4680.0.55.001 - Information Paper: An Experimental Ecosystem Account for the Great Barrier Reef Region, 2015 Quality Declaration 
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SECTION 3 LANDSCAPE


LAND COVER

Land cover affects the provision of ecosystem services and measuring land cover change over time is critical to evaluating and monitoring trends in natural resource condition.

Changes in land cover have many potential drivers, including human activities and natural phenomena. Examples of human activities that drive land cover change include urban development, crop and pasture management and industrial activity. Natural drivers of land cover change include flood events, bushfires and seasonal climatic variation. Attribution of specific causes to observed land cover change requires additional information. Geoscience Australia describes land cover as:

    '... the observed biophysical cover on the Earth’s surface including trees, shrubs, grasses, soils, exposed rocks and water bodies, as well as anthropogenic elements such as plantations, crops and built environments. Land cover changes for many reasons, including seasonal weather, severe weather events such as cyclones, floods and fires, and human activities such as mining, agriculture and urbanisation' (About Land Cover, Geoscience Australia website).

The ABS has produced land accounts for the GBR Region using the SEEA framework (Land Account: Great Barrier Reef Region, Experimental Estimates (cat. no. 4609.0.55.001)), although the Cape York NRM Region was excluded from those accounts. Table 3.1 below presents data on the opening and closing stocks of land cover in the GBR Region, including net changes.

TABLE 3.1. DYNAMIC LAND COVER, GREAT BARRIER REEF REGION, 2008-09 and 2010-11, Area (hectares)

Opening Stock
Total Net Change
Closing Stock
Dynamic Land Cover
2008-09
2008-09 to 2010-11
2010-11

Built-up Surface (a)
57 700
0
57 700
Extraction Sites (a)
81 100
0
81 100
Bare Areas
500
0
500
Inland Waterbodies
153 400
2 700
156 100
Salt Lakes
500
-100
400
Irrigated Cropping
109 500
9 800
119 300
Irrigated Pasture
155 600
30 000
185 600
Irrigated Sugar (a)
189 300
0
189 300
Rainfed Cropping
774 500
-149 400
625 100
Rainfed Pasture
1 631 000
230 200
1 861 200
Rainfed Sugar (a)
47 800
0
47 800
Sedges - Open
0
0
0
Alpine Grasses - Open
0
0
0
Hummock Grasses - Closed
35 300
-9 700
25 600
Hummock Grasses - Open
11 100
-1 500
9 600
Tussock Grasses - Closed
8 504 700
-141 700
8 363 300
Tussock Grasses - Open
1 688 600
-905 200
783 400
Shrubs - Closed
46 900
-23 200
23 700
Trees - Closed
5 738 300
1 100 600
6 838 900
Trees - Open
9 852 700
3 548 300
13 401 000
Trees - Sparse
12 382 800
-3 383 400
8 999 400
Trees - Scattered
766 300
-398 800
367 500
Wetlands
314 700
105 600
420 300
Shrubs - Open
34 800
6 400
41 200
Shrubs and grasses - Sparse to scattered
163 300
-20 600
142 700
Total GBR Region
42 740 400
0
42 740 400

(a) Built-up Surface, Extraction Sites, Irrigated Sugar and Rainfed Sugar are static land cover types. These classes show no change over time.
Source: Dynamic Land Cover Dataset, Version 2 (DLCD V2), Geoscience Australia.


In 2008-09, Trees-Sparse accounted for 12.4 million hectares of all land cover in the GBR Region. Trees-Open is the second largest type of dynamic land cover at 9.9 million hectares, followed by Tussock Grasses-Closed at 8.5 million hectares. Trees-Sparse reported a net decrease of 3.4 million hectares between 2008-09 and 2010-11, from a total of 12.4 to nine million hectares. This was the largest decrease of any land cover type in the GBR Region. The change was driven by an increase of 3.5 million hectares in the Trees-Open category, making it the most abundant type of land cover in 2010-11.


