Survival rate, adaptation ability and carbon production and sequestration of 21 green oak (Quercusrotundifolia Lam.) provenances at Mounts of Saida (western Algeria)

Due to recent global changes, a substantial degradation of natural ecosystems in North Africa and diculties of species regeneration have been observed. A comparison of 21 green oak (Quercus rotundifolia Lam.) provenances in different bioclimatic zones was carried out at two ecologically different stations in western Algeria. The main objectives of the study were to (a) assess the survival rate and development in the natural environment of young individuals who derive from it, (b) gain an understanding of the level of morphological variability and (c) explore the possibilities of adapting the different provenances of green oak in the west Algerian ecological regions. The eld trial was established in 2008 at two sites. The average survival rate ten years after the establishment of the eld trial was 38.50%, with a total height average of 122.95 cm, a dry epigeous biomass production of 0.0630 t/ha and a sequestered amount of atmospheric carbon (CO 2 ) of 0.0859 t/ha. The green oak provenance (origin) of Zaccar from the Tellian Atlas group is distinguished by a higher survival rate and dryer epigeous than other origins. The variability of large regions of the country means that there are four areas in which varieties can show superiority in survival and biomass: those representing the Northern part of the Saharan Atlas, those of the high inner plains, those of the southern facade of the Tellian Atlas and nally those of the Saharan Atlas. 423 E, with an N-N-O exposure and an average slope of 5 to 10%. This site is characterised by: a) the high plant dynamic stage of shrubs dominated by Quercus rotundifolia, Juniperus oxycedrus and Ampelodesmamauritanicum, b) medium dynamic potentialities in fresh semi-arid bioclimates with rainfall greater than 500 mm on brown fersiallitic soil with limono-argilo-sandy, 21 to 60 cm deep, at 0–10/ 1000 active limestone and c) good biological activity at Jasminum fruticans, Smilaxasperaand Clematis ammula. The second site (2), known as ‘Sidi Moussa’, has an average altitude of 1235 m, a longitude of 34–41' 54 43 N and a latitude of 0 18' 39 15 E, with a western exposure and an average slope of 3 to 7%. It is characterised by: a) the clear high matorral phytodynamic stage dominated by Juniperus oxycedrus, Pistacia lentiscus and Stipa tenacissima, with b) mediocre dynamic potentialities in semi-arid cold lower bioclimates, rain-fedness between 350 and 400 mm on modal limestone brown soil, with a limono-sandy texture, 11 to 30 cm deep, active limestone at 0–10/ 1000 and c) an average biological activity at Alluim paniculatum, Euphorbia falcata, Malva rotundifolia and Avena sterilis. two comparative plantations are installed according to a plot scheme to facilitate management. Each device consists of three plots installed horizontally and side by side on relatively at ground on the lower part of the slope. Each plot the 21 provenances randomly distributed perpendicular to the slope and contains 15 families of the same provenance, on 10 plants 9450 The of survival ability and total heights was conducted regularly and any restocking plants. of annual fresh epigeous biomass obtained at the Sidi Benkaddour Sidi very low compared to by Zitouni (2010) in the of Setif the north-east of Algeria with an amount may age This study contributes to the understanding of the constraints of the recovery of the green oak species in the Mediterranean region, which has experienced a signicant regression, especially in the southern part of the Mediterranean. The study compared the behaviour of 21 selected provenances in the main ecological regions of green oak of the west of Algeria (Mounts of Saida). The follow-up spanned nine years and analysed adaptation to the environment such as survival, growth, epigeous biomass and carbon sequestration of shrubs. Measurements taken between January 2008 and October 2016 revealed:


Introduction
Forests in the Mediterranean region play an essential role in maintaining natural resources. They protect water supplies and soil (Harris et  However, in the southern and eastern Mediterranean areas, woodland rates are very low, especially those of deciduous woodland. In fact, they represent are less than 10% in the countries located at the South Shore. According to the food and agriculture organization (FAO; 2010) and Lanly (2010), the average rate of deforestation ranges from 0.72 to 1.1%.
In this region, tree growth is limited by the amount of water available in the soil. A decrease in the amount of available water causes a decrease in carbon assimilation, which is an essential component for the primary growth and for tree reserves of this important element. Many researchers (Quezel and Medail, 2003;Somot et al., 2008;Limousin, 2009) have con rmed that due to climate change, a signi cant decrease in precipitation and an increase in the duration and intensity of summer droughts will occur. Oaks once made up a major part of these forests and are considered to be one of the most typical components of Mediterranean vegetation-type (Saleo and Lo Gullo, 1990;Tsakaldimi et al., 2005). However, these ecosystems have deteriorated and are currently experiencing di culties in their regeneration (Dey et al., 2008;MacDougall et al., 2010;Pandey et al., 2020). This is particularly the case for green oak, which needs to be reconsidered in the various political regulations of plant restoration (Castro et al., 2006;Dey et al., 2008;Leverkus et al., 2015). This species requires a minimum rainfall of 355 mm/year to balance the annual carbon cost related to photosynthesis (Gracia, 2006).
To resolve this issue, research has been done on green oak regeneration procedures by planting, and these studies are providing promising preliminary results. Some of these procedures include a) plantation trials of nurse plants (Padilla and Pugnaire, 2009 The objective of the current study is to explore an alternative approach to ensure the restoration of the green oak forest by improving its survival and productivity. The comparison of green oak provenances (origins) at different bioclimatic zones was carried out in two ecologically different stations. Evaluation of the behaviour of these origins can provide answers to important questions: what is the in uence of ecological conditions on reforestation failure and what possible ecotypes could be appropriate to adopt in future reforestation programmes? Materials And Methods

Plant materials
Based on a survey of the territorially competent forestry services and the literature about the distribution of green oak in northern Algeria, important information on the different stands of the species was collected. Sampling was carried out by geographical area to establish the distribution of genotypes according to bioclimatic ranges. The fruit harvest (glands) was done on the entire crown, with respect for the minimum distance (300 m) between the seeders. This distance is necessary to avoid harvesting from trees that potentially have the same parents (Figure1  and Table 1). The green oaks that are geographically very close and ecologically identical were removed from sampling. The 21 selected green oak origins were collected over the following four bioclimatic zones: a. Group I: represents the most climatically advantageous region for oak growth and corresponds to the sub-humid oor of the Tellian Atlas. The selected origins were: Oued Yesser (OTM), Zaccar (ZAM) and Chaâbat Lakhra (CLS). b. Group II: corresponds to the sub-humid oor with the fresh and cold variants of thesouthern Tellian region. The selected origins were from Théniet El-Had (THT), Bordj-Bounaâma (BBT), Frenda (FRT), Cascade (CSG), El Bordj (BDM), Guelma (GLM), Nador (ZBA) and Sebt (SBR). c. Group III: represent the semi-arid zone of the plains and mountains that contains large areas of green oak in the state of clear and degraded thickets. The sampling was done on Ouled Kada (OKS), Oum Djerane (DLS), Nesmoth (MSN), Mezaouro (MSB) and Sebdou (SET). d. Group IV: represents the zone of the Saharan Atlas. In this zone, the green oak is less abundant and grows in extreme climatic conditions. The selected origins were Belezma (BLD), Dar Echioukh (DED), Boualem (BAM), Sidi Bouzid (ZBA) and Jebel Aissa (ATS).

