Impacts of grazing, restoration by planting on the pastoral potential, floristic richness and diversity of a the southwestern steppe of Naâma (Algeria), in the context of climate change

Boukerker Hassen, Hecini Lynda, Salemkour Nora, Boumedjane Mouna Rachida¹, Kherifi Wahida, Doghbage Abdelghafour², Belhouadjeb Fathi Abdellatif², Bekiri Fadia, Boultif Meriem and Diab Nacima

Scientific and Technical Research Centre on Arid Regions CRSTRA Biskra Algeria
hboukerker@yahoo.fr
¹ Forests Conservation of Biskra Algeria
² Centre de Recherche en Agropastoralisme (CRAPAST), Djelfa, Algeria

Abstract

This study is an analysis of the overgrazing effect, restoration by plantation on three steppe formations in the region of Naâma southwest of Algeria. It is a formation in Aristida pungens and Atriplex canescens, formation in Stipa tenacissima and another based on a plantation of Atriplex canescens; located respectively in the sites of, Swiga, Nofikha and Touifza. These steppes constitute a poor floristic procession subjected to strong anthropozoic pressure and to severe drought effects, despite restoration operations after replanting with the perennial Atriplex canescens shrub to maximize capture of atmospheric carbon and thus have been on the way of regression for many years. The reasons for this phenomenon seem to be linked to excessive man actions and his main livestock activity and the practice of a rainfed cereal crop are at the origin of this degradation coupled with a harsh climate and irregular and rare rainfall have been stumbled for several decades, against a demographic increase and inadequate use of natural resources.

Our study deals with an analytical characterization through evaluating the pastoral potential, floristic richness and diversity of the three large existing formations in these regions and the main factors that threaten them, to lead at the end of this contribution to a sustainable approach that includes the necessary recommendations aimed at the restoration and rehabilitation of the entire steppe regions in the context of climate change.

The floristic analysis of the various formations in the study area is based on carrying out floristic surveys but does not intend to conduct a phytosociological study in the strict sense of the term. This contribution will be coupled with a climatic analysis of the study region to get an idea of the possible effects of climate change on the steppic vegetation of this Algerian southwestern region.

The biological character and the phytochoric spectra of the inventoried taxa shows in general from one hand the predominance of therophytization is all the more important as the accentuation of the aridity of the climate and the disturbances of the environment by grazing, crops. Moreover, the recorded chamephytization seems to be closely linked to low temperatures, aridity and the anthropogenic degradation of the environment with the proliferation of thorny species such as Astragalus armatus. On the other hand ; the large proportion of Therophytes, inventoried at the studied stations, is specific to Mediterranean and arid zones, where strong water stress dominates. This can be explained by the fact that; the richness in Therophytes has often been at the origin of the development of short-cycle species, to the detriment of woody species. Climatic data analysis from our study stations allowed us to observe the spatio-temporel evolution on North-South gradient that depends on irreversible phenomena such as aridity and other climatic indicaors as interannual precipitations irregularity in recent years.etc.

Keywords: anthropozoic, chamaephytes, climate change, formation, grazing, phyto-ecology, steppe

Introduction

Today the steppe is considered to be an ecosystem in danger. The organization and development of the territory, in the sense of an integration of its triple dimension: human, ecological and animal, is a failure of a vision (Khelil 1997).

Indeed, the numerous studies carried out since the 1970s on the steppes all show a significant decline in vegetation cover (Aidoud and al 2006 ; Nedjraoui and Bedrani 2008 ; Taibaoui 2008 ; Hirche and al 2010 ; Moulay et al 2011). According to (Chelling, 1969) ; in 1968, steppe rangelands with 1.6 billion FU, fed 7890103 sheep-equivalents, which gave a load of 1.9 ha/eq.ovine. In 1996 the livestock was equivalent to 19170103 sheep eq. and the real load of 15 million hectares would correspond to 0.78 hectares for 1 sheep eq.

Moreover, the various studies (U.R.B.T., 2002; Le Houerou, 1985; Aidoud, 1989; Kacimi, 1996) ; have shown that rangelands have deteriorated sharply and that forage production is equivalent to about 1/3 of what it was in 1968, i.e. 533 million UF. The potential pastoral load would be about 8 ha/1 eq-ovine and thus 10 times greater than the real load of the pastures, which gives rise to intense overgrazing, which is manifested by the excessively prolonged retention of the herd on grazed areas taking up a much greater quantity of vegetation than the annual production. This overgrazing quantitatively, causes a decrease in perennial vegetation cover and phytomass.

