Ecological Restoration Plan for Palo Laziale Wood, Italy
Project location: ITALY, Palo Laziale
Project start date: October 2010 - Project end date: December 2012
Project number: 2010-39
Beneficiary: Associazione Alsium
FIRST ACTIVITY REPORT (TIMELINE: January - November 2011 )
The Palo Laziale wood together with the wood of the Castel Porziano Presidential Estate and that of the Circeo National Park represents one of the few remnant examples of Mediterranean planitial forests favored by the superficial water table and characterized by natural ponds. These forest habitats have been drastically reduced because of the expansion of agricultural activities and the urbanization. In June 1995 the wood of Palo has been identified as Site of Community Importance according to the European Commission Habitats Directive (92/43/EEC). The motivations for this choice lied on the recognition of the good status of conservation of European community priority habitat "3170* - Mediterranean temporary ponds" together with its importance for migratory birds and the rich fauna of arthropods and vertebrates characteristics of the hygrophilous wood. At the end of 1995 the first records of stresses of tree species, mainly belonging to Quercus genus, were spotted. The following year, a noticeable evidence of an increasing tree mortality occurred. This process continued up today causing the complete collapse of the forest habitat with the death of more than 4000 tree individuals. It has been hypothesized that the concomitant and integrated effects of the increasing drought, the interruption of the traditional silvicultural activities, the lowering of the water table and its salinization could have determined a physiological stress on tree species. This, in turns, made them vulnerable to the attack of phytopatogenous fungi such as Biscogniauxia mediterranea, causal agent of ‘charcoal disease' of Fagaceae and Phytophthora spp. causing severe collar and root rot on Quercus ilex. Several episodes of oak mortality in many European countries have been reported, however because of the complex underlining spatial and temporal patterns of interacting factors (both abiotic and biotic), the fundamental mechanisms underlying tree survival and mortality during drought remain poorly understood. Moreover temporal patterns of tree mortality also can be difficult to interpret due to lagged responses in some species, in which mortality has been shown to occur years or even decades after stress occurred. We have also to consider that the long-lived nature of trees and their ability to shift allocation of resources and change their hydraulic architecture throughout their lives can result in non-linear responses to t stress in both space and time.
Based on the above considerations, the need for an integrated analysis aimed at clarifying the causes of the collapse of the wood and at identifying the current environmental conditions of the site arises in order to identify the best restoration intervention. This activity is also urgent because the occurred degradation process severely impacted the environmental quality of the Site of Community Importance of whose conservation the Lazio Region is responsible. In particular the following tasks have been performed during the first part of the project:
- Identify drought events occurred in the last decades and quantify the changes of temperature and precipitation regimes. (Climate analysis).
- Analyze the land use change and quantify the increase of the surrounding human pressure.
- Evaluate the physico-chemical characteristic and dynamics of the water table aquifer with specific focus on salinization processes. (Hydrogeological analysis).
- Analyze the current pedological characteristics of the site. (Pedological analysis).
- Evaluate the effects of the recent selvicultural change.
- Analyze the current dynamic processes of the vegetation and the capacity of regeneration of tree species in order to forecast potential trends of the forest habitat. (Vegetation analysis and specific renovation analysis of new vegetation).
- Evaluate the status of the pathogen attacks associated and involved in forest decline. (Phytopatology analysis).
- Compare the environmental characteristics of the Palo wood with similar areas such as the forest of the Circeo National Park and that of the Castel Porziano Presidential Estate.
In the last part of the project a plant nursery has to be created in order to grow seedlings of several tree species for the future reforestation. The tree species have to be chosen according to the firsts results of the study and a preliminary and limited reforestation will be conducted in order to obtain indications on the capacity of regeneration of species. By the end a specific and multi-sectorial report will be provide for facing the future restoration ecology of the wood.
Anticipated achievements or outcomes of the project
- Identification of the interacting factors and ecological mechanisms responsible for the decline and mortality of this and other similar forest habitats.
- Elaboration of conservation strategies to prevent future tree die-off.
- Elaboration of a restoration plan that takes into consideration the current and future predicted environmental conditions (i.e. climate change and increasing drought and warmer temperatures.
- Implementation of restoration actions to be undertaken in a step by step approach according to an adaptive strategy. These actions may include the creation of small artificial ponds for irrigation, a structure for the cultivation of seedlings, plantation of seedlings according to the environmental/topographical gradients of the area.
The research as it is appearing before the last confrontation of multi-sectorial data:
The 4 researching groups have been taking from Palo Laziale area specific surveys coming from fixed sample areas (33) inside the wood and other 4 sample area external to the wood as control data providing. Climate studies are pointing out the climatic serie of Palo Laziale starting from the application of IPCC criteria and downscaling data to the Palo Laziale area through specific interpolation. Hydrogeological studies have been analyzing levels and composition of wells water, in order to understand if and how the salt quantity could affect negatively the surviving of the wood. By the first results it seems that an ipothetyc see water intrusion could be erased, and obviously that's the most important factor for continuing the research in order to give the right explanation of Palo Laziale wood deterioration.
Pedological data seem to underline a certain quantity of salt presence in the first soil level and in the soil level line about 1 m deep. These data have now to be compared with the others in order to give an answer from where and how this salt soil composition could affect vegetation, taking itno account that apparently salt elements do not seem to come from water see. Vegetation data have been collect into the sample plots and they all give a good representation of the present situation of the area. In several part of the woods it has been registered a collapse of the main vegetation, and now a thick maquis is starting to grow up as a form of renovation and changing of the woods. In other parts of the area the wood seem to have yet capacity to survive, and in order to give an answer to the future aspects of the wood and about the kind of restoration to be used these data will be faced in the last part of the project with the ones coming out from renovation. Phytopatology data have been collected along of the sample plots. In this days the last collected surveys are still under "colture" and the aim of this analysis is to identify if some pathogens have been affecting the wood beyond Biscougnaxia mediterranea.