Device and experimental plan
After a year of nursery breeding in sachets ( The survival rate by origin (the ratio of the number of live shrubs to the initial number of individuals planted) was estimated by a systematic count of the number of samples alive by family, origin and plot. For each shrub, the measurements taken were the total height and the root collar diameter.
A 3-metre measuring tape was used to obtain measurements (height and a sliding foot diameter). To prevent plant destruction, only one shrub per plot and per origin was felled in each plantation for the measurements of epigeous biomass and carbon sequestration. The determination of the aerial biomass of shrubs from the 21 green oak origins was based on the monitoring of individuals-diameter at the medium collar. Once the shrub with the median collar diameter in each plot had been determined, it was felled. The trunk (main shafts), branches and leaves were separated and weighed on the spot by the use of a precision scale. Samples of each part were placed in well-sealed numbered bags. For the trunk, after measuring the length, three pieces of 10 cm, (bottom, middle and the top of the crown) were taken. For branches and leaves, a 100 g sample of each was taken. The operation was repeated for the average shrub of each of the 21 provenances and in the three plots of each plantation. Every week, 20 subjects from each provenance were cut and transported to the laboratory. Depending on the laboratory's drying capabilities, 189 samples per planting were determined. The different parts were repainted and dried at 65°C for 24 hours to determine their dry weights. The dry weights of the different parts were calculated according to the fresh weight measured on the ground. The sum of the different dry parts (trunk, branches and leaf) represents the dry aerial biomass of the shrub from each origin.
Provenance biomass measurements were taken at the end of the nursery reproduction period (10 months later).The averages of the dry aerial biomass of the 63 shrubs felled in each of the two plantations were modelled on the basis of diameter and/or height. The best correlation is used to calculate the rest of the shrubs in the plantation. The allometric regression models selected in our case are mentioned with their characteristics in Table 2. The total dry biomass of the plantation is obtained by multiplying the number of shrubs of the plantation with the data from the average tree. The total dry biomass per hectare is then deducted.
The carbon stock of each plantation is obtained by determining the amount of carbon (C) of each shrub, which is only the product of the air biomass dry by 0.47%. The atmospheric carbon stock (CO2) of a shrub is obtained by multiplying the amount of C calculated by 3.67. In the same way as for dry biomass, the carbon stock per hectare or planting will be calculated.
Considering that, the value of an X character of an individual k of origin i in a medium j is written in the form of Xijk = u+ Pi+ Mj+ (PM)ij+ Rijk Where u = general average, Pi = effect of origin i, Mj = effect of the medium j (station effect), (PM) ij = interaction origin x medium, and Rijk = residual error.

Statistical treatment
Survival rate data are converted to arc sin before analysis. We tested the origin effect x site (station) on our measurements by a 2-factor variance analysis (ANOVA) at the 5% risk threshold (Stastistica12). This analysis was supplemented by a multiple comparison of the averages by the Newman-Keuls test. It should also be noted that the study of interfamily variability will not be addressed in this article.

Results
The preliminary evaluation of the juvenile period (nursery stage and one year after planting) is now possible, permitting the study of the behaviour of different origins 10 years after the seedling (Nasrallah and Khéli , 2010).

Effect of the station
Survival and plant height measurements taken one month after planting (winter 2007) did not reveal signi cant differences between the two sites. However, the measurements taken nine years later were signi cant. The Newman-Keuls tests show that the green oak origins reacted differently to the environmental conditions. Plant survival was higher at the Sidi Benkadour site (46%) compared to the Sidi Moussa (31%) plantation site. The pedoclimatic conditions of the rst site seem to be more suitable for these 21 green oak origins than those of the second site (Table 3). We noted also that many plants rated dead (either due to a lack of water or grazing by wildlife) were able to resume again as a result of improved weather conditions. The plant height growth at the rst site was 132.10 cm compared to the second site, which was 113.80 cm.
The differences in survival and total heights recorded in the two plantations, 10 years after planting, explain the signi cant differences in biomass production and carbon sequestration between the two sites ( Table 4). The 21 green oak provenances were better expressed at the rst site, producing 417.87g of total fresh biomass (TFB) and 159.26 g of carbon, compared to the second site, which produced 402.04 g of TFB and 144.09 g of carbon.
The average amount of atmospheric carbon sequestered at the rst site was 0.2987 t CO2 /ha compared to 0.1820 t of CO2 /ha at the second site. The amount of CO2 sequestered in the rst plantation was 2.54 t of CO2, compared to 1.55 t of CO2 in the second one.
The average production of fresh biomass was 0.2136 t/ha at the Sidi Benkadour site, compared to only 0.1385 t/ha at the Sidi Moussa site. A total fresh biomass production of 1.82 t/ha was obtained at the rst site, compared to 1.18 t/ha at the second site.