Added to this, as an aggravating factor, is the anthropozoogenic factor linked to the direct effetcs of climate change ; since Vegetation is widely diffused and is a synthetic indicator of ecological conditions (Emberger 1939 ; Ozenda 1994). Climate determines broad type and distribution of vegetation and ecosystems (Walter and al., 1976). Consequently, a climate classification related to vegetation distribution should be appropriate as a basis for small-scale ecological regionalization (e.g. Bailey 1987; Klijn and al 1994), to characterize and compare different ecosystems, even where natural vegetation is poor or not available as an environmental indicator due to lack or excessive disturbance. Adding to that ; in fact the absence of a clear and effective pastoralism policy has accentuated the problem (Boukerker and al 2021).

Unfortunately, the changes, the excesses and the risks that the southwestern algerian steppe undergoes endanger the entire region as a direct result of silting up and desertification (Boukerker and al 2021).

The steppe region of Nâama, located in southwestern Algeria, is particularly exposed to the risk of desertification, like most arid or semi-arid regions around the Mediterranean. It is also in the throes of profound socio-economic transformations, which pose the major challenge of guaranteeing the balance between the protection of the different environments and the development of the rural populations living there Haddouche and al (2006).

In the region of Nâama and since forty years, the pressure exerted on the steppe resources, have greatly increased (Bedrani 1994). In recent years, the overgrazing caused by the impressive number of livestock on the best pastures and around water points far exceeds the feeding capacities of the environment and rangelands of this steppic part; reached sometimes a level of irreversible degradation.

This trend threatens many natural environments that are in danger of disappearing. Ecological studies indeed reveal, in addition to the worrying decrease in original plant formations, a loss of biodiversity (Nedjraoui 2004; Le Houreou 1995), an increase of the distribution of certain biological forms such us phanerophytes and chamephytes, that as a whole, reflect the changes in the state of the environment under the action of ecological and especially anthrozoic factors. This predominance seems to be influenced also by the more intense grazing in the region and strictly linked to seasonal rains if these precipitations fall during the hot season, the Therophytes develop with difficulty. In fact, their proportion increases as soon as there is degradation of the environments because this biological type seems to be better adapted than the Phanerophytes to summer drought as underlined by Danin and Orshan 1990 in (Boukerker and al 2021) ; Benabadji and Bouazza (2002).

This intense degradation of this steppic environment inducing desertification, requires a better understanding in order to see how to fight against this scourge and adapt to it an adequate management and to reduce the effects of climate change. The efforts made to deal with this situation are insufficient given the fragility of the ecosystem. We are thus witnessing an extension of ecologically harmful actions whose negative effects have been aggravated especially by long periods of drought and its repetitive nature.

Revealing the use and evolution of scarce and fragile natural resources, through, biomass assessments and measurements; may, on the one hand, bring out reliable indicators of the state of the environment and contribute to identifying the limits beyond which the pressure of human activities leads to an irreversible impoverishment of natural resources, and on the other hand to ensure rational management of this steppe ecosystem by reducing the animal load, rotation of grazings, defensive planting, reseeding of degraded pastures, planting fodder shrubs in the context of climate change, etc.

It is in this context that our work consists in a study of the evolution of the biomass of three steppic zones located in the wilaya (province) of Naâma; namely the Nofikha , the Twifza and finally the Swiga zone.These stations are characterized by great plant poverty due to anthropogenic and climatic actions. This work proposes to describe the floristic composition, the phyto-ecology and the biological aspect of a very degraded and widespread type of Steppic stand on the high plains of Oran. Although limited to the Naâma study region, this analysis could highlight the dynamics of vegetation subject to the influence of climatic conditions and that of human impact (clearing and overgrazing) in the region. Our results will be compared with those of other authors.

Materials and methods

Selection of sampled sites

One of the objectives of the study being to describe the floristic composition and the biological aspect of the three types of steppe formations very widespread on the high plains of

South west of Algeria, from phytoecological surveys in the range of a mixed-formed steppe of Aristida pungens and Atriplex canescens, formation in Stipa tenacissima and another based on a plantation of Atriplex canescens. The sampled stations are; located respectively in the sites, Swiga, Nofikha and Touifza. The so-called stations depend on the wilaya (province) of Naâma (steppe region of southwestern Algeria). From historical point of view, according to the HCDS (the high commission for the development of the steppe) of the wilaya of Naâma, the stations of Nofikha and Sewiga have not undergone any previous development, except for the second, the HCDS has carried out a plantation by Atriplex canescens to improve the productivity of the latter. For the Touifza station, it was previously occupied by Aristida pungens; but it has become almost naked due to drought and overgrazing. This is why the HCDS decided to plant it with Atriplex canescens.

