Effects of different abiotic and biotic factors on spatial primary seed dispersal in the semachorous species Scrophularia canina

摘要

Seed dispersal is one of the most important steps in the plant life cycle. However, there is, generally, a lack of fieldworks focused on wind dispersal and especially on semachorous dispersal (seeds spread when the fruits are shaken by wind and other vectors, such as animals), including boleochorous dispersal. Therefore, we aimed to determine how different types of wind and animals affected seed dispersal under natural conditions in the widespread species Scrophularia canina. We evaluated the effects of wind gusts (simulating them using a leaf blower) and wild animals (using differently sized dogs) on seed dispersal in a population located in south-western Europe. We found that S. canina is a semachorous species, and its spatial seed dispersal was affected by wind gust speed and direction, plant structure and vector type. The results also revealed the presence of xerochasy, individual anisotropy with strong winds, and primary short-distance dispersal associated with successional processes independent of the vector. Additionally, there was a masking effect of plant structure on the seed shadow outline. It is essential to conduct fieldworks to reveal what actually happens in nature, taking into account the characteristics determining seed dispersal. In addition, in these works it is important to find out what factors affect seed distributions of anemochorous and semachorous species.