Araucárias'  Inventory

Brazilian National Forest Inventory

The 2018 Brazilian National Forest Inventory (IFN) has provided a set of data about the Brazilian forest resources. The technical report concerning the state of Rio Grande do Sul (RS) is available in the link here.

According to the IFN-RS, currently, the total area covered by natural forest in the state is of the order of 4,000,000.00 hectares, that corresponds to 40,000 km2. The Mixed Ombrophilous Forest (MOF), which is formed by araucárias in the canopy layer, is about 9.0% of the total natural forest area occupied in the state. Assuming these data, it is plausible to infer that MOF coverage is approximately 160,000.00 hectares (1,600 km2).  

In the inventory, there were considered 776 sample points, where only 49 of them have shown the occurrence of araucárias. In the MOF were taken 12 sample points, each one of them had 4 subplots with 1,000 m2 each, forming a total of 4,000 m2 = 0.4 hectare. Therefore, the total sample area is of 4.8 hectare. In these 4.8 ha were counted 62 araucárias, which is equivalent to 62/4.8 ha = 12.92 araucárias/ha.

If an uniform distribution model is assumed, an extrapolation may be done, providing 1,292 araucárias/km2. In this sense, the number of araucárias existing currently in the MOF in the RS is around 1,292 araucárias/km2 x 1,600 km2 = 2,067,200 araucárias.   

In a previous study, the original RS area with araucária occurrence, within various typologies, used to be of around 50,000 km2 (some authors/metodologies claim around 46,483 km2). Note that these values are superior to the total area currently covered by natural forest in the RS, which is of 40,000 km2. 

Taking into account these data, and considering the results obtained in the IFN-RS 2018, it is reasonable to estimate that originally the area referent to the MOF was, at least, of 4,500 km2. Here we have assumed the current value of MOF coverage as 9%, but it is fairly plausible that originally this percentage used to be higher.

Considering these estimates, there were a decrease in the MOF area with occurrence of araucárias of around 2,615.87 km2. In other words, at least 62% of the original MOF were lost up to 2018. In number of araucárias this means a lost of approximately 3.379.704,00.

On the other hand, in the Rio Grande do Sul Continuous Forest Inventory - (IFC-RS), published in 2001, the natural MOF coverage was 9,195.65 km2. Note that this value is superior to the value estimated in the IFN-RS 2018. Admiting the IFN-RS data and the occurrence data from IFC-RS, the number os araucárias in the 2002 MOF used to be of 

9.195,65 km2 × 1.292 araucárias/km2 = 11.880.779,80 araucárias

what indicates a lost of approximately 

7.595,65 km2 × 1.292 araucárias/km2 = 9.813.579,80 araucárias

This figure shows that much has to be done to preserve the last stronghold fragments of MOF in the RS and recover what has been lost. Therefore, to try to get near to the number of araucárias in the original MOF in the RS, a Special Reforest Challenge Plan is proposed: The Araucárias' Reforest 100-50 Goal.

Araucárias' Reforest Challenge

100-50 Goal

This goal seeks to reach 100% recovery of the original araucárias' MOF in the Rio Grande do Sul up to the year 2050. That means to reforest 9,813,579 - 2,067,200 = 7.746.379 araucárias within 25 years, starting from 2025.

If its is considered a plantation of araucária with a spacing of 8m x 8m, there will be a need of an area of 495,76 km2 (not continuos) to achieve to goal, while if the plantation follows a spacing of 5m x 5m, the area needed will be of 193,66 km2.

As an example, if it is considered only the area of São José dos Ausentes county, which is of 1173.907 km2 (data from IBGE/Brazil), the area needed to achieve the goal would correspond to 42% of the county's area in a 8m x 8m spacing, while in a spacing of 5m x 5m, it would correspond to only 16% of the county's area. Taking into account that the plantation be distributed over the Campos de Cima da Serra counties, whose area is 21.033 km2, occupation demand would correspond to 2% or 0.9% per spacing, respectively. These occupation percentages will be much smaller if the whole region where the original coverage by the Mixed Ombrophylous Forest in the RS be considered. Therefore, just in terms of land occupation demand the Goal 100-50 is fully viable.

The 100-50 goal can be accomplished in three stages:

1) 2026-2030 (5 years) – plant 15% of the goal value. That means, 1,161,956 araucárias, an average of 232,391 araucárias/year.

2) 2030-2040 (10 years) – plant 35% of the goal value. That means, 2,711,232 araucárias, an average of 271,123 araucárias/year.

3) 2035-2050 (10 years) – plant 50% of the goal value. That means, 3,873,189 araucárias, an average of 387,318 araucárias/year.

The plantation during 25 years is staggered in three increasing steps to facilitate the necessary planning involving identification of the regions to araucária seedlings, formation of the seedlings, cost involved in the process, search for financial sponsorship, and other several demands.