The Wilaya (province) of Naâma is located in the western part of the highplains, on the borders of Algeria and Morocco. It extends between latitude 32° 08045″ and 34° 220 13″ North, and longitude from 0° 36045″ to 0° 46005″ west. From a geomorphological point of view, it is divided into three large zones: a steppe zone in the North, mountainous area in the southwest and a pre-Saharan zone in the South. The study area is spread over two municipalities which correspond to the steppe part of the Wilaya most affected by degradation. These are the communes (district) of; El Mecheria where our 2 study stations are located, those of Swiga and Touifza, situated in the southwest of the town and 20 km north of the capital of Naâma and the communes of Ain Sefra with the station of Nofikha; located 65 km south-west of the Chief Town of the Wilaya. (map.1).

Map 1. Geographical situation of the study stalions

The natural environment

To show a possible effect of climate change, we have based on the one hand on the study of some climatic parameters which can have effect on the evolution of the steppe vegetation and which constitute indicators of possible climatic change; and on the other hand it is based on studies that have been carried out in the same region of study as examples (Maire 1926 ; Seltzer 1946 ; Haddouche et al., 2009 ; Benaradj 2021). So we have based on the processing of data from an old meteorological data (Seltzer 1946), taken over ; 25 years (1913–1938) and from a recent period (1990–2014). All data and the climatic parameters are collected from the National Meteorological Office (NMO) and they come from two meteorological stations Mécheria and Ain Sefra, located in the heart of the study area (ONM 2015). All the tables presentiong the different values of the climatic parameters studied are shown in Table. 1, 2, 3 and 4).

The soils of the two stations, those of Swiga and Touifza commune of Mecheria (Photos 2 and 1 respectively) are generally thin, sometimes non-existent. They are characterized by a much more regressive evolution than the reverse (Haddoche and al., 2009). Also they are characterized by a clear predominance of the sandy texture which appears in the first horizon, this is also what was reported by (Bouchetata and al., 2005). For the Nofikha station (Photo 3) located in the municipality of Ain Safra, the soils are skeletal, poor in organic matter and sometimes sterilized by salinity. These are calcimagnesic soils which belong to the group of brown calcareous soils with a crust (Djabaili, 1984) ; Pouget 1977 and Kadik 1987).

The steppe vegetation of the Naâma region is often in a state of imbalance with the environmental conditions. These imbalances may be of natural origin but, today, within the site, most of the plant successions are disturbed by human activities.

Methodological approach

The approach adopted is based on a floristic inventory based on phytoecological surveys in the distribution area of ​​the selected formations. We opted for systematic sampling. The methodology used includes a device consisting of a series of transects distributed in the different plant formations of the study stations.

Within the distribution area of ​​the groups, a total of 30 floristic surveys were carried out during the spring of 2012-2013 with a minimum area of ​​around 100 m² (Djebaili 1984; Benaradj 2009). The investigations carried out in the study stations made it possible to draw up a floristic inventory. The identification of plant species was carried out using the documents Quézel and Santa (1962-1963); Ozenda (1991); Valdés, Rejdali, Achhal El Kadmiri ; Jury and Montserrat (2002); Tela Botanica (2017).

Sampling of flora and vegetation

To meet the objectives of the study, systematic sampling was conducted. Linear surveys (10 per site) as defined by Gounot (1969) and Long (1974) were randomly arranged at each at sampled site and make it possible to determine species recovery and their contribution to the vegetation cover. The length of the line (20 m) and the reading mesh (10 cm), giving rise to 200 reading points per line, were determined for the Algerian steppes by Aidoud and al in 1983. A double tape is stretched between two stakes materializing the different transects, and a metal needle is descended vertically into the vegetation every 10 cm along the tape, which makes it possible to obtain 200 reading points per line (Photo.4).

Photo 4. Sampling of flora and vegetation in the study region

At each reading point, the species affected by the needle are noted. The data from each line make it possible to calculate the absolute frequency of each species, which, related to the total number of points per line (200), represents an estimate of its percent recovery. These data were used to calculate the recovery of the different biological forms of Raunkiaer according to the different treatments. A minimum area of ​​100 m² was selected for the floristic surveys. These were carried out during the fall and spring of 2012 and 2013. These sampling periods were chosen because they cover the flowering and fruiting period of the vast majority of species (autumn for halophytes and spring for annuals). These phrenological stages are essential for a better identification of the species.Taxon identification was carried out using the guides and keys cited above.

