TRANSFORMATION OF GRASSLANDS INTO FORESTS IN BANAT MOUNTAINS, BETWEEN 1990 AND 2023

. The semi-natural grasslands on the Romanian territory and essentially the Banat Mountains, generally framed by forest areas, over time, can be transformed into forests by the lack of adequate management (grazing, care work) with a significant impact on the rural economy. Having access to geospatial resources and techniques specific to Geographic Information Systems (GIS), this study investigated the transformation of grasslands into forests in the Banat Mountains over a period of over 30 years and their arrangement on altitude steps. The research methodology was carried out in four stages: localization and delimitation of the area of interest; analysis of land use, especially of the grassland areas; analysis of forested grasslands in territorial profile and in altitudinal profile. ArcGIS 10.4 software was used to apply the workflow. Research results show that grasslands undergo a series of transformations as a result of the post-communist socio-political situation. Most of the lost grassland areas, namely an area of 8,237 ha was wooded and therefore passed to forests, a phenomenon that occurred in all component subareas, in different proportions. The analysis of grassland afforestation at ATU level showed that the largest wooded areas were in Sicheviţa ATU (991 ha). On the altitude gradient 57% (4,707 ha) are located below the altitude of 500 m, 24%, between 501 – 700 m, respectively 12%, between 701 – 900 m. At higher altitudes grassland afforestation occurs to a lesser extent, given the smaller grassland areas. Generally, afforestation of grasslands occurs through their abandonment, expressed by the lack of maintenance and exploitation works .


INTRODUCTION
In Romania, semi-natural grasslands, framed by forest, due to lack of proper management (grazing, care works) over time can turn into forests.The process begins slowly by increasing the area of forest vegetation, year after year, until the trees cover the entire surface of the grassland and turn it into forest (Rain, 2020).This primarily affects the economy of rural areas (Man and Otiman, 2004;Meusburger and Alewell, 2008) by reducing and losing the amount of feed for household animals; on the way land is organised and used, and on transformations of the rural landscape (Feranec et al., 2010;Popovici et al., 2016).
The grassland ecosystem through the structural complexity and connectivity of vegetation, facilitates the movements of different organisms and microorganisms through landscapes (Sheik et al, 2011;Borozan et al, 2013) and ecological networks (Cunningham and Johnson, 2006;Baldwin et al., 2014;Drum et al., 2015).
The reduction of grassland ecosystems in a rural area contributes to the reduction of biodiversity (Blala and Zyszkowska, 2004), as a result of vegetation loss, habitats and/or connectivity with other ecosystems (Păcurar et al., 2015;Cojocariu et al., 2018).
Modern technology offers numerous possibilities for investigation, analysis and monitoring of grassland areas (Gu et al., 2013;Oncia et al., 2013;Lillesand et al., 2014;Mishra et al., 2014;Zare et al., 2017;Simon et al., 2020).One of the best known methods is the analysis of changes using the Corine Land Cover database, through techniques and means specific to Geographic Information Systems (GIS).This database, consisting of successive datasets (1990, 2000, 2006, 2012 and 2018) can be used to identify changes in time and space in different land use categories (Xiaojun and Zhi, 2005;Popovici et al., 2013;Cegielska et al., 2018;Khoshnood Motlagh et al., 2021).A detailed analysis of the datasets may result in changes on certain components, e.g. the transition of land originally used as grassland to used as forest categories.
Having access to the aforementioned resources, by applying the specific methodology, this study investigated the transformation of grasslands into forests in the Banat Mountains, over a period of over 30 years, with direct and indirect implications on rural communities.The research has three objectives: (1) analysis of changes in grassland areas between 1990 and 2023; (2) analysis of grassland afforestation process in the territory ("horizontal") and (3) analysis of grassland afforestation on altitudinal gradient ("vertical").

Location of the study area
The study area (Figure 1) overlaps the Banat Mountains and, on a small area, the Southern Carpathians, an area delimited according to the Mountain Law (Law nr.197/2018) and includes the following mountain groups and depressions: in the northwest, Dognecei Mountains, in the southwest, Locvei Mountains, in the southeast, Almăjului Mountains, and in the central-northern part, Aninei Mountains and Semenic Mountains, all of which are included in the Banat Mountains group.From the Southern Carpathians, on the analyzed territory there are, partially, the Ţarcu Mountains, in the northeast, Cernei Mountains and Mehedinţi Mountains, in the east.

