Materials and methods

Study area. The sub-basin is located in the center-south portion of the State, at a distance of approximately 60 km toward south from the city of Guadalajara. The area encompasses part of the municipalities of Amacueca, Atoyac, Concepción de Buenos Aires, Gómez Farías, Sayula, Techaluta de Montenegro, Teocuitatlán de Corona and Zacoalco de Torres. It is located between the coordinates 19°45’ and 20°15’ north latitude and between the coordinates 103°10’ and 103°45’ west longitude. It has an area of 147,585.3 ha, with an altitudinal variation ranging from 1,110 to 2,868 m (Figure 1).

Figure 1 Location of the study area. 

Physiographically, it is part of the Chapala subprovince of the Eje Neovolcánico province in the western part of the country. It is classified as an endorheic basin, consisting mainly of the Tapalpa and Tigre ranges, and the water outlet is only by infiltration or evapotranspiration. Rainfall is the main source of water in the lagoon, which becomes brackish water by the salts of the soil, like Na2CO3 and MgSO4 (^{Flores-Díaz 1984}).

The lithology is mainly of igneous basic extrusive origin, provided in the form of lava, tuff and breccias. A basaltic and andesite composition prevails on the slopes surrounding the lacustrine vessel, acid rocks, the product of explosive expulsions of rapid cooling, predominate in the upper parts of the Sierras del Tigre and Tapalpa. In the low points of the slopes are sandstones and shales (^{Flores-Díaz 1984}). The so-called “islands” are recent extrusions of afritic basalt of labradorite and olivine, and to a lesser extent of andesites (^{Ávila 1994}).

In foothills and moderately steep slopes, predominant fluvisoles soils and calcium. The solonchaks soils are distributed over the lacustrine sediments of the basin, to the north of the saline plain they form a mosaic with the arenosols, by the deposit of sands removed from another part of the plain by wind erosion. (^{SPP 1982}).

In the lower part of the sub-basin, climatic subtypes predominate, according to Köppen, semi-dry BS1hw (w) and sub-humid (A)C(w0) w. The average annual temperature is 21.5 °C in the southern sub-basin, rising to 22.7 °C to the north and the annual mean rainfall is 564.6 mm in the north, rising to 851.1 mm to the south. In the summits of the sub-basin the climate type is subhumid temperate C(w1)(w) and C(w2)(w), the average humidity and the wetter subhumid temperate, respectively), with summer rains and less of five percent of winter rain. Concerning the tops with altitude under 2,000 m the annual average temperature is 16.2 °C and the annual rainfall is 802.8 mm. In the highest tops the average annual temperature is 15.2 °C and the average annual rainfall is 843.9 mm (^{García 1988}).

Fieldwork and Cabinet. Several collections of botanical specimens were made within the study area, from February 2012 to October 2015, of at least one output per month, lasting four days, during which several routes were made through the breaches, trails and roads within the municipalities that are part of the sub-basin. Only native and naturalized plants were collected, discarding the cultivated species. The collected specimens were herborized according to the methodologies proposed by ^{Lot & Chiang (1986)} and ^{Sánchez-González & González (2007)} and deposited in the herbarium of the Institute of Botany of the University of Guadalajara (IBUG). For the determination of the species, taxonomic literature was used as different books, monographs and floras: Trees and shrubs of Mexico (^{Standley 1920-1926}); Flora de Jalisco (^{Cuevas-Figueroa 2001}, ^{Cervantes-Aceves 1992}, ^{González-Villarreal 1986}, ¹⁹⁹⁰, ¹⁹⁹⁶, ^{González et al. 2001}, and ^{Vargas et al. 2003}), Flora del Bajío y Regiones Adyacentes; Flora Novogaliciana (^{McVaugh 1983}, ¹⁹⁸⁴, ¹⁹⁸⁵, ¹⁹⁸⁷, ¹⁹⁸⁹, ¹⁹⁹², ¹⁹⁹³, ²⁰⁰¹); Flora fanerogámica del Valle de México (^{Calderón de Rzedowski & Rzedowski 2001}); The Pteridophytes of Mexico (^{Mickel & Smith 2004}) and Conifers (^{Farjón et al. 1997}, ^{Gernandt & Pérez de la Rosa 2014}). In addition to the support of specialists from different families for their determination.