Results and discussion

Climate analysis

Rainfall

The analysis of precipitation data in the three study stations shows us a decreasing rainfall gradient from north to south. It is thus that in the Touifza and Swiga stations, the average annual rainfall is approximately equal to 293.00 mm and 243.11mm respectively for the old and recent period and in station of Nofikha the average annual rainfall is respectively equal to 192.00 mm and 199.64 mm/year for the old and recent period. These precipitations are characterized by their lowness, their spatiotemporalirregularity with strong inter-annual variations, in the form of downpours or thunderstorms and are generally concentrated in the autumn season. The variability of the mean precipitation shows that for the series of 25 years, 8 years are considered as wet for the old period (1913–1938) and 4 years for the recent series (1990–2014), and 5 years are considered as years dry for the first period and 17 for the second period. Taking into consideration the dry periods which raged in the region during the years 1992, 1995, 1998, 1999, 2001, 2002, 2004 and 2013 and the precipitations irregularity of frequencies, we say that these indicators converge towards a persistent drought, even if significant rainfall episodes occur they do not manage to fill the deficit to reverse the trend.

Thermal differences between P1 ((1913–1938) and P2 (1990–2014)

The comparative study of the two climatic series shows a more marked warming of the minimums and maximums temperatures for all 3 study stations. Data analysis (tab.2.) indicates that there is a slight decrease in minimum temperatures (m C°) with a thermal gap of – 0.01 (C°) for the Mecheria stations (Swiga-Touifza) and an increase in those for the station of Ain Sefra (Nofikha) with a thermal gap of 0.87 (C°). Regarding the maximum temperatures (M C°), there are increases in those with a thermal gap of 0.74°C for the stations of Mecheria (Swiga-Touifza) and 1.68°C for Ain Sefra (Nofikha).

The De Martonne’s aridity index

The comparative analysis of this index between the two periods allows us to advance that the study region is strongly marked by increasing aridity during recent periods and which is accentuated from North to South. This is due to the drought induced by the decrease in rainfall and the increase in minimum and maximum temperatures. The approximate values of the aridity index obtained are respectively 8 and 11 depending on the geographical position of the study stations. In the steppe space, for the stations of Mecheria (Swiga-Touifza) are characterized by a semi-arid to steppe climate. In the stations which are in the central part of the region, the Saharan Atlas (Aïn Sefra) the index is 7.53 and reflects a desert-like climate.

The thermal continentality of the study stations

Basing on Debrach in (Alcaraz L, 1982), we can say that during the ancient period the two stations Swiga and Touifza, present a semi-continental climate. While the station of Nofikha, has a continental climate.However, the analysis of the recent climatic period, show that with a value of (M-m C°) equal to 35.29; the region of Mecheria has experienced an evolution from a semi-continental climate to a continental climate. This change results in a decrease in thermal differences.

The pluviothermal quotient

Figure 1. Variation of the emberger climagrame of the study stations

This Emberger climagram Quotient (Figure 1.) shows that there is a decrease in Q2 values and a change in “m” value between the two chosen periods. We witness a small change of the pluviothermal quotients between the old period and the recent one, through a displacement of meteorological stations from one level to another or from one variant to another. So, the Aïn Sefra station (Nofikha) moves from the arid lower level with cold winter in the old period to the upper Saharan level with cool winter in recent times. The Swiga and Touifza stations are moved from the middle arid stage with cool winter in the old period to the lower arid stage with cool winter in recent times.

Ombrothermal diagram of Bagnouls and Gaussen

From the comparaison of the two periods, through the analysis of the various ombrothermal curves (fig.1.) of the stations, allowed us to record a period of drought varies from 5 to 7 months or more (from June to September) at the level of studied region, the district of Mecheria (Touifza and Swiga stations). However, in the district of Aïn Sefra (Nofikha station), we observe a fairly prolonged period of drought that varies from 10 to 11 months (from March until the end of November). Thus, a fairly short wet period; varies from 4 to 6 months for stations of Touifza and Swiga and from one month and zero for Nofikha stations. This is how Haddouche et al 2009, confirms that the Mecheria station counts 30 wet years against 39 other dry ones over a meteorological series of 99 years (1907-2004). This means that this steppe region is clearly at risk of "sliding" towards hyper arid or Saharan conditions.

Diversity and abundance of taxa

The systematic analyzes of the obtained results at the level of our three study stations; show a diversity in families, genus and species which varies from one station to another (table 5). We noticed that the distribution of species at the families and genus levels is not homogeneous. The stations of Touifza and Swiga are the richest in diversity.

