BIODIVERSITAS ISSN: 1412-033X Volume 22, Number 6, June 2021 E-ISSN: 2085-4722 Pages: 3315-3325 DOI: 10.13057/biodiv/d220637 Profile of geographical variation in marginal land and its relationship with the fruit tree species richness in Jombang District, Indonesia ZULFIKAR 1,2,♥ , ENDANG ARISOESILANINGSIH 3 , SERAFINAH INDRIYANI 3 , ADJI ACHMAD RINALDO FERNANDES 4 1 Department of Informatical Science, Faculty of Informatical Technology, Universitas KH. A. Wahab Hasbullah. Jl. Garuda 9, Tambakberas, Jombang 61419, East Java, Indonesia. Tel. /fax.: +62-321-853533,  email: zulfikardia@gmail.com 2 Program of Biology, Department of Biology, Faculty of Mathematics and Natural Sciences, Universitas Brawijaya. Jl. MT Haryono 169, Malang 65145, East Java, Indonesia 3 Departmen of Biology, Faculty of Mathematics and Natural Sciences, Universitas Brawijaya. Jl. MT Haryono 169, Malang 65145, East Java, Indonesia 4 Departmen of Statistical, Faculty of Mathematics and Natural Sciences, Universitas Brawijaya. Jl. MT Haryono 169, Malang 65145, East Java, Indonesia Manuscript received: 16 March 2021. Revision accepted: 24 May 2021. Abstract. Zulfikar, Arisoesilaningsih E, Indriyani S, Fernandes AAR. 2021. Profile of geographical variation in marginal land and its relationship with the fruit tree species richness in Jombang District, Indonesia. Biodiversitas 22: 3315-3325. The purpose of this study was to determine the sites of fruit tree species richness, in order to analyze the relationship between the locations with fruit tree diversity, and geographical variations, towards the success of marginal land conservation in Jombang Regency. The study area covered four districts, and was divided into 11 sites with different slopes and altitudes. Multivariate analysis was carried out using the R program. The results showed that the structure and composition of fruit trees were discovered to be 21 species from 14 families. The uniqueness of the fruit trees was shown in Tamarindus indica and Cocos nucifera, which were observed as rare plants on slopes with high and low altitudes, respectively. The results of the geographical variation analysis also showed that the slope and elevation with values of 0.5889 and 0.5077, respectively, were significantly correlated with the site of fruit plant species richness at the (α) 0.05 level, as the response formed was not linear for the three geographical diversities studied. Also, the model built between site, slope, and elevation towards the fruit tree species richness was acceptable, due to the fact that the value (Pr> F) = 0.004 was very significant at the (α) 0.001 level. Keywords: ANOVA, geographical variation, fruit trees, species richness, NMDS, marginal land Abbreviations: ANOVA; Analysis of Variance, NMDS; Non-metrics Multidimensional Scaling, DCA; Detrended Correspondence Analysis, CA; Correspondence Analysis, CCA; Canonical Correspondence Analysis, CDA; Cluster Dendrogram Analysis. INTRODUCTION The conservation success is inseparable from environmental conditions and geographical variations in one ecological entity. Spatial and geographical variations in species richness have been a well-documented pattern in ecology (Rosenzweig 1995). Species richness is the total number of different breeds, while equity is the abundance distribution (for example number of individuals, biomass, and others.) in each group (Ludwig and Reynolds 1988). Also, environmental factors such as abiotic constraints, biotic interactions, disturbances, and historical processes, have been designed as the main drivers producing this variability (Ricklefs et al. 2004). Specifically, slope and elevation have been considered to be one of the most important drivers of geographical variability in plant species richness (Allen et al. 2002). Recently, the study linking climate to biodiversity has received major attention for predicting the possible effects of climate warming (Gedan and Bertness 2009), especially leading to marginal land status. Zhang et al. (2010), also stated that the community composition in ecological units was generally sensitive to local environmental conditions, such as soil chemistry, topography, sunlight, and atmospheric humidity. The latitude and elevation patterns of plant species richness are often associated with different climatic variables, such as rainfall, temperature, and evapo- transpiration. Several significant relationships between plant species richness, latitude, and altitude (O'Brien et al. 2000; Whittaker and Field 2000; Kluge et al. 2006) have been observed, with the climate gradients associated with these geographical trends proposed as an explanation. Also, the latitudinal variation of breed diversity, where species richness tends to increase near the equator and decreases toward the poles, has been widely recognized by biologists (Peet 1978; Wang et al. 2006). Moreover, longitudinal variations in species richness have been documented for birds (Jetz and Rahbek 2001) and vascular plants (Qian 1999). Generally, species richness increases with rainfall and temperature, although it decreases in wet and cold or warm and dry climates (Ferrer-Castán and Vetaas 2005). Several studies have also documented a unimodal relationship between species richness and productivity, as measured by evapotranspiration (Field et al. 2005).