No abstract

No abstract

No abstract

Biomass collection could contribute to the reduction of wildfire prevention costs by obtaining solid biofuels from shrublands that pose a high fire risk, using mechanical harvesting methods that have not been sufficiently tested in shrub formations. The objective of this study is to evaluate the performance of a harvester-baler system (Biobaler WB55) for collecting rockrose (Cistus laurifolius L.) shrublands biomass, to asses the influence of the cutting rotor tool (blades or hammers) on weight and surface productivities and operating costs, as well as to determine the influence of the standing shrub biomass load on productivity and biomass collection efficiency.A 31-hour test was conducted on 21 ha of a typical Mediterranean shrubland in the centre of Spain. Data collection included time study, daily collected area, fuel consumption and bale measurements. Samples of fresh biomass from bales were collected for the determination of moisture content. The average collected biomass was 2.3 tDM·ha-1 (tonnes of dry matter per hectare), with an average productivity of 1.6 tDM·PMH-1 and an average yield of 0.7 ha·PMH-1. Better results were obtained with blades than with hammers in the cutting rotor tool (35% more collected biomass, 42% higher weight productivity, 61% higher collection efficiency and 14% greater surface productivity). The average harvest-baling costs with blades were estimated at 99.5 €∙PMH-1, 142.1 €∙ha-1 and 53.9 €∙tDM-1 (34.0 €∙tWM-1, € per tonne of wet matter), and with hammers 91.5 €∙PMH-1, 152.5 €∙ha-1 and 81.4 €∙tDM-1 (51.1 €∙tWM-1).The analysed harvester-baler was operated without difficulty in this type of vegetation and was able to collect up to 31% of the shrub biomass load in the study area. The amount of uncollected biomass and the decrease in biomass collection efficiency, as shrub biomass load increases, suggest that possible mechanical improvements are needed to improve biomass collection efficiency.

Aims of the study: To construct biomass weight equations for rockrose (Cistus laurifolius L.) shrublands in North-central Spain comparing different methodologies and evaluating the applicability of the current Spanish open PNOA-LiDAR data. Area of study: The growing extension of Mediterranean shrublands associated with a high wildfire risk in a climate change scenario is considered a relevant source of biomass for energy use and bioproducts. Quantifying the biomass load of the shrublands provides essential information for adequate management, calling for the development of equations to estimate said biomass loads in the most extensive monospecific shrublands. Materials and methods: Biomass dry weight from 290 destructive sampling plots (ø4m) and 426 individual plants along with LiDAR data from PNOA were related to dasometric parameters to fit weight per surface and weight per plant equations. Main results: Three new equations improve rockrose biomass estimations in North-central Spain: a) Weight per unit area (tDM.ha-1) equation (Eq. 1) based on apparent biovolume (product of crown cover in percentage by average height in meters) (Radj2 0.69, MAE 26.1%, RMSE 38.4%); b) Weight per plant (kgDM.plant-1) equation (Eq. 2) from height and crown diameter (Radj2 0.87, MAE 26.5%, RMSE 45.2%) and c) Weight per unit area equation (tDM.ha-1) (Eq. 3) based on LiDAR data contrasted with field data (Radj2 0.89, MAE 15.1%, RMSE 22.9%). Research highlights: Eq. 1 and Eq. 3 combined with high resolution LiDAR information offer rockrose (Cistus laurifolius L.) biomass estimations without added field work costs that are an improvement on certain more general studies carried out in other areas of Spain.