RESUMO
Mining can significantly alter landscapes, impacting wildlife and ecosystem functionality. Natural recovery in open-pit mines is vital for habitat restoration and ecosystem re-establishment, although few empirical studies have examined this process. Here, we assessed temporal and spatial responses of small rodents at the community, population, and individual levels during natural mine recovery. We examined the abundance, reproductive potential, and individual health of small rodents at active mines and at former mine sites left to recover naturally for approx. 10 and 20 years. We also assessed the effects of disturbance on rodent recovery processes at three distances from the mine boundary. Rodent numbers peaked after 10-13 years of recovery and exhibited the strongest male bias in the sex ratio. The Chinese white-bellied rat (Niviventer confucianus) was the most abundant species, achieving its highest population abundance at sites abandoned for 10-13 years and thriving at locations closer to the mine boundary. Only Chevrier's field mouse exhibited morphological responses to the mine recovery category. Ectoparasite load was unaffected by mine or distance-disturbance categories. Both Chevrier's field mouse (Apodemus chevrieri) and the South China field mouse (Apodemus draco) were affected significantly by vegetation layer cover during recovery succession. Our study highlights the complexities of ecological succession, with a peak in abundance as pioneer communities transition toward a climax seral stage. Careful prior planning and active site management are necessary to optimize abandoned mine recovery. Efforts to accelerate mine recovery through technical restoration should promote conditions that initiate and perpetuate the establishment and succession of wildlife assemblages.
RESUMO
BACKGROUND AND AIMS: It has been demonstrated that nitrogen (N) addition alters flower morphology, floral rewards and pollinator performance. However, little is known about the effects of N addition on plant reproduction, including fruit set and seed set during selfing and outcrossing, floral and vegetative traits, and pollinator performance. We hypothesized that N addition would influence fruit set, seed set in selfed and outcrossed flowers, the relationship between vegetative and flower traits, and pollinator performance. METHODS: A 2-year pot experiment was conducted in which Capsicum annuum was exposed to three levels of relatively short-term N supply, i.e. 0 g m-2 (no N addition, as a control), 4 g m-2 (4N) and 16 g m-2 (16N), which are equivalent to about 0-, 1- and 4-fold of the peak local N deposition. We measured flower rewards, flower morphology, flowering phenology, as well as pollinator visitation rate, fruit set and seed set by self- and outcross-fertilization of C. annuum. RESULTS: The four levels of N addition increased plant biomass, biomass allocation to flowers, flower size, stigma-anther separation, nectar production and pollen production, resulting in an increase in pollinator visitation and fruit set. Nevertheless, the control and 16 levels of N addition reduced plant biomass, biomass allocation to flowers, flower size and stigma-anther separation, and nectar and pollen production, and consequently decreased pollinator visitation and fruit set. Exclusion of pollinators and hand-pollination experiments revealed that low levels of N addition were associated with high seed set in outcrossed flowers; however, this trend was reversed in flowers grown in the control and 16N treatments. CONCLUSION: Our results suggest that an optimal level of 4N can enhance the correlation between flower traits, pollinator performance and plant reproduction. Our findings cast new light on the underlying mechanisms of plant-pollinator interactions and plant adaptation to nitrogen deposition.