Evolution of plant survival and total height plants
The variance analysis of survival criteria, which was done one month after planting, had no signi cant effect on either the sites or provenances. Both sites recorded very low mortality (0.01%). This result shows that transplant shock was prevented (Nasrallah, 2014).
Measurements taken at the end of autumn 2016 in both sites recorded the survival of 38.5% of the plants. Survival varied signi cantly (at the threshold of α= 0.05%) between sites and within the sites themselves, but without interaction between site and origin. Based on analysis of the Newman-Keuls tests, origins were divided into six homogeneous groups (HG) in the rst site and seven HG in the second one (see Table 3): 1. At the site of Sidi Benkadour (1), the origin of Boualem, belonging to the ecological group of the Saharan Atlas, had the highest survival rate (57%), whereas the provenance of Sour Ghozlane of the fourth ecological group had the lowest survival rate (29%). (2), the dar Echioukh origin survival rate was 40% in comparison to 20% for of Oued Yesser origin.

At the Sidi Moussa site
3. The provenances of Saharan Atlas group responded better to the conditions of the plantations of the sites. However, provenances of the northern side of the Tellian Atlas, and to a lesser extent those of its southern side, were responded poorly to the conditions of the sites.
The variance analysis done on the total heights of the plants, one month after planting, revealed a signi cant effect on the provenance (α = 0.05%), but not on the sites. The average total height (ATH) for the entire plantation was 17.28 cm.
Height measurements taken in both plantation sites at the end of autumn 2016 recorded an ATH of 122.95 cm. The ATH of the plants varies signi cantly (α = 0.05%), between the provenances at each site and between the sites, with the presence of an interaction origins x sites. Analysis of the Newman-Keuls tests put the g provenances of the rst site into eight groups, compared to six groups in the second one: 3. The green oak origins of the Saharan Atlas ecological group recorded the highest ATH in both sites, while those of the Tellian Atlas showed the lowest ATH at the both sites.

Fresh biomass and carbon sequestration from origins
The average total fresh biomass (TFB) ranged from 1.15g to 5.19 g. The analysis formed 11 homogeneous groups. The highest weights were recorded for the provenances of Zaouet, Bel Abed and Dar Echioukh and the lowest weight was recorded by the provenance of Câbet Lakhra (Nasrallah, 2014). Analysis of the variance (at the threshold of α= 0.05%), TFB of the aerial parts of the plants of the two sites (from seedling until 10 years of age) revealed 1.15 g to 5.19 g.
The analysis formed 11 homogeneous groups. The highest weights were recorded by the provenances of Zaouet, Bel Abed and Dar Echioukh and the lowest weight by Câbet Lakhra (Nasrallah, 2014). Analysis of the variance (at the threshold of α= 0.05%), TFB of the aerial parts of the plants of the two plantation sites (from seedling until 10 years of age) revealed signi cant differences between the provenances of each site and also between the two sites, with a remarkable interaction between site and provenance.
The Newman-Keuls tests divided the provenances at the rst site into nine groups and those at the second site into two groups (Table4). The Zaccar and Jebel Aissa origins from the northern ecological region the Tellian Atlas and the Saharan Atlas groups were characterised by TFB. The TFB production at the rst site and second site was 474.22 and 461.79 g, respectively. The TFB production of the provenances from Oued Yesser, Chaâbet Lakhra, Bordj Bounaama, El Bordj, Frenda, Gulema, Sebdou and Mezaouro was low at the rst site.
The ecological group of the Saharan Atlas produced the highest TFB average at both sites. The average biomass production of provenance of the northern part of the Tellian Atlas was higher than those of the second site. Nevertheless, the provenances of the second and third ecological groups produced the lowest TFB.
The calculation of TFB in t/ha at Sidi Benkadour showed that the provenances of the Saharan Atlas, followed by those of the inner plains, have the highest production with 0.0110 and 0.0092 t/ha, respectively. The origins of the two slopes of the Tellian Atlas (south and north) have a low TFB/ha value (south: 0.0099 t/ha, north: 0.0079 t/ha). Concerning the Sidi Moussa site, the origin TFB/ha values were not important. The provenances of the Saharan Atlas (0.0068 t/ha) and those of the inner plains (0.0067 t/ha) have better TFB/ha production than the southern (0.0060 t/ha) and the northern (0.0053 t/ha) slopes of the Tellian Atlas.
In the rst site, the provenance of the Saharan Atlas and the south of Tellian Atlas sequestered amounts of CO2 above the general average (0.0154 t CO2/ha and 0.0138 t CO2/ha, respectively). Concerning the two others provenances of the southern intern plains of Tellian Atlas ecological zones and the northern part, the quantity of CO 2 sequestered was 0.0129 t CO2/ha and 0.0111 t CO2/ha respectively. A lesser amount of CO2 was sequestered at the second site, with higher averages for the Saharan Atlas (0.0090 t CO2/ha) and inner plains (0.0089 t CO2/ha) when compared to those in the southern (0.0078 t CO2/ha) and northern Atlas (0.0071 t CO2/ha) groups. Benkadour site compared to 31% in the Sidi Moussa site. This difference of 15% in green oak survival observed between the two sites is mainly due to local environmental conditions, which are represented by the pedoclimatic characteristics of each site.
The effect of the environment on planting is also distinguished, through the evolution of the height growth and the aerial biomass of the plants. Indeed, the average total height and the TFB at the Sidi Benkadour site were signi cantly higher than those at the Sidi Moussa site. These indicators of plant growth are in uenced by the interaction between the origin (provenance) and the environment. Nevertheless, the differences in growth between planting environments seem to be more important than the differences between origins (Sotelo Montes et al., 2003; Rochon et al., 2007;Weber and Sotelo Montes, 2005). The origin interaction x site is a constant concern for the breeder. If the variability between provenances and/or their order of classi cation is not preserved at the different environments tested, origin x environment interaction will be considered as reference (Kremer, 1986a;Vernier and Teissier Du Cros, 1996). The annual average growth in each studied site was around 15 cm/year, which was slightly higher than those reported by the Zitouni study (2010) regarding the Setif region (west of Algeria).

