactus) nigrispina (Endangered, only 3 populations, affected by land clearance, grazing and collected for sale at the roadside). The last two are restricted to the crystalline 'Cordilleras', where the peculiar endemic, Cereus lanosus (probably not threatened), is also found. Non-endemic species discussed by Metzing (1994) include: Frailea cataphracta (ranging to adjacent CW
Brazil and Bolivia, vulnerable), Parodia (Notocactus) ottonis (Vulnerable/ Endangered in Paraguay through land clearance and grazing, but still common in neighbouring countries), P. (N.) schumanniana (NE Argentina and S Brazil, Rare) and Pilosocereus machrisii (P. juaruensis) (Vulnerable in Paraguay, but widespread and not threatened in adjacent Brazil). The non-endemic Discocactus heptacanthus ssp. magnimammus (D. hartmannii), from the campos cerrados of north-eastern Paraguay, is potentially threatened from conversion of its habitat for agriculture.
Besides cacti, there are 5 endemic species of Dyckia described from eastern Paraguay (D. exsertu, D. velloziifolia, D. affinis, D. tobatiensis, D. tomentella) and 3 from Misiones Province, Argentina (D. niederleinii, D. subinermis, D. mitis), all known only from the type or very few collections (Smith and Downs 1974).
Of the protected areas listed in WCMC (1992), the Biological Reserve of Itabo includes the habitat of various non-endemic epiphytic cacti (D.C. Zappi, pers. comm.), while the Cerro Cora National Park may give some protection to Brasiliopuntia brasiliensis, Pilosocereus machrisii, and the endemic Dyckia exserta (Bromeliaceae). It is not known whether the forest reserve of Capivary (13,500 ha) includes and protects populations of the non-endemic Discocactus heptacanthus ssp. magnimammus (D. hartmannii), whose genus is on Appendix I of CITES.
SE Bolivia, W Paraguay and N Argentina
This is the arid vegetation type known as the Chaco, which is often compared with the Caatinga of northeastern Brazil, but has, in fact, very few floristic similarities and a quite different succulent flora. Widespread and conspicuous cactus species include Quiabentia verticilla ta, Cereus (Praecereus) saxicola (Monvillea cavendishii misapplied), C. spegazzinii, Browningia (Castellanosia) caineana, Cleistocactus baumannii, Gymnocalycium marsoneri, G. mihanovichii, G. pflanzii, Harrisia pomanensis, Opun tia quimilo, 0. retrorsa, Pereskia sacharosa, and Stetsonia coryne, none of which is believed to be particularly threatened at present, though up-to-date knowledge is poor and environmental change in the form of clearance for agriculture is accelerating. Another widespread succulent is Ceiba (Chorisia) speciosa (Bombacaceae).
SE Bolivia. The extensive low forest, spiny scrub and dry savanna loosely referred to as Chaco in south-eastern Bolivia is characterised by a hot climate with precipitation of 500-1000 mm/yr concentrated in the four warmest months. Little knowledge of the succulents found here is currently available, but habitat alteration appears to be limited. However, this could change rapidly if modern machinery is employed on a large scale, as is beginning to occur in Paraguay.
W Paraguay. Here Chaco vegetation is said to cover 60 per cent of the territory of Paraguay, yet this area counts less than 100,000 in human population. However, it has a greater number of endemic species than in the adjacent Chaco countries, e.g. Cereus lamprospermus, C. pachyrhizus, C. phatnospermus, and Gymnocalycium eurypleurum, and G. paediophilum (both rare and known only from or near Cerro Leon). According to a Land Utilisation Survey published in 1991 and based on satellite images, only 4.22 per cent of the total area is under cultivation. However, a somewhat different impression is gained from observations on the ground, where large cultivated fields can be seen along the TransChaco highway (and especially in the vicinity of Filadelfia). There is also selective extraction of timber and cattle ranching in some places, but much of the Chaco is insufficiently explored to give an accurate assessment. According to Metzing (1994) Cerro Leon deserves to be designated a National Park. The vegetation in its vicinity is relatively undisturbed at present.
Further west the soils become more sandy and dunes sometimes occur. Here the vegetation is more open, grasses and other herbs predominating, the shrubs in scattered groups ('espartillares'). The land is potentially suitable for cultivation and pasture, which might lead to the endangerment of the non-endemic Gymnocalycium megatae. A distinct species said to come from Paraguay and perhaps from the Chaco region, but of unknown wild status today, is Cereus haageanus.
