The impact of coppice management on spatial structure and intraspecific interactions of Brant's oak (Quercus brantii Lindl.) semi-arid woodlands

Abstract

Coppicing is a common management strategy in oak woodlands; however, our knowledge is limited in the impacts of coppicing on spatial structure and growth dynamics of oak stands. In this study, we compared the spatial patterns of two adjacent high and coppice pure stands of Brant's oak (Quercus brantii Lindl.) in central part of Zagros semi-arid woodlands, western Iran. We used univariate form of scale-dependent summary statistics (nearest neighbour distribution function, L-function, pair- and mark correlation functions) and Analytical Global Envelopes under inhomogeneous Poisson process which allow detection of the intraspecific interactions of the individuals within the high and coppice stands. Our results indicated the aggregation of oak individuals at small spatial scales (i.e., 0-3 m) in the high stand, most likely as a result of aggregation in parts with environmentally benign conditions. The positive interactions of conspecifics had a marked effect on their size (e.g., larger height (5%), DBH (24%), and crown area (50%) than mean size at spatial scale of 2 m) inferred as growth stimulation and aggregation of young trees around their nurse or parent trees. However, the findings revealed the segregation of oak trees at short distances in the coppice stand (i.e., 0–5 m), probably due to strong competition of conspecific neighbors. The negative size correlation of oaks (e.g., smaller height, DRC, and crown area of oak individuals (15%) than mean size at distance of 2 m) was considered as the outcome of competition for scarce resources in the woodlands with unfavourable conditions. In general, it was concluded that the aggregated spatial structure of the high stand has changed to segregation of individuals within the coppice stand. Additionally, we found that environmental heterogeneity and intraspecific competition are the main drivers of the high and coppice stands, respectively.