RIVER LOAD

Suspended solids, nitrogen, phosphorous and photosystem II (PSII) inhibiting herbicides have all been shown to effect negatively the quality of marine environments and represent important indicators on the influence of land based activities on the downstream marine environment. Suspended solids, nitrogen and phosphorous are all naturally occurring river loads, although PSII inhibiting herbicides are of anthropogenic origin. The yield condition provides 'natural state' or ideal reference condition context to the load numbers reported in the tables below.

This section presents load data for indicative river systems for the GBR Region, and as yields of load per square kilometre of catchment compared to a reference condition by NRM Region over the period 2006-07 to 2011-12. Tables 3.2 and 3.3 below provide annual estimates for three types of annual loads: total suspended solids (TSS); total nitrogen (TN); and total phosphorous (TP). Table 3 also provides estimates of PSII inhibiting herbicides (pesticides) for the last two years of the time series; namely, 2010-11 and 2011-12.

TABLE 3.2: RIVER LOADS BY TYPE, BY NRM REGION, GREAT BARRIER REEF REGION, 2006-07 to 2011-12, Weight ('000 tonnes and tonnes)

2006-07
2007-08
2008-09
2009-10
2010-11
2011-12
NRM RegionLoad TypeWeight

BurdekinTSS'000 tonnes
6 503
12 700
9 614
1 937
6 200
3 300
TNtonnes
9 724
32 816
23 283
6 411
21 000
11 000
TPtonnes
3 240
9 179
6 721
2 213
8 400
3 400
Pesticidestonnes
na
na
na
na
882
642
Burnett MaryTSS'000 tonnes
na
na
na
146
2 600
15
TNtonnes
na
na
na
1 262
16 000
400
TPtonnes
na
na
na
330
3 800
47
Pesticidestonnes
na
na
na
na
448
29
Cape YorkTSS'000 tonnes
59
211
104
173
207
46
TNtonnes
711
1 814
1 098
1 326
5 600
490
TPtonnes
84
168
98
159
320
87
Pesticidestonnes
na
na
na
na
na
na
FitzroyTSS'000 tonnes
320
4 751
404
3 563
7 000
1 300
TNtonnes
1 178
15 197
2 016
12 989
36 000
6 400
TPtonnes
403
5 671
657
5 321
15 000
2 700
Pesticidestonnes
na
na
na
na
8 557
1 956
Mackay WhitsundayTSS'000 tonnes
156
255
111
374
820
210
TNtonnes
927
1 378
849
1 929
4 100
1 300
TPtonnes
181
326
134
488
1 000
300
Pesticidestonnes
na
na
na
na
1 254
397
Wet TropicsTSS'000 tonnes
615
866
2 405
693
2 820
661
TNtonnes
5 791
6 306
9 637
5 417
18 300
7 880
TPtonnes
820
882
1 560
839
3 430
1 077
Pesticidestonnes
na
na
na
na
796
780
Total GBR RegionTSS'000 tonnes
7 653
18 783
12 638
6 886
19 647
5 532
TNtonnes
18 331
57 511
36 883
29 334
101 000
27 470
TPtonnes
4 728
16 226
9 170
9 350
31 950
7 611
Pesticidestonnes
na
na
na
na
11 937
3 804

na - not available
TSS - Total Suspended Solids; TN - Total Nitrogen; TP - Total Phosphorous
Note: Data for the period 2006-07 to 2008-09 for the Burnett Mary NRM Region is not presented because no high flow events were recorded.
Sources: See the complete list at the end of this section.


Table 3.2 above shows that the total amount of river loads varies significantly between consecutive years in the majority of NRM Regions. A key reason for this volatility is the effect of rainfall and subsequent volume of river flow. For example, the 2010-11 flood events in Queensland increased river loads across all NRM Regions. There was a threefold increase in total suspended solids between 2009-10 and 2010-11 for the total GBR Region, and an even larger increase in total nitrogen and total phosphates in the same period. Loads, however, returned to pre-flood levels by 2011-12 in most regions.

