Dampak Konversi Hutan Menjadi Sistem Monokultur terhadap Strategi Perakaran Pohon

Abstract

Konversi Konversi hutan tropis menjadi sistem monokultur (perkebunan karet dan kelapa sawit) di lanskap Jambi berpotensi mengubah strategi morfologi akar halus (diameter = 2 mm). Penelitian ini bertujuan menentukan dampak konversi lahan terhadap sifat morfologi dan kadar air akar halus, serta menganalisis tipe strategi akuisisi akar halus pada berbagai sistem penggunaan lahan. Penelitian dilakukan pada empat tipe penggunaan lahan yang merepresentasikan gradien intensifikasi: hutan alam, hutan karet (agroforestri), perkebunan karet monokultur, dan perkebunan kelapa sawit monokultur, masing-masing lima plot. Sampel akar diambil dengan metode root tracing, dipisahkan menjadi akar absorptif (root order 1–3) dan transportif (root order 4–5), diukur sifat morfologinya dengan WinRHIZO Pro, lalu dianalisis menggunakan linear mixed-effects model (LMM) dan Tukey HSD (a = 0,05). Principal component analysis (PCA) digunakan untuk melihat pola multivariat, sedangkan hubungan antarvariabel diuji dengan korelasi Pearson. Hasil LMM menunjukkan bahwa konversi lahan menyebabkan penurunan signifikan pada panjang akar absorptif di kelapa sawit (2,13 ± 0,11 cm) dibandingkan hutan (2,73 ± 0,12 cm) dan hutan karet (2,74 ± 0,12 cm) (p < 0,05). Root length per area (RLA) akar absorptif di hutan (0,10 ± 0,01 cm m?²) juga lebih tinggi daripada karet (0,08 ± 0,00 cm m?²) (p < 0,05). Panjang akar transportif di hutan karet (1,97 ± 0,08 cm) lebih panjang daripada kelapa sawit (1,62 ± 0,11 cm) (p < 0,05). Panjang ujung akar absorptif di kelapa sawit (1,89 ± 0,15 cm) lebih panjang dibanding karet (1,29 ± 0,07 cm) (p < 0,05). Variabel lain seperti SRL, SRA, FRD, RTD, dan kadar air menunjukkan tren perubahan namun tidak signifikan (p > 0,05). PCA akar absorptif (PC1 = 47,7%, PC2 = 30,2%; total 77,9%) mengindikasikan pergeseran strategi dari akuisitif (SRL dan SRA tinggi) pada hutan dan hutan karet ke konservatif (FRD dan RTD tinggi) pada karet dan kelapa sawit. PCA akar transportif (PC1 = 42,0%, PC2 = 26,5%; total 68,5%) menunjukkan pemisahan lebih lemah, menandakan fungsi utamanya untuk pengangkutan air dan unsur hara daripada akuisisi sumber daya. Korelasi Pearson memperkuat temuan PCA: di semua sistem, SRL dan SRA berkorelasi positif sangat kuat (r = 0,87 hingga –0,98; p < 0,05 hingga p < 0,001), sedangkan hubungan konservatif tercermin dari korelasi negatif kuat antara RTD dan SRA/kadar air (r = –0,72 hingga –0,99; p < 0,05 hingga p < 0,001) serta antara FRD dan SRL atau panjang ujung akar. Pola ini menunjukkan bahwa konversi lahan cenderung menggeser sifat akar absorptif dari strategi akuisitif menjadi konservatif, sementara pada akar transportif pergeseran strategi tidak sepenuhnya mengikuti spektrum RES.

The conversion of tropical forests into monoculture systems (rubber and oil palm plantations) in the Jambi landscape potentially alters the morphological strategies of fine roots (diameter = 2 mm). This study aimed to determine the impacts of forest-to-monoculture conversion on fine root morphology and water content, and to analyze the types of fine root acquisition strategies across different land-use systems. The research was conducted in four land-use types representing an intensification gradient: natural forest, jungle rubber (agroforestry), monoculture rubber plantation, and monoculture oil palm plantation, with five plots per system. Fine root samples were collected using the root tracing method, separated into absorptive roots (root orders 1–3) and transportive roots (root orders 4–5), measured for morphological traits using WinRHIZO Pro, and analyzed with linear mixed-effects models (LMM) followed by Tukey HSD (a = 0.05). Principal Component Analysis (PCA) was applied to assess multivariate trait patterns, and Pearson’s correlation was used to examine trait relationships. LMM results showed that land-use conversion significantly reduced absorptive root length in oil palm plantations (2.13 ± 0.11 cm) compared with forest (2.73 ± 0.12 cm) and jungle rubber (2.74 ± 0.12 cm) (p < 0.05). Absorptive root length per area (RLA) in forest (0.10 ± 0.01 cm m?²) was significantly higher than in rubber plantations (0.08 ± 0.00 cm m?²) (p < 0.05). Transportive root length in jungle rubber (1.97 ± 0.08 cm) was significantly longer than in oil palm (1.62 ± 0.11 cm) (p < 0.05). Absorptive root tip length in oil palm (1.89 ± 0.15 cm) was significantly longer than in rubber (1.29 ± 0.07 cm) (p < 0.05). Other traits such as SRL, SRA, FRD, RTD, and water content showed trends but no significant differences (p > 0.05). PCA for absorptive roots (PC1 = 47.7%, PC2 = 30.2%; total 77.9%) indicated a shift from acquisitive traits (high SRL and SRA) in forest and jungle rubber to conservative traits (high FRD and RTD) in rubber and oil palm plantations. PCA for transportive roots (PC1 = 42.0%, PC2 = 26.5%; total 68.5%) showed weaker separation, indicating that its primary function is for the transport of water and nutrients rather than for resource acquisition. Pearson’s correlations reinforced the PCA findings: in all systems, SRL and SRA were strongly positively correlated (r = 0.87–0.98; p < 0.05 to p < 0.001), while conservative traits were reflected by strong negative correlations between RTD and SRA/water content (r = –0.72 to –0.99; p < 0.05 to p < 0.001) and between FRD and SRL or tip length. These patterns suggest that land-use conversion tends to shift absorptive root traits from acquisitive to conservative strategies, whereas transportive roots do not fully align with the acquisitive–conservative spectrum of the Root Economic Spectrum (RES).