The families, genera, species, subspecies and varieties are presented in alphabetical order according to the classification criteria proposed by ^{Mickel & Smith (2004)} for ferns, ^{Gernandt & Pérez de la Rosa (2014)} for conifers, and related plants ^{APG IV (2016)} for angiosperms. The names of the species are cited according to the database Taxonomic Name Resolution Service v4.0 (^{Boyle et al. 2013}).

For each species, bibliographical information was collected concerning their life form, habitat, native or introduced, distribution, conservation status and vegetation type. To establish the categories of life forms the criterion proposed by ^{Rzedowski (1978)} with some modifications was followed. The geographic distribution of the species recorded through the literature review was analyzed and 12 distribution patterns were determined, grouping them into the following elements: 1) cosmopolitan, 2) pantropical, 3) American, 4) North American, 5 ) from Mexico to South America, 6) from the United States to Central America, 7) from Mexico to Central America, 8) from the United States to Mexico, 9) neotropical, 10) endemic to Mexico, 11) disjunct, and 12) endemic to western Mexico. The information regarding the distribution by vegetation types was obtained based on the literature and the records of the plant communities where the species were collected. Finally, species included in a category of the International Union for Conservation of Nature (IUCN), International Convention on Trade in Endangered Species of Wild Fauna and Flora (CITES) and/or the Mexican Official Standard (^{SEMARNAT 2010}) was recorded.

In order to have a parameter of the vegetal diversity of the present study, the richness of species was compared with other areas of different surface that have floristic inventories. For this purpose we worked with the taxonomic biodiversity index, whereby an approximation was obtained of the number of taxa presented in the area studied according to their surface, using the formula B = S / lnA, where S is the number of recorded species and lnA is the natural logarithm of the area in km² (^{Squeo et al. 1998}).

Based on the information generated by the LANDSAT 8 images, a soil occupation map of the study area was elaborated using the supervised classification methodology in the ArcMap 10 geographic information system, which was subsequently verified in countryside. The vegetation of the study area was characterized according to the proposal of ^{Rzedowski (1978)}.

Results

Floristic diversity. The flora of the Sayula sub-basin is represented by 113 families, 415 genera and 687 species (Appendix 1). The group of Eudicots was the one with the highest richness with 79 families (representing 69.9 % of the total), 303 genera and 491 taxa, followed by Monocots, Monophyllites, Pinophytes and Magnoliidae complexes (Table 1).

The most diverse family was Poaceae, with 103 species and 46 genera, followed by Asteraceae (81/58), Fabaceae (47/31), Solanaceae (38/10) Euphorbiaceae (25/7), Malvaceae (20/12), Cactaceae (18/10), Lamiaceae (18/9) and Convolvulaceae (16/6). These nine families represent 53.3 % (366) of the species and 45.5 % (189) of the genera. The remaining 104 families recorded less than 14 species each (Table 2). The genera with the highest number of species were Solanum with 21, Euphorbia with 14, Quercus with 11, Ipomoea with 10, Salvia with nine, Ficus, Muhlenbergia and Opuntia with eight and Bouteloua, Bursera, Cenchrus, Paspalum, and Pinus with six. In these 13 genera, 17.3 % (119) of the species recorded in the study area are represented. For the rest of the genera (402) all presented less than five species (Table 2).

Biological forms. The herbs are the dominant biological form with 411 which accounts for 60 % of the total species, followed by shrubs with 105 (15 %), trees with 73 (11 %) are followed in number of importance vines, succulents, lianas, rosettes and cane (Table 3). The dominant plants according to the type of habitat in which they develop 635 are terrestrial, 25 aquatic, 9 rupicolous (ferns), 9 parasites (mistletoe and cuscuta) and 9 epiphytes (Appendix 1).

