INSTITUTO NACIONAL DE PESQUISAS DA AMAZÔNIA – INPAPrograma de Pós-Graduação em Biologia

Tropical e Recursos Naturais da Amazônia – PIPGBTRN

Reduced-impact logging has subtle median-term effects on fish

assemblages in Central Amazonia

Murilo S. Dias (murilosd@hotmail.com)William E. Magnusson

Jansen A. S. Zuanon

www.igarapes.bio.br

2

Introduction

Amazônia: Actual scenario

Azevedo-Ramos et al. 2004

Soares-Filho et al. 2006

If current trends continue, in 2050 only about 50% of forested areas will remain

(Soares-Filho et al. 2006)

Logging has increased the habitat loss in tropical

forests

3

Introduction

Reduced-Impact Logging (RIL)Reduces the damage to forest cover in comparison to conventional logging (Johns et al. 1996; Barreto et al. 1998)

RIL Conventional logging

Johns et al. 1996

RIL Conventional logging

Careful logging in tropical forests could supply the demand for timber products with reduced impacts on biodiversity and on ecological processes, until better alternatives are available

(Bawa & Seidler 1998)

4

Foto: Helder Mateus

Introduction

Ecological processes and natural history characteristics of organisms in streams are closely associated with adjacent forests and allochtonous

material(e.g. Kawaguchi et al. 2003)

Headwater Streams in Central Amazonia

Acid water

Low light reaching the water surface

low primary production

5

Fish fauna

Reduced-Impact Logging

Sediment load Wood debris Leaf load

Stream width Stream

deaph

Discharge

Water quality

Introduction

Linkage between RIL and fish fauna:

6

Introduction

If the immediate effect of RIL in a biological community is great…

…but with time the community returns to the initial state (high resilience), logged forests may have high conservation value!

Fish

fauna

Time

Disturb

7

Objective

We analyzed the effects of Reduced-Impact Logging in the short- (before and immediately after logging), medium-term (up to 12 years) and time effects on physical-chemical characteristics and fish-fauna composition of headwater streams.

8

Gray areas represent Annual Production Units (APU)

Methods Study area

Mil Madeireira Itacoatiara Ltda.

15 m3/ha

(3.5 trees/ha)

9

Short-term study:

11 plots before and after RIL in APU E1a

(squares)

Methods Sampling Design

Median-term study:

11 pairs of streams in different APU

(circles are control plots and triangles are logged plots)

Time study:

16 logged plots

(red triangles of median-term study plus orange triangles)

10

50 m

Methods Environmental data

pHDissolved oxygen (mg.L-1) Water temperature (ºC)

Canopy opening (%)Flow velocity (m.s-1)

Stream width (m)

Depth (m)

Sand (%)

Trunk (%)

Coarse litter (%)

Fine litter (%)

Fine roots (%)

Large roots (%)

PPBio standardized protocol (Mendonça et al. 2005)

Flow

11

Fo

to:

M.S

. Dia

s

Foto: Helder Mateus

Methods Environmental data

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Fish Composition

(Presence/Absence and

Abundance data)

Methods Analysis

Environmental data

Principal Components

Analysis (PCA)

Short-, Median-term study and Time

analysis:Multiple Regressions

Non-Metric Multidimensional Scaling

(NMDS)

Short-term study:Paired t-test

Median-term study:Wilcoxon test

Time analysis:Multiple Regressions

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The water was ACIDIC (mean= 4.53), with low CONDUCTIVITY

(7.64μS.cm-1), high OXYGEN saturation (6.45mg.L-1) and stable

TEMPERATURE (24.6°C)

Substrate types: SAND (31%), LEAF-LITTER (28%) and FINE LEAF-

LITTER (13%)

They were small (WIDTH=

1.3m; DEPTH= 0.08m;

DISCHARGE= 0.02m3.s-1 ) and

had dense forest cover

(CANOPY OPENING= 7%)

Results Streams

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In the SHORT-TERM STUDY, just the first PCA axis showed differences related to the RIL

Fine leaf-litter

pH

Depth

Discharge

Water flow

Canopy opening

MR: Pillai-Trace = 0.782; F3.8= 9.566; n= 22; p= 0.005

Before After

-20

24

Str

eam

chara

cteri

stic

s (P

CA

1)

