Tania June

Energy and water fluxes above a cacao agroforestry system in Central sulawesi, indonesia, indicate effects of land-use change on local climate

Rapid conversion of tropical rainforests to agricultural land-use types occurs throughout Indonesia and South-East Asia. We hypothesize that these changes in land-use affect the turbulent heat exchange processes between vegetation and the atmosphere, and the radiative properties of the surface, and therefore, induce an impact on local climate and water flows. As part of the international research project (SFB 552, Stability of Rainforest Margins in Indonesia, STORMA) the turbulent heat fluxes over a cacao agroforestry system (AFS) were investigated, using the eddy covariance technique. These first heat flux observations above a cacao AFS showed an unexpectedly large contribution of the sensible heat flux to the total turbulent heat transport, resulting in an averaged day-time Bowen ratio of /3 = H/λE 1. Seasonality of β did mainly coincide with the seasonal course of precipitation, which amounted to 1970 mm yr -1 during the investigated period. The findings are compared to invastigations at four neotropical rain forests where daytime β were substantially smaller than 1. All discussed sites received similar incident short wave radiation, however, precipitation at the neotropical sites was much higher. Our first observations in a nearby Indonesian upland rain forest where precipitation was comparable to that at the cacao AFS showed an intermediate behaviour. Differences in β between the cacao AFS and the tropical forests are discussed as a consequence of differing precipitation amounts, and albedo. From these comparisons we conclude that conversion from tropical forests to cacao AFS affects the energy fluxes towards increased heating of the day-time convective boundary-layer.

Effects of land-use change on matter and energy exchange between ecosystems in the rain forest margin and the atmosphere

Greenhouse gas and energy fluxes between the land surface and the atmosphere are important aspects for the evaluation of land-use options in tropical areas. Changes in vegetation cover alter the capacity to absorb carbon dioxide and solar radiation from the atmosphere and influence the magnitudes of latent and sensible heat flows to the atmosphere. If happening at a larger spatial scale, land-use change can lead to significant local feedbacks like drought, flooding, soil erosion or shifts in local climate.

Sensible heat flux of oil palm plantation: Comparing Aerodynamic and Penman-Monteith Methods

Oil Palm (Elaeis guinensis Jacq) has a unique morphological characteristics, in particular it has a uniform canopy. As the plant become older, its canopy coverage will completely cover the surface and influence characteristics of its microclimate. Sensible heat flux estimation of oil palm plantation could be used to identify the contribution of oil palm in reducing or increasing heat to its surrounding environment. Determination of heat flux from oil palm plantation was conducted using two methods, Aerodynamic and Penman-Monteith. The result shows that the two methods have similar diurnal pattern. The sensible heat flux peaks in the afternoon, both for two and twelve years oil palm plantations. Sensible heat flux of young plantation is affected by atmospheric stability (stable, unstable and neutral), and is higher than that of older plantation, with mean values of 0.52 W/m2 (stable), 43.53 W/m2 (unstable), 0.63 W/m2 (neutral), with standard deviation of 0.50, 28.75 and 0.46 respectively. Sensible heat flux estimated by Penman-Monteith method in both young and older plantation was higher than the value determined by Aerodynamic method with respective value of 0.77 W/m2 (stable), 45.13 W/m2 (unstable) and 0.63 W/m2 (neutral) and 0.34 W/m2 (stable), 35.82 W/m2 (unstable) and 0.71 W/m2 (neutral).

The influence of surface roughness and turbulence on heat fluxes from an oil palm plantation in Jambi, Indonesia

Oil palm plantations are expanding vastly in Jambi, resulted in altered surface roughness and turbulence characteristics, which may influence exchange of heat and mass. Micrometeorological measurements above oil palm canopy were conducted for the period 2013–2015. The oil palms were 12.5 years old, canopy height 13 meters and 1.5 years old canopy height 2.5 m. We analyzed the influence of surface roughness and turbulence strenght on heat (sensible and latent) fluxes by investigating the profiles and gradient of wind speed, and temperature, surface roughness (roughness length, zo, and zero plane displacement, d), and friction velocity u*. Fluxes of heat were calculated using profile similarity methods taking into account atmospheric stability calculated using Richardson number Ri and the generalized stability factor ζ. We found that roughness parameters (zo, d, and u*) directly affect turbulence in oil palm canopy and hence heat fluxes; they are affected by canopy height, wind speed and atmospheric stability. There is a negative trend of d towards air temperature above the oil palm canopy, indicating the effect of plant volume and height in lowering air temperature. We propose studying the relation between zero plane displacement d with a remote sensing vegetation index for scaling up this point based analysis.

Rainfall Prediction Modeling using Neural Network Analysis Technics at Paddy Production Centre Area in West Java and Banten

Rainfall fluctuates with time and changes randomly, which unfavorable for most of the cropping, such as paddy. An early warning system is required to ensure a productive paddy cropping system. This paper describes the rainfall prediction modelling using a neural network analysis at paddy production centre area in the northern coast of Western Java and Banten. Rainfall data from Baros in the northern coast of Banten, Karawang, and Kasomalang Subang in the northern coast of West Java have been used for setting and validating the model. The model provides rainfall prediction for the next three months (Y=CHt+3), using the inputs data of the number of month (X1=t), the rainfall at the current month (X2=CHt), the rainfall atthe following month (X3=CHt+1), the rainfall at the following two months (X4=CHt+2), the southern ossilation index (SOI) at the current month (X5=SOIt) and the NINO-3,4 sea surface temperature anomaly at the current month (X6=AnoSSTt). Rainfall data recorded in the 1990-2002 period have been used for composing the model, and those in the 2003-2006 periods have been used for validating the model. The validated model has been used to predict rainfall in the 2007-2008. The best modelare those that using a combination of those six input variables. These models are able to explain 88-91% of the data variability with 4-8 mm month-1 of the maximum prediction error. At Baros Serang, the predicted rainfall in the 2007-2008 periods will be varied from Normal to Above Normal. At Karawang and Kasomalang Subang, predicted rainfall will be high at the end of 2007 until early 2008, and then will be low in the middle of 2008 and increases at the end of 2008.

ANALISIS KESESUAIAN IKLIM UNTUK PENGEMBANGAN CENDANA (Santalum album L.) DI NUSA TENGGARA TIMUR

Land suitability analysis method is introduced for sandalwood (Santalum album L.) in Nusa Tenggara Timur. It includes analysis on its (I) agro ecological suitability based on crop requirement for climate and soil characteristic, (2) ecological suitability, and (3) social-economic requirement for sustainable and profitable production. Approach to these three components is conducted through desk study/survey and on site research. All information collected and analyzed is combined together in GIS (Geographical Information System) for further use.