Of the total species recorded in the sub-basin, 94.1 % (647) are native to Mexico and 5.9 % (40) are introduced. For the synanthropic species (weeds or disturbance indicators), 307 (44.7 %) of which 270 are native and 37 are introduced (Appendix 1). Of these weeds, 223 (72.6 %) are herbaceous, 35 shrubs (11.4 %) and 19 suffrutexs (6.2 %), vines 16 (5.2 %), trees 10 (3.3 %), lianas 3 (1 %) and cane 1 (0.3 %).

Species under some category of protection. Result of the review of several lists of protected or threatened species such as the International Union for Conservation of Nature (^{IUCN 2015}), International Convention on Trade in Endangered Species of Wild Fauna and Flora (^{CITES 2013}) and Official Mexican Standard (^{SEMARNAT 2010}), a total of 46 species were registered under some protection category. Some species are found in more than one listing, such as Callitropsis lusitanica, Hylocereus undatus, Isolatocereus dumortieri and Myrtillocactus geometrizans (Table 4).

Geographic distribution. Based on 687 species and the establishment of 12 distribution patterns, 171 species (24.9 %) endemic to Mexico were recorded, of which four are pteridophytes, three gymnosperms, two of the magnoliidae complex, 136 eudicots and 26 monocots. For the non-endemic to Mexico, 147 (21.4 %) are distributed in the American continent, 133 (19.4 %), whose distribution goes from Mexico to Central America. 8.3 % (57) are widely distributed or cosmopolitan species, 6.1 % (42) are distributed in the neotropic; For the rest of the species these are distributed in six different patterns (Table 5). Only nine species (1.3 %) are endemic to western Mexico and a single species endemic to the sub-basin, Cleomella jaliscensis (Appendix 1).

Floristic richness. According to the index of taxonomic diversity, the area have a floristic richness of 94 species per km2. A comparison with other similar studies in areas dominated by tropical deciduous forest such as the Baja California Peninsula (^{León de la Luz et al. 2012}) or the Nixticuil-San Esteban-El Diente Forest Hydrological Protection area (^{Zepeda & Velázquez 1999}), allows estimating that the floristic richness of the Sayula sub-basin is a little higher, but it is far below compared to the Balsas River Basin and Cerro Viejo; Although these assessments should be taken with caution due to differences in authors’ sampling effort and imprecision in the calculation of areas (Table 6).

Land use and Vegetation. The vegetation of the Sayula sub-basin is not a homogeneous mosaic, since it presents different vegetal communities that possess a very peculiar and interesting flora, in addition they are carried out different productive activities like agriculture and the cattle ranch. Within the zone we can distinguish eight vegetation types according to the classification of ^{Rzedowski (1978)} and four variants of land use (Figure 2). The order of the descriptions of the plant communities is based on the area occupied within the sub-basin, showing the percentages of the area covered by each current vegetation type.

Figure 2 Land use and vegetation map of the Sayula sub-basin, Jalisco, Mexico. 

Tropical Deciduous Forest. In the study area the tropical deciduous forest occupies an area of 36,436.05 ha (24.69 %), being the plant community with greater distribution. It develops mainly in the foothills of the slopes of the surrounding Sierras to the lagoon, both in the north and west slopes of Sierra del Tigre, as in the east orientation of Tapalpa and in the southern slope of the Cerro de García and El Caracol; Inside of the lagoon is only found in the central parts of two “islands”, (Isla Grande and Isla Chica) on rocky outcrops, since around these they are covered of thorn forest.

The prominent feature of this type of forest is the loss of leaves in almost total form over a period of 5 to 8 months, so it has two strongly contrasting aspects: in drought it is desolate, with gray tones, while in rainy season it is green and vital. The height of the canopy varies from 4-8 (10) m.

The vegetation cover consists of small individuals such as Bursera fagaroides, B. penicillata, Ceiba aesculifolia, Cnidoscolus spinosus, Ipomoea murucoides, Lysiloma divaricatum and candelabriform cacti with Stenocereus queretaroensis and Isolatocereus dumortieri. In this plant community, several large trees stand out, Ficus insipida, F. goldmanii and F. subrotundifolia, which occur near some outcrop of water (^{Villegas-Flores et al. 1995}).

