Correlation of Carbon Stock and Biodiversity Index at the Small Scale Agroforestry Landscape in Ciliwung Watershed

Pekarangan is part of a complex of small-scale agroforestry landscape. Pekarangan have 3 functions i.e. ecological, economic, and social. ecological function, for providing landscape services such as carbon stock and biodiversity; economic function, can supplies foods and nutrition; and social function, for building low carbon communities and increasing the environmental awareness. Therefore, this research aims to correlate carbon stocks and biodiversity index of Pekarangan in Ciliwung Watershed. This study has measured 48 samples which were divided in three stream, namely upstream, midstream, and downstream. The samples were divided into four groups, G1 (pekarangan size less than 120 m2 and doesn’t have other agricultural land (no other agricultural land - OAL), G2 (<120 m2 with OAL < 1000 m2), G3 (120-400 m2 with no OAL) and G4 (120-400 m2 with OAL < 1000 m2). The results show that correlation between carbon stock and biodiversity index value is R2 = 0.05. The results showed no correlation between carbon stocks and biodiversity index could be due to the amount of Pekarangan owners who prefer potted plants than plant a tree, so that the carbon sequestered in the Pekarangan only slightly.


Introduction
Pekarangan or home garden is a part of a complex small scale agroforestry landscape, usually located around the house and its range is only about 0.1 to 0.3 hectares [1]. Pekarangan have 3 functions i.e. ecological, economic, and social [1]. Ecological function is for providing landscape services such as carbon stock and biodiversity; economic function can supplies foods and nutrition; and social function is for building low carbon communities and increasing the environmental awareness. The biodiversity index of area has a great contribution to the preservation and the diversity of ecosystems, thus pekarangan as agroforestry systems provide a significant contribution to carbon storage area while also enhancing rural livelihoods [2] [3]. This research aims to determine correlation between carbon stock and biodiversity index at pekarangan in Ciliwung Watershed. In addition, to figures out whether biodiversity index inside pekarangan can influeces of carbon stock value and vise versa. Both carbon stock and biodiversity index are type of landscape services which also be considered as the asset and ecosystem sharing value to improve rural community welfare [

Location, Tools, and Materials
This study is located in Ciliwung Watersheds ( Figure 1). The tools used in this study consist of hardware and software, such as digital camera, stationery, measuring tools, laptop, and spreadsheet software. Mataerials used in this study is formula of carbon stock and biodiversity index (Table 1) and other materials obtained directly in the field.

Methods
The method used in this study using survey and measurement on the field to get carbon stored and heterogeneity. There are 48 samples pekarangan and each 16 samples are in upstream, midstream, and downstream. Samples were taken by purposive random sampling ( Figure 2). Pekarangan group were divided into four groups, namely as G1 (pekarangan size less than 120 m 2 and doesn't have other agricultural land (no other agricultural land -OAL), G2 (<120 m 2 with OAL < 1000 m 2 ), G3 (120-400 m 2 with no OAL) and G4 (120-400 m 2 with OAL < 1000 m 2 ).  Figure 2. Flowchart on this study that using purposive random sampling

Correlation of Carbon Stock and biodiversity index
Based on the formula in Table 1 and   Based on the data Table 3 and Table 4 the correlation were obtained is R² = 0.058 ( Figure 3). Based on this value the correlation of carbon stock and biodiversity index was positively related even though the value of which is derived relative small, this is because biodiversity index is very diverse while the carbon stock obtained relative small. Things like this happen as more plants were grown in pots as houseplants than trees which incidentally have more carbon stock. Tropical homegardens or pekarangan with high agrobiodiversity have high potential for carbon (C) sequestration, especially under changing environments [8], and particularly in West Java [9] [3].

Conclusion
Based on this study, it can be concluded that the correlation of carbon stock and biodiversity index in Ciliwung Watershed is still relatively low. This is due to increased levels of development in Ciliwung Watershed which impacted to the open space area and the household prefer to potted their plant on pekarangan. The land use change in Ciliwung Watershed is believed tend to reduce the carbon stock and at the same time degrade the biodiversity condition [10] [11]. This condition should be overcome by integrated landscape approach [12] for increasing the community awareness [13]. The community should improve their understanding about the important of home garden or pekarangan. Pekarangan can provide ecological, economical and social function, thus it can be determine as the household capital [14]. Furthermore, pekarangan can be utilized not only for production but also provide landscape services asset [15].

Acknowledgements
This study was conducted under the project entitled Management of Agroforestry Landscape as Landscape Service Provider towards Low Carbon Landscape (LCL) of PUPT IPB 2016. This Study was supported by Kemenristek Dikti of Indonesia.