N Argentina. The Chaco environment of Argentina has been modified on a much greater scale than that in Paraguay. For many years timber of the dominant-emergent quebracho trees (Schinopsis spp., Anacardiaceae) has been extracted as raw material for tanning, manufacture of railway sleepers, and for firewood. The remaining stumps produce sucker sprouts, which are eaten by cattle, preventing regeneration, and the remainder of the vegetation is often exploited for charcoal. Thereafter, the land becomes pasture or is left abandoned, but does not seem able to return to the original climax vegetation. Gymnocalycium spp. suffer immediately after the forest cover is removed, but other succulents, such as Quiabentia verticillata and Frailea spp., seem to withstand habitat modification and may even increase in abundance in some areas.
The cactus genera Austrocactus (6 spp.) and Maihuenia (2 spp.) are endemic to this region. Another important cactus genus, almost endemic to the region, is Pterocactus, an isolated taxon of Opuntioideae with 5 species endemic to Argentinian Patagonia. P. australis is said by Kiesling (1990) to be the most southerly occurring species of Cactaceae.
Discounting a few, mostly weedy species of Portulaca and the non-endemic and wide-ranging Dyckia remotiflora (status unknown), the native succulent plants of Uruguay are all Cactaceae, the most important belonging to the taxonomically complex, dwarf, globular genera Parodia (incl. Notocactus), Gymnocalycium, and Frailea. These three comprise more than 50 species in total, the majority of which, though only provisionally accepted (Hunt 1992), are said to be endemic. Even if many of these taxa are "less-than-species", their conservation status is cause for serious concern, since some 75 per cent of the land surface of Uruguay is said to have been modified with positive or negative effects by agriculture etc. (mainly cattle grazing) and there are scarcely any protected areas (WCMC 1992). Populations of such cacti are often very small, being restricted to isolated rock outcrops surrounded by pasture. Various of the non-endemic globular taxa are otherwise known only from the neighbouring Brazilian state of Rio Grande do Sul (see above), where similar threats apply. Other cacti, such as species of Cereus, Cleistocactus, Harrisia, Opuntia, Pereskia, and epiphytic genera, i.e. about 20 species in all, have probably been severely reduced in abundance. Most of these are widely distributed in the adjacent countries of Argentina, Brazil, and eastern Paraguay, where similar problems exist, though to a lesser degree. While reliable information is lacking it is impossible to make suggestions for action other than to instigate field surveys by botanists taxonomically competent in the species-rich globular genera noted above. There are also logistical difficulties in accomplishing such work, since much of the habitat is privately owned land and good contacts with local farmers would therefore seem a prerequisite to any kind of field study.
Three geographical/vegetational subdivisions can be recognised here: the Monte, the Pampas, and Patagonia proper.
Monte. This is the western desert of Argentina, to the east of the high Andes, and characterised by a spiny scrub in which Larrea (Zygophyllaceae), the creosote bush, dominates. Agricultural activity occurs only in small patches near rivers, due to the irregular and limited rainfall (50-300 mm/yr), but farming of goats and sheep is sometimes intense, especially near villages or isolated houses, where disturbance of the natural vegetation is greatest.
Three genera of Cactaceae are represented by numerous species here: the endemic Tephrocactus Group (s. str.) of Opuntia, Gymnocalycium, and Echinopsis (Trichocereus). Some of the Tephrocactus species have a partly clonal mode of reproduction, and others are known from single populations or very limited areas (e.g. 0. halophila, 0. molinensis), but none seems to be seriously
Rain sticks of Eulychnia and Echinopsis, La Serena, Chile.
threatened. The same applies to the numerous Gymnocalycium spp., although G. schickendantzii plants can be damaged by the trampling of livestock. Echinopsis stngosa, E. candicans, and E. angelesiae are frequent plants. Other succulents are represented by Portulaca(> 3 ephemeral but often abundant spp.) and Talinum (3 tuberous spp.), which do not appear to be severely affected by grazing.
Pampas. A huge part of the territory of Argentina was naturally covered in herbaceous prairies (the Pampas), where rainfall is regular, the climate warm temperate and the soil fertile. This area originally comprised the province of Buenos Aires and S Santa Fe (humid pampa), and Province La Pampa and S Cordoba (dry pampa), but it has long been occupied by agriculture, which has artificially extended its limits northwards into much of Santa Fe and Cordoba (where spiny forest or 'Espinal' formally occurred). Besid
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