From the point of view of forest use, this type of vegetation is of little importance, because the size and shape of its trees do not have desirable characteristics for trade (^{Rzedowski 1978}). It is used more for livestock purposes, although with scarce yields. The topography and climate does not allow irrigated crops, but when it exists, conditions change completely and the forest becomes important agricultural areas, such as the areas near Zacoalco, Amacueca and Techaluta, where one of the most important crops, such as the “Pitaya” (Stenocereus queretaroensis), is established in areas originally occupied by the tropical deciduous forest.

Pine Forest. In the Sayula sub-basin it is distributed mainly in areas with subhumid climates called temperate, corresponding to the highest parts of the sierras that surround the lagoon and Cerro de García, occupies an area of 23,411.26 ha, corresponding to 15.87 % of the surface.

This plant community is formed by species of the genus Pinus, often associated with oak and other species, its physiognomy is very characteristic, being a closed community of always green individuals, with acicular leaves, straight trunks that have heights that go from 15 to 20 m on average; In contrast, the undergrowth in the dry season presents a different aspect, almost yellowish, made up of herbaceous grasses predominating. The shrub layer is almost absent, or is hardly apparent.

The most common species that characterize this type of vegetation are: Pinus devoniana, P. douglasiana, P. leiophylla, P. lumholtzii, P. maximinoi and P. oocarpa. These forests are of major economic importance in the area due to their forestry activities such as timber production, resins, pulp production for cellulose and backyard for the villages of Mazamitla and Tapalpa, where there is a great ecotourism activity.

Halophytic Vegetation. It is present only inside the lake bed and surrounding foodplains, and is distributed almost throughout the length and width of the body, in the form of narrow annular stripes and scattered spots within it, is constituted mainly by an herbaceous stratum conformed by a low zacatal constituted for several annual species. It represents almost 4.65 % of the study area, occupying an approximate area of 6,865.32 ha of the sub-basin.

This vegetation is characterized to develop in soils with high content in soluble salts, can assume diverse forms, floristic, physiognomic and ecologically, since they can dominate in them forms herbaceous and shrub. This fact is at least partly due to the fact that edaphic characteristics fluctuate as regards the quantity and type of salts, as well as the pH, texture, permeability, amount of water available, etc.

Among the species that make up this type of vegetation known as “salty pastures” we find Bouteloua diversispicula, Cenchrus ciliaris, Distichlis spicata, Jouvea pilosa and Sporobolus coromandelianus, as well as other species such as Suaeda torreyana, Scirpus americanus, Trianthema portulacastrum and Oligomeris linifolia (^{Macías-Rodríguez 2004}). Often the zacatal is intermixed with spots of thorn forest with Celtis pallida, Opuntia atropes and Prosopis laevigata.

The halophytic vegetation is not of great economic importance due to its characteristics, although the “Romeritos” (Suaeda torreyana) grow here, there is very little consumption by the inhabitants of the region. In this area also, the extensive livestock is developed, since the cattle takes advantage of the shoots of the grasses in the early rains, before the hardening of the branches and leaves, since after this time, the buds resemble thorns, which harms the esulting in detrimental results.

Oak Forest. It is distributed mainly in the Sierra de Tapalpa, always below the altitudinal limits of the pine forest, and also bordering the tropical deciduous forest and in some parts with temporary agriculture, covers an area of 5,209.59 ha representing the 3.53 % of the total area.

Along with pine forests, oak forests represent another type of temperate major vegetation in the area, Mexico being the largest center of wealth and specific endemism for the genus Quercus (^{Valencia 2004}); It shares space with different species of pine (Pinus spp.), Giving rise to the so-called pine-oak forests, or oak-pine forests, when they dominate the oak forests.

The most common species of these communities are Quercus candicans, Q. castanea, Q. crassipes, Q. gentryi, Q. magnoliifolia, Q. resinosa and some other species that intermingle with ecotonies of tropical deciduous forest, such as Bursera fagaroides, Eysenhardtia polystachya, Ipomoea murucoides and Lysiloma acapulcense.

