30 research outputs found
Adjoint bi-continuous semigroups and semigroups on the space of measures
For a given bi-continuous semigroup T on a Banach space X we define its
adjoint on an appropriate closed subspace X^o of the norm dual X'. Under some
abstract conditions this adjoint semigroup is again bi-continuous with respect
to the weak topology (X^o,X). An application is the following: For K a Polish
space we consider operator semigroups on the space C(K) of bounded, continuous
functions (endowed with the compact-open topology) and on the space M(K) of
bounded Baire measures (endowed with the weak*-topology). We show that
bi-continuous semigroups on M(K) are precisely those that are adjoints of a
bi-continuous semigroups on C(K). We also prove that the class of bi-continuous
semigroups on C(K) with respect to the compact-open topology coincides with the
class of equicontinuous semigroups with respect to the strict topology. In
general, if K is not Polish space this is not the case
Ecohydrological advances and applications in plant-water relations research: a review
Aims
The field of ecohydrology is providing new theoretical frameworks
and methodological approaches for understanding the complex
interactions and feedbacks between vegetation and hydrologic
flows at multiple scales. Here we review some of the major scientific
and technological advances in ecohydrology as related to understanding
the mechanisms by which plant–water relations influence
water fluxes at ecosystem, watershed and landscape scales.
Important Findings
We identify several cross-cutting themes related to the role of plant–
water relations in the ecohydrological literature, including the contrasting
dynamics of water-limited and water-abundant ecosystems,
transferring information about water fluxes across scales, understanding
spatiotemporal heterogeneity and complexity, ecohydrological
triggers associated with threshold behavior and shifts
between alternative stable states and the need for long-term data sets
at multiple scales. We then show how these themes are embedded
within three key research areas where improved understanding of
the linkages between plant–water relations and the hydrologic cycle
have led to important advances in the field of ecohydrology: upscaling
water fluxes from the leaf to the watershed and landscape, effects
of plant–soil interactions on soil moisture dynamics and controls
exerted by plant water use patterns and mechanisms on streamflow
regime. In particular, we highlight several pressing environmental
challenges facing society today where ecohydrology can contribute
to the scientific knowledge for developing sound management and
policy solutions.We conclude by identifying key challenges and opportunities
for advancing contributions of plant–water relations research
to ecohydrology in the future
Land use change effects on catchment streamflow response in a humid tropical montane cloud forest region, central Veracruz, Mexico
Tropical montane cloud forests (TMCF) are recognized for their capacity to maintain high dry-season baseflow and a host of other ecosystem services. Substantial areas of TMCF have been converted to pasture and crops such as coffee, while in other areas TCMF are recovering. However, little is known about the effects of this complex dynamic on catchment hydrology. We investigated the effect of land use on rainfall-runoff response in five neighbouring headwater micro-catchments in central Veracruz, Mexico, dominated by either mature TMCF (MF), young (20 year-old) and intermediate (40 year-old) naturally regenerating TMCF (YF and IF, respectively), shaded coffee (SC), and an intensively grazed pasture (IP). We used a 4-year record of high-resolution rainfall and streamflow (10 min) data collected from 2015 to 2019. These data were analysed via comparison of hydrologic metrics that summarize streamflow responses at various time scales and magnitudes. Results showed no statistical difference in the regulation capacity of high flows in the micro-catchment with 20 years of natural regeneration, compared to the MF. In terms of baseflow sustenance, our results support the hypothesis that MF and IF better promote this hydrologic service than the other land uses. SC exhibited a high capacity to modulate peak flows comparable to that of MF, and an intermediate capacity to sustain baseflow, suggesting that the integrated functioning of this micro-catchment was largely preserved. Finally, 40 years of intense pasture management was found to have degraded the soil hydraulic properties of IP; mainly, reducing its infiltration capacity, causing a fivefold greater peak flow response and a lower baseflow compared to MF