The yield for each selected river basin was compared to the estimated pre-European yield in order to measure loads in the context of condition (see Kroon et al.,2012). It is an example of a reference condition not based upon accounting period considerations, but upon the notion of 'a condition reflecting an ecosystem which is relatively undisturbed or undegraded by humans' (SEEA Experimental Ecosystem Accounting, 2012, para. 4.16). This type of measure relates more to the condition of the landscape, its use and its ability to stabilise mass (or mitigate erosion), than to the physical form of the rivers. The resultant data shows how much the landscape has been functionally changed in this respect since European settlement.

The measure remains greatly influenced by rainfall and volume of river flow, but the size of catchment controlled as yield is measured in kilograms, or tonnes per square kilometre of catchment. Table 3.3 below presents yields of total suspended solids, total nitrogen and total phosphorous indexed to the pre-European reference condition. There were no pesticides present before European settlement, and, therefore, it is not possible to construct an index for this measure.

TABLE 3.3: RIVER BASIN YIELD CONDITION, BY NRM REGION, GREAT BARRIER REEF REGION, by Type of Load, 2006-07 to 2011-12, Index (Pre-European Settlement = 100)

Pre-European settlement condition
2006-07
2007-08
2008-09
2009-10
2010-11
2011-12
NRM RegionLoad type

BurdekinTSS
100
1 250
2 450
1 850
375
1 175
625
TN
100
441
1 488
1 053
288
1 000
476
TP
100
1 250
3 550
2 600
850
3 250
1 300
Burnett MaryTSS
100
na
na
na
133
2 600
15
TN
100
na
na
na
317
4 083
100
TP
100
na
na
na
600
11 000
140
Cape YorkTSS
100
71
229
114
186
300
51
TN
100
117
298
181
219
915
81
TP
100
120
260
160
240
500
134
FitzroyTSS
100
25
425
38
325
625
119
TN
100
1 011
89
1 211
1 033
2 889
511
TP
100
2 500
300
4 100
3 800
11 000
1 900
Mackay WhitsundayTSS
100
176
413
177
472
949
303
TN
100
236
525
517
953
1 742
625
TP
100
320
877
348
1 425
2 636
1 205
Wet TropicsTSS
100
476
638
1 717
434
1 727
413
TN
100
350
370
549
264
870
375
TP
100
466
494
838
353
1 427
413

na - not available
TSS - Total Suspended Solids, TN - Total Nitrogen, TP - Total Phosphorous
Note: Data for the period 2006-07 to 2008-09 for the Burnett Mary NRM Region are not presented because no high flow events were recorded. Yields for the Total GBR Region have not been derived. Yields for the Wet Tropics NRM Region are weighted by basin size for aggregate NRM yield.
Sources: See the complete list at the end of this section.


Table 3.3 above shows that there is considerable variance in the condition of selected rivers in the GBR Region. The selected river basin yields in the Cape York and Burnett Mary NRM Regions are closer to the reference condition in 2011-12 than other regions. There is a decrease of 49 per cent in the Cape York NRM Region in yield of total suspended solids relative to pre-European yields, and a decrease of 85 per cent in the Burnett Mary NRM Region of the same yield. In 2010-11, all yields were significantly increased by very heavy rainfall (including total suspended solids), to 300 per cent of the pre-European yield in the Cape York NRM Region, and by 2,600 per cent in the Burnett Mary NRM Region.

Increases in yield have been observed for the majority of measures each year in areas between the Cape York and Burnett Mary NRM Regions. The Fitzroy and Burnett Mary NRM Regions recorded the highest index value of all measures in 2010-11 (11,000), when both regions recorded a total phosphorous yield 110 times the pre-European condition. Total phosphorous in the Fitzroy NRM Region recorded the highest index value in 2011-12, with a yield nineteen times (1,900) that of the pre-European condition (100).


