Data from a botanical survey of the Anogeissus cloud forest in Jabal Qamar, Dhofar, Oman
Description
This data was collected from thirty sites in Jabal Qamar, Dhofar, Oman in September 2016-April 2017. Sites were located between 300 and 900 m above sea level in the altitudinal range of the Anogeissus cloud forest, which is endemic to the central South Arabian mountains in Yemen and Oman. The data comprises measurements of 120 adult and 120 juvenile woody plants and 30 quadrat samples at each site, totalling 7200 woody plants and 900 quadrat samples. Measurements include; location (lat, long, elevation), species, height, living/dead, PCQ distance, diameter at root collar, diameter at breast height (where applicable), density, cover, frequency, importance, bark-stripped area, browsing pressure, broken limbs, bent limbs, percentage cover of grasses, herbs, rock and bare ground, canopy cover, sward height and percentage cover of the three dominant ground species.
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The point-centered quarter (PCQ) method was used to sample the composition, density and structure of woody vegetation at thirty sites in the Jabal Qamar mountain range in western Dhofar, Oman. PCQ point locations were randomly generated in a GIS over an area of approximately 1 km2 at each site. At each sample point, the distances to the closest adult and the closest juvenile woody plant were recorded in each of the four PCQ quarters, resulting in a total of 120 adult and 120 juvenile records per site. For each individual the diameter at root collar (DRC), and where applicable, diameter at breast height at 130 cm above the ground (DBH130) were measured using a diameter tape or callipers. For multi-stemmed plants all stems were measured, however thin suckers growing from large trees and shrubs were ignored. Stem status was recorded as alive, dead, broken or missing and stems that had been cut by a machete or chainsaw were noted. Very old or deteriorated cut or missing stems were ignored. If a plant only had dead stems at DBH130 but additional live stems were present, it was recorded as alive and stem statuses recorded accordingly. DBH130 was not recorded for juveniles. An adult individual was recorded as dead when more than 80 percent of the plant was dead and a DBH130 was present. Individuals with only dead stems below DBH130 were classed as stumps and were ignored. Preliminary work determined DRC thresholds to distinguish adults and juveniles for each species because existing methods that utilise diameter and height measurements could not be used as many plants have altered morphology due to browsing activity. Adult and juvenile height was measured from the ground to the top of the plant unless the plant had fallen horizontally then the trunk length was measured. For all individuals, browsing intensity was estimated by five classes according to the percentage of browsed branches below the browse line (~3 m). For adults, the proportion of broken branches was estimated on a five-class scale according to the percentage of broken branches. To assess the prevalence of tree management practises, the proportion of bent or cut branches was estimated on a five-class scale. The classes were defined as: (1: undamaged) ~0%, (2: low) 1% – 33.3%, (3: medium) 33.3% – 66.6%, (4: high) 66.6% – 99%, (5: entirely damaged) ~100%. Areas of stripped bark were also measured, and additional relevant information was recorded. Canopy cover was also recorded. At each PCQ point a 1.2 m x 1.2 m quadrat was deployed to sample the ground vegetation which also served to guide the PCQ quarters. Grass and herb species richness and the percentage cover of grasses, herbs, rock and bare ground were recorded. Additionally, the percentage cover of the three most abundant species was estimated.