Secondary succession after perturbations in a shrubland community

Abstract

Shrubland responses to experimental burning, cutting and ploughing treatments were studied over 15 years in two shrubland communities dominated by Erica australis. The treatments represent the most frequent forms of anthropogenic disturbances experienced by these communities throughout their history. The response to burning and cutting treatments is similar, and the succession process is characterised as autosuccession. The highest values for herbaceous annuals and perennials were observed in the third and fourth years. Generally, herbaceous species remain present throughout the study period, while woody taxa ones increase their cover values over time. The quantity of herbaceous species present is in inverse proportion to the quantity of woody taxa. The woody species that appear immediately after treatments are sprouting species, namely Erica australis and Arctostaphylos uva-ursi. The response to ploughing is slower, reflecting the recovery mechanism (seedlings). However, after 15 years, there are no significant differences in regeneration between treatments. The first stages of this post-ploughing succession are dominated by annual species until the fourth or fifth years, after which woody species begin to dominate and herbaceous taxa decrease considerably. Woody species with high germination values are Halimium alyssoides and Halimium umbellatum. These shrubland communities have a very high resilience to such perturbations and start regenerating rapidly, reaching the original state in about 9 years. The appearance of the climax arboreal species of the area, Quercus pyrenaica, when it comes from germination, occurs 15 years after the perturbations.

Recovery after Experimental Cutting and Burning in Three Shrub Communities with Different Dominant Species

“…Recovery occurs by autosuccession in the Cistus and Erica communities (Ta´rrega et al 2001;Calvo et al 2002a). However, after 10 years the Calluna community has not attained a situation similar to that existing before the disturbances (Calvo et al 2002b).…”

“…Fire is one of the common management methods used by shepherds to reduce the proliferation of woody species and maintain pastures, both in the mountains (higher than 1500 m above sea level) and on the plains (800-1000 m). The second most common type of disturbance is cutting in order to obtain domestic fuel and fertilizers, for example (Casal 1985;Calvo et al 2002a). Most of the shrub species in these communities recover by vegetative resprout, but others, like Cistus species, are considered obligate seeders, with seeds whose germination is stimulated by heat (Valbuena et al 1992;Trabaud 2000).…”

“…Climatic features are different in each area, but all of them had the common characteristic of being very homogeneous before disturbance, with only one shrub species clearly dominant, although a different one in each area (Calluna vulgaris, Erica australis and Cistus ladanifer). These communities have composed by three different shrub species with different recovery response: Erica australis is a facultative resprouter and recovers mainly by vegetative resprouting (Calvo et al 1998(Calvo et al , 2002a; while, Cistus ladanifer is an obligate seeder (LuisCalabuig et al 2000;Ta´rrega et al 2001) as is Calluna vulgaris in these areas (Calvo et al 2002b). Knowledge of the recovery dynamics of each community in relation to the type of disturbance is essential for suitable landscape management.…”

Natural forest regeneration in abandoned sugarcane fields in northeastern Brazil: floristic changes

“…According to Chazdon et al (2009), convergence seems to be related to the level of anthropogenic disturbance, the duration of the time that the area was used, and the regional landscape context. The interrelations of these parameters make the outcomes of succession less predictable, and measurable differences in the floristic compositions of secondary forests may persist even centuries after they have been abandoned and left to recuperate (Finegan 1996, Aide et al 2000, Denslow & Guzman 2000, Calvo et al 2002, Ribas et al 2003.…”

Studies on the restoration succession of PFU microbial communities in a pilot-scale microcosm

“…Significant amounts of research have been conducted in an attempt to elucidate succession regularity of populations and communities during manmanipulated or natural restoration process of various ecosystems (Schrott et al, 2005). These ecosystems include grassland (Hemerik and Brussaard, 2002;Warren et al, 2002), bottomland hydrology (Kolka et al, 2000), shrubland (Calvo et al, 2002), semi-arid (Bonet, 2004), terrestrial ecology (Berg and Hemerik, 2004), forest ecology (Chen et al, 2003;Haeussler et al, 2004;Kauffman, 2004) and mine ecology (Grant and Loneragan, 2001). …”