Soil Insect Diversity in Arboretum Sumber Brantas and Potato Farmlands
Beneath the tranquil beauty of Arboretum Sumber Brantas and the orderly rows of potato fields in Bumiaji, Batu City, a silent but vital drama unfolds—a complex world teeming with life that most of us never see. Soil insects, the unnoticed custodians of our ecosystems, work tirelessly to maintain the delicate balance of nature. These tiny creatures serve as powerful bioindicators, revealing the health of their environment through their presence, diversity, and behavior.
A fascinating scientific investigation conducted in 2016 unveiled striking differences between the rich insect communities of the protected arboretum and the simplified ones in nearby agricultural land 1 . This research doesn't just satisfy scientific curiosity—it provides crucial insights for sustainable land management practices that benefit both agriculture and conservation. As we delve into this hidden world, we discover that the humble soil insect holds secrets to understanding and protecting our precious ecosystems.
Soil insects represent a specialized group of insects that spend all or significant portions of their lives within the soil environment. Though largely invisible to the casual observer, these organisms perform fundamental roles that sustain ecosystem function and resilience.
These insects consume dead organic matter, initiating the breakdown process that recycles nutrients back into the soil. Without these efficient cleaners, ecosystems would gradually choke on their own waste.
Working alongside detritivores, decomposers further break down organic material, transforming it into rich humus that enhances soil fertility and structure. This group represents nature's ultimate recycling system.
These plant-eating insects interact with living plants, influencing plant community dynamics and nutrient cycling. In balanced ecosystems, they help maintain biodiversity by preventing any single species from dominating.
The hunters of the soil world, predatory insects help regulate populations of other soil organisms, including potential pests, thus maintaining a natural balance that supports ecosystem stability 1 .
The diversity and population dynamics of these tiny organisms provide valuable insights into ecosystem health. When an environment becomes degraded or faces pollution, sensitive insect species disappear, offering an early warning system long before problems become visible to human observers. This principle forms the foundation for using soil insects as biological indicators in environmental monitoring 1 .
To understand how different land management practices affect soil insect communities, researchers designed a comprehensive study comparing the protected environment of Arboretum Sumber Brantas with actively cultivated potato farmlands in the same region. Conducted from April to June 2016, this investigation employed rigorous scientific methods to capture an accurate picture of the hidden biodiversity in these contrasting habitats 1 .
The research team employed pitfall traps—simple yet effective devices consisting of containers buried flush with the soil surface—to capture active ground-dwelling insects. At each study site, they installed 30 such traps, creating a systematic sampling network that would provide reliable data. This method is particularly effective for capturing beetles, ants, spiders, and other mobile arthropods that move across the soil surface 1 .
Study period
Arboretum & Potato Farmland
30 per location
After collection, the scientific work moved to the laboratory, where researchers photographed each specimen and began the painstaking process of identification. Using specialized taxonomic guides and the online platform Bugguide.net, they classified each insect according to its morphological characteristics. Meanwhile, soil samples from both locations underwent detailed physicochemical analysis at Brawijaya University's soil laboratory, measuring parameters including temperature, moisture content, pH, organic matter, nitrogen, phosphorous, and potassium levels 1 .
The final stage involved sophisticated statistical analysis using specialized software (Past 3.12 for diversity indices and SPSS 16.0 for correlation analysis) to uncover patterns and relationships within the data. This multifaceted approach allowed researchers to move beyond simple inventory to understand the ecological dynamics governing soil insect communities in these contrasting environments 1 .
The findings from this meticulous investigation revealed striking differences between the two study sites, painting a compelling picture of how land use influences soil insect communities. The data told a story of dramatic contrast between the rich biodiversity of the protected arboretum and the simplified communities of the agricultural landscape.
| Parameter | Arboretum Sumber Brantas | Potato Farmland |
|---|---|---|
| Total Families | 16 families | 7 families |
| Total Individuals | 9,266 individuals | 1,573 individuals |
| Detritivores | 1 family | Not detected |
| Decomposers | 4 families | 4 families |
| Herbivores | 6 families | 1 family |
| Predators | 5 families | 2 families |
| Diversity Index (H') | 0.595 | 0.224 |
The numbers reveal a compelling narrative: the arboretum supported significantly greater diversity across virtually all measures. With more than twice the number of insect families and nearly six times the number of individual insects, the protected forest environment demonstrated its superior capacity to support complex soil insect communities 1 .