Work Methodology
The research presented in this study was phased according to figure 2.

Analysis of changes in grassland areas between 1990 and 2023
In the Banat Mountains in 1990 (Figure 3), according to Corine Land Cover, 1990 edition, the grasslands occupied an area of 65,860 ha and represent 13.07% of the area of 503,821 ha afferent to the Banat Mountains, in Romania, delimited according to the Mountain Law (Law nr.197/2018).In 2023, grasslands occupy 70,366 ha, respectively 13.97% of the total area of the Banat Mountains.In 2023, the total grassland area was 4,507 ha higher, compared to the beginning of the interval, namely 1990.Although grassland areas were lost (for example, through afforestation on 8,237 ha), the extra area is explained by the transition from other categories (vineyards, orchards, arable land, land with shrub vegetation and so on).
The detailed analysis of the changes produced in the case of grasslands showed that in some subareas they "gained ground" by reclaiming land from other categories of use, but also "lost ground" through different mechanisms and thus transformed into land with other uses.The process occurs differently, depending on the demographic potential of each sub-area: especially, after 2007 (Romania's entry into the European Union), in more accessible areas, with low altitudes, grasslands are exploited and maintained for agricultural purposes, the owners being financially supported by national or European policies.In the high-hill and mountainous areas, which are largely depopulated, interest in agriculture is low, and grasslands are abandoned and at risk of afforestation.

Analysis on the process of afforestation of grasslands in the territory
The change of political regime in Romania after 1990 also attracted socio-economic changes, reflected also in the way the land was used.If in the past, the right to own and use land belonged exclusively to the state, after 1990, land passed into private ownership, which meant "decentralization" and use according to the needs of new owners.Also, there have been changes in the economic activities of the population: possibility of territorial mobilization, including abroad, abandonment of the agricultural sector, change of local profile of occupations and so on.In this general context, the grassland areas in the Banat Mountains were also affected, through surface changes or "relocations" in different subareas.
Taking into account the purpose and objectives of the research, in the following it will be presented the detailed analysis of the forested grasslands between 1990 and 2023 will be presented.We will refer strictly to those areas of grassland which, through various mechanisms, have been passed into categories of forest use, according to the Corine Land Cover classification.
Between 1990 and 2023, a grassland area of 8,237 has been forested and therefore excluded from that category.In a territorial aspect, grassland afforestation occurred in all component sub-areas, in different proportions (Figure 4).The analysis of figure 4 shows four areas where grassland afforestation was more pronounced (Figure 5, Table 1): Zone 1, at the contact of Almăjului Mountains with Locvei Mountains and Danube Gorge (Şopotu Nou ATU, Sicheviţa ATU); Zone 2, in the eastern part of Semenic Mountains and contact with Tirovei Hills (Lapuşnicel ATU, Luncaviţa ATU, Mehadica ATU); Zone 3, in the northern part of the Semenic Mountains and at the contact with the Timiş-Cerna Corridor (Buchin ATU, Bucoşniţa ATU, Slatina-Timiş ATU) and Zone 4, in the Dognecei Mountains (Dognecea ATU, Goruia ATU, Lupac ATU).
In test area 1 (Figure 5, Table 1), there is a reduction in grassland areas.In Sopotu Nou ATU, 667 ha were forested and in Sichevita ATU, 991 ha of grasslands were forested.Afforestation took place, in particular, on the western slopes of the Aninei Mountains and in the Danube Gorge.
In test zone 3, a special situation is highlighted: overall, the area of grasslands at ATU level has increased (Buchin ATU and Slatina-Timiş ATU), due to the fact that they are predominantly low, accessible areas; The afforestation of the grasslands took place in the higher areas, on the slopes of the Semenic Mountains.In test zone 4, the largest areas of forested grassland were identified in Lupac ATU, namely 255 ha.As in previous cases, grassland afforestation occurred in the pre-mountainous and mountainous areas of the Dognecei Mountains.