NET PRIMARY PRODUCTIVITY

Net primary productivity (NPP) is defined as the net flux of carbon from the atmosphere into green plants per unit time. It is a fundamental ecological variable. It not only measures the energy input into the biosphere and terrestrial carbon dioxide assimilation, but also indicates the condition of the land surface area and the status of a wide range of ecological processes.

NPP is used in this information paper as an indicator for the 'vegetation' characteristic of terrestrial condition. The term 'net' refers to the balance (over time) between the rate of gain of carbon in leaves, stems, and roots by photosynthesis (known as gross primary productivity or GPP) and the rate of loss of biomass via respiration. It is positive in cases where the photosynthetic rate exceeds the respiration rate and negative where the respiration rate exceeds the photosynthetic rate.

The NPP estimates reported in this release are produced from the BIOS2 model developed by the CSIRO.

NPP is also applicable to marine areas, but an analysis of those areas has not been undertaken as part of this release. There are a range of possible derivation methods for estimating changes in area of seagrass, coral and mangrove but the required time series data are not available. Chlorophyll concentration is used in some derivation methods to measure marine NPP, and is included in the water quality indicator in the Seascape section.

Table 3.4 below shows the total amount of NPP in kilotonnes of carbon for each NRM Region for the period, 2000-01 to 2012-13.

TABLE 3.4: NET PRIMARY PRODUCTIVITY, BY NRM REGION, GREAT BARRIER REEF REGION, 2000-01 to 2012-13, Carbon ('000 tonnes)

2000-01
2001-02
2002-03
2003-04
2004-05
2005-06
2006-07
2007-08
2008-09
2009-10
2010-11
2011-12
2012-13
NRM Region

Burdekin
85 772
58 077
45 586
54 192
42 497
61 798
62 061
91 428
90 418
81 657
112 380
86 321
73 885
Burnett Mary
38 156
33 316
40 161
44 690
35 665
38 610
27 663
44 885
43 684
41 897
56 600
47 960
45 956
Cape York
30 095
29 676
24 588
26 563
27 223
26 772
31 070
29 705
31 088
26 534
33 334
29 782
29 469
Fitzroy
104 600
74 061
83 255
86 524
72 011
84 707
67 191
124 477
112 166
112 639
158 341
117 765
108 137
Mackay Whitsunday
10 593
9 401
7 826
8 895
7 913
8 782
9 241
10 468
9 514
9 346
9 888
10 247
9 802
Wet Tropics
22 722
23 118
20 628
20 693
21 387
20 938
23 079
23 626
23 994
21 826
22 776
22 317
22 421
Total GBR Region
291 939
227 647
222 043
241 557
206 696
241 608
220 304
324 588
310 865
293 899
393 321
314 392
289 670

Source: Haverd et al.,2013b


The GBR Region recorded a small decrease from 291,939 kilotonnes to 289,670 kilotonnes (or 0.8 per cent) between 2000-01 and 2012-13. Variation across years is very large, with a low of 206,696 kilotonnes in 2004-05 (a drought year), and a high of 393,321 kilotonnes in 2010-11 (a high rainfall year).

The Cape York NRM Region recorded a 2.1 per cent decrease over the period, 2000-01 to 2012-13; the Wet Tropics NRM Region recorded a smaller decrease of 1.3 per cent. The Burdekin NRM Region recorded the largest decrease both in percentage and absolute terms, by assimilating 11,888 kilotonnes less in 2012-13 than in 2000-01 (or 13.9 per cent).

Figure 3.1 below highlights the impact of variable rainfall. This map shows the differences in net primary productivity across the terrestrial area of the GBR Region between the very dry year, 2002-03 and the very wet year, 2010-11. The coastal area of Burdekin NRM Region and the inland area of Fitzroy NRM Region show some of the greatest variations in NPP between the two years.