These forests have been heavily exploited for logging purposes for the extraction of wood, for the production of charcoal and boards for domestic use, which causes this vegetation type to reach secondary phases, which are later incorporated into agricultural activities.

Oak-Pine Forest. It appears as a spot in the study area, to the east, between the Cerro de García and the northern orientation of the Sierra del Tigre below the communities of pine forest, while in the western orientation of the Sierra, Is intermingled with tropical deciduous forest and seasonal agriculture areas, with a lower proportion also found in the Sierra de Tapalpa, northwest of Usmajac; Covers an area of 5,015.74 ha, which corresponds to 3.4 % of the total of the region.

This community is characterized mainly by the dominance of oaks on the pines. It develops below the altitudinal limits of pine, oak-pine and above the tropical deciduous forest. These communities show a lower height than those where the pine dominates over the oak.

The most representative trees species in these communities are: Clethra hartwegii, Pinus devoniana, P. leiophylla, P. oocarpa, Quercus candicans, Q. castanea, Q. crassipes, and Q. magnoliifolia. Like the pine-oak communities, these also present forest use, in addition, in many areas there is an alternation with agricultural activities. Due to activities such as clearing for pine extraction, some oak forests obey their physiognomy and structure more than anything to the competition factor, where the oaks predominate over the pines; being also evident the presence of Dodonaea viscosa in the manner of dense patches, which is indicative stages successions of disturbed forests.

Thorn Forest. It includes a plant community whose common denominator is its rather reduced height and the fact that at least to a large extent are thorny individuals, with perennial leaves, characteristic of flat or slightly sloping land, soils are clayey, pH slightly alkaline, poorly drained and often flooded periodically. It often develops in places with drier climates than tropical deciduous forest, but occupies deeper soils (^{Rzedowski 1978}).

Thorny elements abound, where the Fabaceae family is the most abundant. Among the numerous prickly plants, there are also often cactaceae in the shape of a candelabra that protrude from the arboreal canopy. The species constituting this plant community are mainly Opuntia atropes, O. fuliginosa, Prosopis laevigata, and less frequently Pithecellobium dulce. They dominate thin trees, with small leaves or leaflets, deciduous in the vast majority of cases for variable periods of time. The species Prosopis laevigata is dominant in the arboreal stratum (^{Villegas-Flores et al. 1995}). The shrub stratus is generally well developed and rich in spiny species such as Acacia farnesiana, Celtis pallida, Opuntia pubescens, Neurolaena lobata, Pereskiopsis diguetii and Solanum torvum.

In the region, the Thorn Forest is estimated at about 2.15 % of the territory (3,169.96 ha). Such lands are and have been the most used for agriculture and livestock, consequently, what is left of the thorn forest, are only relict or small patches around the lagoon, intermixing with halophytic vegetation, tolerating the basic soils and in some occasions these lands are flooded in the rainy season, when the water level rises. The area occupied by this community tends to diminish its extension in the lagoon, due to the clearing for the establishment of crops, whether of irrigation or of temporary.

Pine-Oak Forest. This community, like pine-oak forests, are also called mixed forests, are considered transitional phases of pure pine or oak forests, however, some authors claim that many of these forests are considered the climax vegetation of many Temperate zones, which is shared by the different species of Pinus and Quercus; Being dominant the pines on the oaks.

This type of forest is the least distributed arboreal community, occupying only 0.27 % of the study area, corresponding to 404.77 ha; is distributed only to the east and southeast of the towns of Tepec and San Antonio, in the eastern slope of the Sierra de Tapalpa. Some of the most common pine species are Pinus devoniana, P. leiophylla, P. oocarpa, Quercus candicans, Q. crassifolia and Q. crassipes.

