By Arif Setiawan
shade grown coffee gibbon habitat, sokokembang forest, central java
El Niño is a global climate phenomenon—simply put, the warming of the sea surface in the central and eastern Pacific Ocean. Under normal conditions, rising sea surface temperatures influence air pressure, driving warm air—laden with moisture and cloud-forming potential—from the Western Hemisphere (the Americas) toward Indonesia, thereby bringing rainfall. When El Niño occurs, these winds weaken; the rising sea surface temperatures (and the resulting warmer air) cause a drop in air pressure, preventing the moisture-bearing winds from reaching Indonesia. Consequently, most regions in Indonesia experience a dry season that is longer and more intense than usual.
The impacts of El Niño in Indonesia are evident today: widespread drought, drying rivers and springs, and—as seen in 2026—forest and land fires. This global climate phenomenon intersects with other factors, particularly commodity production sectors linked to land management. Coffee is one such sector; initiatives combining coffee cultivation with primate conservation—specifically aimed at protecting the Javan Gibbon—offer a chance to observe the effects of El Niño on a smaller scale within the gibbons’ habitat in Pekalongan. Robusta coffee (*Coffea canephora*) dominates the landscape in and around the hamlets and cultivated forest plots within the gibbons’ habitat; while specific research on El Niño’s impact on these plants is pending, the effects are undoubtedly present.
rivers drying out, reduce water volume in sokokembang
Currently, the forest habitat where most of this Robusta coffee is grown is exposed to the intense heat of the El Niño-driven dry season. Our observations show that coffee plants grown without shade appear severely wilted and parched. Furthermore, the flowers—normally white—are turning pink, and many buds are drying out before they can even bloom. Rivers that would typically continue to flow during a normal dry season… The area appears dry, with surrounding vegetation also parched and withered. Temperature monitoring equipment installed indoors at Sokokembang indicates an average of 35°C, while outdoor temperatures can reach 37°C at midday. Humidity, typically 80–90%, is currently recorded at just 35%.
open sun coffee farming
Aerial drone observations clearly reveal that coffee plants exposed to direct sunlight have yellowing leaves. A stark contrast is visible in the drone footage: coffee plants growing under the shade of natural forest stands appear lush green and healthy. In terms of microclimate, natural forest shade provides a protective canopy against sunlight; the layered vegetation structure and diverse plant composition offer varying degrees of protection from sunrise to sunset. Naturally, air temperatures are also cooler than in unshaded areas.
Although comprehensive research specifically addressing the direct impact of El Niño on this habitat—home to both gibbons and Robusta coffee—has not yet been conducted, existing studies serve as valuable references. One such study offers a detailed look at the El Niño phenomenon’s effect on coffee growth and productivity in East Java. It aimed to examine the impact of the 2015 El Niño event on the microclimate, growth, and productivity of Robusta coffee (Tugusari 6 clone) across various agroforestry systems in the Mount Gumitir area of Banyuwangi, East Java.
Regarding the impact on microclimate: the El Niño phenomenon caused a significant drop in annual rainfall—from an average of 3,975 mm to 1,801 mm—and prolonged the dry season. Unshaded plantations experienced extreme conditions, with average peak temperatures reaching 32.05°C and humidity dropping as low as 57.66%. In contrast, coffee plants growing beneath the natural forest canopy maintained a more stable temperature of 26.33°C.and a maximum humidity of 85%.
Regarding the impact on growth and productivity, lower light intensity in shaded systems resulted in leaves that were broader, internodes that were longer, and higher chlorophyll content. Coffee grown under a natural forest canopy produced the highest number of clusters, number of fruits per cluster, and total fruit per tree. The highest Robusta coffee productivity during El Niño was achieved in natural forest systems (1,497 kg/ha) and Leucaena shade systems (1,355 kg/ha), owing to their ability to maintain soil and environmental moisture.
Source:
Yuliasmara, F., 2017. El Nino effect on coffee growth and productivity on several agroforestry systems in Gumitir Mountain Coffee Farms, East Java, Indonesia. Pelita Perkebunan, 33(3), pp.168-179.