Behaviour of origin
Studies on the reproduction of green oak species have been more focused on the survival di culties encountered by this species during the early years of its regeneration (Tsakaldimi et al., 2005;Smit et al., 2009). However, there is some data on the behaviour and the adaptation of the green oak provenances of this species after the juvenile period. In our current study, the origins from various bioclimatic zones and the choice of two ecologically different plantation sites made it easier to detect the behaviour of green oak species according to its provenance. The change in the order of provenances from one site to another indicates the importance of the effect of the medium and/or the environment of origin (Kremer, 1986a;Vernier and Teissier Du Cros, 1996).
Due to the climatic and edaphic differences between the two sites, the green oak survival of the four group provenances was more successful at the rst site than at the second. Although both sites have the same south-north direction, it appears that the rst site is more favourable to the survival of the species.
In addition, it was found that the height growth of the plants is highly dependent on the expression of the original origins based on the local environmental conditions (annual variation in temperature and severity of drought) at each site.
If the growth of the seedlings of the four provenances groups showed an advantage for the rst site, those of the Saharan Atlas group responded effectively to the environmental conditions in both sites. For the three remaining groups, the two sites of planting were more favourable to their growth due to: a) the distance that separated them from each group, b) the degree of similarity between sites, 3) the climatic conditions and 4) the soil characteristics of each origin.
Growing the biomass of green oak by selecting the most suitable provenance for reforestation will contribute to an increase of organic substrate in the soil, as well as to the sequestration of more carbon ( Variability within the large regions, characterized by a relatively stable classi cation from one region to another. In addition to superiority in survival and vigour of the provenance of the groups of the Tellian Atlas north and south, which reacted better to the more favourable conditions of the rst site? However, the provenance of the groups of the Saharan Atlas and, to a lesser extent, those of the internal plains, was highly expressed on the second site.
Production of epigeous biomass and varying amounts of sequestered CO 2 , depending on the zone from which the green oak provenance was taken. With the exception of the Zaccar origin, belonging to the group of the northern Tellian Atlas, the rest of the origins were classi ed according to a south-north cline. The provenances of the Saharan Atlas have an important biomass and CO2 sequestration compared to the others groups.
In conclusion, the selection of a suitable provenance from the southern region of green oak specie for reforestation in the north region, can contribute to the choice of climate-resistant provenance for better survival, and can improve biomass production as well as carbon sequestration. This approach, compared to other techniques employed for plant regeneration, can be adapted to current trends and to overcome the future risk of an increase in temperature and aridity in the Mediterranean region.
These results should be reinforced by surveys of new genetic provenances at each ecological region by further sampling of the green oak in the southern geographic area and in the southern part of the Tellian Atlas in the case of Zaccar provenance.