Mangroves from a social and economic
perspective: environmental perception and
valuation of the Paraíba do Sul River mangrove
Layra Passareli, Master in Ecology, UENF
Carlos Eduardo de Rezende, Adviser, UENF
James Randal Kahn, Co-adviser, Washington and Lee University
August/2013
Introduction
• Mangroves are natural ecosystems that occur along the coast in tropical and
subtropical regions.
-Ecological importance;
-They have been devastated throughout the world;
-Social importance;
-Economic importance.
-Environmental quality -> flow of goods and
services -> population well-being
Research issue:
-The present study investigates the environmental knowledge and perception the
population have about the mangrove ecosystem, its importance and the
problems that threat it, as well as estimates people’s willingness to pay (WTP)
with money or volunteer work for the restoration of the mangrove forests.
Question
-How or to what extent do the access to information, the type of use and the time
the individual lives in the proximity of the mangrove influence environmental
preference with respect to preservation and environmental quality of the
ecosystem?
Study Area
• The
mangrove
occupies
(originally) 800 hectares and
is considered the largest one
of the North Fluminense
region.
• However,
Bernini
(2008)
demonstrated in her thesis
that the mangrove, at that
time, had its area reduced in
about 20% (~187 ha) due to
the
convertion
of
the
mangrove -> urbanization and
cattle raising.
Figura 2. Estuário do rio Paraíba do Sul e os Municípios de São
João da Barra (principal) e São Francisco do Itabapoana
(secundária ao Norte).
• SJB: ~33,000 → ~15.500
• SFI: ~41,000 → ~17.500
Economically Active Population
Metodology
• Surveys that included a Choice Experiment;
• 318 surveys were carried out in these two towns (São João da Barra, and São Francisco),
from June to November 2012.
Economic Evaluation of the mangrove
-The choice experiment (Choice Modelling).
Atributes and atributes levels of the choice sets.
Atributes
Option A
Option B
Status quo
Mangrove
Restoration Level
(1) Complete
(2) Moderated
(3) Minimal
(1) Complete
(2) Moderated
(3) Minimal
-
Time
(1) 0 - 10 years
(2) 11 - 20 years
(3) 21 - 40 years
(1) 0 - 10 years
(2) 11 - 20 years
(3) 21 - 40 years
-
Payment
(1) No payment
(2) R$ 5,00
(3) R$ 10,00
(1) No payment
(2) R$ 5,00
(3) R$ 10,00
-
Volunteer Work
(1) 4 hours/week
(2) No volunteer
work
(1) 4 hours/week
(2) No volunteer
work
-
Each person surveyed was offered 6 choice sets like the one below. The person
always had to choose one of these three options (A, B or C). Option C
represented the status quo -> null option, or the option of keeping the present
situation instead of changing it. Status quo has no cost.
Opção A
Opção B
Restauração
Restauração
Moderada
Completa
21-40 anos
21-40 anos
para restauração
para restauração
Nenhum valor/mês
5,00/mês
Não há pagamento de
taxa
4 horas trabalho
voluntário/semanal
Sem trabalho voluntário
Não há trabalho
voluntário
Eu escolho Opção:
(
)A
Opção C
Não há recuperação da vegetação e as perdas
de área de manguezal aumentam, assim
como a erosão na costa. O funcionamento do
ecossistema fica comprometido.
0 anos
(
)B
(
)C
Results
Sample Socioeconomic Description
• In general, most of the people in SJB and SFI finished high school OR did
not finish elementary school;
• The mean income found was two minimal wages (~R$ 1.400 - ~US$ 700).
Environmental perception and people preferences
• People perceive the ecological and social functions of the mangrove;
• They consider themselves responsible for mangrove conservation;
• Mangrove degradation would have a negative impact on the population
well-being in the area;
• They pointed to many environmental problems that would be threatening
the environmental quality of the ecosystem at the study area.
Results
Tabela. Tabela 9. Estimativas do Modelo Logit Multinomial para a restauração do manguezal do rio Paraíba do Sul.
Variável
Coeficiente
PREÇO
-0,1312
TRABALHO
-0,7010
CO-REC
0,5006
MO-REC
0,2320
TEMPO 0-10
0,7006
TEMPO 11-20
0,6744
A_ALT1
0,0620
A_ALT2
0,2999
P[|Z|>z]
0,0000
0,0000
0,0000
0,0137
0,0000
0,0000
0,5962
0,0085
• Statistically significant coefficients;
• Negative coefficients indicate negative contribution for the utility of the individuals;
•Accomplishment of volunteer work and payment for the restoration contribute
negatively to the utility of the surveyed people.
