Tree species with narrow ranges are a conservation concern because heightened extinction risk accompanies their small populations. Assessing risks for these species is challenging, however, especially in tropical flora where their sparse populations seldom appear in traditional plots and inventories. Here, we utilize instead large scale databases that combine tree records from many sources to test whether the narrow-range tree species of Panama are concentrated at certain elevations or in certain provinces. Past investigations have suggested that the Choco region of eastern Panama and the high mountains of western Panama may be potential hotspots of narrow-range tree species. All individual records were collected from public databases, and the range size of each tree species found in Panama was estimated as a polygon enclosing all its locations. Species with ranges <20,000 km2 were defined as narrow endemics. We divided Panama into geographic regions and elevation zones and counted the number of individual records and the species richness in each, separating narrow-range species from all other species. The proportion of narrow endemics peaked at elevations above 2000 m, reaching 17.2% of the species recorded. At elevation <1500 m across the country, the proportion was 6-11%, except in the dry Pacific region, where it was 1.5%. Wet forests of the Caribbean coast had 8.4% narrow-range species, slightly higher than other regions. The total number of narrow endemics, however, peaked at mid-elevation, not high elevation, because total species richness was highest at mid-elevation. High elevation forests of west Panama had higher proportions of narrow endemic trees than low-elevation regions, supporting their hot-spot status, while dry lowland forests had the lowest proportion. This supports the notion that montane forests of Central America should be a conservation focus. However, given generally higher diversity at low- to mid-elevation, lowlands are also important habitats for narrow-range tree species, though conservation efforts here may not protect narrow-range tree species as efficiently.

中文翻译：

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巴拿马窄幅树木分布：有热点吗？

范围狭窄的树种是一个保护问题，因为它们的小种群伴随着更高的灭绝风险。然而，评估这些物种的风险具有挑战性，特别是在热带植物群中，它们的稀疏种群很少出现在传统的地块和清单中。在这里，我们使用大规模数据库，结合来自许多来源的树木记录来测试巴拿马的窄范围树种是否集中在某些海拔或某些省份。过去的调查表明，巴拿马东部的乔科地区和巴拿马西部的高山可能是窄范围树种的潜在热点。所有单独的记录都从公共数据库中收集，在巴拿马发现的每个树种的范围大小被估计为一个包含所有位置的多边形。范围小于 20,000 平方公里的物种被定义为狭窄的地方性物种。我们将巴拿马划分为地理区域和海拔区域，并计算每个记录的数量和物种丰富度，将窄范围物种与所有其他物种分开。狭窄特有种的比例在海拔 2000 米以上达到峰值，达到记录物种的 17.2%。在全国海拔<1500 m 处，该比例为6-11%，但在干燥的太平洋地区为1.5%。加勒比海岸的湿林有 8.4% 的窄范围物种，略高于其他地区。然而，狭窄的地方性物种总数在中海拔而非高海拔达到峰值，因为总物种丰富度在中海拔最高。巴拿马西部高海拔森林的狭窄特有树木比例高于低海拔地区，支持其热点地位，而干燥的低地森林比例最低。这支持了中美洲山地森林应成为保护重点的观点。然而，鉴于中低海拔地区的多样性普遍较高，低地也是窄幅树种的重要栖息地，尽管这里的保护工作可能无法有效地保护窄幅树种。