Global dryland vegetation memory

1. Vegetation memory describes the effect of antecedent environmental and
ecological conditions on the present ecosystem state and has been proposed
as an important proxy for vegetation resilience. In particular, strong
vegetation-memory effects have been identified in dryland regions, but the
factors underlying the spatial patterns of vegetation memory remain
unknown. 2. We aim to map the components and drivers of vegetation memory
in dryland regions using state-of-the-art climate-reanalysis data and
refined approaches to identify vegetation-memory characteristics across
dryland regions worldwide. 3. Using a framework which distinguishes
between intrinsic and extrinsic ecological memory, we show that: (i)
intrinsic memory is a much stronger component than extrinsic memory in the
majority of dryland regions; and  (ii) climate reanalysis data
sets change the detection of extrinsic vegetation memory effects in some
global dryland regions. 4. Synthesis. Our study offers a global picture of
the vegetation response to two climate forcing variables using satellite
data, information which is potentially relevant for mapping components and
properties of vegetation responses worldwide. However, the large
differences in the spatial patterns in intrinsic vegetation memory in our
study compared to previous analyses show the overall sensitivity of this
component in particular to the initial choice of extrinsic forcing
variables. As a result, we caution against using the oversimplified link
between intrinsic vegetation-memory and vegetation recovery rates at large
spatial scales.