The species inventoried in the Nofikha station namely; Atractylis serratuloides; Peganum harmala; Lygeum spartums, Hordeum murinum, Astragalus armatus ; are species that manage to maintain themselves in certain stations and testify to a regeneration or testify to an accentuated degradation on the pastoral level. The species present in the two stations, those of Swiga and Touifza, Constitute by Helianthemum lippii; Atractylis humilis, Atractylus flava, Atractylus serratuloides, Atriplex canescens; Stipa parviflora and Lygeum spartum; are the companion species of Atriplex canscens in these planted stations. Also we assist in the three studied stations; the presence of species such as; Thymelaea hirsuta; Salsola vermiculata; Astragalus armatus.etc, which are psammophilic species.

Generally, it can be said that the more advanced degradation leads to a substitution of the Saharan elements by species much more adapted to the xericity which is accentuated by this deterioration of the stationary ecological conditions.

According to Aidoud (1989), the floristic richness in the arid zone depends mainly on the annual species, the environmental conditions and the correlation of all the characters (climate, edaphic and exploitation). However, we noted that, according to the scale of Daget and Poissonet (1997), the recorded flora is poor. This flora is not representative of the regional situation, there are differences from one station to another and dependingon the type of development.

Family diversity

Our results show that the three families of Asteraceae, Fabaceae and Poaceae; are best presented at the three study stations (tab. 1 in annexe). We have also noticed that the families identified are, on the whole, common for the stations studied (fig.2). Nevertheless, the two families, of Salsolaceae and Thymelaceae which are presented by psammophile species are absent at the Nofikha station based on Stipa tenacissima, but which are present at the two other stations based on Aristida pungens and Atriplex canesens for the Swiga station or based on a pure plantation of Atriplex canesens in the Touifza station. This can be explained by the improvement of soil characteristics Aidoud (1989). The specific place occupied by the Asteraceae, Fabaceae, and Poaceae is justified, since they are cosmopolitan families which are very widespread over the entire surface of the globe. Overall, the same families predominate in the flora of southern Oran, Algerian and Constantinian (Bouzenoune 1984; Boughani 1995; Boughani and al 2009).

The floristic comparison of the study region with the data of Quézel (1965) ; Ozenda (1991) ; Boughani (2014) shows that it is floristically representative: Asteraceae, Poaceae and Fabaceae are dominant in the Saharan Atlas sector of the Maghreb steppic domain.

Figure 2. The families inventoried in the study stations

Our results are in agreement with the floristic studies of Chehma (2005); Chehma and Youcef (2009); Boughani (2009 and al); SelmKour and al (2013); Bouallala (2013); Merdas and al (2017) and Benaradj et al. (2017). Moreover, the main families inventoried in this study are the same ones found by other authors, but in a different order. We cite the work of Quézel (1978); Bouznoune (1984); Le Houérou (1995); Aidouds (1997); Dahmani (1997); Amghar (2012) and Boughani (2014). It should also be noted that the preponderance of the Asteraceae family at the three study stations is consistent with the work of Quézel (1978); Amghar (2002); Selmkour and al, 2013; Boughani (2014); Zedam (2015). All these works report that the Asteraceae are the best represented family in the Algerian flora and the flora of North Africa. As for the presence of Zygophylaceae in the Nofikha station, this could result in the arid climatic conditions of the study region (Naâma) or the introduction of the species Atriplex canescens in the Twifza station (Amghar 2012-2016).

Biological spectrum

The biological type of a plant is the result, on the vegetative part of its body, of all the biological processes including those which are modified by the environment during the life of the plant and are not hereditary (Polunin 1967 in Benabdellah 2007).

Through the observation of estimated values ​​of the spectrum, in terms of contribution of biological types to specific richness, we see a clear preponderance of Therophytes with (31.57%) Figure 3.

(Th: Therophyte; Ch: Chamaephyte; Ge: Geophyte; He: Hemicryptophyte; Ph: Phanerophyte)

Figure 3. Distribution of biological types in the study

In the Swiga station of the 20 species inventoried, we observe for this station a preponderance of Hemicryptophytes and Therophytes and to a lesser degree the Chamephytes. Finally, for the Touifza station and out of the 23 species listed, there are 10 Hemicryptophytes, (43.47%); 6 Therophytes (26.08%); 5 Chamephytes (21.73%) and finally 2 Geophytes (8.69%).