Results Streams

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The environmental characteristics did not show differences related to

RIL (Pillai-Trace= 0.180; F3,7= 0.512; n= 22; RIL: p= 0.686; Flow: p= 0.129)

There were no significant changes related to the TIME since logging (Pillai-Trace= 0.072; F3,11= 0.286; n= 16; Time: p= 0.835; Flow: p= 0.252)

Results Streams

Median-Term Study

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• 34 species (six orders and 14 families) and most of the fish fauna was represented by Characiformes (13 species and 80% of collected specimens)

• More fish were collected in logged areas than control areas

• The most abundant species were Pyrrhulina brevis and Hemigrammus cf. pretoensis, with 49% and 20% of all captured specimens

Apistogramma sp.

Foto: F.P. Mendonça

Results Fish fauna

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Short-term study

There were diferences in abundance and detectability

Despite these differences, there were no significant differences in overall composition as summarized by NMDS axes before and after logging (Abundance: t= -1.157; n= 11; df= 10; p= 0.274; Presence/Absence: t= 0.666; df= 10; p= 0.521)

Foto: F.P. Mendonça

Results Fish fauna

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Median-term study

Abundance data Presence/Absence data

Richness in Control plots= 24

Richness in Logged plots= 18

The scores of presence/absence axes

in logged areas were not significantly

different from scores in control plots

(Wilcoxon= -0.622; n= 11; p= 0.534)

Wilcoxon= 2.845; n= 11; p= 0.004

Control Logged

-10

12

3F

ish

com

posi

tion

(NM

DS

)Results Fish fauna

RM: r2= 0,38; F2,13= 3,986; n= 16; p= 0,022

0 5 10 15

-10

12

3

Years after loggingAb

un

dan

ce fi

sh c

om

posi

tion

(N

MD

S)

0 5 10 15

-2-1

01

Years after logging

P/A

fish

com

posi

tion

(N

MD

S)

Results Fish fauna

Presence/Absence data

Median-term study: TIME ANALISYS

Abundance data

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Conclusions

Our results indicate that the physical-chemical characteristics change in the

short-term however the effects detected were subtle when compared to

clear-cutting practices (Douglas et al 1992, Douglas et al 1999; Davies et al. 2005b).

Deforestation affects headwater fish fauna (Jones et al. 1999), however companies

that practice RIL are obliged to maintain Adjacent Forests around water

bodies and this strategy helps avoid strong modification in functioning of

streams (Wright & Flecker 2004; Gomi et al. 2006) and further changes in fish

assemblages.

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Conclusions

All species occurred in the general area, and we have no evidence that any species was extirpated in logged areas. However, fish assemblages in streams appear to be sensitive to environmental changes caused by reduced-impact logging in Central Amazonia.

The RIL practices seem to be adequate to maintain the overall fish species

composition in the studied area, despite changes in assemblage composition

within individual stream stretches.

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Acknowledgments

IBAMA (02005.002385/06-76)

H. Vasconcelos, C. Azevedo-Ramos, G. Ferraz, C.E. Freitas, E.M. Venticinque,

N. Higuchi, W. Laurance, L. Bini, E. Caramaschi; J. Lopes J. Eremildes; H.M.V.

Espírito-Santo, V. Pazin, R. Frederico, J.S. Almeida, F.P. Mendonça, V.L.

Landeiro, J.J. Toledo and F.G. Oliveira

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REFERÊNCIAS BIBLIOGRÁFICAS

Mendonça, F.P., W.E. Magnusson, and J. Zuanon. 2005. Relationships between habitat characteristics and fish assemblages in small streams of Central Amazonia. Copeia 4:751–764.

Soares-Filho, B.S., D. C. Nepstad, L.M. Curran, G.C. Cerqueira, R.A. Garcia, C. Azevedo-Ramos, E. Voll, A. McDonald, P. Lefebvre, and P. Schlesinger. 2006. Modelling conservation in the Amazon basin. Nature 440: 520-523.

Wright, J.P., and A.S. Flecker. 2004. Deforesting the riverscape: the effects of wood on fish diversity in a Venezuelan piedmont stream, Biological Conservation 120: 439-447.