Aquatic Vegetation. It is called aquatic vegetation to all those vegetal groupings that develop in an aqueous medium or in soils saturated of water; Together constitute an important part of the vegetation of the sub-basin. This plant community is distributed within the study area, as small patches, occupying a 0.07 % with 96.41 ha, located towards the central part of the lagoon. The species that constitute it are grouped in dense masses that sometimes cover important surfaces of the lacustrine area, to borders of ditches, channels of irrigation and streams; its physiognomy is mainly given by monocotyledons from one to three meters high and narrow leaves. In this type of vegetation we can distinguish broadly three main associations: tular and carrizal, floating vegetation and underwater vegetation.

Irrigation Agriculture. In this type of agriculture, it uses supplementary water systems to obtain crops during the agricultural cycle, and can be of different variants depending on how the application of the water is carried out, for example sprinkling, dripping, or distribution of water along furrows or a pipe starting from a main channel which is distributed directly to the crop by pumping from the source of supply (a well, dam or body of water) or by gravity action when it goes directly to a main channel from upstream.

This type of agrosystem occurs in most of the territory, mainly in the plains areas, mainly in the southern portion of the lagoon, and in the Teocuitatlán de Corona plain, between the southern slopes of the Cerro de García and El Caracol and the north face of the Sierra del Tigre. It occupies the second place (18.71 %) of distribution in the study area, with an approximate area of 27 609.14 ha. The main crops in the area are maize for the production of seeds, alfalfa and vegetables mainly tomato and red pepper.

Temporary Agriculture. It is called temporary agriculture the type of activity that takes place in all those lands where the cycle of crops that are planted depends on rainwater; So the success of the harvest depends on the amount of water that falls and the ability of the soil to retain it.

Within the study area, it is presented in the form of manchones, distributed throughout the area, but mainly near the populations, it covers a greater area in the western and eastern part of the Sierra del Tigre, and considerable portions the Sierra de Tapalpa in the villages of Techaluta and Amacueca; and occupies 18.51 % of the total area (27,307.52 ha). They can be areas of monoculture or polyculture and can be combined with secondary pastures, mixed with irrigation areas, or in areas that clear the deciduous tropical forest called cuamiles; which forms a complex mosaic, difficult to distinguish or separate, but which generally presents dominance of crops whose growth depends on rainwater.

The main crops are maize and sorghum but there are also cultivated areas of pitaya (Stenocereus queretaroensis) and zacate rhodex (Chloris gayana).

Livestock. It is denominated with the term of farming to all those areas where the human activity is oriented so much to the culture of the field as to the raising of animals. Generally they are areas devoid of vegetation, or this is in some phase of its process of succession, which are denominated matorraleras, cuamiles, or secondary vegetation.

These areas are mainly made up of shrub and herbaceous species, which do not pass more than 1.5 m high, their coverage is often poor, but in advanced stages of the process of succession can be very closed communities. The main species that form it are Acacia farnesiana, A. pennatula, Argemone ochroleuca, Datura stramonium, Nicotiana glauca, Solanum ferrugineum, Ricinus communis, Wigandia urens, and a great number of grasses and composites among which we can mention Cenchrus echinatus, Chloris gayana, Cynodon dactylon, Dactyloctenium aegyptium, Eleusine indica, Melinis repens and Paspalum notatum among grasses and Baccharis salicifolia, Bidens aequisquama, Melampodium divaricatum, Stevia serrata, Tagetes filifolia and Verbesina fastigiata, within Asteraceae.

It is present throughout the study area, mainly near the populations and intermixing with tropical deciduous forest, oak forest and seasonal agricultural areas, on the eastern slope of the Sierra de Tapalpa and on the north face of the Sierra del Tigre. Occupies an area of 4,939.81 ha, which represents 0.64 %. Both activities, both agriculture and livestock, are closely linked as they benefit each other. The cattle provide manure, which is used as fertilizer for pastures and crops and these serve to feed the animals.

Areas with no apparent vegetation. Corresponds to all areas that are devoid of vegetation such as bodies of water, populations and existing infrastructure, and therefore can not be included under any of the types of vegetation mentioned above, and corresponds to 4.62 % with a surface occupation of 6,815.58 ha (Table 7).

Discussion

Floristic diversity. The diversity of the flora in the study area is the result of the great heterogeneity of environments that allow the development of a variety of plant communities, each of which offers special conditions for the development of different species.