According to the overall list of species recorded, the results obtained for the three study stations are presented in the figure 2 ; we can say that the predominance of therophytization is all the more important as the accentuation of the aridity of the climate. Daget (1980) and Barbero and al (1990) agree to present the Therophytes as being a form of resistance to drought as well as to the high temperatures of arid environments. The meaning of the Therophytes has been widely debated by these authors who attribute it either to adaptation to the stress of winter cold or summer drought, or to disturbances of the environment by grazing, crops, etc. Daget (1980) thought that, in any case, the rate of Therophytes is linked, whatever the scale of the analysis and the level of perception adopted, to the opening of the vegetation and the overall humidity of the environment. On the other hand, chamephytization seems to be closely linked to low temperatures, aridity and the anthropogenic degradation of the environment with the proliferation of thorny species such as Astragalus armatus (Floret and al (1978) ; Orshan and al (1985) in Kerroum (2014). The large proportion of Therophytes, inventoried at the studied stations, is specific to Mediterranean and arid zones, where strong water stress dominates (Daget 1980; Madon and Médail 1996; Kadi-Hanifi 2003 ; Amghar 2012; Boumakhleb and Chehma 2014). This can be explained by the fact that; the richness in Therophytes has often been at the origin of the development of short-cycle species, to the detriment of woody species (Dahmani 1997; Amghar 2012; Zedam 2015).

Distribution of biological types in the study stations

The analysis of biological spectra of the prospected stations (fig.3), shows that Hemicryptophytes are the most represented in the stations of Swiga and Touifza, with rates generally exceeding 40%. Therophytes are also well represented with different percentages, varying between 26% and 30%. Chamephytes are less represented, their percentage is not negligible (20 to 21.73%), followed by geophytes and Phanerophytes which record a reliable percentage of 5% each for the Swiga station and 5% of Geophytes for the Touifza station. In the Nofikha station, we notice the predominance of Chamephytes, Therophytes and Hemicryptophytes. In this station; the Phanerophytes are absent and the Chamaephytes are the dominant ones because the latter; are better adapted to drought than Phanerophytes, as they are more xerophilic (Amrani 2021).

The plants of the Nofikha station are Chamaephytic in nature, they dominate in abundance.

We record a dominance of Hemicryptophytes which constitute a third of the floristic set, with a total of 23 species, or 32.59%. The second largest group is the Therophytes, which are represented by 18 taxa, or 29.21%. The Chamephytes occupy the third position with 15 species, which represents 24.43 %. These three biological types are largely in the majority compared to the other biological types which represent only 5% ; with an equal share for the geophytes and the Phanerophytes, or 1 species for each.

This distribution is similar to that described by Floret and al (1978), in agreement with Orshan and al (1985) in Kerroum (2014) and who consider Chamaephytes to be better adapted to low temperatures and aridity and accordine to Benabadji and al (2004); are also favored globally by grazing; for they are weakly palatable add. Regarding ; the Therophytes; several authors (Grime 1977; Daget 1980; Barbero and al 1990; Aidoud 1984 and Barbero and al 2001).

On their part; Benabadji and Bouazza (2001); the predominance of Therophytes is strictly linked to seasonal rains if these precipitations fall during the hot season, the Therophytes develop with difficulty. These mayflies seem to be influenced also by the more intense grazing in the region. In fact, their proportion increases as soon as there is degradation of the environments because this biological type seems to be better adapted than the Phanerophytes to summer drought as underlined by Danin and Orshan (1990) ; Benabadji and Bouazza (2002). This therophytization may also be due to the phenomenon of self-mulching, a mechanism occurring in areas with high evaporation and in deep silty soils covered with sand on the surface. This phenomenon allows water to be stored and thus promotes the development of annuals (Harrane 2012). The distribution of Hemicryptophytes throughout the flora of our study area is generally linked to the richness of the soil in organic matter; a phenomenon confirmed by Barbero and al (1989). The low rate of the biological type of Geophytes, recorded in all of our study stations, is in agreement with the results reported by; Dahmani (1996); which points out that the geophytes are certainly less diversified in degraded environment but insome cases they canbe represented with mono specific tendency (overgrazing, repetition of fires), being impose themselves by their covering. Finally, the Phanerophytes, as a whole, reflect the changes in the state of the environment under the action of ecological and especially anthrozoic factors.

Phytochoric spectra

Our study stations in the present work belong to the Holarctic Empire, the Mediterranean region and northern Africa.

