Deforestation rates in Papua New Guinea (PNG) are more rapid than the Brazilian Amazon. This high rate of forest degradation and loss largely impacts scientific understanding of biodiversity in PNG. While many factors have been linked to deforestation and land degradation in PNG, the relationship between agricultural practices and deforestation have not been fully examined. The effects of agricultural expansion have been overestimated in some areas due to population growth, the negative perception of swidden agriculture (slash-and-burn), and difficulties in discerning agriculture from logged areas in aerial imagery. To examine how swidden agricultural strategies contribute to land cover changes a coastal village was selected. This village, Kamiali, has thwarted logging industry advances and maintained primary forest cover. To assess agricultural and land use changes participatory research was conducted and responses were linked to land cover change via aerial imagery. Temporal analyses of satellite imagery revealed that cultivated area in Kamiali has increased by 9% between 1992 and 2010 despite an estimated population growth of 63%. Thus, agricultural strategies other than expansion were employed to sustain the population. Interviews supported intensification strategies, which included 1) shortened fallows, 2) an increase in crops planted per area, and 3) new cultivar and crop introductions. The intensification was supported with brightness-wetness index, a tasseled cap band subtraction analysis. Image differencing then suggested a temporal increase in crop coverage and density. These results show that subsistence agriculture has influenced land cover changes, but has not been a major contributor to deforestation rates in Kamiali.

1. Forest Loss in Papua New Guinea:
How much does subsistence
agriculture contribute?
Jamie Fuller
PhD Student in Ecology
Colorado State University
Jamie.fuller@colostate.edu
http://warnercnr.colostate.edu/~jdfuller

2. Papua New Guinea and relative area
Introduction Data and Methods Results Discussion

3. …
Culturally and biologically diverse:
•~800 distinct languages and tribal cultures
•Contains 5-10% of world biodiversity and only 0.5% land surface
Introduction Data and Methods Results Discussion

4. Food and agricultural Organization (FAO) Forestry Department, website 2012
Introduction Data and Methods Results Discussion

5. Degradation Deforestation
Potential Change
Combined forest degradation and deforestation
Between 1972 and 2002 - 24% forest loss (9% degraded and 15% deforested)
(Shearman et al. 2009; Shearman and Bryan 2011)
Introduction Data and Methods Results Discussion

6. PNG Population
8
Population (millions)
7
6
5
4
3
2
1
0
1980 1990 2000 2010
Introduction Data and Methods Results Discussion

7. Primary forest Fallow
Hard to distinguish:
•Size and distribution
•Heterogeneous cover
•Seasonal variation
•Fallow periods
Results in over estimation
(Mertz et al. 2009;
Slashed garden plot
Messerli et al. 2009;
Schmidt-Vogt et al. 2009
3nd year crops Fox et al. 2000)
Introduction Data and Methods Results Discussion

8. Recent ecological research:
• Minor disturbance to ecosystem
Perceptions of swidden: • Increased edge habitat
• Simple, naïve and destructive • Fallow regeneration
• Runoff and erosion lessened
• Practiced by indigenous and poor
– (Ziegler et al 2009, Fox et al. 2000)
populations
• Governments began to ban it to Transition to more permanent
reduce deforestation agriculture causes:
• Above and below ground carbon
decline
• Native plant diversity decreases
• Fewer crop varieties
• Economic vulnerability & losses
when crops fail or markets change
• Land sparing vs. land sharing
(Ziegler et al. 2011; Sturgeon 2005; Cramb
et al. 2009; Perfecto and Vandermeer
2010)
Introduction Data and Methods Results Discussion

9. Kamiali, PNG
Kamiali village
-Quantify how the land has changed
-Understand the decisions influencing land use change
-Identify the drivers of change
65 km from Lae, PNG
Ocean access only (no roads)
WMA area: 500 km2
Current Population: ~850
Subsistence livelihood
Introduction Data and Methods Results Discussion

10. Satellite imagery:
•Landsat: 1992, 2003, 2010 (end of Sept-early Oct)
•Cloud mask (LEDAPS by NASA)
•Tasseled cap
•Wetness-Brightness Difference Index (WBDI)
•Helmer et al. 2009
•Unsupervised classification
Participatory research: (Conducted July 2011)
•Participatory mapping
•Structured household surveys
•Resource use interviews
•e.g. fishing, gardening, forest resources
•Oral history with elders
•Economic organization exercise
Introduction Data and Methods Results Discussion

11. 1992 2003 2010
Cloud
Water
Cloud
Water
Riparian
Ag.
Riparian
Riparian
Ag.
9%
11%
12% Ag.
11%
18% 18%
Mixed
10%
Mixed Mixed
12% 16%
Forest Forest Forest
67% 59% 57%
Introduction Data and Methods Results Conclusion

12. Agriculture conversion 1992 to 2003 2003 to 2010
=17%
3% 6% =27%
4%
8% 28% 16%
45% Loss to riparian
Loss to forest 7%
Loss to mixed
38% Ag. - no change
Ag. gain 45%
Introduction Data and Methods Results Discussion

13. Forest conversion 1992 to 2003 2003 to 2010
=23% =20%
10% 5% 8% 4%
17% 12%
4%
10%
Loss to riparian
Loss to mixed
Loss to ag.
68% Forest - no change 63%
Forest gain
Introduction Data and Methods Results Discussion

14. Mixed cover conversion 1992 to 2003 2003 to 2010
3% =34%
2% =32%
16% 15%
47% Loss to riparian 48%
15% Loss to forest 15%
Loss to ag.
Mixed - no change
19% 20%
Mixed gain
Introduction Data and Methods Results Discussion

15. Land use is dynamic and rates of change
vary over time
• Agricultural expansion is not directly correlated
to population growth
• Other subsistence strategies were employed
Time span 1990-2000 2000-2010
Population 1.4% per year 8% per year
Time span 1992-2003 2003-2010
Agriculture 2.6% per year 0.14% per year
Introduction
Introduction Data and Methods
Data and Methods Results
Results Discussion
Discussion

16. Mechanistic pathways in land change
(Lambin et al. 2003)
1) Cultural and land tenure 4) Economic influences
systems • Modern goods & conveniences
• Smaller plot sizes • Cash economy
• Shorter fallows
5) Demographics
• Increased # of crops per plot
•Population increase
2) Natural variability •Shifts
• Changes in weather/climate •In/Out migration
• Pest increases 6) Technological changes
3) Institutional changes • Access to different varieties &
• Support from NGO crops
• WMA status • Fishing equipment changes
• Fishing cooperative 7) Globalization
• Visiting researchers • Local and global fish markets
• The Jones’s
Introduction
Introduction Data and Methods
Data and Methods Results
Results Discussion
Discussion

17. Conclusion
• Agricultural expansion did not occur to the same
extent as national levels
– Suggesting that agricultural expansion may be
overestimated in other regions of PNG
– Intensified agriculture
• These results improved our understanding of the
rate of land change in this conservation area.
– Ecological importance: pressures from logging,
mining and climate changes are likely to increase
Introduction
Introduction Data and Methods
Data and Methods Results
Results Discussion
Discussion

18. Questions ?
Jamie Fuller
PhD Student in Ecology
Colorado State University
Jamie.fuller@colostate.edu
http://warnercnr.colostate.edu/~jdfuller