The banks of the M.N. Laguna del Arquillo

The assessment of the quality of riverine ecosystems is a topic of great interest not only because of the importance of knowing their ecological functioning but also because of the recent regulatory regulation entailed by the Water Framework Directive, which, together with the National Strategy for River Restoration developed in Spain accordingly, require the establishment of guidelines for the management, conservation and recovery of water resources.

There are numerous methodologies for evaluating the quality of riverbanks based primarily on visual recognition techniques, although they have certain limitations in their application since they do not include the principles of the Water Framework Directive (DMA). In the present work, it was decided to apply a protocol adapted to the philosophy of the DMA and that at the same time would make it possible to detect existing deficiencies in the components of the river system and to propose actions for their recovery. The chosen method was the Riverside Ecological Quality Index or RQI.

The Laguna del Arquillo Natural Monument (MNLA) is located in the southwest of the province of Albacete (Spain), about 1,000 m above sea level, in the foothills north of the Sierra de Alcaraz, occupying the superMediterranean bioclimatic floor (UTM 30SWH55). This wetland was declared a Protected Natural Area (ENP) under the heading of Natural Monument by the Order of June 12, 1996 of the Ministry of Agriculture and Environment and Decree 184/2000 of December 19.

The study focused on the two areas with a legal protection regime: the Natural Monument or Zone 1, with a priority conservation category, which covers the Arquillo Lagoon and the first stretch of river that flows into it together with the adjacent ecosystems; and the Peripheral Protection Zone or Zone 2, with a buffer function and encompassing the stretch of the Arquillo River and the ecosystems farthest from the lagoon complex not included in Zone 1.

The Arquillo Lagoon has a karstic-fluvial origin, formed by the travertine damming of the Arquillo riverbed. It has an area of 3.84 ha, with a maximum length of 378 m and a maximum width of 112 m. It has a depth of up to 8 m, with vertical edges almost all the way around. Only in the southern area, where the Arquillo River enters, is the slope smoother due to the deposition of fluvial materials carried away by the current. On the other hand, the Arquillo River rises 1,300 meters above sea level in the Sierra de Alcaraz, flowing in a boxed way between travertine deposits and flowing into the Jardín River next to the town of the same name. [/vc_column_text] [/vc_column] [/vc_row]

To characterize the quality of the banks of the MNLA, the Riverside Ecological Quality Index or RQI has been used, where the conservation conditions of the banks are established following hydrogeomorphological criteria based on the analysis of processes and riparian dynamics, adapting to the principles of the Water Framework Directive, and facilitating the design of management strategies for improvement or restoration and their subsequent evaluation.

First, the reference conditions or potential vegetation conditions were defined by virtue of the hydrogeomorphological characteristics and the biogeographic region where the study section is located. The establishment of the reference conditions was based on the information collected in the field surveys, the cartographic analysis of the terrain and the bibliographic review.

Subsequently, sampling stations were established consisting of 100 m linear riverbank sections, which in the Natural Monument were arranged covering the entire riverbed, while in the Peripheral Protection Zone the sampling sections were distributed systematically every 300 m to cover 26% of the shore. In total, a riverbank length of 5 km was characterized. The following attributes were recorded at each sampling station:

I. Longitudinal continuity of riparian vegetation,

II. Dimensions in width of the space with vegetation associated with the river,

III. Composition and structure of riparian vegetation,

IV. Natural regeneration of tree and shrub vegetation, V. Condition of the banks,

I SAW. Cross-cutting connectivity

and VII. Permeability and condition of the riparian substrate.

The results obtained provide RQI values both on the coastal perimeter of the lagoon and on the banks of the Arquillo river itself, which associate them with a poor ecological state.