FIGURE 3.1: NET PRIMARY PRODUCTIVITY (NPP), GREAT BARRIER REEF REGION, 2002-03 to 2012-13, Percentage Change (%)

Figure 3.1: Net Primary Productivity (NPP), Great Barrier Reef Region, 2002-03 to 2012-13, Percentage Change (%)



The indicator used to measure vegetation condition is mean grams of carbon assimilated per square metre per day (g C/ m2 / day). Table 3.5 below shows the index values for each NRM Region in the GBR Region.

TABLE 3.5: VEGETATION CONDITION, BY NRM TERRESTRIAL REGION, GREAT BARRIER REEF REGION, 2000-01 to 2011-12, Index (2000-01 = 100)

2000-01
2000-01
2001-02
2002-03
2003-04
2004-05
2005-06
2006-07
2007-08
2008-09
2009-10
2010-11
2011-12
NRM Region
g C/m2/day
points
points
points
points
points
points
points
points
points
points
points
points

Burdekin
1.70
100
68
53
63
50
72
73
106
106
95
131
100
Burnett Mary
1.90
100
87
105
116
93
101
72
117
114
110
148
125
Cape York
2.12
100
99
82
88
91
90
103
99
104
88
111
99
Fitzroy
1.84
100
71
80
82
69
81
64
119
107
108
151
112
Mackay Whitsunday
3.59
100
89
74
84
75
83
87
99
90
88
93
97
Wet Tropics
3.11
100
102
91
91
95
93
102
104
106
96
100
98
Total GBR Region
2.38
100
88
81
88
80
87
86
106
103
96
117
103

g C/m2/day — grams of carbon per cubic metre per day
Source: Haverd et al., 2013b


There are large differences between NRM Regions in terms of the amount of carbon assimilated per square metre. For example, the Mackay Whitsunday NRM Region assimilated more than twice the carbon per square metre than the Burdekin NRM Region in 2000-01. On the one hand, the vegetation condition of the Burnett Mary NRM Region has improved by 25 per cent over the reference period, and the Fitzroy NRM Region by 12 per cent. On the other hand, the condition of the Mackay Whitsunday NRM Region decreased by three per cent in the same period.


LIST OF REFERENCES

CSIRO (2014) Assessment of freshwater ecosystem condition, status and trends in the Wet Tropics region. Supporting study to the Wet Tropics Water Quality Improvement Plan. Canberra: Commonwealth Scientific and Industrial Research Organisation (CSIRO).

DSITIA (2013) Total suspended solids, nutrient and pesticide loads (2010-2011) for rivers that discharge to the Great Barrier Reef Great Barrier Reef Catchment Loads Monitoring 2010-2011. Brisbane: Queensland Department of Science, Information Technology, Innovation and the Arts (DSITIA).

Haverd, V. et al. (2013a) 'Multiple observation types reduce uncertainty in Australia’s terrestrial carbon and water cycles', Biogeosciences, Vol. 10, No. 3 (March), pp.2011–2040.

Haverd, V. et al. (2013b) 'The Australian terrestrial carbon budget', Biogeosciences, Vol. 10, No. 3 (February), pp.851–869.

Joo, M. et al. (2012) 'Estimates of sediment and nutrient loads in 10 major catchments draining to the Great Barrier Reef during 2006–2009', Marine Pollution Bulletin, Number 65, pp.150-166.

Kroon, F.J. et al. (2012) 'River loads of suspended solids, nitrogen, phosphorus and herbicides delivered to the Great Barrier Reef lagoon', Marine Pollution Bulletin, Number 65, pp.167-181.

Turner, R. et al. (2012) Sediment, Nutrient and Pesticide Loads: Great Barrier Reef Catchment Loads Monitoring 2009-2010. Brisbane: Queensland Department of Science, Information Technology, Innovation and the Arts.

Wallace, R. et al. (2014) Total suspended solids, nutrient and pesticide loads (2011–2012) for rivers that discharge to the Great Barrier Reef – Great Barrier Reef Catchment Loads Monitoring Program 2011–2012. Brisbane: Queensland Department of Science, Information Technology, Innovation and the Arts.