Within the vascular flora of the Sayula sub-basin is represented 3 % of vascular plants, 14.54 % of the genera and 38 % of the families for Mexico (^{Villaseñor 2016}). In only 1.84 % of the state territory is represented 48 % of families of the 235, 27 % of the genera of 415 and 9.6 % of the 7,155 species reported by ^{Villaseñor (2016)} for the State.

The main families recorded Poaceae, Asteraceae, Fabaceae, Solanaceae and Euphorbiaceae coincide equally with the 15 most diverse families of Mexico, results that are ratified with the present study.

Similarly, the five most diverse genera such as Solanum, Euphorbia, Quercus, Ipomoea, Salvia, are also the most numerous and widely distributed in the country (^{Villaseñor 2016}). This is corroborated by the different floristic works carried out in different regions of the country (^{Cabrera-Luna & Gómez-Sánchez 2005}, ^{Frías-Castro et al. 2013}, ^{Morales-Saldaña et al. 2015} and ^{Morales-Arias et al. 2016}).

In Jalisco, the genus Solanum has the highest number of species within this family, and it should be noted that in this area of study 21 species were recorded, corresponding to 38 % of the 55 species reported for Jalisco (^{Cuevas-Arias et al. 2008}). The dominance of this genus may be due to the fact that, like many other Solanaceae, they are favored by disturbed ecological conditions preferring degraded or rudimentary areas (Cuevas-Arias op cit.); Others prefer very specific ecological habitats, such as Lycium carolinianum, which grows exclusively around salt lakes and periodically flooded, collected around the Laguna de Sayula.

^{Villegas-Flores et al. (1995)} reported in the area the presence of Cirsium horridulum Michx. var. horridulum and Ledenbergia macrantha Standl., with this study expanding the distribution of the two species. The first one was previously known of the type locality, in the Villa Corona lagoon (^{McVaugh 1984}). And the second had only been reported from localities in the states of Colima, Veracruz and the southern portion of Jalisco in the Atenquique gorge (^{Oliva & Ramón 1992}).

Biological forms. Herbs and shrubs were the dominant biological forms, coinciding with many floristic works carried out in Mexico (^{Villegas-Flores et al. 1995}, ^{Guerrero-Nuño & López Coronado 1997}, ^{Fernández-Nava et al. 1998}, ^{Contreras-Rodríguez et al. 2000}, ^{Hernández-Toro 2003}, ^{Villaseñor 2004}, ^{Cabrera-Luna & Gómez-Sánchez 2005}, ^{León de la Luz et al. 2012}, ^{Frías-Castro 2013}, ^{Villaseñor & Ortíz 2014} and ^{Morales-Saldaña et al. 2015}. It was also observed a great correspondence between biological forms and vegetation types in the same way that ^{Cabrera-Luna & Goméz-Sánchez (2005)} mention as grasses and shrubs grow in the thorny forest, halophytic grassland and vegetation while trees and shrubs do so in tropical deciduous forest and oak-pine forest.

The great diversity of biological forms found in the study area could be due to the great environmental heterogeneity, as well as to the presence of eight different types of vegetation from the thorn forest of semiarid climate to the aquatic vegetation. The diversity of species and life forms recorded coincides with that reported by ^{Rzedowski (1998)}, who mentions that the flora of Mexico is rich in species numbers and is also diverse in biological forms, especially in arid and semiarid vegetation.

Species under some category of protection. Only five species included in the NOM-059 were recorded, 18 species in CITES II and 24 species in ^{IUCN (2015)}. Although the information for protected species, the population status is stable, in many of them it is unknown (Table 4). It was found a report of a new species for the zone according to ^{Villegas-Flores & Ramírez-Delgadillo (1998)} Cleomella jaliscensis, for the moment the species is only known of this region, it develops in thorny forest with halophytic vegetation at 1,300 m asl (Figure 3). Is in danger of disappearing since the area where it is developed is subject to grazing. And the most worrying thing is that it is not on any national or international list as a species to be protected. Therefore it is suggested to implement studies on population ecology for some species (Mammillaria scrippsiana, Cleomella jaliscensis, Begonia spp., Hylocereus spp. and Sedum spp.) (Figure 4). Since many of these are still extracted from their natural habitat for sale, others are destroyed by the change of land use, due to the fact that the area is under temporary agriculture and irrigation, mainly those areas of thorny forest that are surrounding the lagoon and those species that develop in the tropical deciduous forest, to have a more objective assessment and include them in the corresponding categories.