Analysis of grassland afforestation by altitudinal gradient
The abandonment of grasslands in certain areas can produce two effects: afforestation and therefore inclusion in the category of use "forest areas", a phenomenon that requires a longer period of time, and degradation of grasslands by installing shrub vegetation and inclusion in the category of use "land with shrub vegetation", a phenomenon with faster production over time and which can be regarded as an early phase of afforestation.
At the level of the study area, the two situations mentioned above were considered: loss of grasslands through afforestation and cover with shrub vegetation, analyzed and classified by altitudinal floors (Figure 6).
Figure 6 shows that of the 8,237 forested grasslands, 57% (4,707 ha) are located below 500 m.The situation is similar in the case of shrub vegetation.Simultaneously with the increase in altitude, the percentage of forested grasslands is reduced to 24%, between 501 -700 m, respectively 12%, between 701 -900 m.The explanation is related to the altitudinal distribution of vegetation levels: in the Banat Mountains, mountains with low altitudes, the lower limit of forest floors can start above an altitude of 500 m, which means that these areas are predominantly covered by forests, with isolated and small areas of grasslands.Following spatial analyses, by overlapping with orthophotoplans from different periods of time, it was found that, in most cases, grassland afforestation occurs in marginal areas, by advancing the forest boundary.Several cases have also been identified in which afforestation has occurred from inside and outside, especially in grasslands located inside forest bodies, a situation mentioned by other studies in that area (Rain, 2020).

CONCLUSIONS
In the Banat Mountains, over a period of over 30 years, the grasslands undergo a series of transformations as a result of the post-communist socio-political situation.
In 2023, grasslands occupy 70,366 ha of the total area of the Banat Mountains, with an increase of 4,507 ha compared to 1990.The increase in grassland areas is explained by the difference between losses and gains (vineyards, orchards, arable land, land with shrub vegetation and so on).Most of the lost grassland areas, namely an area of 8,237 ha, was wooded and therefore passed to forests.
Afforestation of grasslands occurred in all component sub-areas, to varying degrees.The situation is more pronounced in test area 1, where there is a reduction of grassland areas overall during the analyzed period and 667 ha were forested in Şopotu Nou ATU and 991 ha in Sicheviţa ATU.
The analysis of grassland afforestation by altitudinal gradient shows that of the 8,237 forested grasslands, 57% (4,707 ha) are located below the altitude of 500 m, 24% between 501 -700 m, respectively 12% between 701 -900 m.At higher altitudes grassland afforestation occurs in a smaller proportion, given the smaller areas of grassland.
The general cause of grassland afforestation is their abandonment, namely the lack of maintenance works in grasslands bordered by forests and which entails, over time, the modification of the forest boundary until the total assimilation of grasslands in certain areas.

Figure 2 .
Figure 2. Research methodology a.The location of the study area implied the selection of ATUs included in the mountain area -Group 8, described in the annex to the Mountain Law.After outlining the area at ATU level, the overlap was made with the Map of relief units in Romania, elaborated by Posea and Badea (1984), available on the Geospatial platform.This resulted both in the external contour of the area and in its component mountain units; b.Analysis of land use, stage in which land use in general and grassland areas in particular were analyzed.Two Corine Land Cover datasets were used, the 1990 edition and the 2018 edition.In order to update the database to 2023, it was superimposed with orthophotoplans, satellite images and cadastral plans, available in the ANCPI archive; c.The identification of forested grasslands was based on the two Corine Land Cover datasets, from 1990 and 2018 (updated 2023), which were intersected in ArcGIS; of all the changes in the grassland class, only cases of their transition to forest areas and shrub vegetation were taken into account; Four test areas were selected from the map of forested grasslands that overlap the areas with the largest magnitude of the phenomenon and were analyzed as case studies.d.The analysis of forested grasslands on altitudinal floors implied, in the first phase, the classification of the Digital Elevation Model with spatial resolution of 25 m on altitudinal steps, as follows: 53 -500 m; 501 -700 m; 701

Figure 6 .
Figure 6.Areas of grasslands changed to forests and lands with shrub vegetation, by altitudinal floors (1990 -2023)