The Chilean native forest and that in the Argentinean border zone include more than one hundred species and constitute one of the forest ecosystems richest in biodiversity in the world (
Araucaria distribution is fragmented and restricted to some specific areas in Chile and Argentina. In Chile, it covers over 261 000 ha representing about 65% of the total area in which it is found. The principal location is situated in the Andean Cordillera at latitudes between 37º30’ and 39º30’ S, in Bio-Bio and Araucania Regions and there are some isolated stands in the north Andean limit in the Lakes Region. The second area is found in the coastal cordillera (Nahuelbuta Cordillera) between 37º20’ and 38º40’ S (
The araucaria’s current distribution is a remnant of a more extensive former distribution that was severely diminished by the intense exploitation of the species in the past. Other factors which have a great impact are domestic herbivores and seed harvest (
Although this species is not under imminent risk of extinction, its structure and natural forest dynamic show deep perturbations (
Studies based on the spatial distribution of the araucaria’s genetic variation have been conducted using different markers as gas liquid chromatography (
In this study an expedition to the areas of
Aerial photographs and satellite imagery were used to select the study area. These fulfilled two objectives, the stratification and the initial plot measurement, both carried out in Concepción University (Chile). Geographic Information System (GIS) software was also used to provide information on the status and condition of the araucaria forests. Coverage included all forested lands in Chile: private and public.
Permanent sample plots have been recognised as an interesting approach in determining changes in forests. This type of sampling has two objectives: to provide a description of the stand and to determine areas to be repeatedly measured over time. Accordingly, this permanent method was used for establishing the tree network to detect changes in araucaria regeneration.
With this basic information, field trips were carried out from March to April 2007 across the species range. Field trips were based on one field sample site of 261 000 ha. The tree network was designed by an expert panel (DELPHI method) covering as many different habitats as possible.
The locations chosen for this study included areas from both the Chilean and Argentinean sides of the Andean Cordillera and the coastal range of Chile (
The position of all trees in each plot was mapped and data of their altitude, latitude and longitude were measured using the Geographical Positioning Satellite system (GPS). Selected trees were located in a latitude range from 37º48’ S to 39º47’ S and an altitude range from 950 to 1500 m.
In each site, tree diameter, understory species, natural regeneration and topographic attributes were measured within each plot (
To estimate the genetic diversity, the criterion was to catalogue 30 female and 30 male trees in each location, given that araucaria is a dioecious species. In the case of female individuals, seeds from each tree were collected for future genetic analyses using three age classes: thicket (< 50 years), polewood (100-200 years) and all growth (> 400 years). The assignation of each tree to its age class was conducted according to the index site and the diameter class equation proposed by
being DBH the diameter measured at breast height. In total, five index sites were calculated according to climatic and forestry attributes (
Concerning the different locations studied, the stand composition associated with
Lolco and Lanin N.R. were the most fragmented areas (
In Nahuelbuta Cordillera, araucaria showed medium levels of natural regeneration forming even aged stands associated with
Altogether, 371 trees were catalogued, 193 males and 178 females. Nevertheless, the different characteristics of the evaluated stands made our initial objective feasible in only two locations, Cunco District and Malalcahuello N.R. The target number of female trees was also achieved in two other sampling sites, Nalca Valley and Lanin N.R. and the target male in one more, Nahuelbuta N.R. (
Nevertheless, we consider that not only the number of catalogued trees but also their distribution (spatial, sexes and age classes) is an excellent basis for genetic analysis, providing for a first round examination of the species from a broad distribution range and allowing the identification of further areas of interest.
Our future goal, whenever funding will be available, would be to address the above studies using genetic markers as seed storage proteins and SSRs. Indeed, the former have been used as an estimator of the genetic diversity in forest species (
In fact, as the collecting mission was carried out in the fruit ripening period, an additional activity of sampling seeds from all female trees was undertaken. We consider that the use of both kinds of the above markers will provide good information to set up lines of action aimed to ensure the preservation of the species genetic resources and its survival for future generations.
The expedition showed that the natural regeneration of
Taking into account both regeneration ability and the total number of catalogued trees in each site, the best conserved areas were Malalcahuello N.R., Cunco District and Nahuelbuta N.R. Conversely, a severely altered situation was detected in Villarrica N.R., Lanin N.R. and Lolco. In fact, preliminary results allowed areas of dramatic landscape alteration to be identified as Lolco, which according to the available information has experienced an extensive loss of populations throughout its distribution range. This should be a priority area for conservation because if the current will persist, the above araucaria population will be lost, as it happened with other habitats.
To sum up, the complex structure and distribution range of the species makes a strategic approach necessary to conserve the genetic resources of the species and guarantee its future. In fact, the genetic studies that can be carried out on the basis of this tree network will be of great utility for the development of this strategy.