(Ameri: American ; End: Endemic; Med: Mediterranean; Med-Iran: Mediterranean-Irano-Turanian; Sah: Saharo-Arabic; Med-Sah: Saharo-Arabian Mediterranean)

Figures 4, 5, 6. The global phytochrological spectrum in the different stations

From the analysis of the phytochoric spectrum of the Touifza station, the predominance of the Mediterranean element is shown with a high rate of 43.47 % or 10 species followed by the Saharo-Arabic Mediterranean element with a rate of 34.78 % or 8 species, and the Saharo-Arabian element with a recorded rate of 21.73 % or 4 species. As for the other elements, they contribute little to the floristic richness, it is the Medi-Irano-Turanian element with 4.34% or 1 species. Also for the Nofikha station, the predominance of the Mediterranean element has been showen with a high rate of 61.11 % or 13 species followed by the three elements; the Saharo-Arabic Mediterranean with 16.66% or 3 species and the Saharo-Arabic and the Medit--Irano-Turanian with equal rates of 11.11 % or 2 species each.

Finally, in the Swiga station, the dominance of the Mediterranean element with a high rate of 45 % or 9 species is noticed, followed by the two elements, the Saharo-Arabic and the Mediterranean-Saharo- Arabic with rates of 30 % and 15% respectively, or 6 and 3 taxa. As for the other elements, they contribute weakly to the floristic richness, it is the endemic element and the American element with equal rates of 5% or 1 species each.

From the analysis of the global phytochoric spectrum for our study area, the predominance of the Mediterranean element emerges with a high rate of 52.45 % or 32 species. The taxa of Med-Sah-Arab and Sah-Arab origin occupy an appreciable place in the study area; represented respectively by 20.89% and 19.67% of the overall population. As for the other elements, they contribute little to the floristic richness; including the Med-Irano-Turanian types, the Endemic and the American element, which are poorly represented; respectively by rates of 4.47%; 1.49% and 1.49% (Figure 4, 5 and 6).

For the connecting element (connecting species, namely, the Mediterranean-Saharo-Arabic (Med-Sah), Euro-Mediterranean (Euro-Med), Mediterranean- Saharo-Iranian (Med-Sah-Iran), Euro-Asiatic (Euro-Asia ): Gathered in a so-called «linking group» group (Ozenda 1977), this element is formed in our study by a single group, that of the Mediterranean-Saharo-Arabic element (Med-Sah) of which we have recorded the values ​​of 34.78 %; 16.66 % and 24.52 %; corresponding respectively to the numbers of taxa, 8 ; 3 and 3 taxa; for Touifza, Nofikha and Swiga stations respectively. Quezel (2000), explains the importance of the biogeographical diversity of Mediterranean Africa due to the climatic changes that have taken place in this region since the Miocene, resulting in migrations of tropical flora. This same author emphasizes that a phytogeographic study is an essential basis for any attempt to conserve biodiversity.

Distribution of phytochoric elements according to biological types

The Mediterranean element:

This element is represented by 13.04 % of therophytes, 8.69 % of geophytes, 17.39 % of hemicryptophyte and 4.34 % of chamaephyte in the Touifza station. For the Nofikha station, it is estimated to be 27.77 % therophytes, 16.66 % hemicryptophytes, 11.11 % geophytes and 5.55 % chamaephytes. In the Swiga station we recorded 20 % hemicryptophyte, 15 % therophytes and an equal share of 5 % for chamaephytes, geophytes and phanerophytes.

The Endemic element

Endemism is represented only in the Swiga station, where it is estimated at 5 % for chamaephytes, which is a single taxon.

The Saharo-Arabic element

At the Touifza station, it counts 6 taxa of which it is represented by 2 biological types, with equal parts of 8.69 % of chamaephyte and hemicryptophyte. Thus there is only 1 biological type in the Nofikha station, it is that of the chamaephytes of which it is estimated at 11.11 %. At the same time, 4 biological types are recorded in the Swiga station, these are hemicryptophytes with 15 % and equal parts of 5 % for chamaephytes, therophytes and phanerophytes.

The connecting element (connecting species)

Mediterranean-Saharo-Arabic (Med-Sah), Euro-Mediterranean (Euro-Med), Mediterranean-Saharan (Med-Sah-Iran), Euro-Asian (Euro-Asia): Gathered in a so-called "linking" group (Ozenda 1977), this element is formed in our study by a single group, it is that of the Mediterranean-Saharo-Arabic element (Med-Sah) of which we recorded in the Touifza station 3 biological types, namely the hemicryptophytes , therophytes and chamaephytes, for which; we recorded respectively, 17.39 %; 13.04 % and 4.34 % . Thus only one biological type is observed in the Nofikha station, it is that of therophytes with 5.55 %. Finally, in the same way for the Swiga station, two biological types are observed, therophytes with 10 % and chamaephytes with 5 %.

