Sir,— When reading the appalling accounts of the effects of the long-lasting drought
in the desert districts of the interior, we are ever led to reflect by what measures
the miseries thus from time to time arising might be alleviated or obviated. On various
occasions I have pointed out publicly that the wide dissemination of trees in the
arid parts of the interior would exercise a marvellous effect on the increase of rain,
on the retention of humidity, and on the mitigation of burning winds. For the purpose
of raising timber in shadeless barren wastes, perhaps no country possesses greater
facilities than Australia, inasmuch as some of our trees seemingly surpass those of
any other country in celerity of growth, and in power to resist the dry heat of our
summer season. I am satisfied that if over the extensive sheep-runs now visited by
the drought such plants as the common so-called Cape wattle (the West Australian
), the ordinary wattle tree of Victoria (
), and additionally Eucalypti of quick growth, were raised, merely by scattering during the earlier part of the
cool season large quantities of the seed over the ground, we should in due time no
longer have to lament the destruction of vast flocks for want of fodder, and perhaps
water, because the general climate of such districts would gradually become more humid,
a tegument of herbage and grass would, under the shelter of timber vegetation, continue
to cover the now generally naked soil even during summer, and from a heated bare surface
of soils no longer that heat would emanate which now disperses every rain-cloud often
for many a month, and which sweeps in currents of burning winds now widely over the
continent. Moreover, the absorbing power of vegetation would prevent to a large extent
the rain-water to flow away into temporary channels, and perhaps even the sudden and
transient floods after thunderstorms would discontinue. Why the pastoral tenants in
districts subject to drought do not cause the seeds of trees, especially such as mentioned,
to be gathered and sown, with a view of establishing belts of timber, appears almost
enigmatical. The seeds of
and
might be gathered by tons for the most trifling expense, and sufficient seeds for
100,000 eucalypti might be obtained for the value of a few head of cattle. If merely
the flocks were kept away for a season from the spots on which the acacia seedlings
spring up, it would with the least care become an impossibility to annihilate the
copses again, even by subsequent invasion of the pastoral animals, which indeed might
to some extent browse on the young trees, and finally find in dry years even much
additional food. Around Jerusalem, in Natal, in some of the South Sea Islands, in
the dry high lands of India, and in Algeria, we have endeavoured by transmission of
seeds from here to clothe the naked soil and ameliorate the climate. In Australia,
however, almost no exertions are made in this direction. Not the least of the advantage
of the measure which I urge anew on the pastoral settlers consists in the augmentation
of the fertility of the land, by bringing, through the ever-active power of vegetation,
the latent and dormant alkalies, and earths and acids needed for the nutrition of
plants to the surface from strata below, into which the roots of trees will penetrate
for food, to convey it to their foliage, and to leave these fertilisers with the decay
of the leaves on the surface soil, not to be washed away, as was long erroneously
supposed, but to be stored up for subsequent vegetation. But the remarks here offered
apply as advice not to Australia alone. Who can cast a view over a North African landscape
without reflecting what changes an extensive Australian acacia and eucalyptus vegetation
would effect on the pictures of treeless desolation which mountains and plains, alike
bare and waterless, there present? What amount of timber might not be realised on
the desert ridges; what a cheerful image within a very few years be impressed on whole
countries so near to the seats of ancient industry and learning; and what vast extension
of means for human settlement, and activity, and support be afforded?
Yours respectfully,
Ferd. Mueller.
Melbourne Botanic Gardens, Oct. 24.