This research was partially supported by grant No. 207.141.018-1.0 from the Research Service of Concepción University (Chile) and by grant B/6585/06 of the Spanish Agency of International Cooperation (AECI) from the Ministry for Foreign Affairs and Cooperation (Spain).
Map showing the eight locations sampled in the collecting mission in Chile and Argentina.
A representative sample of the
Data of latitude, longitude and altitude measured in each location in Chile and Argentina.
Area | Region | Location | Latitude (S) | Longitude (W) | Altitude (m) | Country |
---|---|---|---|---|---|---|
Andean Cordillera | Bio-Bio (VIII) | Nalca Valley | 38º 17’ | 71º 27’ | 1200-1500 | Chile |
Lolco | 38º 16’ | 71º 28’ | 990-1000 | Chile | ||
Araucania (IX) | Cunco District | 38º 57’ | 71º 40’ | 1200-1450 | Chile | |
Conguillio N.P. | 38º 39’ | 71º 50’ | 1100-1170 | Chile | ||
Malalcahuello N.R. | 38º 25’ | 71º 32’ | 1350-1430 | Chile | ||
Lakes (X) | Villarrica N.P. | 39º 32’ | 71º 57’ | 950-1000 | Chile | |
Lanin N.P. | 39º 47’ | 71º 40’ | 1000-1100 | Argentina | ||
Coastal Cordillera | (IX) | Nahuelbuta N.R. | 37º 48’ | 71º 57’ | 1200-1400 | Chile |
Ecological attributes measured in the eight locations in Chile and Argentina.
Plot | Name | Stand composition | Understory composition | Slope (%) | Aspect | Regeneration | Stand development | Observations | |
---|---|---|---|---|---|---|---|---|---|
full shade zone | open zone | ||||||||
1 | Nalca Valley |
|
5-15 | South-Eastern | Low | High | Even aged | Volcanic soil | |
2 | Lolco | - |
|
0-5 | North-Western | None | None | Old grown stage | Dense shrub load |
3 | Cunco District |
|
15-30 | South | Low | None | Even aged | - | |
4 | Cunco District |
|
5-15 | Flat | Low | None | Even aged | - | |
5 | Cunco District |
|
5-15 | North | High | High | Uneven aged | Cattle | |
6 | Conguillio N. P. |
|
0-5 | Flat | Medium | None | Uneven aged | Lava cone | |
7 | Conguillio N. P. |
|
0-5 | Flat | Low | None | Uneven aged | Lava descendent way | |
8 | Malalcahuello N. R. | - |
|
5-15 | North-Eastern | High | Medium | Even aged | Presence of recent volcanic ash |
9 | Malalcahuello N. R. | - | Grassland | 0-5 | Flat | High | High | Uneven-age | Stand altitude limit |
10 | Malalcahuello N. R. | - | Grassland | 5-15 | South-Eastern | Medium | None | Uneven-age | Stand altitude limit |
11 | Villarica N. P. |
|
0-5 | North-Eastern | None | None | Even aged | Sparce regeneration. Thalweg | |
12 | Lanin N. P. |
|
0-5 | South | Low | None | Even aged | - | |
13 | Lanin N. P. | - |
|
0-5 | Flat | None | None | Old grown | Steppe |
14 | Nahuelbuta N. R. |
|
5-15 | South | Medium | Medium | Even aged | Rocky surface | |
15 | Nahuelbuta N. R. |
|
5-15 | North | Low | Medium | Even aged | Recreational area. Old surface fire |
Ecological attributes measured in the eight locations - DBH: diameter at breast height.
Index site | DBH(cm) | Height(m) | Temperaturerange (Cº) | Precipitation (mm) | Location |
---|---|---|---|---|---|
1 | 54.04 | 37 | 4.6/13.9 | 2900-3300 | Villarrica N.P, Lanin N.P. |
2 | 40.39 | 30 | -0.9/13.9 | 3200-3500 | Cunco District |
3 | 57.86 | 25 | 5.4/26 | 1300-1600 | Nahuelbuta N.R |
4 | 56.77 | 27 | -3 to 2/12 | 1800-2050 | Nalca Valley, Lolco, Conguillio N.P. |
5 | 44.79 | 15 | -3/12 | 1850-2100 | Malalcahuello N.R |
Number of female and male trees sampled in the collecting mission.
Location | Nº Female trees | Nº Male trees | Nº Total trees |
---|---|---|---|
Nalca Valley | 30 | 25 | 55 |
Lolco | 3 | 5 | 8 |
Cunco District | 30 | 37 | 67 |
Conguillio N.P. | 25 | 22 | 47 |
Malalcahuello N.R. | 30 | 39 | 69 |
Villarrica N.P. | 8 | 20 | 28 |
Lanin N.P. | 31 | 0 | 31 |
Nahuelbuta N.R. | 21 | 45 | 66 |
Total | 178 | 193 | 371 |