Figure 3 Some of the vascular plants present in the Sayula sub-basin. Part I. 1) Isolatocereus dumortieri; 2) Cleomella jaliscensis; 3) Sedum jaliscanum; 4) Bursera bipinnata; 5) Opuntia pubescens; 6) Arctostaphylos pungens. 

Figure 4 Some of the vascular plants present in the Sayula sub-basin. Part II. 7) Polypodium madrense; 8) Cheilanthes kaulfussii; 9) Bursera penicillata; 10) Sedum greggii; 11) Agave inaequidens; 12) Salvia mexicana; 13) Stenocereus queretaroensis. 

Geographic distribution. In only three distribution patterns (endemic, American and from Mexico to Central America), 65.8 % of the recorded flora is housed. It should be noted that of the total number of species registered, only 25 % are endemic to Mexico and 1.3 % are endemic to the west of the country, remaining well below that suggested by ^{Villaseñor (2016)}, which is 49.8 % for the national flora. This is probably explained by the fact that in the study area, much of the natural vegetation has been replaced by large areas of agriculture, both irrigation and rainfall, which leads to the loss of native biodiversity, which has been replaced by species of cosmopolitan, pantropical or neotropical distribution, benefited by these anthropogenic activities.

Floristic Richness. One of the main reasons that the Sayula sub-basin has registered fewer species/km2 compared to other sites may be due to the anthropic degradation suffered by the region, as mentioned above, large areas for irrigation and temporary agriculture, as both areas make up 37 % of the region, in addition to livestock activity. Due to the great agricultural activity that occurs in the region, in 1978 an intermediate and partial closure was decreed for the extraction of groundwater in the southern part of the lagoon, it was recommended not to increase the exploitation for agricultural purposes and to reserve this area to satisfy future demands of drinking water for the population (^{Ávila 1994}).

Vegetation and land use. This study is a contribution to knowledge of the flora and vegetation of Jalisco, taking into account that only 60 % of the State has been explored (^{Ramírez-Delgadillo et al. 2010}), because there are many areas to explore and many species to be discovered; in addition this floristic information is complemented with a map of current vegetation and the use of soil that develops within the region.

The Sayula sub-basin is crossed by the highway Guadalajara-Colima, which brings as a consequence a great disturbance, mainly in the neighboring plant communities such as aquatic vegetation, thorn forest and halophytic vegetation. The latter being of great importance to waterfowl, both migratory and resident, as it maintains large populations migrating from Alaska, Canada and the USA. During the winter season, as the “Canadian goose” (Chen caerulescens) “freshwater seamstress” (Limnodromus scolopaceus), “western playerito” (Calidris mauri) among others, which feed on different salty grasses such as Distichlis spicata, Eragrostis obtusiflora and Sporobolus pyramidatus. Because this type of vegetation provides shelter, food and protection to these wild species, has been declared a priority area for conservation and has been declared RAMSAR site since 2004.

Based on what has been observed in the field during the years that have been worked in the sub-basin, it is necessary to publicize the problems that affect these vegetable communities and that have an impact on them, since some activities have been detected that break the natural balance of the region, such as garbage dumps, sewage dumps to the lagoon.

On the other hand, agricultural use and extensive livestock tend to reduce natural areas and modify the landscape, which leads to the disappearance of native species and the establishment of invasive species. Other species, on the other hand, are favored by anthropogenic activities such as fires, breach openings, land use change, such as the Cuscuta spp., Heliotropium curassavicum, “mistletoe” Phoradendron spp., Psittacanthus calyculatus, Salsola kali and Verbesina encelioides, whose populations have to increase and spread to other communities.