Towards a More Efficient In and Ex Situ Conservation of Sri Lankan Wild Rice Species

Abstract

Five species of wild Oryza (O. nivara, O. rufipogon, O. eichengeri, O. rhizomatis and O. granulata), including the endemic species O. rhizomatis, have been recorded in Sri Lanka. These species are facing continuous decline in their populations due to natural and anthropogenic processes, with habitat loss being the main threat. This study aimed to provide information on the distribution, the current status of ex situ and in situ conservation, and to identify high-priority species and sites of wild rice in Sri Lanka, in order to improve the effectiveness of conservation efforts. Occurrence records of Sri Lankan wild rice species were collected from literature, gene banks, and field surveys. The distribution of these species was mapped, and areas with high species richness were identified. A gap analysis was conducted to determine the high-priority areas and species for ex situ and in situ conservation. It was found that about 23% of the wild rice populations in Sri Lanka were within protected areas, and by expanding these protected areas by 1 km, an additional 22% of the populations located on the border of these areas could be effectively conserved. Our analysis also revealed that 62% of Sri Lankan wild rice populations were not represented in gene banks. The species-rich areas were found to be in only two districts (Polonnaruwa and Monaragala), and less than 50% of these areas were within protected areas. Based on these findings, O. rhizomatis, O. eichengeri, and O. rufipogon were identified as high-priority species for in situ conservation. Ex situ collections were also deemed necessary for O. granulata and O. rhizomatis to ensure diversity representation in gene banks.

Keywords: conservation; dormancy; germination; seed; wild rice.

Figure 1

Distribution map of Sri Lankan wild rice species (a) O. nivara, (b) O. rufipogon, (c) O. eichengeri, (d) O. rhizomatis, (e) O. granulata based on the information from ex situ seed accessions held at IRRI (pink quadrats) and recent literature (blue circle) overlaid with the wildlife protected areas (under the Department of Wildlife Conservation and Department of Forest conservation of Sri Lanka). Confirmed (+) or extinct (×) or new populations (yellow triangle) found during the field survey are reported.

Figure 1

Distribution map of Sri Lankan wild rice species (a) O. nivara, (b) O. rufipogon, (c) O. eichengeri, (d) O. rhizomatis, (e) O. granulata based on the information from ex situ seed accessions held at IRRI (pink quadrats) and recent literature (blue circle) overlaid with the wildlife protected areas (under the Department of Wildlife Conservation and Department of Forest conservation of Sri Lanka). Confirmed (+) or extinct (×) or new populations (yellow triangle) found during the field survey are reported.

Figure 2

Species richness map of Sri Lankan wild rice species superimposed to protected areas (under the Department of Wildlife Conservation and Department of Forest Conservation of Sri Lanka). Colors indicate the number of wild rice species present in a 1 km × 1 km grid cell.

Figure 3

Distribution of Sri Lankan wild rice species over layered with the protected areas (green): blue squares (10 km × 10 km) represent effectively protected (>50% of cell surface included in the protected area); yellow squares (10 km × 10 km) represent ineffectively protected (<50% of cell surface included in the protected area); white squares represent totally unprotected cells.