Results
Regarding the worst option (MI 21-40)
Variável
PREÇO
TRABALHO
CO 0-10
CO 11-20
CO 21-40
MO 0-10
MO 11-20
MO 21-40
MI 0-10
MI 11-20
A_ALT1
A_ALT2
Coeficiente
-0,1374
-0,7100
1,1161
1,2932
0,4220
0,9805
0,7414
0,2538
0,6835
0,6365
0,1251
0,3467
P[|Z|>z]
0,0000
0,0000
0,0001
0,0000
0,1248
0,0003
0,0064
0,3869
0,0175
0,0195
0,6417
0,2485
Regarding the worst option among each
restoration level (time 21-40 years)
Variável
PREÇO
TRABALHO
CO 0-10
CO 11-20
MO 0-10
MO 11-20
MI 0-10
MI 11-20
A_ALT1
A_ALT2
Coeficiente
-0,1399
-0,7537
0,8282
1,0186
0,6530
0,4464
0,3828
0,3140
0,4518
0,7098
P[|Z|>z]
0,0000
0,0000
0,0000
0,0000
0,0000
0,0013
0,0071
0,0076
0,0000
0,0000
•Interaction of the variables;
•People seem to prefer shorter restoration periods considering the same restoration
level;
•Slight inversion between CO 0-10 and CO 11-20;
•People seem to prefer the complete restoration of the mangrove in the time 11 to 20
years, among all the alternatives;
Results
Part-worth of the variables (in Reais per month)
Variável Parte Valor
TRABALHO
-5,39
CO 0-10
5,92
7,28
CO 11-20
MO 0-10
4,67
MO 11-20
3,19
MI 0-10
2,74
MI 11-20
2,24
-Part-worth varying between R$ 2,24 and R$ 7,28 monthly;
- Part-worth for the diference between the variable and the worst choice which was
excluded from the regression;
-Both work and payment consist of contribution (costs) for participants;
-Negative part-worth for work (R$ - 5,39) shows that there is a trade-off between
these variables (work and payment).
Results
Present Value calculated with different interest rates
Valor Presente Líquido (R$)
Variável
r=1%
r=2%
TRABALHO -1.281,00 -1.268,00
CO 0-10
1.407,00 1.393,00
CO 11-20
1.730,00 1.713,00
MO 0-10
1.110,00 1.099,00
MO 11-20
758,00
751,00
MI 0-10
651,00
645,00
MI 11-20
532,00
527,00
-Total present value (updated) at the end of 20 years, per person;
-The population prefers a complete restoration from 11 to 20 years for the
mangrove in comparison to the worst scenario (restoration from 21 to 40 years);
Results
Restauração
CO 0-10
CO 11-20
MO 0-10
MO 11-20
MI 0-10
MI 11-20
Total.pessoa
1.407,00
1.730,00
1.110,00
758,00
651,00
532,00
-1
Valor Presente Líquido para r=1% (R$)
-1
-1
-1
Total.ha
Total.ano .pessoa
Total.ano-1
Valor Total
70,35
46.484.466,00 2.324.223,30 248.580,03
57.155.740,00 2.857.787,00 305.645,67
86,50
55,50
36.672.180,00 1.833.609,00 196.107,91
37,90
25.042.804,00 1.252.140,20 133.918,74
21.507.738,00 1.075.386,90 115.014,64
32,55
93.990,46
26,60
17.576.216,00
878.810,80
Total.ano-1.ha
12.429,00
15.282,28
9.805,40
6.695,94
5.750,73
4.699,52
-1
-Annual value of contribution for the preferred restoration level is R$ 86,50 per
person;
-R$ 57 million (at the end of 20 years, considering the economically active
population of the towns);
-R$ 15 thousand per hectare of restored mangrove (~187 ha).
Discussion
Mangrove values found in the literature
Local
Manguezais em geral
Pagbilao, Filipinas
2
Pagbilao, Filipinas
2
1
Manguezais em geral3
Surat Thani, Golfo da
4
Tailândia
Surat Thani, Golfo da
4
Tailândia
Campeche, México4
Manguezal do RPS,
5
Brasil
Componente Valorado
Método de Estimação
Valor
VET de serviços ecossistêmicos
DAP
US$ 9.990,00 (ha .ano )
Preço de bens substitutos
US$ 151,00 (ha .ano )
Preço de bens substitutos
US$ 60,00 (ha-1.ano-1)
Preço de mercado
US$ 750,00 - 16.750,00 (ha-1.ano-1)
Valor do benefício anual líquido de
bens (silvicultura)
Valor do benefício anual líquido de
bens (pesca)
Valor anual de recursos cujo habitat
é o manguezal
Valor de mudança na área do
manguezal
Valor da perda anual de 1200
Função de Produção (Modelo
Estático)
Função de Produção (Modelo
hectares
Valor da redução marginal da área
Estático)
Função de Produção (Modelo
do manguezal
dinâmico)
Valor da restauração do manguezal
DAP (Modelagem de Escolhas)
-1
-1
-1
-1
US$ 33,00 - 110,00/ha
US$ 100.000,00 por ano
US$ 140.000,00/ano
US$ 7.418,00 (ha-1.ano-1)
-Our values are among those described in the literature for mangroves.
Conclusions
-Despite the surveyed people have claimed to consider themselves responsible for
the conservation of the ecosystem and that the mangrove degradation would
impact their well-being, work or pay for the restoration seems to contribute
negatively to the utility of the people;
-Trade-off between work and payment → perhaps they want to receive money to
work;
-This study contributes with information about the benefits of the PSR mangrove
restoration, which compared to a cost analysis for restoration programs, might
orient the stakeholders about the viability of preserving the studied ecosystem.
-Furthermore, the mentioned values might serve as reference for penalties
establishments, such as fines, to be charged in cases of environmental damage.
Aknowledgments