The Med-Irano-Turanian element

This element is present only in the two stations, that of Nofikha and Touifza of which we recorded rates of 11.11 % and 4.34 % respectively and which corresponds respectively to the numbers of taxa of 2 and 1 taxon.

The American element

This element is observed only in the Swiga station with a single taxon thus representing a rate of 5 %.

Biological preservation

Species Statues (Protected Species)

To know the status of the inventoried species, we used on the one hand the IUCN red list and on the other hand the Executive Decree n°12-03 Safar 1433 corresponding to January 4, 2012 establishing the list of non-cultivated plant species protected in Algeria. This analysis showed us the existence of a single endangered species to be protected on a national scale and it is the Saccocalyx satureioides inventoried in the Swiga station based on Aristida pungens and Atriplex canescens

Conclusion

The analysis of the current state of the flora of the plant formations of the wilaya of Naâma highlights a more advanced state of degradation from a floristic point of view, of which we recorded only a maximum of 23 taxa in the Touifza station. Also we can distinguish that there is a difference between the three stations from a biodiversity point of view. This study showed that the families of Asteraceae, Poaceae and Fabaceae are the most diversified and dominate this flora. Sometimes the taxa belonging to these families such as that of the Asteraceae family; are generally species with low energy and ecological value; this is the case of the genus Atractylis.

In general, therophytes, hemicryptophytes and chamaephytes constitute the main flora of the studied stations, followed by geophytes and phanerophytes. The low percentage of phanerophytes reflects a worrying ecological situation. Moreover, the various observations made in the field show the disturbing state of health of the steppe formations in this region in the context of climate change.

The dominance of species chamaephytics species confirms the two phenomena of degradation of steppic formations, chamaephytization and therophytization, which characterize the flora of plant formations in arid and semi-arid zones. It is a strategy for adapting plant formations to the anthropogenic and climatic pressures that this region is subject to. Regarding; geophytes are, on the whole, the least well represented in most of the studied formations. Indeed many researchers have demonstrated that their rate is however relatively higher in forest environments than steppe areas where they completely disappear in accordance with the observations of Barbero et al. (1989).

From the geographical distribution point of view, the flora of the study region showed the Mediterranean affinity of the studied flora. Thus the latter is dominated above all by species belonging to the Mediterranean, Mediterranean-Saharo-Arabic and Saharo-Arabic elements, followed by species of the Medit-Irano-Touranian, Endemic and American element types.

This study has shown that the synergistic action of climate throuh aridity and anthropic action generate significant changes in the vegetation in the dynamic sense. The impact of bioclimatic criteria should not be forgotten: the rate of precipitation, the increase in average annual temperatures and the lengthening of the summer drought period are reflected in the field by either an adaptation of plants or by the elimination of other plants. Also significant changes in the floristic composition are needed and a xerophilic vegetation more adapted to ecological stress is growing. This dynamic will allow a physiognomic restructuring of the landscapes.

Like other countries in the region, Algeria is particularly affected by climate change and the resulting desertification, leading to a decline in plant cover and a disruption of traditional balances. Indeed, the Algerian steppe, a region essentially with a pastoral vocation, is subject to regular threats linked to climate variability, as well as to the frequency and intensity of extreme events, the trend of which is increasing. Faced with these threats on the steppe, which represents a vital space for pastoral populations, the latter must face this situation which hinders their socio-economic development and threatens their survival; by seeking to adapt in an optimal way through their local know-how to the consequences of climate change and develop diversified adaptation strategies to try to mitigate the harmful impacts. In effect; the current environment present strong constraints and especially subject to disturbing factors in a context of uncertainty.

To conclude, we will recall that these first approaches on the flora of Naâma, only give a general idea on the subjects approached. Many questions still arise. In this kind of work, the need for regular updating is more than obvious. Our main ambition is that these essays should be useful references for all interested parties who, hopefully, will soon come forward to comment on and enrich them. This type of work must be continued by other work in order to identify plant dynamics in a constantly changing environment.

Acronyms definition

The Forage Units (FU) system consists of calculating, for each food; the amount of energy that the animal that ingests it is able to use for growth and maintenance of its tissues or to produce (Démarquilly et al, 1996). And by convention this energy is expressed in Forage Units (FU), compared to the net energy value of one kg of reference barley, equal by definition to 1 FU. For each feed two UF values, one for dairy females and maintenance animals (UFL), the other for fast growing animals (UFV) (Zembri 2014). According to (Meyer 2022), the fodder unit is the energy value provided by 1 kg of average quality standard barley containing 86% DM, harvested at the ripe grain stage equivalent to 1.65 kcal.

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