The analysis of the results shows poor values related to the Continuity, Regeneration and Composition attributes. Herbaceous formations dominate, with a practically non-existent tree and shrub stratum that does not cover 25% of the surface. The composition of the vegetation is altered by grazing, threatening the natural regeneration of woody vegetation due to the scarce presence of young and new feet. However, the hydrogeological attributes related to the dynamic functioning of the riverbank are in good condition, with shores protected by vegetation and few symptoms of erosion and compaction, excellent connectivity conditioned by the low height of the shore and good permeability due to the absence of compacted soils in the environment.

It is concluded that the anthropogenic modifications exerted on the environment by agro-livestock activities have profoundly altered the ecological structure of the MNLA riverbank. The main consequences are: loss of continuity of the woody vegetation of the riverside forest, reduction of botanical diversity -especially of trees and shrubs-, an almost total lack of generational renewal due to the elimination of young feet due to burning, livestock and clearing, and occupation of riverbank space by agricultural activities. Likewise, the uncontrolled presence of visitors to the very edge of the lagoon has encouraged erosive processes in the soils, damage to the riverside vegetation as previously non-existent accesses and beaches were created, and discomfort to fauna. These threats were already described a decade ago and continue to a greater or lesser extent today, reflecting the need to develop a comprehensive management program to recover the original characteristics of the area's ecosystems.

Based on these conclusions, recovery based on correcting those attributes that were deficient in the assessment has been projected. The objective of this project pending execution has been to restore the MNLA environment to the reference conditions of the banks, contributing to compliance with the Water Framework Directive, as well as the objectives of the National Strategy for River Restoration and the Natural Resources Management Plan for this space. The main management action has focused on strengthening the population of the woody vegetation of the riverside forest by planting native species following the defined guidelines and foundations. The selection of species for planting has aimed to recover diversity and vegetation cover, giving priority to those taxons that contribute to greater biomass and that in some way constitute the structural framework on which botanical communities are based. Thus, the central Iberian Mediterranean fluvial geoseries of the Rubio tinctorum-populo albae geosigmetum white poplar forests was defined as a reference community, and the species and their planting frameworks recommended for this community were taken as a basis. The selected species were Salix purpurea subsp. lambertiana, Salix alba, Populus alba, Ulmus minor, Fraxinus angustifolia, Rubus ulmifolius, Crataegus monogyna, Clematis vitalba and Cornus sanguinea. For the execution of the plantations, a mechanical puncture has been chosen following the Jandu method, which provides a greater degree of swelling of the soil, facilitating colonization by the roots, and then proceeding with the manual planting of the specimens. In addition, in specific areas of the lagoon shore with a significant degree of erosion and compaction, it has been proposed to install rolls structured with fiber and revegetated with Juncus inflexus or Cladium mariscus, species that currently occupy the perilagunar margin.

On the other hand, measures have been taken to regulate public use to safeguard botanical and faunistic communities, and the ethnographic and archaeological elements of the MNLA. Thus, a recreational and parking area has been delimited to concentrate the arrival of visitors and vehicles, and to serve as the starting point of the interpretive walking route. This itinerary would cover the most significant points of the ENP and would be accompanied by explanatory posters on the environmental values of the environment and recovery actions. In the same vein, it is recommended to install access restriction signs at the beginning of paths and roads that affect protected and/or restored areas. It is also worth mentioning the proposal to install a semipermeable fence on the north and west flank of the lagoon complex that would provide a non-opaque visual barrier and would control access to areas attached to roads, reducing disturbances to fauna and the deterioration of vegetation in these areas.
Finally, and as a measure to control the effectiveness of the proposed restoration and recovery interventions, it is recommended to apply the RQI index to the same sampling stations initially selected in successive years. Obtaining the index before and after the execution of restoration projects is a fundamental measure to assess how the riparian attributes have improved, and to verify to what extent the objectives of restoration, rehabilitation or river improvement considered have been met. Or if, on the contrary, the previously existing causes of degradation have been maintained, or even increased, or new ones have appeared that were not foreseen in the evolution of the development of ecological processes.