Perhaps even more revealing is the differences in functional roles represented at each site. While the arboretum maintained a balanced representation of all four functional groups, the potato farmland showed simplified community structure, with complete absence of detritivores and dramatically reduced herbivore and predator representation. This pattern suggests that agricultural intensification doesn't merely reduce insect numbers but fundamentally reshapes the ecological community, potentially compromising ecosystem functioning 1 .
The Shannon-Wiener Diversity Index values further quantified this contrast, with the arboretum's higher value (0.595) indicating more equitable distribution of individuals across different families compared to the potato farmland (0.224). While both values fall within the low to moderate range of diversity—which is typical for soil insect communities—the substantial difference between them highlights the arboretum's greater ecological complexity 1 .
Beyond simply counting insects, the research team sought to understand the environmental factors driving these diversity patterns. By examining the correlation between soil physicochemical properties and insect distribution, they uncovered fascinating relationships that help explain why certain insects thrive in specific environments.
| Soil Parameter | Most Correlated Insect Group | Correlation Value | Interpretation |
|---|---|---|---|
| Temperature | Gryllidae 2 (crickets) | 0.414 | Moderate correlation |
| Humidity | Gryllidae 2 (crickets) | 0.329 | Low correlation |
| Soil pH | Forficulidae (earwigs) | 0.366 | Moderate correlation |
| Organic Matter | Gryllidae 1 (crickets) | 0.552 | Moderate correlation |
| Total Nitrogen | Gryllidae 1 (crickets) | 0.527 | Moderate correlation |
| C-Organic | Gryllidae 1 (crickets) | 0.546 | Moderate correlation |
| Phosphate | Gryllidae 2 (crickets) | 0.467 | Moderate correlation |
| Potassium | Gryllidae 1 (crickets) | 0.424 | Moderate correlation |
The correlation analysis revealed that soil composition, particularly organic matter and nutrient content, exerted stronger influence on insect distribution than physical parameters like temperature and moisture. Various cricket families (Gryllidae) showed moderate correlations with multiple soil nutrients, suggesting they serve as excellent bioindicators for soil fertility 1 .
The relationship between earwigs (Forficulidae) and soil pH further illustrates how specific insect groups have particular environmental requirements. These findings have practical implications for land management—by monitoring certain indicator species, farmers and conservationists can infer soil conditions and make more informed management decisions 1 .
The fascinating findings from this study relied on specialized techniques and equipment designed to capture, identify, and analyze soil insect communities. These tools form the essential kit for any researcher venturing into the world of soil ecology.
Capture active surface-dwelling insects using containers buried flush with the soil surface.
30 traps deployed at each siteDetailed documentation of morphological features for precise identification.
Used optical microscopy facilitiesSpecies classification based on physical characteristics using taxonomic keys.
Used books and Bugguide.netMeasure physicochemical parameters in specialized laboratories.
Conducted at Brawijaya UniversityAnalyze diversity patterns and correlations using specialized programs.
Past 3.12 & SPSS 16.0This comprehensive toolkit enabled researchers to move from simple collection to sophisticated analysis, revealing not just which insects were present, but what their distribution patterns said about the ecosystem as a whole. The combination of field methods, laboratory techniques, and statistical analysis represents the gold standard for ecological diversity studies 1 .
The silent world beneath our feet speaks volumes about the health of our landscapes. The dramatic differences between the soil insect communities of Arboretum Sumber Brantas and the potato farmlands of Bumiaji offer a powerful lesson in environmental stewardship.
The rich tapestry of life in the protected arboretum—with its detritivores, decomposers, herbivores, and predators all playing their ecological roles—stands in stark contrast to the simplified communities of the agricultural landscape.
Preserve natural areas to safeguard complete ecosystems
Adopt practices that support greater biodiversity
These findings carry significant implications for both conservation and agriculture. They suggest that preserving natural areas like arboretums isn't just about protecting trees and charismatic animals—it's about safeguarding the complete ecosystem, down to the smallest soil inhabitants. For agricultural lands, the research points to the need for management practices that support greater biodiversity, such as reducing chemical inputs, maintaining organic matter, and creating habitat refuges for beneficial insects.
As we face growing environmental challenges, from climate change to food security, understanding and protecting these unseen ecosystem engineers becomes increasingly urgent. The humble soil insects of Arboretum Sumber Brantas have given us a precious gift—knowledge. It is now our responsibility to use that knowledge to create a future where both natural and agricultural systems can thrive, supported by their smallest but most vital inhabitants.